GROWTH MANAGEMENT AND URBAN ECOLOGY
Volume 2
URBAN HABITAT CLASSIFICATION
douglas college
Institute of Urban Ecology
THE REAL ESTATE
FOUNDATION
GROWTH MANAGEMENT AND URBAN ECOLOGY
Volume 2
URBAN HABITAT CLASSIFICATION
prepared by
Valentin Schaefer, Ph.D., R.P.Bio
Mona Aston, B.Sc.
Renata Cacik
Joseph.,West
Patrick Whalen
November 1993
Canadian Cataloguing In Pubflcatlon Data
Main entry under title I
Growth management and. urban ecology'
CO-published by' the Real Estate Foundation.
Includes bibliographical references.
Contents! v. 1. Queensborough I 8. case study -v. 2. urban ha.b1 ta.t clMslfieat10n
ISBN 1-896019-01-3 (v. 1). -- ISBN l-A9601902-1 (v, 2). -- ISBN 1-896019-00-5 (set)
1. Urban eeologr-Brftish Columbla.--New
Westminster. 2. Urban eaolf.}EQI' (B101ogy)British Columbia-aNew ~estmin8ter. 3. City
p1anning--Britieh 001umb1a--New Westminster.
4. Queensborough (New Westminster. B.C.). I.
Scha.efer, Valentin, 1951II. Dougla.s
College. Institute of Urban Ecology. III.
ReaJ. Estate Founda.tion (Vancouver, B.C,)
HT2 43.C22B75 4 1993
307.76'0971'133
C93-091865-7
Copyright Douglas College 1993
Douglas College
P.O. Box 2503
New Westminster, BC
V3L 5B2
ACKNOWLEDGEMENTS
This study involved the input and encouragement from a great number of people. The
planners from the City of New Westminster in particular provided much useful
inf()rmation and were very helpful. Jim Hurst and Mary Pynenberg were involved
addressing the development and green space aspects, and Stephen Shevings arranged
for the legal descriptions of the industrial and major residential sites. Wayne Easton
of Engineering provided useful feedback on the floodplain development section of the
report, and summarized the major residential developments in progress on a map.
Paul Daminato of the Parks Department provided useful advice on parks.
Historical photographs for the area were obtained from the New Westminster
Historical Society, Irving House, with the assistance of Valerie Frances and Archie
Miller.
Ekistics Town Planning Inc. was the consulting firm used by the City of New
Westminster to oversee the review of Queensborough's official community plan. The
finn was extremely forthcoming with information about the community. In particular,
we would like to thank Cameron Campbell and Kent Munro for all of their help.
Susan Hollingshead and Bryan Watts of Klohn Leonoff Ltd. reviewed the section of
the report concerning the use of fill to meet the flood construction level. They
provided invaluable advice in clarifying some of the more technical issues.
Marlene Baalen of AccuPlan Consultants Inc. explained some of the future
development plans for housing between Salter Street and South Dyke Road.
Kevin Conlin of the Department of Fisheries and Oceans made a presentation to the
project team on habitat enhancement for salmon. Colin Levings of the Department
of Fisheries and Oceans provided us with references on inventories offoreshore areas
arou.nd Lulu Island. Sue Neale of the Fraser River Estuary Management Program
and Ian White of EnviroWest Consultants explained various stream and foreshore
enhancement techniques.
Many people at Douglas College assisted us in the analysis of our results and the
prod.uction of our report and the the Open House display. They include: Barb Brawn
and Bob Cowin of the Research Department, and; Mike Looney, Len Millis, and Helen
Pa1mer of Biology. Melody Hessing of Sociology particpated in the design of the
community survey questionnaire.
Urban Habitats
1
The Advisory Committee for the study consisted of: Hilda Bechler (Queensborough
Citizens Committee), Roland Kaulfuss (Royal City Remax), Melody Hessing
(Sociology, Douglas College), Des Wilson (Geology, Douglas College), and Terry
Farrell (Chair, Department of Arts and Humanities, Douglas College). Their
assistance was much appreciated.
Special thanks to the Board of Governors of the Real Estate Foundation of B.C for
their support of the concept of the study, and approving financial assistance. The
three students on the study were also funded in part through Challenge '93.
Finally, a warm thanks to all of the people in Queensborough who participated in our
community survey. Their enthusiastic response and the many lengthy converstaions
they had with us provided valuable insights into the pressing growth management
issues facing the community. We especially would like to acknowledge Edna
Anderson, Alec J anyk, and Leanne Leduc. Their strong ties with the surrounding
natural areas also provided inspiration to us in our attempts to relate the value of
nature to the quality of life in a residential neighbourhood.
Moura Quayle of the UBC School of Landscape Architecture offered valuable advice
on the organization of the Urban Habitat Classification System.
The cover illustration was drawn by Patrick Whalen. Other illustrations were drawn
by Debbie Duncan (Robertson), and were reproduced through the courtesy of the
Lynn Canyon Ecology Centre, North Vancouver. A few illustrations are reproduced
as clip art from Dover Publications. Several illustrations are from previous Douglas
College publications.
Urban Habitats
11
" Preface
PREFACE
The populations of Greater Vancouver and other major urban centres in North
America continue to grow rapidly. Housing sprawls into the surrounding agricultural
and wildlife areas, and fiUs in remaining undeveloped or abandoned industrial sites
within cities. Existing communities are faced with an increase in population densities
and a loss of green space.
Queensborough in New Westminster is one community facing the dramatic changes
caused by population growth. For 100 years the residents have enjoyed a rural
lifestyle next to a major city. It has been isolated on Lulu Island, apart from the rest
of New Westminster. Its residents have gone through three generations growing up
in the spacious expanses provided by the Fraser River, agricultural fields, and large
lots dedicated to light industry, primarily saw mills along the river.
This has now changed. Within the next 10 years Queensborough may well grow from
a community of 1,800 to one of 10,000.
The study presented in Volume 1 explores the issues arising from the changes facing
this well established community. It describes the present situation, the changes that
are in store, and how the community would like to respond. The results are relevant
in many other communities experiencing the same changes.
This study also extensively explores the value of urban green space. In a previous
work on urban ravines, the Institute of Urban Ecology at Douglas College drew
attention natural areas forgotten or overlooked in communities because they were
hidden. There are no ravines in Queensborough. However, some forms of nature are
hidden, and they can be used to enhance the quality oflife in the community. Volume
2 of this report presents a classification system for urban habitats which will be
useful in raising the profile of nature in any urban community. The system provides
valuable information on the types of natural environments present and their value.
The system was used as part of the description of Queensborough given in Volume
1. It was also used to guide our recommendations for future development.
A major incentive to do this project was that Queensborough is presently undergoing
a review of its Official Community Plan. The information we gathered was intended
to assist this review, and to serve as a resource for other communities faced with the
challenge of accommodating population growth in the future.
Urban Habitats
111
Table of Contents
Table of Contents
Acknowledgements
Preface
Table of Contents
Introduction
The Uniqueness of Urban Habitats
1
111
IV
1
2
The Forest
I.
2.
3.
Woodlots
Linear forests
Mature forest fragments and
successional forests
7
13
20
Shrub Communities
4.
5.
Thickets
Blackberry thickets
27
31
Wetland Environments
6.
7.
8.
9.
10.
1I.
Ponds
Lakes
Marshes
Streams and Rivers
Bogs
Estuaries
38
43
49
53
59
64
Abandoned lots
Agricultural land
70
75
The Clearings
12.
13.
The Barren Landscape
14.
15.
16.
Urban Habitats
Exposed ground
Bridge undersides
Toxic industrial landscapes
82
87
91
IV
Table of Contents
Table of Contents
D€relict Landscapes
17.
18.
Masonry rubble
Rock debris
95
100
The Paved Landscape
19.
20.
21.
Buildings and pavement
Containerized habitats
Alleys/lanes
105
Linear right-of-way
Linear along a stream or
drainage ditch
Boulevards: Street Trees
Railways
119
111
114
The Corridors
22.
23.
24.
25.
124
129
133
The Private Landscape
26.
27.
28.
29.
30.
31.
Lawns
Exotic landscape
Ornamental shrubs and thickets
Ornamental forests
Climbing plants on buildings
Rooftops
139
143
149
154
159
164
The Public Landscape
32.
33.
34.
Urban Habitats
Recreation Park
Golf courses
Community gardens
168
172
178
v
Table of Contents
Table of Contents
Page
Bibliography
Urban Habitats
181
VI
INTRODUCTION
There are many ways of looking at natural environments in urban areas. Perhaps
the most obvious is to consider the biome and other large natural ecosystems for
the geographic area. In a very general sense, the majority of the cities in North
America are found in three of these biomes - the coniferous forest or taiga to the
northwest, the temperate deciduous forest along the eastern part of the continent
(the beech - maple association to the north, the oak - hickory to the south), and
the grassland in the centre. These general vegetation types are a part of the
general character of the cities found there.
On a more regional scale the natural ecosystems are more numerous and more
unique to each area. In the Lower Mainland, for example, there are four large,
interrelated ecosystems outlined by the Greater Vancouver Regional District
(1992). These include: 1) the North Shore System of hemlock, redcedar, and
Douglas-fir containing the Capilano, Seymour, and Coquitlam watersheds which
still are estimated to be 40% old growth forest; 2) the Coastal/Intertidal Systems
which include the marshes and mudflats around Burrard Inlet, the Fraser River
foreshore, and Roberts and Sturgeon Banks; 3) the Fraser River System which is
the lower part of the Fraser River watershed bringing about 20 million tonnes of
silt to the Lower Mainland annually; and 4) the Fraser Lowland Systems with
shallow water tables consisting of wetlands, bogs, and other areas with shallow
water tables.
The larger natural ecosystems in urban areas are generally found in relatively
large intact blocks around the outside of the city itself. Within the city such areas
may remain as fragmented habitats of varying size. For example, in Greater
Vancouver fragments of the original forest are found in Stanley Park adjacent to
the West End, Central Park on the eastern border of Burnaby, and Burnaby
Mountain.
However, most urban habitats are far from being remnants of the original
ecosystems in the area. More typically they represent early successional stages
within these ecosystems. In order to build the city the natural ecosystems were
removed with the local topography, soil, and drainage patterns completely altered.
Sites within the city which were not developed would then be colonized by pioneer
plant species. If left undisturbed, begin to reestablish the natural ecosystem for
the area.
Urban Habitats
1
THE UNIQUENESS OF URBAN HABITATS
There are also habitats which are uniquely urban. They are habitats created by
the buildings themselves, and the landscaping associated with them. Far from
being biological deserts they often contain a rich biological diversity of plants, and
contain numbers of birds and mammals greater than that of the natural
ecosystems they replaced. However, the rich plant biodiversity is due in to the
large numbers of introduced species, and the greater density of wildlife is due to
larger numbers of fewer species.
Over the past few decades there has been an increasing interest in natural
habitats within urban areas. To a large degree this is due to an increasing
awareness that green space within the city greatly adds to the quality of life.
Trees in particular contribute shade on a hot day, provide protection from wind,
and tend to make the humidity more pleasant. In a general sense any form of
greenery is visually pleasing and softens the sharp features of buildings. The
vegetation also attracts birds and mammals which most people value. Bird song
and foraging wildlife introduce an element of relief from the hectic pace and street
noises which are a part of the city.
The recent focus on sustainable urban environments has also contributed to the
recent interest on urban habitats. Sustain ability addresses the notion of the
carrying capacity of the local ecosystems - their ability to support he numbers of
people and their lifestyles. Having a natural presence within the city serves as a
constant reminder that we are part of an ecosystem, and that we must live our
lives with a sensitivity to its limits to deal with our wastes, and to supply us with
food and the basis for material wealth.
Sustainability also redefines what we mean by "quality of life". In the past it
appears that an increased quality of life was seen to mean an increase in material
wealth and machines which increased leisure time. More recently quality of life
has come to mean physical and emotional well-being. There is less emphasis on
material goods, speed (mainly automobiles) to do more things faster, and
individual assets. These qualities are being increasingly replaced by more spiritual
values, the concept of environmental citizenship, and a renewed focus on the
community. Urban green space provides the connectedness with nature that is an
integral part of the new lifestyles which are evolving.
Urban Habitats
2
URBAN LANDSCAPES
Since 80% of us live in cities and spend the majority of our time there, natural
environments in urban areas are extremely important. However, it is difficult to
appreciate their true value without understanding what natural habitats exist and
what makes them unique. Seemingly small and insignificant clumps of flowers,
bushes, trees or hedgerows can contribute greatly to the atmosphere of a
community, and in fact are in themselves biologically interesting. Trees in
particular are highly visible and have a high species diversity. Usually the most
beautiful and interesting species from around the world have been selected to be
part of the urban landscape. The descriptions of the trees of Vancouver (Straley
1992) and Victoria (Chester et al. 1988) in terms of their diversity and heritage
value point to a rich natural asset, right in the city.
Landscaping within the city has undergone an evolution over the last century. The
city has traditionally been seen as a testimony to human culture. There was no
attempt to save natural environments, or to acknowledge the biological value of
urban plant and animal life. Planners and landscape architects traditionally used
the gardenesque approach which involves controlled planting emphasizing visual
aesthetics and design. The elements within the plantings can only be maintained
through continuous management.
Within the city centre another highly artificial landscape exists. This is the
technological landscape style which incorporates concrete, brick, asphalt, glass,
and other synthetic materials. The plantings are small and even more uniform
than in the gardenesque style. They are totally devoid of any local character.
A more recent approach to urban landscaping is the ecological style. In this case
natural local environments are used, and the natural elements are allowed to
function with no (or very little) maintenance. In addition to retaining natural
habitats in development, this style also encourages the use of native vegetation in
landscaping. The result is a unique urban landscape which adds to the character
of a city and distinguishes it from other cities in the international community.
CHARACTERISTICS OF NATURAL ENVIRONMENTS IN URBAN AREAS
The structure of the city and the high degree of mobility of its inhabitants has
profound implications on the composition of natural habitats. Clearly, the high
degree of disturbance and the removal of most or all of the original natural
vegetation means that there is no functioning natural ecosystem within the city
itself, although there may be around the outlying areas
Urban Habitats
3
Changes in Biodiversity
There are three general categories of biodiversity: ecosystem diversity, species
diversity, and population diversity. Within BC there are about 2580 species of
vascular plants (557 introduced), 20 species of amphibians (2 species introduced),
19 reptiles (4 introduced), 454 birds (14 introduced), and 143 mammals (12
introduced) (BC Ministry of Environment, Lands and Parks 1993).
Although cities do not have any ecosystem diversity, the majority of the introduced
species of plants are concentrated within cities, making the species diversity very
high. There ware more species of plants within a city than within a comparable
area of a natural ecosystem. In fact there are some species which only exist in
cultivation no longer occur in nature. The ginkgo tree is a famous example. It was
spared extinction from development because it was cultivated in the gardens of
the Great Emperors of China.
With birds and mammals the species diversity decreases in a city. Although there
are over 350 bird species found in the Lower Mainland, of which 250 regularly
breed here, less than 50 species are commonly found in the city. However, the
numbers of the species found in cities can be great. Perhaps a good example here
is the Starling which in the fall occurs in flocks of thousands of birds.
Bird life in the city is not only reduced by human disturbance but by other bird
species which do well in urban environments. For example, the bluebirds are
thought to have been pushed out by the European Starling; both birds are holenesters (nesting in cavities), and the larger, more aggressive Starling displaced the
bluebird, even though it would otherwise be expected to do well.
Disturbance
Urban lands are frequently by clearing and development. They are also disturbed
through the application of pesticides, weediJ;1g, and mowing. Such disturbance has
two major effects. First, it tends to favour introduced, alien species. The native
species are prevented from reestablishing themselves, and in the absence of
competition from them, the alien plants thrive. A second effect is that the native
vegetation which does become established consists primarily of pioneer species. A
natural habitat in -a city would not be expected to remain undisturbed long enough
to form a mature, climax community.
The disturbance also has an affect on the interactions between native plant and
animal species as well. In natural ecosystems the native plants are often
Urban Habitats
4
restricted to their optimal habitats by competition from other native species. In
disturbed environments some species may find that their competitors are no
longer present, enabling them to occupy more marginal environments. An example
here might be the horsetail which does best in moist habitats. However, in
disturbed sites in the absence of its competitors it may be found in drier areas.
Microhabitats
In a natural ecosystem the vegetation creates certain types of microhabitats such
as a rotting log, a sword fern herbaceous layer, leaf mold, a vine maple/elderberry
understory, and so on. These microhabitats are abundant and are controlled by
climate and topography, which can create uniform environments over large areas.
In an urban environment the number of microhabitats may actually be greater
than in a natural ecosystem in a comparable area, although each one may not be
abundant. With the presence of buildings, natural habitats of native vegetation,
and a large number of introduced plant species, there is a broad spectrum of
microhabitats in a small area.
A CLASSIFICATION SYSTEM FOR URBAN HABITATS
In this broad assemblage of microhabitats, altered interactions between species,
and a high influx of introduced species it can be difficult to focus on what may
exist as a reasonable unit which defines a "habitat". As mentioned earlier it may
be sufficient to merely recognize the biome in which the city occurs, and the larger
natural ecosystems around the city.
However, such a broad consideration of natural habitats fails to capture the value
of individual representatives of species, or small communities, which may form the
largest representation of nature in large parts of a city. Such areas are especially
valuable to people's lifestyles because they exist in the community, and can be
enjoyed on a daily basis.
In the classification system presented here there are 40 urban habitats recognized.
Each of these is unique, and offers a surprising opportunity for exploring the
wonders of nature.
Urban Habitats
5
The Forest
Urban Habitats
6
WOODLOTS
Physical Appearance
Urban woodlots vary in their characteristics and physical appearance due to
factors such as age, size, past use and present management.
The two basic types of urban woodlots considered here are distinguished by the
presence or absence of significant understory vegetation. With the exception of
understory vegetation both types share many similar structures and appearance.
The majority of urban woodlots are composed of spontaneous recent growth
resulting from natural regeneration, particularly on neglected sites such as
abandoned dumps, old agricultural land, or areas possessing characteristics which
inhibit easy development.
A woodlot is usually large enough to have many tall often thin-boled trees growing
close enough together to form a definite canopy. The canopy regulates the amount
of light reaching the understory, and thus influences the amount and particular
type of understory vegetation growing there. Other significant factors affecting
understory growth are the age of the woodlot, soil condition, the availability of
water, and its successional status. In turn successional status is a function of past
use, present management, and disturbance.
Urban Habitats
7
Mature woodlots with dense canopy foliage receiving little or no management or
significant disturbances are usually characterized by a lack of thick ground or
shrub cover. Typical understory vegetation usually consists of shade tolerant
species which have persisted from earlier stages of succession. Because of the lack
of thick understory growth, it is easier to move about in this type of woodlot.
In younger woodlots with occasional to frequent openings in the canopy cover,
understory growth is more prevalent and is usually composed of a mixture of
shade tolerant shrubs, herbs and a variety of other fast colonizing species. Moving
about in the understorey is more difficult due to the larger amounts of vegetation.
The age of a particular wood lot can easily be approximated by comparing the
relative ratios of understory species with lowlhigh colonizing ability and shade
tolerant species (Peterkin 1981).
In both types of woodlots the presence of dead fallen trees or standing deadwood is
rare and so are the associated wildlife which make use of these particular niches.
Location
Woodlots tend to occur in areas which are historically or physically unsuitable for
development, e.g. ravines, neglected areas such as old farms, dumps or landfill
sites, portions of industrially zoned areas which have not yet been developed and
public property which has not been disturbed or managed extensively. They are
generally surrounded by housing, industry, roads, or other types of development.
General Description
A typical wood lot may consist of a number of closely spaced usually fast growing
pioneer woody colonizing trees which are capable of forming a canopy. Woodlots
composed of mixed tree species usually do not have a single distinct canopy layer,
but may display different levels of cover consisting of:
Main Canopy: the height to which the tallest trees such as oaks and maples grow.
Sub-Canopy of understorey trees: e.g. flowering dogwood, western hemlock
Shrub Layer: e.g. mountain laurel
Herbaceous Layer of ferns and wildflowers: e.g. swordfern, buttercup
Urban Habitats
8
Woodlots can be partially or totally deciduous depending upon climate, soil
conditions and previous and present use of the land. Alders for example pioneer on
sites with poor mineral soils and neutral pH. Birch favours damp sites with more
acidic soils, while black cottonwoods are dominant on sites where water is
common. Scouler willow is capable of pioneering on sites where little soil has
accumulated and is tolerant of drier conditions.
Woodlots with understory
A significant amount of understory vegetation is characteristic of recent, less
mature woodlots. Canopy coverage is patchy with frequent openings allowing light
to filter through to the understory. The dominant understory species are fast
colonizing shrubs, herbs and flowering plants which are shade intolerant. If the
site is located near water, ferns and other water loving species will also thrive.
Seedlings and sapling trees are usually not of the same species as the fast
colonizing species forming the canopy but the next wave of secondary growth
trees, which if left undisturbed will replace the primary colonizers in succession.
Because of the often dense understory growth in these woodlots, movement is very
restricted.
Woodlots without understory
These woodlots are characterized by significantly less amounts of understory
vegetation and usually by a layering in the canopy levels. The denser canopy
foliage more completely shades the woodlot interior and inhibits the prolific
growth of shade intolerant species. Less dense understory vegetation makes it
easier to move about in this type of woodlot. The predominant type of vegetation is
shade tolerant species which have persisted from earlier stages. The layered
canopy effect results from a sub-canopy of understory trees and taller shrubs
which have grown since the fast colonizing primary growth trees provided the
initial canopy coverage.
One interesting result of increased canopy layering is that the more layers of
trees there are, the more bird species that can be accommodated. Bird species
diversity often correlates with foliage height complexity (MacArthur and
MacArthur 1961).
Since larger woodlots are more productive than smaller woodlots and also have a
greater biomass, this directly translates into more space for more species, and
therefore higher diversity (Janzen 1976). Mammalian diversity also correlates
with productivity and habitat characteristics (Emmons 1984). Both density and
Urban Habitats
9
number of species of mammals correlate positively with soil fertility and
undergrowth density.
If a woodlot is left undisturbed, two of the primary factors influencing the slow
successional interaction between competing species will be the soil conditions and
soil development. Soils which are dry and acidic generally tend to favour conifers,
which have adapted needle or scaly-like leaves to inhibit water loss. Fallen
needles, especially cedars, further contributes to soil acidity and slows down the
processes of decomposition and nutrient cycling, making the soil nutrient poor.
Predominantly deciduous woodlots tend to occur on soils which are less acidic and
more moist. The periodic shedding of leaves and the resultant decomposition
makes the soil nutrient rich, which supports more plant species than the acid,
nutrient poor soils of the conifer dominant woodlots.
Many pioneer woodlot species such as lodgepole pine and red alders are capable
of using marginal soil conditions to their advantage. Red alder seedlings prefer
poorer mineral soils, and they do not need soil nitrogen because they are capable
of nitrogen fixing. They grow fast and quickly improve soil structure and fertility
as their leaf litter is plentiful, fast decomposing and nitrogen rich.
As succession proceeds and the soil characteristics slowly change, different species
may begin to emerge. Birches, for example, prefer mineral type soils with a
slightly acidic pH, while black cottonwoods prefer sites with organic or mineral
soils and lots of moisture.
Flora and Fauna
Urban woodlots with closely spaced trees and large amounts of understory growth
provide excellent habitat for a variety of wildlife. The trees and shrubs provide
good perching, nesting and cover sites for a .variety of birds. The diversity of bird
species is closely linked to type of vegetation present. The presence of an extensive
shrub layer, foliage height complexity, and freedom from disturbance can greatly
increase the diversity of bird life in a woodlot (MacArthur and MacArthur 1961),
(Gilbert 1989).
Woodlots are also important habitat for a variety of wildlife which may take
advantage of the nearby urban areas a food sources. Animals such as raccoons
may leave the woodlot at night to forage in the surrounding residential areas for
food, while crows usually participate in such activities during the day.
Urban Habitats
10
Another significant factor affecting the plant and animal species is the size and
productivity of the woodlot. The larger and more productive woodlots usually
accommodate more species. High productivity and biomass translate into more
space for more species (Janzen 1976).
Disturbance
Urban woodlots are subject to a variety of disturbances. Natural disturbances
include fire, wind storms, cold stress, droughts, landslides, insects and disease.
Human disturbance results from traffic, ground, air and water pollution, and
clearing for urban development.
Since many woodlots are designated as parks and recreational areas, the degree of
"parkification" affects the wildlife value and the diversity of species (Gilbert 1989).
A woodlot managed for public recreational use may be kept more open than one
managed for other purposes, to allow for easy access, easy movement within, and
as well as to provide more habitat for wildlife. Not surprisingly, when human
disturbance and management is less of a force in these habitats, it permits more
intensive and continuous ecological interactions and produces even greater species
diversity and better regeneration of the tree layer.
It is interesting to note, however, that low diversity sites may be representative of
the final outcome of long term interspecific competition (in the absence of
disturbance). If the frequency of disturbance is sufficiently high the woodlot
habitat will remain in a non-equilibrium state; i.e. high complexity and high
diversity (Connel 1978).
Other than people, insects pests are the most serious threat to the urban woodlot
habitat. Species which are particularly destructive include the spruce budworm,
the larch sawfly which destroys larch or tamarack, the pine weevil, and the pine
bark beetle which destroys ponderosa pines, and more recently the gypsy moth.
Monoculture woodlots which are composed predominantly of single tree species are
more susceptible to insect infestations than woodlots harbouring a greater
diversity of tree species. In managed woodlots the best protection from these and
other natural disturbances include maintaining healthy, vigourous trees by culling
diseased trees and trees likely to become infected, and by maintaining good soil
quality and the maximum diversity possible.
Comments
The need for green islands amidst the ever swelling concrete seas of urban growth
Urban Habitats
11
becomes greater as cities expand and greens pace diminishes. The demand for
recreation areas, park space and wildlife habitat is both large and increasing.
Green island woodlots are particularly suited to offer many ecological benefits to
the ever increasing urban population, and if they are managed and administered
appropriately, they can serve both the needs of the human and wildlife
populations well. The presence of these natural communities in the urban
environment also enhances the quality of life by providing quiet refuges of
aesthetic value for those who appreciate the values of natural settings and the
many benefits that can be derived from them.
Flora
Fauna
Alder
Bedstraw
Birch
Fireweed
Blackberry
Black Cottonwood
Red Elderberry
Mountain Ash
Western Hemlock
Scouler Willow
Lodgepole Pine
Flowering Dogwood
Mountain Laurel
Pacific Dogwood
Red Osier Dogwood
Salmonberry
Indian Plum
European Blackberry
Hazelnut
Waxberry
Bedstraw
Buttercup
Stinging Nettle
Tall Lettuce
Horsetail
Tamarack
Northwestern Crow
Song Sparrow
Savannah Sparrow
Chipping Sparrow
Black-capped Chickadee
Red-winged Blackbird
Purple Finch
American Robin
Ring-necked Pheasant
Barn Owl
Raccoon
Mole
Vole
Coyote
Bald Eagle
Red-tailed Hawk
Woodpecker
Rufous-sided Towhee
Grouse
Urban Habitats
12
LINEAR FORESTS
Physical Appearance
The dominant structural characteristic which distinguishes a linear forest from a
woodlot type forest is that it is more physically elongated and usually of a uniform
width along its entirety.
These linear forests can also form closed loops, as in the case where they may
encircle a small urban island or a large suburban estate. More frequently,
however, they generally follow a linear often winding route within the urban
environment, particulary if they are associated with natural or man made features
such as rivers or roads.
Because of the linear nature of these forests, the physical appearance may vary
somewhat from place to place due to changing topography, soil conditions, etc.
The density and width of these forests may also vary from location to location and
in many areas where the tree density is high, the understorey vegetation is
usually sparse. In less dense areas and under more open canopies, the
understorey vegetation, and in particular herbaceous species, tends to be more
lush.
Urban Habitats
13
Location
Within the urban setting, linear forests are often found parallelling roadways,
waterways, railways, and utility right of ways, such as pipelines or powerline
corridors. In urban canters located on islands or adjacent to large bodies of water,
they may constitute an integral part of a continuous linear park system adjacent
to the shoreline, while in other parts of the urban landscape they made be found
on the edges or slopes of other natural features such as ravines or bluffs.
General Description
The ecology of linear forests is very similar to that of the urban woodlots. The
same mechanisms which govern understorey growth, succession, and species
diversity in the woodlot habitats are also at work in these linear habitats. Since
the main difference between the woodlot and the linear forest is essentially the
shape of the habitat, similar general patterns emerge with differences due
primarily to its linear nature. Because of the linearity of these habitats, structural
complexity, as determined by such factors as tree density, canopy coverage,
understorey growth and tree type (deciduous or coniferous), may vary with from
location to location within the linear forest as a result of changing topography
(gradient, altitude, etc ... ), soil characteristics, and proximity to water. There are
six general terrain types which influence the structural complexity of any linear
forest situated on them.
1.
Hilltops and Ridges
The characteristics of the sectors of the linear forests which occur in this type of
terrain are determined by such features as shallow well drained soils, often sandy
in texture, and with frequent exposed rock outcroppings. The forest in this terrain
is usually patchy, and often discontinuous. It is usually dominated by such
species as Douglas-fir and to a lesser extent others such as Lodgepole pine and
Arbutus. The under storey vegetation is usually sparse and is often limited to a
clumpy shrub layer such as Salal or Blackberry growing in a thicket form.
These portions of the linear forest are well suited for recreational use as they tend
to offer scenic views and open spaces. The frequent rock outcrops also makes
these areas relatively resistant to disturbance from human traffic.
Urban Habitats
14
2.
Steep slopes (Gradients in excess of 60%)
This terrain is characterised by well drained, moderate to thin soils, with a loamy
to sandy texture. Linear forests in these areas are usually dominated by Douglasfir, Western cedar, or Grand firs in the main canopy. Deciduous species such as
Red alder or Big Leaf maples may also form a sub-canopy layer~ particularly along
the edges. These sections of the forest are usually very dense, with the resulting
effect of patchy under storey vegetation. Understorey species including shrubs
such as Oregon-grape, Salal, and herb species such as Bedstraw, may be sparsely
distributed.
3. Upper and Middle slopes (Gradients between 35-60%)
Shallow well drained soils, with a loamy texture and often containing variable
amounts of gravel and stones are typical of these areas. Typical tree species
occurring in a linear forest traversing this type of terrain may include Douglas-fir
as a major species with significant representation from others such as Western red
cedar or Western hemlock. The understorey vegetation although not particulary
vigorous may include such species as Salal, Red huckleberry, and Trailing
blackberry.
In these sectors of the linear forest recreational potential is limited because of the
steep gradients, lack of open spaces, and the moderate amounts of under storey
shrubbery.
4.
Middle to Lower slopes (Gradients less than 35%)
Thick, well drained mineral type soils are characteristic of this terrain. Sections
of linear forest over this type of terrain can support species such as Douglas-fir,
Western hemlock, Western red cedar, and Grand fir. These sections are relatively
dense, resulting in a sparse understorey. Salal, Red huckleberry, and Baldhip
rose are common speCIes.
5.
Lower slopes, Undulating or Level Bottomlands
Loamy, imperfectly drained soils of varying depths often with an ample supply of
moisture and nutrients are characteristic of this terrain. Stands of linear forests
in these areas generally contain mixtures of many species including Western red
cedar, Big Leaf maple, Red alder, and Black cottonwoods. The understorey
vegetation is usually composed of a well developed herbaceous layer of ferns and
wildflowers, while shrub species may be present with lower cover under thick
Urban Habitats
15
canopy or denser thickets under openings.
6. Water filled Depressions and Sites adjacent to Water
These sites may include such areas as small marshes, flats, or bogs which may
develop in depressions. The soil type is usually organic with a high moisture
content. Sections of linear forests encompassing this type of terrain may be
limited to such species as stunted Red alders, Willows, or Black cottonwoods along
the margins. Other vegetation may include sedges, rushes, and a variety of
grasses.
Forest litter, (coniferous or broad-leaf), often produces mild acids upon
decomposition, with conifer dominant forest soils being more acidic than
predominantly deciduous forests. These acids which percolate through the soil
have a leaching effect. In primarily deciduous areas, however, because of the
greater biomass of leaf litter deposited, and the more abundant minerals in them,
leaching is less of a problem than in conifer dominant areas. The constant
addition of organic material and minerals to the topsoil improves the soil fertility,
and thus it can support a greater diversity of understorey growth.
Flora and Fauna
Because of the potential of a linear forest to encompass a number of distinct
topographical regions, the aggregate tree and plant species characteristic of each
of these individual' sectors may be able to accommodate and support a greater
diversity of wildlife than for example a woodlot habitat located on a more
homogenous site. The potentially greater structural complexity provides more
ecological niches for wildlife to exploit. The diversity of terrain, soils, and
moisture regimes primarily influence the types of flora which occur in these
distinct regions, and in turn the diversity of the flora influences the diversity of
the fauna which make use of the vegetation resources in a particular area.
Another distinct difference between linear forests and woodlot forests is that the
linearity provides a somewhat less restricted or confining environment for wildlife
species needing range habitat. If the linear habitat is sufficiently extensive, and if
it connects other widely spaced urban habitats then it becomes even more useful
and important for those species as a natural corridor through which they can
travel, forage and move through the urban environment in a somewhat natural
setting. This is particularly true in forests parallelling waterways where the
Urban Habitats
16
foreshore area is not as accessible to human traffic.
Interruptions and discontinuities in a linear forest caused by roads or highways
are significant hazard for wildlife species using these linear habitats as range
corridors. The numbers and variety of roadkill can often provide an informal
survey of the wildlife species utilizing these habitats, and the times they are most
active.
Since the structural complexity may vary from location to location in a linear
forest, so too can species composition. In general some of the most conspicuous
and commonly occurring wildlife includes an abundant bird community which
makes use of any available cover, nesting areas, perching sites, and food supply.
Nesting crows, foraging raptors along the forest edges, and feeding flocks of Blackcapped chickadees are common examples. Sites with extensive vegetation can
provide excellent cover and foraging areas for a variety of Passerines. Sections of
a linear forest with moderate to heavy understorey growth and adjacent to a
waterway can also provide cover and protection from disturbance to many species
using the foreshore areas. Typical examples include Mute swans, Great-blue
herons, and a variety of ducks and geese.
Other wildlife inhabiting the linear forests such as raccoons and coyotes may not
restrict their foraging to these areas, but may venture abroad into any adjacent
urban development. Nearby residential areas and town dumps are a particularly
attractive resource for many of the larger species.
Disturbance
Since the linear forest may cover widely varying terrain its sensitivity to
disturbance will also vary from location to location. The impact of any specific
disturbance on the forest will depend not only upon the magnitude and type of
disturbance but the nature or resiliency of the particular site to the disturbance.
For example, human traffic, (footpaths, trails, bicycle paths etc), can lead to soil
compaction and erosion in some locations but can be well tolerated in the other
areas where there are more rocky soils and frequent rock outcrops.
Because of the linear nature, the forests are particularly attractive to urban
planners who often designate them as linear parks and recreational areas
connecting a network of more conventional parks. While these areas offer may
excellent recreational opportunities for hiking, biking, and wildlife viewing, they
must be managed and maintained appropriately to limit disturbance to sensitive
and less resilient sectors, while providing the maximum recreational potential to
Urban Habitats
17
burgeoning urban populations. Restricting access to sensitive areas, and by
locating bicycle and walking trails in more robust areas where rock is already
exposed or forms natural corridors, are just two ways of minimizing disturbances
as a result of concentrated human activity. Other sectors of the linear forest,
because of the steep terrain, or because of the dense understory vegetation or
thickets naturally discourage human traffic and are less prone to disruption. If
these areas are left undisturbed and undeveloped, they may, over a period of time,
harbour a greater diversity of wildlife seeking refuge from more disturbed portions
of the linear park. With careful management these forests can serve both the
recreational need of man and the habitat need of wildlife.
Urban Habitats
18
Expected Flora
Alder
Birch
Blackberry
Black Cottonwood
Red Elderberry
Mountain Ash
Western Hemlock
Scouler Willow
Lodgepole Pine
Flowering Dogwood
Mountain Laurel
Pacific Dogwood
Red Osier Dogwood
Salmonberry
Indian Plum
European Blackberry
Hazelnut
Waxberry
Bedstraw
Fireweed
Buttercup
Stinging Nettle
Tall Lettuce
Horsetail
Tamarack
Douglas-fir
Arbutus
Salal
Western Redcedar
Baldhip Rose
Huckleberry
Oregon Grape
Broadleaf Maple
Grand Fir
Urban Habitats
Expected Fauna
Northwestern Crow
Song Sparrow
Savannah Sparrow
Chipping Sparrow
Black Capped Chickadee
Red-winged Blackbird
Purple Finch
American Robin
Ring-necked Pheasant
Barn Owl
Red-tailed Hawk
Woodpeckers
Rufous-sided Towhee
Grouse
Bald Eagle
Raccoon
Mole
Vole
Coyote
19
MATURE FOREST FRAGMENTS AND SUCCESSIONAL FORESTS
Physical Appearance
Sections of original forest, called fragment forests, may be rare in urban centres.
They vary in size and are characterized by their mature trees and mayor may not
lack a defined understory. Species of tree vary with location from coniferous to
deciduous stands or a combination of both. Typically, such arboreal stands are not
considered old growth but are usually uniform, even-aged second and third growth
forests (Whitney 1987).
Urban Habitats
20
Location
Forest fragments may be found in the centre or outskirts of an urban area.
Typically, as a forested area becomes developed for urbanization, clear cutting of
the site is routine. If the developer is aware of the value in keeping a large grove
of mature trees, urbanization will encircle the stand. Also, if development proves
difficult or too costly, as is the case with ravines, such areas become the source of
a mature tree population and display unique habitat diversity. In this way, the
forest becomes a green oasis in the concrete of a city.
General Description
Urban forests may be classified by the species they are comprised of and by
whether they display a well-defined understory. Discussed here are the two
common types of forests found in urban areas:
1)
Coniferous stand without understory: This category is typical of large urban
parks where old growth conifers have been retained but their understory
removed.
2)
Coniferous-deciduous mix with understory: This category includes smaller
urban parks where the understory has not been removed.
Coniferous stands without an understory, as seen in some sections of Stanley
Park, are not formed naturally. In areas of high density, public safety becomes an
important issue. Thick undergrowth, typical of well-developed forests, poses
hazards to citizens who use the area. Once an area has been cleared, it remains
barren because of the shading provided by a dense coniferous canopy. Although
this may be ideal to parks managers who do not need to maintain the site, it
sterilizes the habitat and ultimately limits species diversity.
A mixed stand of coniferous and deciduous species with a true understory is
common in urban areas. Typically, such urban forests allow for limited public
access by way of narrow footpaths and trails. This allows for a somewhat natural
habitat for those organisms living there. The term "somewhat natural" is used in
this case because public disturbance, surrounding environmental conditions and
the size of woodlot are unlike those a true, natural stand. However, compared to a
site without an understory, species number and diversity is much greater.
Urban Habitats
21
Soil type is dependent on the type of vegetation it supports. In general however,
the forest soils characteristic of our cool and fairly moist climate are the zonal
soils: podzols and gray-brown podzols.
Forests made up of coniferous stands display podsol soil. These soils are
representative of the pedalfer group where the loss of calcium carbonate from the
soil profile indicates extensive leaching. Aluminum and iron are also carried down
in the soil profile, but they tend to precipitate out and accumulate in the lower
horizons (Andrews 1979). Podsol soils are very low in minerals and conifers such
as the Douglas-fir and western hemlock require less of the basic minerals than do
most other tree species and thrive in such environments. Decaying vegetation
which produces an acidic humus aids podzolization and conifers, when they shed
their acidic needles, exemplify this action.
Deciduous forests are supported by gray-brown podzols. These forest soils are
similar to the podzols except they have a thinner A- horizon and less leaching
occurs. Dead leaves of trees such as birch and maple return bases to the soil
surface making it less acidic and more fertile (Brewer 1989).
Flora and Fauna
Areas that have been left with an understory provide a number of habitats for a
variety of floral and faunal species. Microclimatic conditions within these stands
allows for different types of vegetative growth and distinct layers may be observed.
This layering effect is the result of different seral stages of succession. Typically,
in an urban forest some sections of the canopy are not representative of true
climax species. For example, young conifers may be succeeded by faster growing
alders or vine maples. This may have a deleterious effect in that some species,
especially pines and larch, are intolerant of the shade provided by the deciduous
trees. However, some species such as the estern hemlock and western redcedar are
very shade tolerant and so may prosper under such conditions, eventually
displacing other trees.
Sub canopy tree layers are typically composed of species such as flowering
dogwood, salmonberry, blackberry, and oregon grape. Herbaceous species of the
forest floor include ferns, a variety of mosses, and flowering plants such as
Bleeding heart, Wild lily-of-the-valley, and creeping buttercup.
In urban forests where the understory has been removed, species diversity is
Urban Habitats
22
naturally limited to the trees that remain. Such areas display a forest floor nearly
void of vegetation except for horsetail capable of inhabiting harsh environments
and a few sword ferns where holes in the canopy have permitted some light
penetration.
Faunal diversity is greatest in a habitat providing food, shelter and nesting .sites.
The urban forest comprised of coniferous and deciduous species with an
understory allows for such diversity. These forests also allow for many animal
species to remain in the area over the winter season because conifers and
evergreen shrubs provide cover and nesting sites for birds, rodents and larger
mammals such as coyotes and deer.
Size and proximity to the city are two contributing factors to faunal number and
diversity. A small urban forest close to the centre of a city limits diversity: food
sources are not as plentiful and other factors, such as increased environmental
disturbance, come into play. For example, in a small closed-canopy urban forest,
cornmon city birds such as Northwestern Crows, Black-capped Chickadees, and
wa:rblers, will likely outnumber more intolerant species such as Swainson's
Thrush and Steller's Jay.
The barren forest cleared of its understory provides no cover and limits food
sources for most animals except for species such as the gray and Douglas
squirrels. The forest soil is also low in invertebrate number and diversity because
the floor contains little or no leaf litter and of the coniferous stands, the soil
rernains acidic and dry.
Disturbance
Segments of forest surrounded by a city are not representative of the original
stan.d. The harsh environment of the city is largely responsible. Trees in urban
centres have lower survival rates than rural trees with longevity decreasing as
prox:imity to the city core increases (Schafer ed. 1989). Reduced vigour is likely
due to factors such as higher toxin concentrations from vehicles and industrial
waste, dumping, and vandalism including fire setting and tree cutting. Footpaths
provided for public access also pose a threat to tree vitality. Constant foot traffic
over root systems can compact the soil so that air and moisture drainage can be
severly impaired and root damage emminent.
Comments
Urban forests provide unique habitat islands in our cities and serve to encourage
Urban Habitats
23
rather than displace wildlife. They also serve as a reminder of the public's
understanding of their role in ecological processes of the natural world that we
depend on for survival (Whitney 1987).
Vine Maple
Urban Habitats
24
Flora
Fauna
Douglas-fir
Western Hemlock
Western Redcedar
Western White Pine
Mountain Hemlock
Lodgepole Pine
Sitka Spruce
Red Alder
Broadleaf Maple
Black Cottonwood
Sitka Alder
Dogwood
Vine Maple
Cascara
Pacific Willow
Black Hawthorn
Oregon Grape
Purple Pea
Trilium
Trailing Blackberry
Devil's Club
Red Elderberry
Sitka Mountain ash
Red Osier Dogwood
Bedstraw
Bleeding Heart
Goldenrod
Salmonberry
Thimbleberry
Wild Rose spp.
Youth-on-Age
Wild Lily-of-the-valley
Wild ginger
Red-tailed Hawk
Screech Owl
Downy Wood peeker
Red-bellied Sapsucker
Western Wood-Pewee
Steller's Jay
Northwestern Crow
Common Raven
Black-capped Chickadee
Bushtit
American Robin
Hermit Thrush
Swains on's Thrush
Hutton's Vireo
Warbling Vireo
Orange-crowned War bIer
Townsend's Warbler
Yellow-breasted Chat
Black-headed Grosbeak
White-throated Sparrow
Fox Sparrow
Coyote
Deer
Rabbit
Deer Mouse
Urban Habitats
25
Shrub Communities
Urban Habitats
26
THICKETS
Physical Appearance
A shrub thicket is a dense area of shrubs that dominate a site almost completely.
Typically only the outer edge of the thicket is visible as the growth is so dense
that light does not penetrate the interior and larger animals have difficulty
moving through it. The shrub thicket can be as small as a couple of square metres
or as large as a couple of acres. Thicket creating species are a diverse group
including small, fleshy plants and large, woody, tree-like shrubs. The appearance
of a thicket depends greatly on the species present; what colour it is, its growth
pattern, whether it flowers, whether it is deciduous or evergreen. These factors
also determine the faunal species attracted to the site.
Urban Habitats
27
Location
Shrub communities can be found in association with many other urban habitats,
including grasslands, forests, ponds, and road verges. They occur in areas where
disturbance or forest type allows light to penetrate or where soil and other
conditions preclude larger plant species.
General Description
Shrub communities tend to be homogenous; one species dominates. There are
many shrubs capable of creating a thicket monoculture: hardhack, broom,
red-osier dogwood, red elderberry, salmonberry, thimbleberry, salal and Oregon
grape are a few of the species commonly found. From these varied species two
main types of shrub communities can be identified :
1)
Open shrub communities: Shrub thickets found in areas with little
shading such as grasslands.
2)
Shaded shrub communities: These thickets are shaded by other
plants and are usually found in forests.
Both shrub communities provide a great deal of cover to song birds for feeding and
nesting but the shaded community, in conjunction with a forest, adds a significant
amount of diversity to the forest habitat. The shrub layer adds one more
dimension to the layering already found in the canopy (see woodlots).
Soil is the main determinant of shrub species present on a site. Such
characteristics as nitrogen and calcium content as well as water content restrict or
promote individual species.
Flora and Fauna
Flora that flourish amidst thickets tend to be small, shade-tolerant species that
can exploit the region under the shrub leaf canopy.
Some thickets, especially those made up of woody shrubs like hardhack, are able
to reach an almost climax-like dominance on some sites. These shrubs will cover a
large area, which can be the whole site in an urban habitat, and the denseness of
their growth and the shading caused under the canopy restrict most other plants
Urban Habitats
28
that could otherwise colonize.
Another type of thicket, although it does not quite match the dense, impassable
description, is formed by creeping buttercups. In extremely wet, muddy areas this
herb is capable of dominating a site completely. These thickets are quite short and
easily passable but the monoculture it forms is quite different from pasture lands
and more closely resembles the thicket community.
Animals and birds that find shrub thickets attractive include bears, savannah
sparrows, ring-necked pheasant, coyote and voles. As food, some thickets provide
berries for a variety of song birds while others have tender shoots and leaves that
voles and deer can browse. Ring-necked pheasant and savannah sparrows are
able to find protected nest sites deep in thorny thickets while coyotes may be able
to create a den by pushing through the outer layer of growth to the empty interior
of some shrubs.
Disturbance
Disturbance in thickets is often final in nature. Because thickets cover a lot of
grouna and tend to be almost impassable they are frequently destroyed completely
in attempts to allow more desirable species to grow. Fire is a common method of
destroying a thicket and bulldozing is quite effective, too. In urban forests human
fears can lead to the clearing of underbrush to destroy potential hiding places. The
destruction of the undergrowth in forests reduces the number of layers available
to song birds, and other species.
Comments
Thickets are important in urban areas because they offer areas to wildlife that
humans cannot enter. This refuge is the only safe area for many bird and animals
to nest, den and raise young.
Urban Habitats
29
Expected Flora
Hardhack
Broom
Red Osier Dogwood
Red Elderberry
Salmonberry
Thimbleberry
Mountain Ash
Urban Habitats
Expected Fauna
Ring-necked Pheasant
Savannah Sparrow
American Robin
Brown-headed Cowbird
Steller's Jay
European Starling
Red-winged Blackbird
House Sparrow
Brewer's Blackbird
Chi pping Sparrow
Song Sparrow
Voles
Coyote
Raccoon
30
BLACKBERRY THICKETS
Physical Appearance
Blackberry thickets are dense shrubs with woody, persistent stems, (canes), no
distinct trunk and capable of reaching heights of up to ten feet. The upright or
arched branching canes, usually form dense thickets, linear along roadways or edge
habitats, or as asymmetric clumps in understorey growth. The canes are well armed
with strong sharp thorns and in many places the growth is so dense as to be
impenetrable. In other understorey areas or on hillsides, the density of growth is
such that a machete may be required to pass through.
The whitish-purple flowers are widely spaced throughout the thickets and are
usually composed of five semi-fused petals. The fruits vary in colour among the
different species from red (Sub-alpine berry), to glossy black (Trailing blackberry),
and are usually covered by a mat of fine white haIr.
Urban Habitats
31
Location
Blackberry brambles or thickets can be found in a variety of locations in the urban
environment. Evergreen blackberry which can form dense linear thickets are
common along roadsides in the lower mainland and are particularly prolific along
infrequently manicured shoulders of suburban highways. They can also occur as
understorey growth beneath openings in deciduous or mixed canopies of urban
woodlot, linear forests, and at the borders and edges of streams and waterways. One
of the most natural habitats for blackberries is at the edges of urban forests. They
are usually well represented in the transition zone between the woodlot or linear
forest and the adjacent grassland or developed areas.
Blackberry brambles are also cultivated and manicured as a hedge species. The
forbidding thorns and often impenetrable thickets form effective natural fences on
private or commercial properties.
General Description
The four species of blackberry commonly found in the lower mainland urban habitats
are the Trailing or Wild blackberry (Rubus ursinus), Sub-Alpine blackberry (Rubus
nivalis), Himalayan Blackberry (Rubus discolor), and the Evergreen blackberry
(Rubus laciniatus). The Trailing or Wild blackberry is the only native species to this
region, but is usually outnumbered in the urban habitats by the other exotic and
introduced species.
All four species share the similar general characteristics in that they are rapid
colonizers and pioneers, very prickly (many thorns), and tend to establish dense
thickets or brambles. New stems are produced every year and the roots are
perennial. They can reproduce by seeds but do so more often by rooting branches.
The stems or canes are usually very stout, angular and round, with strong sharp
recurved thorns. The leaves are all toothed and compounded into 3-5 leaflets. Both
young leaves (undersides), and young stems have a wooly or velvety texture of finely
matted hairs). All four species produce whitish-purple solitary flowers during May
and June and fruit during July and August. The leaves of all four species often
persist through mild winters. With the exception of the native Trailing blackberry
the other exotics all have bisexual flowers, robust tall shrubs and heavy flattened
thorns.
The fruit is highly sought after by both animals and people and makes good jams,
jellies and desserts. The leaves are sometimes used to make teas, and peeled young
Urban Habitats
32
sprouts can be eaten raw.
Trailing or Wild Blackberry (Rubus ursinus)
Common pioneer on disturbed areas, widespread in clearings and understorey gaps,
with a preference for recently cleared or burned areas. Occurs frequently in
association with bracken and/or fireweed. It leaves are compounded (3 or 5),
elliptical, pointed, and toothed. Its thorns are slender but sharp. This is the only one
of the four species which have male and female flowers occurring on separate plants.
The fruit is glossy black in colour.
Himalayan Blackberry (Rubus discolor)
Imported from India via England, it is one of the most common urban species. The
tall arching shrubs have finely toothed oval compound (3-5) leaflets, which usually
survive mild winters.
Evergreen Blackberry (Rubus laciniatus)
Most common species along roadsides and highways, and usually in association with
Himalayan blackberry. Its five dark green compound leaflets are deeply incised and
it has very stout stems and strong recurved thorns.
Sub-Alpine Blackberry (Rubus nivalis)
The shortest of the four species, the sub-alpine blackberry produces trailers which
may only grow a few feet in length. It is, however, very prolific and can form
overgrown tangles of ground cover very quickly. It has many small "weak" thorns,
and the leaves are usually lobed (3), or compounded. Flowers are bisexual and often
widespread on the bushes. The fruit is covered in a fine wooly hair and is bright red
in colour.
All four blackberry species thrive in well drained soils, which is either neutral or
slightly acidic. They are generally shade intolerant, and prefer open or slightly
shaded exposures.
Since blackberry shrubs can spread their roots quickly and extensively, and since
they do not have a high root to shoot ratio, they are able to utilize soil moisture and
Urban Habitats
33
soil nutrients more effectively than either trees or grasses. Because of the low root
to shoot ratios, shrubs draw less nutrients and moisture into the above ground
growth and more into the root systems. These characteristics confer a competitive
advantage over trees and grasses where soil moisture and nutrient regeneration is
irregular. Their perennial nature also allows immobilization oflimiting nutrients and
thus further decreases nutrient cycling, reducing competition and increasing shrub
propagation (Smith, 1977).
Blackberry brambles are also very efficient soil stabilizers, and are effective in
preventing soil erosion and soil degradation. The extensive root systems and prolific
growth even on barren and marginal soils can prevent further loss of soil especially
on moderate to steep gradients. They are thus very useful for soil conservation in
areas undergoing ecological restoration.
Flora and Fauna
Since blackberry is a pioneer and an effective colonizer of recently disturbed habitats,
it tends to occur in association with other vegetation also adept at colonization.
Typical associations with Bracken and Fireweed are common as also associations
between blackberry species themselves. Himalayan and Evergreen Blackberry are
often found growing together.
Because most thickets are dense and impenetrable the deep shade beneath them
usually discourages much understorey growth and because they have a lower
energetic and nutrient investment in above ground biomass, than trees for example,
they usually outcompete the latter in the short to mid term successional stage (Smith
1977).
These shrubs provide excellent cover and forage potential for a wide variety of
animals. The dense nearly impenetrable thickets provide ideal nesting areas for
many birds such as robins, pheasants, and finches to name a few. Blackberry
brambles are also the favoured habitat of other such animals as the coyote and the
raccoon. The blackberry communities along forest edges and perimeters of fields may
also support their own distinctive animal life. Some species such as quail, cottontail
rabbits, and ruffed grouse depend heavily on these shrub communities and may
disappear if they are destroyed (Smith, 1977).
Urban Habitats
34
Disturbance
Blackberry shrub communities are very hardy and resistant to many forms of
disturbance. Since their dense impenetrable thickets usually discourages significant
amounts of human traffic they are a favoured species for periphery vegetation
surrounding residential or commercial properties and other areas- sensitive to human
intrusion.
Blackberry shrubs can form stable communities which will persist for many years.
Therefore, if successional tree growth is limited or curtailed by herbicide use or by
cutting, the shrubs can eventually form a closed community resistant to further
invasion by trees. This has wide application in the management of power line rights
of way and other urban utility right of way corridors (Egler 1953; Niering and Egler
1955; Niering and Goodwin 1974).
Comments
Sweet and delicious! The berries are prized for their tastiness and often made into
jams and desserts. In mid-summer when the berries are in season, berry-picking is
one of the popular events for both the young and old along country roads and trails.
Birds and even the racoons sought the delicate berries as food.
Often considered as nasty, prickly, they make good natural fences keeping the cows
and horses in. They provide shelter and food to various wildlife. Most importantly,
they are efficient soil stabilizers, minimizing soil erosion especially on moderate to
steep gradient.
Urban Habitats
35
Flora
Fauna
Trailing or Wild Blackberry
Himalayan Blackberry
Evergreen Blackberry
Bracken
Fireweed
Hardhack
Quail
Ruffed Grouse
American Robin
Pheasant
Finch
Sparrow
Urban Habitats
36
Wetland Environments
Urban Habitats
37
Wetland Environments: Ponds
Physical Appearance
Ponds are areas of shallow water that have only a littoral zone with rooted plants
throughout. They are generally eutrophic in nature: low in dissolved oxygen, high in
nutrients and organic matter, and having a slightly acidic. Ponds look like small
lakes and can be seen as a late successional stage of a lake, just before bog formation.
The main difference between a pond and a lake is the area of rooted plants. A lake
has large areas of open water with no rooted plants while a pond should have very
little to no open water, with any open water having rooted plants beneath the
surface.
Artificial, or ornamental ponds are usually much smaller than natural ponds, having
an area usually less than 6m2 (Gilbert 1989). They are often lined with cement or
polyethylene and are often stocked with plants and animals. Artificial ponds are
generally created to be aesthetically pleasing to evoke a sense of beauty and
tranquility.
This ornamental pond, designed by John Alway and J ochi Schuhberger
of All Seasons Garden Design, illustrates the diverse aquatic and
terrestrial communities possible with a well designed pond.
Urban Habitats
38
Location
Natural ponds are occurs in depressions where water collects. Ponds, like lakes, can
be formed through glaciation, volcanic and tectonic activity, landslides and by human
intercession. Old, undisturbed areas are more likely to have a pond than a lake as
the process of succession will move a lake, through eutrophication, toward pond
formation if left alone.
Artificial ponds are common in parks, ornamental gardens, in front of public and
institutional buildings, or as part of a residential lawn or garden.
General Description
Natural and artificial ponds differ in wildlife and habitat. They can be defined as
follows:
1)
Natural ponds: Ponds that have arisen through the natural processes of
erosion, eutrophication and succession or by man in an attempt to create
a natural type pond.
2)
Artificial ponds: Ponds created by man as an ornament
surrounding area.
III
the
The neighbouring habitats of a pond may affect productivity but eutrophication is not
as large a problem for the already eutrophic pond as it is for a lake.
The main difference between ornamental and natural ponds is species content. A
natural pond has a more diverse community because it is larger and most species
present can propagate themselves (Gilbert 1989). The ornamental pond often contains
introduced plant and fish species. In an ornamental pond only the smaller species like
algae, insects and some amphibians have enough room to reproduce. Introduced fish,
like carp and goldfish seldom reproduce themselves, and must be stocked.
The perception of ornamental ponds as less than useful habitats is incorrect. In an
urban environment these "wetlands" provide living space for many native species.
Frogs and salamanders invade ornamental ponds and their concentrations may be
higher in these ponds than in the wild (Gilbert 1989). Molluscs and water breeding
insects may find these ponds the only available habitat while native plants may be
introduced by visiting birds.
Urban Habitats
39
Water
Water quality and type varies between natural and artificial ponds. A natural pond
is usually quite eutrophic. The pH is generally acidic, dissolved oxygen is commonly
under 7 ppm, and high concentrations of nutrients and dead organic matter are
present. The ornamental pond water types vary by the type of water supply, aeration,
concentration of plants and animals, filtration, and maintenance. The water supply
is usually tap water and can be hard or soft and the pH depends on the source of the
water supply. Aeration through waterfalls, fountains and filtration can greatly
increase dissolved oxygen levels. The concentration of wildlife will affect nitrogen,
nutrient and organic matter levels; large wildlife populations may foul the water with
faeces and dead plants will rot, increasing the level of organic matter. Filtration will
reduce nitrates and dead organic matter and may increase oxygen levels and control
algal blooms.
Flora and Fauna
Fish, amphibians and invertebrates are the most common pond animals. In natural
ponds trout, catfish and feral carp are most common while in artificial ponds goldfish,
koi, and many other non-tropical introduced fish may be present. Frogs and toads are
common in both pond types and both provide breeding opportunities for insects like
mosquitoes and dragonflies.
Native aquatic and marsh plants are prevalent in natural ponds and may include
cattails, sedges, white and yellow water lilies, and water plantain. Ornamental ponds
often contain all of these as well as some exotics.
Disturbance
Natural ponds are easily disturbed by fertilization, pesticide and herbicide poisoning
through lawn run-off, invasion by detrimental foreign species like eurasian millfoil
and purple loosestrife, and soil compaction by waterfowl in shallower areas as well
as contamination by their faeces. Artificial ponds may be over-fertilized and poisoned
as well but introduction of foreign species often fulfils their purpose, in fact, artificial
ponds are often the source of contamination by foreign species in natural ponds.
Comments
Both natural and artificial ponds provide important habitats for urban wildlife. They
attract water dependent species that would otherwise not be present and add some
variety to the urban landscape.
Urban Habitats
40
A pond is a compelling urban environment. The water can cool the air, and the
shimmering surface affords a calming distraction from the harshness of urban life.
The larger ponds in particular, commonly contain turtles and fish, and are vvisited
by Great Blue Herons, all of which contribute to a rich setting which appears almost
tropical in contrast to the surroundings.
Urban Habitats
41
Flora
Fauna
Cattail
Duckweed
Goldenrod
Yellow Pond Lily
White Pond Lily
Purple Loosestrife
Yellow Iris
Water Parsley
Close-leaved Pondweed
Curled Pondweed
Canadian Waterweed
Softstem Bulrush
Small-fruited Bulrush
Diffuse Rush
Creeping Spike-rush
Bigleaf Sedge
Grey Sedge
Cusick' Sedge
Dewey's Sedge
Sitka Sedge
Sawbeak Sedge
Blue-green Algae
Euglena viridis
Vertebrates
Carp
Goldfish
Rainbow Trout
Bullhead
Mallard
Red -wiged Blackbird
Brewer's Blackbird
Cliff Swallow
Barn Swallow
Salamanders
Western Painted Turtle
Common Garter Snake
Raccoon
Muskrat
Invertebrates
Water Bear
Hydra
Water Boatman
Water Strider
Dragonfly
,Mosquito
Giant Water Bug
Crayfish
Orb Snail
Urban Habitats
42
LAKES
Physical Appearance
A lake is a body of water that displays three distinct regions based on depth:
A)
Littoral zone: A region of shallow water with rooted plants.
B)
Limnetic zone: The upper regions of open water beyond the littoral zone
from the surface down to a depth where photosynthesis produces a net
primary productivity.
C)
Profundal zone: The lake waters below the limnetic zone down to the
lake bottom.
A lake differs from ponds and marshes by having all three regions. A lake has greater
depth which forms regions of open water and lake bed with no rooted plants. This
differentiates it from ponds, which typically have rooted plants throughout. A lake
also has good drainage in the form of a stream or river. A marsh is distinguished
from ponds and lakes by vegetation type (Brewer 1988).
Urban Habitats
43
Location
Lakes are located in depressions or low points in the terrain that collect water and
are formed by many geologic processes. Lakes can be formed through landslides,
volcanic activity, tectonic movement, river activity, and glaciation (Wetzel 1983).
Artificial lakes are also sometimes created. In urban areas most lakes are found in
glacial depressions or are artificially made and maintained through dredging. Old
gravel pits are often flooded and then marsh plants are introduced. Urban lakes can
be found in association with most other urban habitats. In urban parks lakes are
often surrounded by lawns or landscaping while the same lake in an urban forest
may be surrounded by old growth trees. Some lake shores have residential lawns
right to the water's edge while others may have trail systems or industrial sites
surrounding.
General Description
Lakes vary with age and location and are characterised by factors like dissolved
oxygen content, depth, thermal stratification, pH, nutrient content, and dead organic
material. The two major classifications of lakes are:
1)
Eutrophic lakes: These lakes are generally older, shallow, warm lakes
with a low dissolved oxygen content and large amount of dead organic
material. This is the typical lake found in a city.
2)
Oligotrophic lakes: These lakes are younger, tend to be deeper and
stratified, and the lower temperatures usually result in a higher
dissolved oxygen content. The oligotrophic lake has less organic matter
and silt.
Urban eutrophic lakes can be further classified by the habitat they are associated
with:
la)
Residential Eutrophic: An eutrophic lake surrounded by residences with
lawns or by a manicured park.
Ib)
Woodland eutrophic: An eutrophic lake surrounded by trees or grasses
usually in a park or large undeveloped tract.
Ic)
Mixed eutrophic: An eutrophic lake with varied habitats along differing
regions of lake shore.
Urban Habitats
44
Oligotrophic lakes tend to be much larger than eutrophic lakes and are not usually
completely surrounded by an urban type of habitat. Rather, urban areas are built up
to the shore but give way to rural regions around the lake. The impact of varying
habitats on an oligotrophic lake shore is quite small compared to the impact habitat
has on a smaller eutrophic lake.
Oligotrophic lakes are less productive but the higher oxygen content allows for a
diverse benthic, or open water community (Brewer 1988). The water in oligotrophic
lakes is usually clearer than in eutrophic lakes with smaller algal blooms. Free
swimming fish such as trout need more oxygen and are more common in oligotrophic
lakes. With fewer large plants there are fewer waterfowl using these lakes to breed
or feed. These lakes may resemble eutrophic lakes at the shoreline if the littoral zone
is large, causing eutrophication of the lake's edge. The food chain of an oligotrophic
lake has microscopic photosyhthetic plankton at its base.
Eutrophic lakes, the most common in urban areas, are very productive. The large and
diverse plant and plankton communities in these lakes generates large amounts of
dead organic material and much decomposition. Decomposition reduces oxygen levels
and restricts fish diversity but also opens opportunities for insect larvae and
waterfowl such as ducks and rails such as coots. The food chain of an eutrophic lake
Water
Water quality in urban lakes can be measured by oxygen content, pH, nitrates, faecal
coliform counts and algal content. An urban eutrophic lake usually has a dissolved
oxygen content below 7 ppm, a somewhat acidic pH, may have nitrate and phosphate
levels above 0.4 ppm, and often has highly visible algal blooms.
An oligotrophic lake generally has oxygen levels above 7 ppm and often to 12 ppm,
neutral to slightly alkaline pH, very low nitrate and phosphate levels, and very little,
if any, algal blooms.
Flora and Fauna
Eutrophic lakes support a diverse community of plants, plankton, fish, insects and
insect larvae, reptiles, birds and mammals. Plants that can be found in eutrophic
lakes include lilies, cattails, irises, and sedges. The lake is home to many insects
including the toe-biter waterbug, water striders, and water boatmen. Insect larva that
inhabit these lakes include dragonfly, mosquitoes, some dipterans (flies), and
mayflies. Introduced fish to urban lakes include rainbow trout and cutthroat which
must be constantly stocked - the warmer temperatures and lower oxygen levels in
Urban Habitats
45
eutrophic lakes do not support breeding populations of these fish species. Resident
fish may include bullheads, sticklebacks and catfish. Many native and introduced
reptiles are found in urban lakes including painted turtles, garter snakes and redbacked salamanders. Birds that frequent lakes include mallards and Canada geese
feeding in the shallows or on shore. Barn and Cliff Swallows feed on flying insects
over the water, scavenging crows and coots looking for insects. Raptors may use the
lake to hunt open water fish like trout. Mammals use urban lakes as well. Raccoons
may hunt the shoreline while muskrats and beaver can take up residence along the
stream inlets and outlets.
The native yellow waterlily is a common lake species found in shallow water (Klinka
et al. 1989). The white waterlily is also common to shallow areas but is actually an
introduced species (which is spreading rapidly and displacing the yellow waterlily in
many lakes). Plants common around the shoreline of lakes include the Sitka sedge,
which is an indicator of nitrogen rich organic soils and the common rush which can
be seen in many lakes and is an early indicator of eutrophication (Klinka et al. 1989).
Water plantain is a common shallow rooting plant found in muddy ground. Often
found with the the water plantain are cattails, bulrushes, and arrowheads (Fish
Habitat and Enhancement 1990).
Disturbance
Chemical disturbance in urban lakes comes from pollutants, insecticide and herbicide
run-off, and fertilizer run-off. Industrial pollutants like oils and dissolved chemicals
enter lakes through run-off and streams, and groundwater seeps. Because lakes tend
to have sluggish currents and slow water turnover, pollutants may remain for longer
periods of time and have a greater chance of entering the food chain. In residential
areas, the over-use of lawn herbicides and pesticides (See Lawns) can lead to
contamination of the ground water and adjacent streams which flow into lakes.
Again, these chemicals can easily build up in a lake food chain.
The problem of over-fertilization is possibly the greatest. Fertilizers containing
nitrates and phosphates wash in from lawns and gardens and promote larger plant
communities and algal blooms. These plants then die adding greatly to the organic
matter at the bottom of a lake. Not only does this fill the lake, it also increases
anaerobic decomposition depleting the lake of oxygen. This process is similar to the
natural eutrophication of oligotrophic lakes but is much more rapid than natural
succeSSIOn.
Eutrophication is also speeded by the introduction of foreign plant species like
Eurasian millfoil and purple loosestrife. Millfoil grows and reproduces rapidly, and
Urban Habitats
46
can be rooted at a greater depth than many native species. This can expand the
littoral region of a lake, adding to the dead organic material and may fill the lake
bottom rapidly. Purple loosestrife, is a woody plant that inhabits the shoreline of
lakes. It quickly overcomes native species and forms a monoculture. The destruction
of native plants reduces the availability of food for waterfowl beacuse these birds
cannot eat the tough loosestrife. The consequence is a loss of diversity and stability
of the food chain. Eradication programs using mechanical, chemical and biological
methods are being researched and instituted for for both plant pests.
Comments
Urban lakes are different from most other urban habitats because of the water.
Obviously, aquatic creatures are quite different from terrestrials, as a lake is quite
different from land. This watery area greatly enhances any habitat it is in contact
with because it attracts a larger variety of plants and animals, which helps stabilize
the food chains present, and because it acts as a moderator of extremes. The presence
of a lake in conjunction with another urban habitat must be seen as a positive factor
in any designation of value with respect to wildlife.
Urban Habitats
47
Flora
Cattail
Duckweed
Goldenrod
Yellow Pond Lily
White Pond Lily
Purple Loosestrife
Yellow Iris
Water Parsley
Close-leaved Pondweed
Curled Pondweed
Canadian Waterweed
Softstem Bulrush
Small-fruited Bulrush
Diffuse Rush
Creeping Spike-rush
Bigleaf Sedge
Grey Sedge'
Cusick' Sedge
Dewey's Sedge
Sitka Sedge
Sawbeak Sedge
Blue-green Algae
Euglena viridis
Fauna
Rainbow Trout
Bullhead
Three-spine Stickleback
Canada Goose
Wood Duck
Mallard
Green-winged Teal
Common Coot
Common Merganser
Barrow's Goldeneye
Great Blue Heron
Common Loon
Killdeer
Belted Kingfisher
Red-winged Blackbird
Brewer's Blackbird
Cliff Swallow
Barn Swallow
Red-backed Salamander
Painted Turtle
Common Garter Snake
Beaver
Muskrat
Raccoon
Mink
Invertebrates
Giant Water Bug
Western Crayfish
Urban Habitats
48
MARSHES
Physical Appearance
The fresh water marshes are sometimes called swamps in tropical areas where they
often contain large trees. They are typically wet most of the year: inundated with
water during the wetter months and dry up during the arid months. Even during the
arid months, there is enough moisture to keep the vegetation growing and the ground
soft and mucky. Skunk cabbage predominates in the marshes found in shady areas.
The marshes that are exposed to full sun are generally dominated by cattails, sedges,
reeds and bulrushes.
Urban Habitats
49
LOCATION
Fresh water marshes are generally associated with slow moving streams or creeks,
and shallower portions of ponds and lakes. They can also occur at drainage basins of
underground springs. Interestingly, some marshes do occur in depressions along
highways where they serve as storm drainage basins.
GENERAL DESCRIPTION
Fresh water marsh vegetation is typically grass-like, upright and tall. Cattails,
rushes, reeds and sedges have long and narrow leaves with little or no branches.
They have hollow and fibrous stems enabling them to bring oxygen to roots, thereby
withstanding long periods of being inundated with water. They have extensive
network of rhizomes with which they propagate vegetatively. The rhizomes penetrate
the muddy substrate and are capable of extending towards the water's edge. The flow
of water is considerably decreased once colonization of the water's edge begins.
Sediment accumulation accumulates. Along with this process, the accumulation of
organic debris on the mud due to the slow decomposition of the stems and leaves
further increases the level of the marsh and extend the drier upland habitat.
FLORA AND FAUNA
Fresh water marshes are important habitats for various mammals, birds, amphibians
and reptiles which use these areas for food and shelter. Red-winged Blackbirds and
Yellow-headed Blackbirds live in the cattails. Herons often sit and wait for fish, frogs
and snakes. Waterfowl such as Mallards, Gadwalls, and wigeons are voracious
grazers of roots and rhizomes. American coots build their nests amongst the marsh
vegetation. Marshes are also frequented by raccoons, muskrats, weasels, opossum,
and shrews during their foraging activities. Invertebrates such as snails and worms
are common in muddy substrate of the marshes.
Flowering plants like the water plantain, skunk cabbage, purple loosestrife,
redshank, arrowhead, water cress, water dock and brooklime often grow within the
cattail-sedge-rush communities of the fresh water marshes. Hardhack, salmonberry,
willow, and young alder are often found growing on the drier portions of the marshes
where flooding is minimal.
DISTURBANCES
For many people marshes seem to be a wasteland and valueless. Consequently, they
are filled, destroying marsh habitat robbing it of its value for wildlife.
Urban Habitats
50
A marsh is a natural successional stage for either a bog or upland forest. The muddy
substrate is nutrient rich because of slowly decomposing dead marsh vegetation.
Marshes are commonly converted to farmland by draining the standing water and
eliminating the marsh vegetation.
Purple loosestrife, introduced from Europe ha spread rapidly throughout Canada. Its
success is attributed to the lack of natural predator and the ability to out-compete
other marsh vegetation. It rapidly invades wetland environments such as marshes
and ultimately choking out the natural marsh vegetation. This weed poses a grave
ecological threat to native marsh plants. Natural biodiversity of the marsh is greatly
reduced. An area infested with purple loosestrife does not provide the wildlife with
food, nesting sites or shelter.
COMMENTS
Garbage in urban marshlands is a common sight. As previously mentioned, marshes
are perceived as areas with no values to society. Old tires, bicycles, broken household
appliances including organic refuse have been found in marshlands. The vegetation
is severely impacted by the garbage which reduces their normal growth and
productivity. Furthermore, the garbage may degrade and release toxic chemical to the
environment. Organic debris encourages eutrophication of the area along with the
adjacent body of water.
Urban Habitats
51
Flora
Fauna
Bulrush
Sedge
Water Plantain
Arrowhead
Water Cress
Skunk Cabbage
Red-winged Blackbird
Yellow-headed Blackbird
Great Blue Heron
Mallard
Gadwall
Widgeon
'.-.~~
~~-~
-~
:=
---.
g ...
11
Urban Habitats
52
STREAMS AND RIVERS
Physical Appearance
Streams discharge water in watersheds. They are usually narrowest at the top of the
watershed. Water is collected in the watersheds and filtered through the permeable
soils and rocks into the groundwater level. Here, the underground water flows above
the impermeable layers of rocks or clay until becoming exposed to the headwaters of
a stream channel. As the water flows it can cut through soft ground forming ravines
and valleys.
Generaliy, streams that are fed by rainfall in the winter and glacial melt over the
summer months have continuous water flow. In urban areas, where majority of the
headwaters are developed and paved, urban streams have storm drains as another
source of water. Following a heavy rainfall or storm, water flows are usually greater
in urban streams and rivers fed by storm drains than in natural areas where water
can more easily be absorbed into the ground. The heavy water flows can temporarily
flood a stream, often overflowing the streambanks and damaging the riparian
habitats through "flash" floods. In dry months, water levels in such streams may fall
considerably due to the decrease in ground water level.
Urban Habitats
53
A river is a large, flowing body of water draining a large area called basin. Rivers
vary in characteristics determined by the topography, geology, adjacent land use, soil,
and sediments of the land they drain (Oglesby et al. 1972). Essentially rivers are
formed by many smaller tributary streams converging together where the additional
amount and flow of water enlarge the main stem. The tributaries themselves drain
the high slopes of their individual basin also known as watersheds.
Location
Streams and rivers can be found flowing down a hillside, mountainous slopes, along
ravine bottoms, and valleys; draining water from higher elevation and emptying into
a basin or ocean, or on flatlands where the flow may be barely noticed. In urban
areas, the majority of streams may have been contained in culverts and paved over.
Some urban streams that survive this fate can be found in ravines. Ravines in
Vancouver's Lower Mainland cut through various land formations and can be
hazardous for development. They are often ignored by developers and left in natural
condition. Their streams however become the drainage for the residential surrounding
the ravines. Some municipalities have designated the urban ravines and streams as
ecologically sensitive areas.
General Description
A stream or river is unique to the watershed it drains. The physical and chemical
characteristics of a stream or river are determined by the characteristics of the
drainage area. Its gradient is dependent on the steepness of the drainage topography.
In turn the gradient plays an important role in determining the composition of the
stream or river bed, and the velocity of the current. Rock and gravel predominate in
streams with a steep gradient; whereas waterways with relatively low gradient tend
to accumulate silt and sand. From headwaters to the mouth, waterways flow from
higher to lower gradient. Along with the change in gradient, the cobble of the stream
bed becomes smaller, the channels wider and the streambanks lower.
There are three types of habitats associated with streams and rivers, namely the
shoreline (riparian), the streambed or riverbed (benthos), and the water itself. Both
are important components in the ecology of these waterways.
1.
Riparian zone: A waterway system is dependent on the vegetation that
grows along and above. Riparian vegetation functions in filtration of
pollutants; bank stabilization; providing shade; and providing important
nutrients. The leaves of the riparian vegetation fall into the stream and
provide food for aquatic insects, and release proteins during
Urban Habitats
54
decomposition. In the summer, insects that live in the riparian
vegetation fall into the streams and become important food source to
fishes. Riparian zones are also important habitats to other wildlife such
as shrews, voles, mink, muskrats, weasels, Great Blue Herons, Belted
Kingfisher and numerous songbirds that utilize the canopies of the trees
and shrubs for their nests.
2.
Streambed or riverbed habitat: Substrate of these beds is important in
determining their productivity. The different types are bedrock and
boulder; cobble and gravel; sand; and silt and mud. Each indicates
characteristic velocity of the current. Each type of substrate is capable
of supporting a unique biotic community.
a. Bedrock and boulder beds: Stream velocity is extremely high. This
environment has a very limited nutrient supply, and therefore contains
little animal life. Mayfly nymphs and nematodes (round worms), can be
found here.
b. Cobble arid gravel beds: Water velocity is highand the water is highly
oxygenated and capable of carrying food supply. Algae such as bluegreen algae and fountain moss grow on the gravel and are the primary
food source for aquatic invertebrates. These invertebrates have adapted
to the life in a fast flowing stream. Such adaptations include flat bodies
clinging to rocks, and possess powerful suction discs on the underside
(e.g. midge fly larvae). Mayfly, stone fly, and caddisfly larva are found
here in close association with one another. They are voracious predators
capable of capturing food particles such as diatoms in swift current.
These larva are an important food source for juvenile salmonids. Some
of the fish found here include cutthroat trout, minnows, stickleback, and
juvenile salmon.
c. Sandy beds: Productivity here is. quite low. Algae and moss are
incapable of growing without adhering to rock surfaces. Food is often
washed downstream. Some animals that may inhabit this type of
environment are nematodes, caddisfly, and mayfly larvae.
d. Silty and muddy stream beds: Current velocity has considerably
decreased allowing for sedimentation. Productivity is high. The diversity
of the primary producers is increased which includes water weeds,
arrowheads, water plantain and cattail. The diversity of aquatic
invertebrates is also increased. Fish species found here include catfish
Urban Habitats
55
and suckers.
3.
Water zone: There are two basic types of water environments in streams.
These are the areas of moving water (lotic environments), and the areas of
standing water (lotic environments) in pools. The moving water of rapids
(heavier, turbulent flows) and riffles (lighter, less turbulent flows) contain fish
such as trout which are strong swimmers feeding on clinging invertebrates on
the rocks and flies on the surface. Pools contain fish such as catfish which are
not strong swimmers.
Algae and detritus are the primary producers in the food chain. Aquatic invertebrates
such as insect larva, aquatic insects, leeches, snails, and worms are primary
consumers. They in turn become food for fish, amphibians, reptiles, and birds which
are predated on by larger animals.
Disturbance
Streams and rivers are subject to a variety of land-uses which are important in
determining the survivality, productivity and quality of the habitat.
1.
Storm drains: In urban areas, streams may originate as runoff into
storm drains. The storm drains collect runoff from residential,
commercial, and industrial areas as well as streets, arterial roads and
highways. They can pollute urban streams and rivers with detergents,
oils, pesticides, herbicides, and spilled chemicals. Occasionally, streams
may also be contaminated with backed-up sanitary sewer water. Water
from one of the storm drain outlets in Byrne Creek, Burnaby was tested
in June of 1991 and had a pH of9.25 and a dissolved oxygen level of 0
ppm (Royann Petrell, U.B.C.).
2.
Development: With increasing of human population and the expansion
of cities, more natural land is being converted to residential, commercial
and industrial developments. Watersheds may consequently be paved to
make way for these developments causing an increase in runoff due to
decreased infiltration, which ultimately augments flood and drought
cycles.
3.
Channelization: This practice of straightening a waterway and removing
trees and shrubs from its banks is used for agricultural irrigation,
wetland drainage, flood control, and possibly road construction. It
removes critical habitats for wildlife which in turn reduces diversity and
Urban Habitats
56
simplification of the ecosystem. Furthermore, it increases current
velocity and erosion and creating siltation problems downstream.
4.
Grazing animals: These animals (cows, horses, sheep), can cause serious
damage to the banks by destroying riparian vegetation and destabilizing
the ground. Their manure pollutes the water increasing biological
oxygen demand (BOD), accelerating eutrophication and elevating fecal
coliform counts.
5.
Riparian devegetation: This is a result of logging, creation of
pasturelands, and development. Without riparian vegetation, there are
no overhanging plants to provide shade and protection. Water
temperature is increased, food supplies (detritus and fallen insects) are
removed, and the recruitment of large organic debris is reduced.
Moreover, streamand river banks are destabilized causing an increase
in erosion and sedimentation.
·6.
Eutrophication: Fertilizer from crop fields, golf courses, lawns, gardens,
and pastures may leach into the water causing an influx of excess
nutrients, (especially nitrogen) causing the eutrophication of streams.
Oxygen-depleting algal blooms are induced with an increase in
atmospheric temperature and sunlight, increasing biological oxygen
demand decreasing dissolved oxygen.
7.
Siltation: This comes from road and building construction adjacent to
streams, streambank erosion, landslides, logging and mass wasting. Silt
deposited on the beds can destroy spawning beds killing fish eggs and
alevins. Populations of aquatic insects are also reduced because they can
no longer cling to the silt covered rocks. In general, siltation greatly
disrupts the ecology of the stream.
8.
Chemical contamination: Industrial accidents may occur which may
cause a major fish-kill or sterilization of a waterway. Any number of
chemicalscould be involved. Industries may also release warm water,
elevating the temperature of natural waterways, thereby making it less
habitable for some aquatic life.
9.
Pesticides and herbicides: These may originate from residential lawns
or agricultural fields. In large quantities, they may cause fish kills and
disrupt life cycles of aquatic organisms.
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57
10.
Water diversion: Water may be diverted for drinking water, residential
and industrial purposes, irrigation and livestock watering. Diversion can
cause lower summer water levels, drought and increased water
temperatures. Many fish species such as trout cannot tolerate the
warmer temperatures.
11.
Garbage: Urban streams are commonly found flowing through ravines.
Due to hazardous conditions for development, ravines are often ignored
and left in natural state. However, they become areas for illegal garbage
dumping. Garbage produces harmful leachates and can obstruct the
stream course.
Comments
Stream and river ecosystems are very sensitive to imbalances created by human
activities. Urban streams have an excellent potential in supporting a wide diversity
of wildlife. Furthermore, they are important landscape features in providing a place
to retreat and enjoy nature.
Many streams are used by schools as a focus for community involvement, such as
salmonid enhancement. Students may raise the salmon from eggs in small hatcheries
and release them as fry or smolts.
Flora
Fauna
Blue-green algae
Arrowheads
Watercress
Water Plantain
Skunk Cabbage
Sedges
Bulrush
Cattail
Salmonberry
Thimbleberry
Willow
Red Elderberry
Alder
Caddisfly larva
Mayfly larva
Stonefly larva
Dragonfly larva
Water Striders
Cranefly larva
Damselfly larva
Midge larva
Crayfish
Cutthroat Trout
Coho Salmon (juvenile)
Great Blue Heron
Raccoon
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BOGS
Physical Appearance
Bogs are mineral and nutrient-deficient, and considerably acidic environments which
support interesting plant communities that have adapted to survive in such extremes.
Groundwater level here is well below the raised layer of peat. Bogs in Vancouver's
Lower Mainland are characterized as domed bogs. They dominated by Sphagnum
moss with raised centres and surrounded by depressed margin called lagg
(Agriculture Canada 1976). Domed bogs are of the low shrub type with dense growth
of Labrador tea, bog laurel, cranberry, salal, along with stunted shore pines.
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Location
Bogs in Vancouver's Lower Mainland occur in the floodplain of the Fraser River.
General Description
Bogs in the Lower Mainland have been formed through the process of hydric
succession. Process begins with the infilling of a lake by sediments and colonization
of wetland vegetation. Over time organic matter accumulates and gradually blocks
the flow of incoming water. The area then becomes isolated from nutrient supply.
With the increase of plant growth, the organic substrate of available nutrients is
eventually depleted resulting in a decrease in productivity. Further accumulation and
decomposition of the detritus matter causes the depletion of the available oxygen, The
incoming water is solely derived from rainfall. Bogs are dependent on the rain and
airborne detritus particles for nutrient. Rainwater, however, is nutrient poor. This
environment then becomes oligotrophic and anaerobic which is a suitable habitat for
Sphagnum moss. It can tolerate the marginal nutrient regime and its own physiology
maintains the low pH (Moore and Bellamy 1974). Sphagnum also maintains the
water table at the growing surface by capillary action.
Flora and Fauna
Sphagnum species dominate the bog environments which help in retaining a unique
microclimate (Taylor 1990) which created refuge habitats for the typical bog plants
that are not normally found at this latitude and climate regime (Kringa 1969). These
plants are able to survive without any interference and competition from other
mainland-type vegetation.
Bog plants are successful because of their adaptation to a nutrient and oxygen poor
environment. Bog shrubs such as bog-rosemary, bog-laurel, and labrador tea cope
with the environmental extremes by developing characteristic growth habits and
forms. They have thick, shiny evergreen leaves with heavy cuticles, recurved margins,
woolly undersurface and sunken stomata for protection against the loss of water
through evapotranspiration. Bog huckleberries and blueberries lose their leaves and
overwinter in dormancy (Crum 1988).
Plants like the sundews are insectivorous and rely on animal proteins as dietary
supplement. They have leaf blades that are covered with hairs that secrete sticky
substance to trap insects.
Cloudberry (Rubus chamaemorus L.), a rare plant, was found growing in Vancouver's
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60
Camosun Bog. Other rare plant include Alaska huckleberry, velvet-leaved blueberry,
etc. These plants are classified as tundra plant that are found growing in their
southernmost periphery of their range.
Disturbances
Adjacent land-use is important in determining the survivability of bogs and the
associated flora and fauna.
1.
Construction of drainage ditches and canals: Ground watertable is
lowered by drainage into these ditches and canals resulting in destabilization
of the Sphagnum community. Lowering of the watertable allows oxygenation
of the soil, thus increasing the establishment potential of upland vegetation
such as hemlock. Hemlock grows well on deep organic soil (Watts 1983). The
higher rate of evapotranspiration in hemlocks accelerate the drying process of
bogs. Furthermore, they contribute nutrient-rich litter. As a superior
competitor, they shade out the shade intolerant bog plants thus resulting in
a hemlock forest succession.
2.
Land-fill and pre-construction fill: Wetland areas are quickly becoming a
more valuable land base for development and land fill. With increase of human
population in the metropolitan area, the land-use designation of these bogs are
gradually converted to either residential or commercial and industrial. Prior
to construction or development, sand or other incompressible materials are
placed as pre-load fill on top of the soft peatlands. The weight of the fill
material then displaces the soft peat in the adjacent areas. Excessive weight
in a short period of placement of the fill can cause severe buckling of adjacent
lands. Furthermore, this releases the stored water causing flooding on the
adjacent grounds. Leachate from the fill may contaminate underground water
supply, fish-bearing streams and rivers. Toxicity of the leachate is dependent
on the type of the fill material. The City of Vancouver owns 1600 acres of
Burns Bog, Delta, which is currently being used as a sanitary landfill. A
system of double ditching surrounds the landfill to collect leachate. It is toxic
to the wildlife and vegetation of the bog. The leachate flows into the adjacent
lands and may contaminate the watertable. The double ditches was "found to
be acutely toxic" by Ministry of Environment (Memo, MOE, file#:50.150103).
3.
Farming: Cranberry and blueberry are the two common crop plants of
bog/peat-lands. Cranberry fields are surrounded by a system of dykes and
drainage ditches. The fields are flooded during harvest using water obtained
from the watertable. The watertable may experience some fluctuation which
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61
may cause a degradation of the sphagnum moss community.
4.
Peat mining: Peat moss is a popular horticultural growth medium. First of
all, the area is drained one year before mining can proceed. In addition,
shallower ditches are dug about 60 feet apart, and the surface between them
is contoured for better surface drainage (Crum 1988). Crum (1988) estimated
that about 2 inches of peat are harvested a year for horticultural purposes.
Drainage of water alters the level of the watertable, causing the area to dryup. With the lowering of the watertable, upland-type vegetation will gradually
dominate and shade-out the shade-intolerant bog vegetation.
Comments
Bogs are unique natural phenomenon. They are capable of harbouring unique plant
species that are normally found in tundra and boreal climates. The bogs of
Vancouver's Lower Mainland develop over the centuries to become refugia for these
specialized plants.
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Flora
Faauna
Bog Laurel
Bog Rosemary
British Soldiers
Cloudberry
Cranberry
Crowberry
Blueberry
Hair-cap Moss
Hardhack
Labrador Tea
Reindeer Lichen
Salal
Sphagnum spp.
Sundew
Swamp Laurel
Sweet Gale
American Coot
Barn Swallow
Black-capped Chickadee
Common Raven
Common Snipe
Mallard
Gadwall
Great Blue Heron
Killdeer
Northwestern Crow
Pintail
Red-winged Blackbird
Ringed-necked Pheasant
Rufous-sided Towhee
Sandhill Crane
Tree Swallow
Wood Duck
Salal
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ESTUARIES
PHYSICAL APPEARANCE
Estuaries and brackish marshes of Vancouver's Lower Mainland are important
component of the Fraser River delta. This deltaic system is the largest estuary on the
Pacific Coast of Canada and it is one of the critical habitats for both migratory and
resident birds. For the migratory, the estuary serves as a stop-over and feeding area
between the wintering grounds in the southern USA and the breeding grounds in
Canada, Alaska, and eastern Russia. During winter, it is capable of supporting the
highest densities of waterbirds, shorebirds, and raptors in Canada (Butler and
Campbell 1987).
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LOCATION
An estuary, as defined by Pritchard (1967), is a semi-enclosed coastal body of water
which has a free connection with the open sea, and within which sea water is diluted
with fresh water derived from land drainage. It is generally located at the lower end
of a river delta. Brackish marshes may be found along the bank of the river delta
where the river water is affected by the salinity of the tidal sea water. Harris and
Taylor (1973) have stated that the area of estuarine influence of the Fraser River
extends about 19 miles from New Westminster to the Strait of Georgia. This area
approximately encompass 130 square miles which is located on the foreshore of
Richmond, Delta, New Westminster, and Vancouver Municipalities.
GENERAL DESCRIPTION
Estuaries are important component of a watershed system. They essentially function
as nutrient traps. They occur at a land-water interface which is greatly influenced by
salinity, inundation of water during tidal exchange. Nutrients are brought in from the
marine environment, the terrestrial environment, and the watershed environment.
The traped nutrients are distributed throughout the estuary by natural phenomenon
of tides, wind, river current and the salt wedge created by the seeping action of salt
water along the river bottom which results in the upwelling of nutrients. The Fraser
River Estuary supports a diversity of wildlife from waterfowl; shore- and water-birds;
raptors and including mammals and fish.
The soils of the estuary are deltaic in origin where the river carries alluvial deposits
from the watershed and deposited in the sea water.
FLORA AND FAUNA
There are three types of habitat associated with an estuary:
1.
Benthic zone: Marine plants such as -seaweeds may grow on stable mud flat
surfaces. Eelgrass are commonly found growing in sand and submerged in
water permanently. Eelgrass occurs in the lower intertidal zone of many
estuarine habitats with salinities of 10 to 30 parts per thousand and
temperatures of 10 to 20 degrees Celsius (Fish Habitat Enhancement 1990).
They are important in sediment stabilization and provide excellent feeding
habitat and cover from potential predators. Pacific herring migrate into the
estuaries during mating and egg-laying period of their life cycle. The eggs are
attached onto the eelgrass. The faunal community of this habitat are snails,
clams, sea stars, isopods, amphipods, copepods, and crabs (Fish Habitat
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Enhancement 1990). Surfperch, gunnels, sculpins, rockfish, cabezon, pipefish
greenlings, tubesnout, and sole are among the common resident here that take
advantage of the eelgrass meadows for food and cover. The intertidal zone is
an important habitat for the juvenile salmonids; they spend some time here to
feed and acclimatize their physiology prior their oceanic migration. Canada
geese, widgeons, pintails canvasback ducks, mallards, and- green-winged teals
are important herbivores of the eelgrass. Northcote (1952) found that the
mysid Neomysis to be abundant in the arms of the lower Fraser River (estuary
portion). Hallam (1973) found hydrozoa, errant, 2 to 3 species of polychaetes,
oligochaetes, mussels, clams, shipworm, snails, barnacles, amphipods, a
decapod, dipteran larvae and nematodes. Some of the halophytic invertebrates
such as shipworms, are capable of survive in a brackish environment. They
inhabit depressions near pilings which do not come in contact with freshwater
during tidal exchange.
2.
Intertidal zone: The estuarine marshes are predominately colonized by Scirpus
species and Carex species. The distribution of these plants are dependent on
length of tidal flooding, drainage and importantly water salinity. Moody (1978)
found that the distribution of Scirpus and Carex are dependent on the
relationship of the elevation-tidal level. Cattails are found in areas with
freshwater influence. Various studies (Bradfield and Porter 1982, Hutchinson
1982) on the estuarine marshes have reported that the marsh community can
be grouped into distinct vegetation community zones: low, middle and high
marsh zones. These three zones have varied exposure to the tidal flooding.
3.
Upland zone: The uplands of the Fraser Delta prior to the first European
settlement were wooded; the dominant trees being broad-leaf maple, red alder,
mountain alder, Douglas fir, and western red cedar (North et.al. 1984). Since
then the area had been dyked and converted to agricultural lands. Some of the
grassland communities found in areas like the Sea Island, are typical of the
primary and secondary successions (Hoos and Packman 1974). Some of the
more abundant grasses are canary grass, rye grass, creeping bent grass, and
fescue. Waterfowls such as Canada Goose, Snow Goose, mallard, northern
pintail, American widgeon, green-winged teal, cinnamon teal, and gadwall
frequent these areas to -feed of the grass rhizomes, especially during
migrational stop-overs.
Disturbance
Erosion of the valuable Fraser Delta is the gravest concern to the land owners. The
first dykes were constructed to protect against erosion when European settlers
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66
started farming in the Fraser River Delta. Construction of dykes alters the marsh
vegetation communities considerably by increasing the gradient of substrates and
decreasing the intertidal zone. Boulders, rocks and mineral soils are placed along the
delta banks to elevate the land well above the high tide level. As an inexpensive way
to protect land, old vehicles were placed along the Fraser River banks.
Majority of the lumber industries are located along the Fraser River. The river banks
are commonly used for log storage. The logs have a major impact on the estuarine
marsh communities. Their lateral movement with the tidal exchange cause severe
compaction of the mudflats, and furthermore, cause extensive scouring damages to
the vegetation. Other industries that utilize the waterfront areas of the river are fish
processing plants; ship-building; towing, dredging, and pile-driving industries; and
building material plants that have converted some of the estuarine habitat into
industrial lands.
Shipping ports and docking facilities are the major waterfront users which are
directly built on top of the marshes. The river is dredged yearly to prevent upland
flooding and the dredgate used to raise the waterfront lands to the height of the
surrounding dykes (Hoos and Packman 1974).
Comments
Butler and Campbell (1987) reported that there are half a million birds estimated
each year to use the Fraser River delta whether foraging in the marshes or the
uplands. On the other hand, more than half of the freshwater species have been
recorded here, some of which are important food for birds. Interestingly, an area with
such a high ecological significance only has about 1% protection afforded by
government legislation. The "Ramsar" Convention of 1971 had listed several criteria
for identifying wetlands of international significance from which the Fraser Delta
with its associated habitats have been identified as such.
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Flora
Fauna
Eelgrass
Cattail
Lyngbyei Sedge
Bulrush
Rye Grass
Canary Grass
Creeping Bent Grass
Fescue spp.
Canada Goose
Snow Goose
Cinnamon Teal
Green·winged Teal
Mallard
Northern Shoveler
American Widgeon
Dunlin
Blue·winged Teal
Wood Duck
Greater Scaup
Bufflehead
Common Merganser
Herring Gull
Bonaparte' Gull
Brandt Goose
Great Blue Heron
Bald Eagle
Peregrine Falcon
Eulachon
Flounder
Juvenile salmonids
Sole
Sculpin spp.
Crab spp.
Clam spp.
Neomysis
Surfperch
Gunnel
Rockfish
Cabezon
Pipefish
Greenling
Tubesnout
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The Clearings
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ABANDONED LOTS
Physical Appearance
A grassland lot is basically an expanse of grass, possibly with some scattered trees.
The grassland will not have extensive shrub communities except in smaller, localized
clumps. The grass itself will be of many species, and of varying height, from a couple
of centimetres to a couple of metres, as a result of its successional age.
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Location
Urban grasslands are found most often in areas of recent disturbance. Because
grassland is one of the earliest seral stages it appears quickly on land that has had
the dominant vegetation removed. Grasses will be the first to colonize where housing
has been demolished, where agricultural grazing occurs, and in- areas where forest
or other later successional stages are destroyed. A somewhat rarer grassland type is
the climax grassland: an area of grassland that will remain grassland with no further
successional change.
General Description
Calling all regions of grass by the general term "grassland" is roughly equivalent to
calling all bodies of water "lakes". The range of grass species present in any given
area is vast, and identifying the dominant grass can be difficult. Considering that the
nature of any grassland is dependent on the species present, classifying grasslands
becomes a very difficult task. Other systems of classification have used soil type,
species type, or succesional type (Duffey et al. 1974) as the dividers between classes.
In an urban habitat the number of possible species should be lower and less
dependent on grass type. This classification will be based on the types of flora and
fauna found in relation to the grasses. These classes are:
1)
Grasses-only: This region is usually in early seral stage and has only
grass colonizers present.
2)
Grasses with shrubs: This area IS mid-seral with small shrub
communities and perhaps some saplings.
3)
Grasses with shrubs and trees: This is a later seral area with trees
beginning to change the seral stage to a forest stage.
A grasses-only grassland is usually found soon after disturbance; usually after a
couple of years. Wildlife species diversity here is low because the nesting
opportunities are restricted to ground nesters such as the ring-necked pheasant.
The addition of shrubs will enhance species diversity by allowing more nest sites and
a greater availability offood. Shrubs like scotch broom and butterfly-bush can attract
insects like bees and butterflies.
With the addition of trees to the grassland nesting opportunities may be available at
all levels. Tree nesters such as crows, warblers and robins may find suitable sites
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here. The trees add perching sites for hunters like owls who need the open grassland
to find voles and mice. Colonization by trees usually indicates the end to the
grassland as succesion has begun towards a scrub forest.
Soil is a major determiner of the type of grassland and the speed at which succession
will occur. Grassland soils can be wet and acidic to dry and basic and most
combinations in between. The species of grass present is determined by its ability to
tolerate the specific conditions present. Beside testing, the identification of indicator
species may allow a determination of soil type and the future successional path the
site will follow. An examples is California brome, a grass that prefers dry, nitrogenmedium soils (Klinka et al. 1989). On this site it is possible to predict the succession
will not be to trees prefering dry soil like the Ponderosa pine, but may proceed to a
black cottonwood forest then to a sitka spruce dominated forest. Indicator plants may
also be used to identify soil type, calcium and nitrogen content, wetness, and whether
it is water shedding or water receiving.
FLORA AND FAUNA
A grassland is a very open habitat with few perching sites for birds and limited cover
for larger animals. It is mainly used for foraging. Larger animals such as deer,
browse the grass and shrubs while hunters like owls, hawks and coyotes cruise for
small prey like field mice and voles. Many insects live in grassland and attract
insectivores such as cliff and barn swallows. Some species, voles for example, actually
nest in the grass, often under plywood dumped in the field. Interestingly, ring-necked
pheasants nest in the open grassland. As the grassland ages, the shrub communities
will colonize along with some tree saplings. This allows a diversity of wildlife species
to use the grassland, including tree nesters like the yellow-rumped warbler and the
black-capped chickadee.
An open grassland receives a lot of direct sunlight and provides good habitat for
manu shade intolerant wildflowers and weeds. Yarrow, Scotch broom, St. John's-wort,
fireweed, and Nootka lupine require open ground and direct sunlight to flourish
(Klinka et aI1989). Legumes such as Scotch broom and Nootka lupine are symbiotic
with nitrogen-fixing bacteria which enhance the soil, increasing the nutrient
composition making it favourable to other colonizers like the red alder. The openness
also allows the wind borne seeds of trees to take hold and germinate. For plants, the
main theme in the grassland is this type of succession: grass gives way to grass and
shrub, then tree s-eedlings colonize, until the grass is finally shaded out and the
grassland then disappears.
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Disturbance
Grasslands are often the result of earlier disturbance. A forest destroyed by fire is
usually succeeded by grassland, opening new opportunities for many plants and
animals. In this context disturbance is not undesirable because it breaks the monohabitat hold of the climax community and increases diversity. Unfortunately,
grasslands are also very open and accessible to the public and their use by trailbikers
and four-wheel drive trucks slow succession by crushing shrubs and trees. Further,
people find grasslands to be a very convenient place to dump garbage which may
include from old couches to discarded building materials.
Many grasslands are found in urban agricultural areas and are used as grazing
pastures. The repeated and frequent disturbance by farm animals maintains the
grassland at a very early seral stage. The grass often does not reach maturity and
may not pollinate. Overgrazing can create a completely barren land and with
increased erosion by wind and water.
Comments
In urban areas grasslands are frequently the few wild space left. As neighbourhoods
change, buildings may be torn down and the lots left vacant for several years
allowing a grassy place to sprout. Because of the increasing value of urban lands,
these grassy areas are usually short lived.
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AGRICULTURAL LAND
Physical Appearance
Agricultural fields are characterized by open spaces that have been tilled for the
purpose of growing crops. The land is typically uniform in appearance and one type
of crop is sown over large areas. Land design and color is dependent on the crop and
its cultivation requirements: corn is planted in parallel rows, cranberries are flooded
in trenches, and hops are hung from supports in their characteristic Y-shape.
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75
Location
Farmland is located in areas of high cultivation potential. This means that suitable
soil and climate requirements are present. Generally, agricultural fields are found in
valleys where soil and drainage make for acceptable growing conditions.
General Description
Agricultural fields may be divided into two general types for habitat classification
purposes:
1)
Zero or minimum grade: This is farmland on a low gradient so that soil
erosion is minimal. Soil and water qualities are maintained without
extreme intervention.
2)
Medium grade: This type of land lies on a slope and is subject to soil
damage by water erosion. Intensive integration is necessary to maintain
crop quality.
Zero or minimum grade land provides an ideal habitat for a large diversity of
organisms. Although this land is continually managed, the top layers of soil and
organic matter are retained. This is important because a large porportion of the
biodiversity is located here.
Land with a well-defined slope is subject to erosion and so species diversity may
fluctuate depending on the amount of rich soil available. Erosive action of water and
wind results in organisms found in the top layers of the soil profile to be washed
down the slope. Many of these microorganisms are important in retaining high soil
quality in terms of nutrient turnover, aeration, nitrogen-fixation, and plant hormone
production. Without them, maintenance and functioning of the soil deteriorates.
Soil fertility, a soil's ability to provide essential chemical nutrients for plant growth,
is perhaps the most important component of agricultural land. Fertility is affected by
a soi1's structure, texture and living components. In terms of structure, the topsoil is
the most important layer for farm crops because it contains life-sustaining nutrients
in their most readily available form. Maintenance of this layer is achieved by
mechanical plowing and fertilizing but deep-rooted crops also contribute by bringing
up materials from the subsoil, losing their leaves, or dying and so restore much of the
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76
nutrients to the topsoil.
Soil texture, determined by particle size, plays a fundamental role in terms of waterholding capacity and aeration capability. Soil water is dependent on the amount and
type of clay present, and on the amount of organic matter within the soil. Clay
particles, having a diameter of 2 microns, have a large amount of surface area
relative to their weight and, therefore, have the capacity to absorb water, other
molecules and ions on its surface (Brewer 1989). Organic materials also have this
property and cause the soil to aggregate. A soil deficient in clay or organic material
is structureless and does not hold together well. As well, if the clay component is too
high, the soil becomes hardpacked and impenetrable to plant roots.
Soil biota may be overlooked in its importance to maintaining high soil quality.
Organisms range in size from burrowing vertebrates to insects and to the microscopic
fungi and bacteria. They are vital in the breakdown, decay, and recycling of the
chemical constituents without which the soil would stagnate and crop yield and
production would deteriorate.
Important organisms such as the common earthworm survive best in moist, loosely
packed soil containing a large amount of organic matter (Andrews 1973). Worms are
important in that they allow for soil aeration by creating tunnels. This permits
oxygen to circulate throughout the soil, supplying it to the roots and shafts of
underground vegetation. Another important role of the earthworm is that they pass
soil that is rich in minerals up to higher levels, within reach of the surface roots.
Other important organisms of the Ao horizon are the enchytraeids, or white worms,
which are confined to this top portion of the soil profile. Their function is to coat
moist plant remains in the upper humus with a secreted alkaline solution. When the
plant tissues have dissolved, they can easily be eaten and the waste further mixed
into the humus (Andrews 1973).
Flora and Fauna
According to B.C. Erivironment (1993), in British Columbia, the Lower Mainland, only
4% of which is good farm land, has the best climate and soils. The type of crop grown
depends on the climate, soil substrate, and water availability.
Much of the cultivated land in the southwest portion of B.C. is planted in pasture and
feed grains but excluding this, principle crops are corn, potatoes, market-garden
vegetables and small fruits, especially strawberries, raspberries, and blueberries.
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77
Each crop requires different types of soils and varying amounts of nutrients and this
explains the reason for large areas of uniform crop-type. White potatoes for example,
require sandy, well-drained soil to grow. Strawberries are easily grown in any fertile,
well-drained soil with plenty of manure provided prior to planting. They are shallowrooted and so moisture must be maintained in the top 30 cm of the soil (Sunset 1973).
Hops, used in the brewing of beer, must be grown in areas having an abundant
rainfall during the growth period and sufficient sun during the fruiting period.
Usually planted in rows two meters apart, the plants are guided by strings suspended
above the rows (Funk and Wagnalls 1982). Corn must be planted in a series of
parallel rows to allow for pollen dispersal by the wind and these plants require
significant amounts of water and thrive on heat (Sunset 1973). Cranberry is
cultivated in sand-covered bogs that can be flooded or drained at will and this
protects the vines from frosts and destroys insect pests (Funk and Wagnalls 1982).
Weeds flourish well on agricultural lands competing for space and nutrients with crop
plants. Green smartweed, wild buckweed and purslane are common in rich cultivated
fields. Hare's-ear mustard, wild raddish, white cockle, and wild oats on the other
hand are quite troublesome in grainfields and hayfields.
As mentioned previously, the importance of soil biota is underestimated. Invisible to
the naked eye, microorganisms may, at times, be far more active in producing new
growth than we are aware of. The weight of bacteria alone in some soils has been
estimated at one ton or more per acre! (Desman 1976). Soil fungi may be more
abundant than bacteria especially in acidic soil and in the deeper regions of soil
where oxygen levels are lower and carbon dioxide levels higher. Like bacteria, fungi
are essential in the decomposition of organic matter such as cellulose and starch and
also breakdown protein which releases essential nitrogen compounds within the soil
(Desman 1976).
Macrofauna of agricultural land is diverse. Although it is true that the majority of
organisms are the annelids, nematodes, arthropods, and molluscs, there does exist
a population of vertebrates. Other animals that are attracted to agricultural fields
include birds, mice and deer which feed on soil organisms, crop fruits, roots, seeds
and leaves.
Disturbance
Three types of disturbance to agricultural land are soil erosion, soil degradation, and
urbanization.
Soil erosion is evident by obvious gullies formed by water flow or by bare mounds and
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78
is typical of sloping land and current agricultural practices (B.C. Environment 1993).
Erosion may partially or completely remove the vital topsoil and the underlying
subsoil. Ultimately, the result is poor farm production because water-holding capacity
and nutrient content become adversely affected. Another effect of soil erosion that
may be overlooked is the potential habitat destruction of nearby rivers. Increased
sediment loads carried from land by water may decrease stream habitat or dry the
stream completely.
Degradation is not as obvious as erosion but is just as damaging to productive
capacity of the land and crop yield. Caused by compaction, salinization, excessive
tillage, depletion of organic matter, and changes to the water table. Land degradation
leads to a reduced productive capacity of the land. Land degradation is often slow and
difficult to recognize because the changes are small compared to the changes caused
by climatic variations (Ministry of Environment and Environment Canada, 1993).
Soil erosion and degradation are of major concern and farmers have been encouraged
to employ new management techniques. The Canadian - British Columbia Soil
Conservation Program promotes conservation farming and includes reducing tillage,
the protection of winter and spring soil by covering with crop residues or clover,
improving the use of manure, and improved surface water management.
Cover crops provide good ground cover which protect the soil from the winter rains.
Apart from soil conservation and protection, the fields planted with cover crops also
provide habitats for a diversity of wildlife.
Farmlands of the coastal lowlands are important winter habitat for migratory
waterfowl, shorebirds as well as other wildlife. Wintering ducks such as American
wigeon use the fields and pastures as their main foraging habitat. With continued
urbanization and reduction of the number of farmlands, the utilization by waterfowl
is greatly affecting the crop production, and productive capacity of the land. In the
Lower Mainland, Greenfields Project was initiated to promote the widespread use of
cover crops in an attempt to disperse waterfowl grazing (Duynstee, 1992).
Urbanization is the largest threat in the destruction of agricultural land and the
habitat it supports. Between 1980 and 1987, 750 hectares of prime agricultural land
in the Lower Fraser Valley was permanently lost to urban uses (B.C. Environment
1993). The loss is significant and is provincially recognized. Created by the
Agricultural Land Commission, the Agricultural Land Reserve (ALR) role is to protect
the best land from urbanization. Lands under this classification cannot be used for
other purposes although some golf course use has been permitted.
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79
habitat it supports. Between 1980 and 1987, 750 hectares of prime agricultural land
in the Lower Fraser Valley was permanently lost to urban uses (B.C. Environment
1993). The loss is significant and is provincially recognized. Created by the
Agricultural Land Commission, the Agricultural Land Reserve (ALR) role is to protect
the best land from urbanization. Lands under this classification cannot be used for
other purposes.
Comments
We simply cannot afford to continuously urbanize at the expense of agricultural land.
Although the ALR recognizes this, it is interesting to note that in southwestern B.C.,
the area of farmland in the ALR decreased by almost 9% between 1970 and 1990.
Awareness and appreciation of the fact that land is nonrenewable resource must be
recognized.
Flora
Fauna
Oilseed
Grain spp.
vegetables
fruits
vine crops
sunflowers
Mourning Dove
Ring-necked Pheasant
Canada Goose
Mallard
White Goose
Brewer's Blackbird
American Tree Sarrow
Chipping Sparrow
American Goldfinch
Purple Finch
Brown-headed Cowbird
House Sparrow
Yellow Warbler
American Robin
Black-capped chickadee
Northwestern Crow
Western Kingbird
Rock Dove
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The Barren Landscape
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81
EXPOSED GROUND
Physical Appearance
This category consists of relatively large tracts of open areas with bare ground highly
disturbed by construction, excavation or fill activities.
1)
Demolition site: an area of compact soil where a building had been
demolished.
2)
River dredgate as fill on organic soil: areas of organic soil (peat) origin
require remediation for soil stabilization prior to construction. River dredgate
consisting of silt and clay is used to preload organic soil.
3)
Demolition and/or construction waste as fill on organic soil: another
type of preloading material. Instead of using river dredgate demolition and
construction waste are brought into the site and used as fill.
4)
Excavated mineral soil as fill on organic soil: mineral soil excavated from
another area brought in as a fill material.
These areas may then be left relatively undisturbed over a number of months to
years while awaiting the suitable land use designation, or purchase and later
construction of the site. During this period, plant pioneers such as the weeds and
grasses colonize the area and proliferate to establish their colonies in poor soil
conditions. There is little to no cover for wildlife in many these areas. With the
increase vegetation, there is an observable increase in wildlife population and
diversity.
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Location
These open ground environments can be found in industrially designated areas,
predeveloped areas, demolition areas and areas that are awaiting the changes in land
use designation from one category to another.
General Description
Being highly disturbed by intensive human activities, these areas can be considered
hostile to both plants and animals. Craul (1985) summarized the consequences of
man's activities on the area, in terms of its habitat potentiality.
1)
Great spatial variability. (i.e. open environments can range from 0.1 to 10 ha
in size)
2)
Compaction leading to modified structure.
3)
Presence of surface crust that is usually water repellent.
4)
Modified soil pH.
5)
Restricted aeration and drainage of water.
6)
Interrupted nutrient cycling and modified activity of soil organisms.
7)
Presence of contaminants and occasional manufactured materials.
8)
Modified temperature regimes.
Flora and Fauna
Early successional stages of vegetation is .strongly influenced by soil conditions,
especially nutrient availability (i.e. nitrogen, phosphorus, and potassium) and water
supply (Ash 1991). Furthermore, the presence of species pool available to each site
such as dislodged roots, tubers, and seeds, transported seeds and wind-dispersed
seeds play an important part in early vegetation succession.
a)
Areas with limited supply of water and nutrients: such areas include
demolition sites, and demolition/construction fill. The primary colonizers are
the weedy annuals and perennials. The annuals include rockets, ragwort,
mustards etc. The perennials include clovers, chickweed, crucifers, plantains.
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83
b)
Areas with severe deficiencies in nutrients and/or water: include areas with
highly compacted soils where there is no layer of loose material to act as soil
(Ash 1991). The major colonizers here are generally mosses, liverworts and
lichens which are capable of obtaining sufficient nutrients from runoff.
c)
Areas with undisturbed sandy soils: are usually colonized by lichens.
The colonizing communities may dominate the environment until the quality of soil
improves. Colonization by clovers tends to increase the rate of succession from
pioneers to grassland and on to scrub/woodland (Ash 1991). Clovers and other
legumes are nitrogen fixers which have the ability to fix atmospheric nitrogen,
especially with the presence of Rhizobium bacteria in the soil.
Colonization by animals is generally a continuous process (Gilbert 1989). The pioneer
species are typically mobile such as birds, butterflies, bees, spiders and other winged
insects colonizing the disturbed environments and establishing permanent
populations. The establishment of these populations are often observed to infest and
individual plant. A specimen of goldenrod may support a large population of aphids.
Birds such as Red-winged Blackbirds, Savannah Sparrows and White-crowned
Sparrows are observed utilizing the areas once the scrub stage is established.
The soil structure of these areas is dependent on the types of activities carried out.
1)
Demolition site: After demolition, sites are removed of all demolition wastes
and the ground levelled. Even though compacted, the substrates may have
considerable variations in particulate make-up and size. The soil is usually
slightly alkaline, and low in organic materials and nutrients (Gilbert 1989).
2)
River dredgate as fill on organic soil: River dredgate is composed of silt
and sand with an average water content of 50% (Klohn Leonoff 1992). Water
is released during the fill placement process and in 'time will decrease as the
settlement of the organic soil below is achieved. The physical properties of this
fill material has made it a popular choice as a fill material. Smaller-sized sand
grains with irregular shapes provides the fill with the ability of packing (i.e.
the ability of smaller particles to fit into the spaces between larger particles),
thus increasing the density (Mullins 1991).
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84
3)
Demolition and/or construction waste as IIlI on organic soil:
Composition of the wastes varies considerably from one site to another. The
type of materials brought in are dependent on the approved permits issued by
the provincial government.
4)
Excavated mineral soil as fill on organic soil: The mineral soil layer is
typically lacking the necessary nutrients to sustain vegetation growth, and is
more acidic. Furthermore, these area are considerably drier due to the
compaction process during the soil transport.
Disturbance
Soils in disturbed areas are compacted by heavy machinery during preloading,
excavation and demolition. Soil compaction is the process of reduction of the porosity
of a soil (Mullins 1991). Compaction cause the cementing of soil particles which create
a physical blockage for downward water drainage.
Trampling is one of the most common form of disturbance. People make footpaths as
a short-cut to their destinations. The first observable results from trampling are the
increase of certain perennial species which are tolerant to this form of stress. As
paths become increasingly trodden, bare patches become observable along with
compaction of the soil.
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85
Flora
Clover spp.
Grass spp.
Plantain spp.
Chickweed
Veronica spp.
Sticky geranium
Mustard spp.
Goldenrod
Horsetail
St. John's wort
Broom
Sedges
Curled dock
Blackberries
Dames rocket
Ox-eye daisy
Fireweed
Common thistle
Indian thistle
Sheapard's purse
Vetch
Fauna
Starling
American Robin
Northwestern Crow
Red-winged Blackbird
Killdeer
Savannah Sparrow
White-crowned Sparrow
Canada Goose
Raven
Barn Swallow
Cliff Swallow
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86
BRIDGE UNDERSIDES
Physical Appearance
Bridges are structures which provide continuous passage over a body of water,
roadway, or valley. They are constructed from a variety of materials of which wood,
steel and reinforced concrete are most common. There are three types of bridges that
may be found within an urban centre and each provides its own unique habitat:
A)
Causeway: Low road bridge over a swamp, shallow lake, or bay and
consisting of many short spans.
B)
Overpass: Relatively short bridges crossing highways or railroads.
C)
Viaduct: Bridge over dry land or over a wide valley, consisting of a
number of small spans.
Bridges range in length from a few feet or meters to several miles or kilometres and
may be classified as single- or multi-span.
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Location
Bridges can be found in areas of obstruction where roadways or other rights of way
need to cross. Rivers, canyons, valleys, other roads, and some tracts of land are
typical of obstructions that are bridged in urban areas.
General Description
Most urban centres have bridges which allow traffic to flow from one area to another
by easily crossing over obstacles such as bodies of water, railway tracks, or highways.
Of the types which cross over land, the area beneath the bridge may be classified
into:
A)
Areas of high maintenance: These sites are regularly maintained to give
a clean, manicured appearance. Such areas typically have public access
and activity.
B)
Areas of low or no maintenance: These sites are generally found
beneath bridges that have no access, are difficult to maintain due to
physical structure or rough terrain, or have no need for maintenance.
Under-bridge sites are referred to as harsh or stressed habitats in that they are
extreme compared with most of the biosphere (Brewer 1988). For example, conditions
beneath the bridge deck are generally drier, cooler, and darker. Soil is typically
compacted and consists of sand, gravel and rubble left over from construction of the
bridge. Such nutrient-poor soil and adverse climactic conditions may limit the
diversity of species. Indeed, in such habitats high populations of a few species may
be found because the resource range is narrow (Brewer 1988).
The heights and widths of bridges are two important factors determining the presence
and abundance of flora and fauna. In general, low bridges (less than 20 ft) display
little diversity because of the extreme shading. Bridges higher than 120 ft allow more
light and greater plant diversity but height also restricts nesting potential, keeping
fauna variation low. Cliff-dwelling birds such as Cliff Swallows, and typical urban
bird species such as pigeons (Rock Doves) and European Starlings inhabit taller
bridges. Occasionally a tall bridge may be home to a Peregrine Falcon. Cliff swallows
prefer bridges made of concrete (mud nests attach more securely and are protected
by overhangs) and those sites which span bodies of water (swallows take their food
on the wing (Harrison 1984) and insects are often plentiful in air above water).
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88
Bridges of intermediate height and those that are bordered by diverse habitats
provide the greatest diversity. Barn Owls for example, can be found nesting under
concrete bridges surrounded by grasses and shrubs where rodents such as mice and
voles may be found.
Flora and Fauna
Ecotones, transition zones between two ecosystems, may occur between the underbridge habitat and the surrounding habitat. Unmaintained or ignored sites encourage
a diversity of species. Most ecosystems beneath bridges are highly stressed with
relatively few species whereas the surrounding habitat may be diverse in comparison.
The size and composition of the plant community are largely determined by two
factors, stress and disturbance (Bullock and Gregory 1991). Soil quality in harsh
habitats typically does not improve because establishment of early successional stages
is problematic. Stress-tolerant species such horsetail and hardier grasses are capable
of surviving harsh conditions. Horsetail is unique in that it is capable of exploiting
areas where there is no interspecific competition (under a bridge) and is a good
example of an edge species, found in the ecotone and surrounding area.
Disturbance
In situ site contamination from construction debris and waste disposal may stress the
under-bridge ecosystem to the point of non-regeneration. Vehicle emissions and
bridge-deck maintenance may affect the habitat in indirect ways. Rate of deposition
of contaminants decreases with distance from the ground (Bullock and Gregory 1991).
Possible effects include stunted growth of vegetation or if disturbance is severe, a
reduction in species diversity.
Comments
Bridges provide habitats that may not otherwise be available to animals within urban
centres. Enhancement of under-bridge environments, such as nesting boxes, can be
done easily and has the potential of increasing species' diversity.
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Flora
A)
Fauna
Intermediate Bridges
various grasses
Horsetail
Vetch
Clover
Barn Owl
Rock Dove
Cliff Swallow
Starling
Red-tailed Hawk
Cliff Swallow
Red-winged Blackbird
Raccoon
Vole
B) Tall Bridges
Clover
Common Thistle
Vetch
Phagmites (grasses)
Blackberry
Tall Lettuce
Scotch Broom
Horsetail
Yarrow
Buttercup
Dandelion
St. John's Wort
Bindweed
Ox Tongue
Tansy
Crucifers (mustards)
Urban Habitats
Invertebrates
Spiders
Pill Bugs
Wood Bugs
Bumblebee
90
TOXIC INDUSTRIAL LANDSCAPES
Physical Appearance
Toxic industrial landscapes occur throughout the city in industrial parks, building
sites, and dump sites. They are frequently found around the periphery of residential
developments or business districts, or in more remote areas but still within easy
driving distance of the city center.
Location
Because cities have grown so much over the last few decades it is not unusual for
residential and business districts to sprawl around industrial sites which originally
were on the outskirts of the historical city limits. This creates a situation where these
contaminated sites pose problems for residential and commercial development. The
Pacific Place site in downtown Vancouver is an excellent example of such a situation.
General Description
Waste materials in urban soils are described by Bridges (1991, In: Soils in the Urban
Environment edited by Bullock and Gregory). The types of chemical contamination
depends upon the nature of the waste materials present. These waste materials
reflect the type of construction and industrial activity carried out on the site.
1.
Buildings: Building construction obviously creates considerable physical
disruption to the soil, and invariably involves completely removing the topsoil,
which mayor may not be replaced later on. The physical disruption aside, a
number of building materials and practices introduce chemical contaminants.
One common impurity on a building site is plaster or gypsum (calcium
sulphate). The sulphate and its various chemical forms can alter the soil
chemistry, making the site uninhabitable by native flora and fauna.
Waste asbestos may also be a problem. This is especially true of former railway
land, shipbuilding yards, power stations, scrapyards, and former asbestos
works where the asbestos is present in thermal insulation materials and brake
pads. In developing land with asbestos present there is always the danger that
it will be inhaled.
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91
2.
Metal industries: Some industrial activities involve smelting and metal
manufacture. Although contaminants are not as abundant as around smelters
with their metallic slag and soils polluted by leachate, they may nevertheless
exceed acceptable levels. Copper, lead and zinc are the more common metals
which may leach from industrial sites working with metals. The contaminants
may also leave the site as fine particles blown by the wind.
3.
Power stations: Coal-burning power stations do not occur in the Lower
Mainland, but they are near some cities in other parts of the world. They
release an ash composed of particle sizes 60% in the fine sand range (0.2-0.02
mm), and 40% in the silt range (0.02-0.002 mm). The ash itself is composed
of silica (48%), aluminum (26%), iron oxides (10%), and small amounts of
residual chemicals such as boron, chromium, and molybdenum.
4.
Carbonization plants: These industries are involved in the manufacture of town
gas, tar and coke, and again do not occur in the Lower Mainland. Gasworks
are also not very common any more because of more abundant supplies of
natural gas. The spent oxides from gasworks were usually disposed of on site;
they are strongly acidic and contain ferric ferrocyanide, as well as the
impurities removed from the gas such as hydrogen sulfide, cyanide and
ammonia. Coal tar contains many toxins: benzene. toluene, xylene, styrene,
cresol, phenols and fluorene, to name just a few.
5.
Oil spills and wastes: Gasoline may leak from underground pipes and storage
tanks at gasoline stations. Small spills from oil changes and gasoline fillups at
the pump, and more serious larger spills from accidents to oil and gas truck
carriers, together result in significant quantities of these contaminants
entering urban soils, especially near the sources. If the gas and oil reach the
water table they can move laterally through the soil for some distance.
Waste oils pose an additional problem in that they contain the contaminants
from the processes in which theywere.used. Waste oils are sometimes sprayed
directly onto dirt roads to keep dust down. In one incident at Times Beach,
Missouri, such oils were contaminated with dioxin and the town was no longer
fit for residence.
6.
Chemical wastes: The problem of chemical wastes in urban areas was
highlighted in 1978 with the Love Canal disaster. A chemical company had
dumped 148 neurotoxins, pulmonary toxins, hepatotoxins, renal toxins,
carcinogens, teratogens and embryotoxins into the Love Canal site, including
benzene, carbon tetrachloride, and hexachlorocyclohexane.
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92
Some chemical wastes produced by industry include: toluene, xylene, lead,
cadmium, and zinc from dyestuffs; chromium in the manufacture of leather
and special steels; benzene, alcohols, ketone, and esters in the chemical, paints,
and dyestuffs industries; copper, nickel, cobalt, strontium, barium, and
mercury in metallurgical work; trichloroethylene and chloroethylene in paper
making, metal plating, chemical engineering, laundries, and dry cleaners; and
dioxin which are a contaminant produced in the manufacture of several organic
pesticides and from burning plastics at low temperatures. Saw mills have
chlorophenols on site for preserving lumber. Earlier in the century the wood
preservative was copper arsenate, leaving an arsenic contaminant in the soils.
7.
Railway lines: Along rail lines contamination is usually minor, with more
serious concerns arising at the railyards. Oils and degreasing fluids are
common, along with paint residues, solvents, asbestos, and residues of
polychlorinated biphenols (from the destruction of old electrical equipment).
8.
Scrapyards: These may contain some of the most highly contaminated soils in
urban areas. Contaminants include cyanide, chlorides, fluorides, acids, alkalis,
and PCBs.
9.
Landfills: Although domestic waste is not highly contaminated, it does contain
cadmium, copper, lead, mercury, nickel, copper, zinc and asbestos. There may
also be illegally disposed of hazardous materials. Landfills can be dangerous
in that they can release methane gas and leachate for many years.
In British Columbia standards were developed as guidelines for the cleanup of the
Pacific Place site downtown (Ministry of the Environment 1989).Three levels of
remediation standards were established depending on the seriousness of the problem.
Flora and Fauna
Many of the problems caused by chemical contaminants result from chronic exposure
and generally do not repel plants and animals. The flora and fauna would be expected
to be similar to other barren ground sites. However, the ch-emicals may kill some
bacteria and invertebrates (earthworms, slugs, snails) in the soil. In addition to their
absence, there may be food chain effects.
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93
Derelict Landscapes
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94
MASONRY RUBBLE
Physical Appearance
Vacant lots with brick and concrete rubble are areas where buildings once stood. The
buildings have long been demolished and removed from the site. What remain here
are broken concrete and asphalt slabs. Interestingly, majority of the demolition areas
in the Lower Mainland of Vancouver, the building debris is quickly removed from the
site. The debris is often transported segregated into usable and unusable wastes. The
usable wastes are recycled and used in other construction sites such as steel and
other metals. The unusable wastes such as broken bricks, concrete and asphalt slabs
are usually used as fill on unstable ground prior to development. Other wastes such
as gypsum boards, building insulations and asbestos are transported to the local
transfer station for their removal.
The vacant lots may have some small rubble piles with concrete, brick, rock and
asphalt composite on topsoil. For example, an old school site may once have a
playground made of gravel. When left unattended and undisturbed over a period of
time, colonizing species, both plants and animals invade the site and proliferate.
These species initiate the ecological succession processes where they are succeeded
by more efficient species once the nutrient status of the site improves.
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95
Location
These vacant lots can be found in areas where demolition and removal of buildings
has occurred leaving only the concrete pads and some rubble composite. Areas that
are undergoing some changes in their land-use designations may demolish the old
buildings on the site creating an open space for the construction of the new ones.
Properties that have been ravaged by fire are often demolished and removed from the
site for safety to the adjacent neighbours. The owners may leave the property vacant
until such time when development of his property is feasible or affordable.
General Description
The vacant lots often left undisturbed for a number of years before redevelopment.
These area are quickly colonized by a wide variety of plants and their associated
wildlife. Physical and chemical status of the areas are often the restrictive factor in
their propagation. The various vacant lots found throughout the urban centre have
varying constituents of building material debris. Furthermore, size of the debris and
the degree of stoniness are important in determining the extent of vegetation growth
and propagation. Vacant lots located along Columbia Street in New Westminster have
large patches of exposed ground with some form of top-soil material and scattered
brick fragments and broken concrete. Here, there is a tremendous diversity of plants
including weeds, wildflowers and saplings of deciduous trees and shrubs.
Demolition areas have soils usually dominated by brick fragments, broken paving
slabs, and broken concrete of varying sizes and weight. Compaction of the soil is often
difficult owing to the physical characteristics of the composite materials previously
mentioned. Therefore, these materials create spaces and air pockets which contribute
to easy drainage of water as well as being highly aerated; both factors promote
rooting of the colonizing plants. Eventually, these areas can support a highly
productive environment in urban centres.
The nutritional status of these areas are usually poor and imbalanced with an excess
of certain elements and lacking in others. Concrete is made up of mortar, sand and
gravel; when degraded by the weathering process contribute calcium to the
environment. Bricks are commonly made out of clay which has a high concentration
of phosphorus and magnesium originating from the decayed organic matter found in
clay (Gilbert 1989). Weathering of brick materials release phosphorus into the soil
adequate for plant growth even in areas with considerably high pH (Gilbert, 1989).
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96
Nitrogen in the soils of the demolition sites is usually deficient and inadequate for
plant growth. The common sources of nitrogen comes from wind blown organic debris
(leaves, insects etc.) or brought in by rain. Accumulation of organic matter then
functions as nitrogen pool made available by the decomposition process. Nitrogen
fixing plant (legumes) along with their symbiotic Rhizobium bacterium are capable
of fixing atmospheric nitrogen and making it available to the soil.
Flora and Fauna
Vegetation growth is dependent on the nutrient status of the soil medium. The soils
in these areas are typically deficient in nitrogen, but has adequate phosphorus
content (Bradshaw and Chadwick 1980). The early seral stage is dominantly colonized
by short-lived annuals and perennials. Plants with nitrogen-fixing abilities such as
the clovers, vetch, trefoils, wild pea and medic quickly invade and proliferate. Their
presence have been reported by Bradshaw and Chadwick (1980) to accelerate the
succession from pioneering colonizers to the next seral stages. Some crucifers,
goldenrods, horsetails and plantain have been observed to grow in association with
the clovers. Gradually, these plant are out-competed by grasses and within a few
years of limited disturbance, the areas appear as meadows of tall grass with clumps
of herbs.
The wildlife colonizing these areas are often mobile such as winged insects, birds,
feral cats and dogs. These animals are transitory in which their presence here are
attributed to the presence and abundance of food. In the initial seral stage,
herbivorous winged insects invade the areas and utilize the colonizing plant as their
source offood. Lazenby (1983,1988) found that ground beetles (Carabidae) are among
the first insects to colonize and establish their population. in the rubble in the.
demolition sites. The changes of vegetation composition with succession is quickly
followed by the changes in the wildlife diversity. Vole runs become observable in the
grassland stage and the presence of birds are influenced by the availability of cover
provided by trees and shrubs.
Disturbance
The survivability of these vacant lots are almost all dependent on the owner of the
land. Vacant lots with some weed or other "wasteland-type" vegetation are considered
as unaesthetic in urban centres. Quite often, these areas are redeveloped as soon as
it becomes feasible and affordable to the owners. Therefore, majority of the vacant
lots do not undergo successional changes past the tall herb or grassland stage.
However, some areas with undecided land-use designation may have escaped
redevelopment and remain relatively undisturbed. The common type of disturbance
Urban Habitats
97
is garbage dumping. The garbage dumped here is usually made up of materials that
are difficult to get rid of such as furniture, household appliances, carpets,
lawnmowers, etc. These items are heavy and usually metalliferous in origin that do
not degrade readily. They impede vegetation growth and they contaminate the soil
with metallic oxides released from their degradation. There are the occasional
household organic debris which end up in vacant lots creating the increase in
numbers of unwanted urban pests such as feral cats, dogs, and raccoons.
Furthermore, the household refuse degrade creating eutrophication of the immediate
area.
Comments
Although perceived as unaesthetic in the urban centres, vacant demolition sites are
ecologically interesting and may be one of the productive ecosystems. They harbour
a wide diversity of plants as well as wildlife. These areas undergo rapid successional
changes giving rise to different vegetation communities along with their associated
wildlife.
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98
Flora
Fauna
Sweet White Clover
Pink Clover
Tall Buttercup
Rough Ox-tongue
Goldenrod
Vetch
Common Dandelion
Giant Horsetail
Common Thistle
Ox-eye Daisy
Barn Swallow
Tree Swallow
Purple Finch
European Starling
White-crowned Sparrow
Savannah Sparrow
American Robin
Brown-headed Cowbird
House Sparrow
Brewer's Blackbird
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99
ROCK DEBRIS
Physical Appearance
Open areas of rock and gravel composite on sand or top soil. These areas range in
size from 2 - 3 m along roads, or an empty lot. The excess rock and gravel are usually
pushed to the side after the completion of road construction. This space is graded and
levelled to create road-side parking for vehicles. The empty lots are often areas that
are not yet developed or areas that have not been included in the development of the
adjacent areas. Furthermore, these areas are left empty or vacant to create parking
lots. Again excess rocks and gravel from the constructions on the adjacent lots are
pushed into the vacant lots. In some areas, the rocks and gravel may not be graded
and levelled; they may have been left in mounds and piles. This may create
interesting niches of a variety of vegetation growth.
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100
Location
These open areas of rocks and gravel can be found along some residential roads
commonly used as roadside parking. There are some vacant lots with rock and gravel
as mineral base located adjacent to development area. Some vacant lot may be part
of the development complex awaiting for future construction project to initiate.
Occasionally, they can also be found under electrical towers. Some parking lots are
constructed using rock and gravel as the top layer instead of the costly and labour
intensive asphalting.
General Description
Areas with rock and gravel exposed as top mineral layer are usually areas that have
been severely disturbed from construction activities. Rock and gravel are primary
construction materials used in concrete production and road construction. Once after
the construction has been completed, the excess rock and gravel are pushed to
adjacent vacant lots and road sides.
Soil
Bare rock are commonly colonized by mosses and lichens such as the crustose lichen.
These plants excrete chemicals which aid in the degradation of the rocks and enable
them to extract nutrients from the rocks. These activities contribute to the
weathering of the rocks which is the basis of soil production. Furthermore, the dead
organic matter of the mosses and lichens contribute to the humus accumulation in
soil which enhance the rock weathering process. Other organic debris are brought
into the area by wind and rain which are lodged amongst the moss and lichens.
Flora and Fauna
Majority of the large vacant lots are left undisturbed for a period of time during
which colonization by pioneering species, initially by mosses and lichen. Their rock
degradation process is outlined in the previous section. Other herbaceous plants and
grasses that have been introduced to the areas via wind, rain and stored roots and
seeds begin to take hold and germinate in the thin layer of soil. Many of the legume
colonizers namely white sweet clover, yellow clover, pink clover, and lupine are
capable of fixing atmospheric nitrogen contributing to and increasing the levels of
nitrogen in the nutrient-poor soil.
Honey bees frequent the patches of clover collecting nectar. Winged aphids invade
these first seral communities and form stable populations of the vegetation. As their
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population increases, their predators such as the ladybugs follow suit. These open
areas are frequented by starlings, savannah sparrows, white-crowned sparrows, house
sparrows and crows. Domestic cats often visit these areas during their daily prowl.
Disturbance
These areas are commonly left undisturbed while awaiting development. At the
commencement of construction, all the vegetation is removed from the site and the
ground levelled and graded. On road verges, the vegetation is constantly exposed to
exhaust emissions. Furthermore, these linear spaces which are commonly used as
parking, are compacted by the weight of the cars. Over a period of time, the substrate
becomes cemented and impenetrable by the roots of vegetation.
Comments
Although these areas have extreme environmental features, they are quite quickly
colonized by lichens and mosses. These specialized colonizers are essential in the soil
formation process which allow other plants to stabilize their roots and proliferate.
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Flora
Fauna
Crustose Lichen
Moss
Sweet White Clover
Pink Clover
St. John's Wort
Savannah Sparrow
White-crowned Sparrow
European Starling
Invertebrates
Lady Bugs
Aphids
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The Paved Landscape
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BUILDINGS AND PAVEMENT
Physical Appearance
Buildings, concrete and metal structures, open plazas, parking lots, and high-rise
tower blocks are an integral component of the urban landscape. Whether concrete,
brick, glass or wood, buildings provide the general populace with shelter,
accommodation, work-place as well as recreation. Energy transfers in the urban
centres rely on the support structures: metal, wood, concrete, etc. All these structures
are the product of economic forces created by man-power available to the city.
Although, their creations are often perceived as cold and sterile landscapes commonly
illustrated as in the term "concrete jungle". From an ecological point of view, such
environments are unique which are capable of supporting various wildlife and plants.
These natural invaders are typically opportunistic and often characterized as pests.
Alas, these species do contribute to the overall complexity of an urban ecosystem.
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Location
Humans are builders! Urban centre occur at the nucleus of human economic
successes with suburban communities surrounding it. Urban centres can encompass
a lange expanse of land interconnected by vehicular thoroughfares, and supplied by
energy extracted from the earth.
General Description
Where do all these urban wildlife live? Like humans, they also take refuge in manmade structures like buildings. Urban centres with numerous building are somewhat
analogous to rock cliff environment, both are harsh environments but are capable of
providing excellent habitat for wildlife. Like the ledges on cliff faces, buildings and
other structures have many crevices, openings and designed holes or pockets which
can function as their homesites. Energy transfer towers serve as excellent perching
sites. Occasionally, in sheltered parts of the towers, bird nests are observable. The
following describes some of the areas that are frequented and utilized during their
foraging, roosting, and nesting activities.
1.
Basements: underground or partially underground areas of buildings with
limited openings or access to the outside.
2.
Underground and covered parking lots: dark, covered areas where access is
unlimited.
3.
Industrial buildings, warehouses, and storage facilities: high-ceilinged
buildings with ample hiding, nesting, roosting, and perching places.
4.
Ledges: analogous to the ledges of cliffs having platforms that are often usea.
as communal roosting and nesting.
5.
Smaller crevices and holes: created by dilapidated roof tops and spaces
between roof tiles and buildings.
6.
Docks and wharves: mooring and shipping centres. Underneath the platforms
are large covered areas excellent for accommodating large populations of
mammals.
7.
Towers, pylons and dolphins: tall structures, some with platforms and others
with cross-bars which are commonly used by birds.
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Flora and Fauna
Dorney (1979) showed that city centres are capable of supporting a higher breeding
bird populations than other areas. These birds are highly opportunistic and are
capable of exploiting the urban landscape to their benefit. Feral pigeons favour
buildings with ledges for communal roosting and utilize the sheltered crevices and
holes for their nests. They forage in commercial centres, food and beverage
establishments, and open spaces frequented by people. The pigeons are efficient
scroungers, always at an arm's length away from their benefactors. They are also
common on railway tracks and at train transfer stations foraging for the dropped
seeds.
European starlings originally from Europe, have stable populations across North
America. They are common birds in urban and suburban areas. They often flock in
large numbers while foraging, roosting and nesting. They nest in the urban trees and
also on ledges and crevices of buildings. Crested myna, native to China was
introduced to Vancouver early in the 20th Century. They had successfully established
three population groups; one in New Westminster, Marpole area and around the
intersection of Kingsway and Broadway St. They also commonly nest on buildings as
well as some of the urban trees.
House sparrows, another group of urban birds, are the most dependent on man for
their survival. They utilize the smaller cracks and crevices of buildings for their
nests. Occasionally, they nests in nest-boxes built by the compassionate birders. They
forage in city parks, on sidewalks, linear grass-lanes as well as areas of human
congregation. They compete well with other urban birds, expeditiously foraging in
flocks.
Another common resident of the urban centres is the Northwestern crow. Scavenger
by habit, they congregate landfills, where there are easy excess to the litter barrels,
and frequently feeding on road-kill victims. Generally, they are solitary birds,
occasionally flocking when there is a large source of food or chasing away the large
predators like the red-tailed hawks. They usually nest in trees, however in treeless
areas, they may nest on tall towers with platforms.
Mammals of the urban centres are feral cats, house mice, rats and raccoons. These
mammals are scavengers by habit often are considered as wildlife pests in cities and
towns. The Society for the Prevention of Cruelty to Animals (SPCA) traps the feral
cats, thus controlling their populations, but most frequently become the victims of
road-kills. The Norway and Black rats are originally from Europe, accidently
transported on cargo ships. They can be found in large numbers under wharves,
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107
docks, in the sewers systems and service ducts. They are voracious feeders that can
consume anything and can cause serious damage to buildings. Raccoons, surprisingly
have adapted well to living in urban centres. They utilize the storm drainage
systems, culverts, and the sewer systems as their homesites and passageways from
one foraging site to another. They often favour wetland environments, and have been
observed around the Lost Lagoon area in Stanley Park. Being omnivorous, their
feeding habit depends on the type of the available food and commonly scavenge for
food in garbage bins.
Dark and damp parts of buildings such as basements are ideal habitat for
invertebrates. Cockroaches, a common household pest, are nocturnal and scavenge
for food in garbage bins and kitchens. Silverfish and firebrats (Thysanura) feed
mostly on starchy materials. They are attracted to starch in glues and laundry starch
thus causing serious damages in libraries, as well as linens, draperies and clothing.
The common house fly is one of the commonest insects found all over the world.
House flies multiply rapidly and can establish a viable population in a matter of days.
They are carriers and transmitters of diseases as well as transport pathogenic
organIsms.
The urban centres are landscaped beautifully with ornamental plants and trees which
are regularly maintained. Urban centres are harsh environments for wild vegetation.
They have to cope with periods of extreme heat and drought. They are constantly
exposed to pollution from exhaust emissions. Species of lichens invade the concrete
faces of buildings, road and highway barriers. There are various weeds found growing
in sidewalk cracks and in some open spaces. Some grass species have colonized some
of the old gravel roof tops of buildings.
Disturbance
Urban centres are constantly undergoing changes or redevelopment, whether
demolition of a dilapidated building, renovation or construction of new ones. The
wildlife here are generally kept under control by pest management programs or
exterminated by professional exterminators. Weeds in urban centres are considered
as unaesthetic and often removed.
Comments
City environments, at a first glance are perceived as sterile and incapable of
supporting wildlife. Mammals, birds, and invertebrates invade these harsh
environments and adjust their habits enabling them to exploit the human successes.
These opportunists become dependent on humans for their survival. Often regarded
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as urban pests once their population becomes uncontrollable.
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Flora
Fauna
Lichens
St. John's wort
Broad-leaved Plantain
Common Dandelion
ornamental trees and flowers
European Starling
Crested Myna
Northwestern Crow
House Sparrow
Norway Rat
Brown Rat
feral cats
Raccoon
Invertebrates
Silverfish
Firebrat
Common House Fly
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CONTAINERIZED HABITATS
Physical Appearance
There are several types of containers widely used by gardeners and landscapers to
grow flowers, vegetables and herbs. They can be made out of wooden planks or even
rotted out tree stump, red clay, concrete, ceramics and bricks with varying sizes and
shapes. These containers are available at several specialized garden centres and
manufacturers.
Wooden barrels have grown increasingly popular as garden containers. They have a
large enough space to plant several types of shrubs and flowers. Large clay pots and
concrete containers can be used to plant small trees such as an Indian rubber tree,
hibiscus and fucias.
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Location
Containers are common in open plazas, concourses, lobbys oflarge offices, hotels and
apartment buildings. People with little or no ground space often do their gardenings
in containers. Their available gardening space is often restricted to balconies,
entranceways, and patios. Further, container gardening often accentuate the beauty
of a landscaped residence.
General Description
The types and sizes used varies with the type of gardening and purpose.
1.
Vegetables and herbs: Vegetables are commonly grown by individuals to
complement their produce. Vegetables are best grown in large, well drained
containers and slightly raised above the ground. They are easily constructed
using wood planks. Each vegetable determines the size and style of container
it requires for adequate harvest (U.S. Department of Agriculture 1977). For
example, deep half barrels and wooden tubs are best for growing crops that
produce large root systems like tomatoes, corn and beans. Herbs can be grown
in smaller and shallower containers such as window boxes.
2.
Flowers: They can be planted in hanging baskets or pots, long boxes, as well
as different sized clay pots.
3.
Shrubs: They require moderate to large containers that are deep to
accommodate root growth. There are many varieties of shrubs that do well in
containers. Open concourses and plazas often have large containers of
rhododendron and azalea varieties.
4.
Small Trees: Dwarfvarieties of fruit trees are well suited for container gardens
with a few flowers as ground cover. Offices with large foyers offer a suitable
climatic and moisture regime for exotic tropical trees.
5.
Water Plants: Containers can be constructed large enough to maintain pond
habitat.
The soil is usually obtained from a mixture of composted manure, washed (clean)
sand, sterilized garden topsoil, and peat moss or bark mulch. Soilless mixtures
specially formulated for containers are commonly used by landscapers. The mixes are
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112
usually lightweight and absorbant yet fast draining. Addition of fertilizers are
required before planting and regular fertilizing regime is needed throughout the
growing season.
Flora and Fauna
Several types of flowers suitable for various types of containers. Petunias, fushias,
geraniums, lobelias, as well as ivy are commonly grown inhanging baskets which are
very attractive to hummingbirds. Seasonal bulbs add beautiful colours as each season
progresses. Marigolds do exceptionally well in containers adding colours under shrubs
and dwarfed trees.
Native shrubs such as red-osier dogwood, salal and oregon grape are also commonly
used not only because of their easy care and maintainence, but they growth habits
are aesthetically pleasing.
Birds are usually attracted to the different colours. Butterflies are especially
attractive to sweet-smelling flowers that advertise the presence of nectar. Wasps and
bees are common pollinators of compositaes such as chrysanthemums and daisies.
Spiders spin their webs in the small branches of shrubs and trees trapping insects
in flight.
Disturbance
Diseases, insect infestations and lack of care are the major disturbance to this type
of habitat. Both tomatoes and potatoes are affected by tomato blight which is caused
by spore-forming fungus. Aphid infestation is common in roses, some vegetable crops
such as lettuce, cabbage and broccoli. Butterfly larva (caterpillars) do the most
damage to plants; they frequently chew large holes in leaves and flowers and
seriously interfering with growth. Beetles such as the cucumber beetle and the
Japanese beetle are vericious pests both as adults and larva (Lenanton 1980).
There are also many beneficial insects that are predatory and parasitic to insect
pests. They are the ladybug, praying mantis, lacewing, syrphid flies, and parasitic
wasps (Laenanton 1980). Birds and frogs are also helpful in controlling insect pest
population down.
Smog can cause major damage to some delicate flowers and vegetable crops such as
lettuce and tomatoes.
Comments
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ALLEYS AND LANES
Physical Appearance
Alleys and lanes are a variable habitat. They can be stark environments as occurs
downtown where there is no vegetation, the ground is paved, and there is frequent
disturbance from cars. In the suburbs the lanes may have grass on the ground, and
there would be vegetation lining both sides; disturbance from cars could be minimal.
These are linear environments which act as corridors for the movement of wildlife
through the city.
III
I JlI
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Location
Alleys and lanes are common throughout urban areas in the Lower Mainland. They
occur in all types of land uses - residential, commercial, and industrial.
General Description
Several distinct categories of lanes and alleys can be distinguished reflect the flora
and fauna which might occur in each.
1.
Downtown alley: In downtown Vancouver the alleys are typically paved and
extend completely surrounded by buildings. There is no natural vegetation
except for the occasional tuft of grass or patch of weeds growing in cracks. The
only source of food would come from discarded foodstuffs in dempsters and
garbage cans.
2.
Residential alley: This type of environment is found in most residential areas.
It mayor may not be paved. The garages of houses back onto the alley, and
garbage cans are frequently stored along its borders. Vehicle traffic is sporadic
but never heavy. The backyards of houses also line the edges and they are
frequently planted with shrubs and trees to afford some privacy.
3.
Lanes: These occur in less densely populated areas of the Lower Mainland.
They are characterized by having very little vehicle traffic and they are usually
not paved. They are more natural than the alleys and are usually only
distinguished from the adjoining environment by a fence.
The alleys and lanes, along with natural corridors such as streams and ravines or
artificial corridors such as railway lines, provide a continuous network of passages
for wildlife to travel through the city. Coyotes, skunks, and raccoons regularly use
them to gain access to foraging sites in the heart of business and commercial districts
downtown. The numerous perches and hole-nesting or "cliff-like" nesting sites
provided by the buildings, utility lines, and garages attract many urban bird species
such as pigeons, European Starlings, House Sparrows, and House Finches.
The residential alleys attract feeding flocks of Black-capped Chickadees, Bushtits,
and Dark-eyed Juncos which enjoy foraging on the trees and shrubs along these edge
environments. Northern Flickers are also found in this habitat. People frequently
plant berry producing plants which also attract Cedar Waxwings and American
Robins. If the alley is close to a large open field or a larger urban park (such as
Burnaby Lake Regional Park), black-tailed deer may also wander through.
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Alleys and lanes may also attract less desirable species. Rats and mice are usually
found here in association with the garbage, backyard composts, and the many hiding
places provided by wood piles and garages.
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Spotted. Skunk
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The Corridors
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LINEAR RIGHT·OF·WAY
Physical Appearance
Utility corridors are undeveloped linear plots through urban areas that are necessary
to allow safe passage of power lines, gas pipelines, water mains, and sewer. A utility
corridor is usually overgrown with a shrub community or covered by maintained
lawn. Signs along the corridors usually indicates the type of corridor and hazards
present. A power corridor is easily identified by tall metal structures with large wires
connecting them. The high tension wires are often accompanied by a low humming
sound. Gas and sewer corridors tend to be open land with the piping buried beneath.
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119
Location
Utility corridors can be found by finding the source of the utility, like a power
generating plant, natural gas producing or processing plants, or sewage treatment
plants. The corridors radiate from this point, with smaller corridors branching from
these main corridors. The main corridors can be found traversing most urban and
rural habitats, including mountains and valleys, or over rivers and gorges. The
smaller branch corridors are more common in urban areas, where they carry the
utility to the regions where they are used.
General Description
Utility corridors transect many urban habitats and the maintenance level of these
corridors is dependent on their type and location. Buried corridors are maintained as
trails and walkways in some areas and allowed to be overgrown in others. Power
corridors are usually minimally maintained, but where they cross developed urban
areas, like Eagle Ridge park in Coquitlam, they can be maintained as playing fields
and parks. These maintained areas would best be classified with the grassland
environments (see "Grassland Environments" p. ). The regions with some
maintenance can be classified by the type of habitat present, and the utility type:
la)
Above ground, minimal maintenance: This utility corridor has an above
ground pipeline or power line and is maintained every few years to
prevent trees from overgrowing the utility. Dominant vegetation will be
shrubs and deciduous saplings.
2a)
Buried, no maintenance: This utility corridor will be undergoing
succession towards the dominant vegetation of the region; either
grassland, coniferous forest or deciduous forest.
2b)
Buried, minimal maintenance: This corridor will be disturbed every few
years and will display early successional stages of the dominant form in
that region.
The wildlife and plants found in each of these habitats will correspond closely to the
general habitat it resembles; corridor grassland will be similar to other grasslands
and corridor forest will be similar to other forests. It is the presence of the utility
itself that influences which of the above habitats the corridor will resemble by the
manner in which the utility is maintained or disturbs the habitat.
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120
The soil quality and type will resemble the soil of the related habitat.
Flora and Fauna
The species diversity is expected to be high on most rights-of-way because of the edge
effect, a phenomenon caused when disparate habitats come together. Species from
both habitats invade from the edges and colonize the middle ground. The corridor is
also important as an urban path between isolated habitats, allowing separated
populations of terrestrial animals to breed, increasing the genetic diversity. As a
linear habitat, it also allows for an animal to "range" about. A block habitat may have
the same area but movement is restricted compared to the long, straight utility
corridor.
Maintained corridors are often planted with lawn grasses like fescue and blue grass.
Species like creeping buttercup, clover and blackberry runners can also be found.
Mowing tolerant plants like plantain and dandelion may also be present. In contrast,
the minimally maintained corridor will have wild grasses like canary grass and cut
grass as well as larger shrubs such as hardhack and blackberry thickets. Alder,
cottonwood, and various coniferous saplings will also begin growth here until
maintenance removes them. Finally, an unmentioned corridor will gradually move
through various seal stages with grasses giving way to shrubs and saplings until a
climax forest may generate if conditions allow.
Animal species present on the maintained corridors will include small birds like
Robins and Starlings. and possibly small mammals like voles. The minimally
maintained corridor will have more birds present, like Red-winged Blackbirds, Ringnecked Pheasant, and possibly smaller raptors like the Northern Harrier. Mammals
like coyotes and raccoons may take up residence if the cover is thick enough, and
larger populations of vole, meadow mice and rats are likely.
Disturbance
Disturbance along utility corridors occurs mainly through maintenance. Herbicides
like spike are applied using the "cut and dab" method to deciduous trees, work crews
clear the right-of-way of shrubs using power equipment and switchback roads are
built and maintained to allow access to the corridor. The roads encourage public
access to corridors. This use may include motorized trail biking, mountain biking,
hiking, and partying. Hiking and biking creates new trails, and partiers cut trees for
firewood and leave trash at the party site.
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The utility present may disturb the site, as well. Oil pipelines and water mains may
burst, spilling oil or water contaminating or eroding the corridor. Power lines emit
electro-magnetic radiation which may increase the likelihood of childhood Leukaemia
in humans, but there has been no thorough scientific studies linking electro-magnetic
radiation to other ailments in humans or other organisms (Ahlborn et al. 1987).
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Flora
Fauna
Hardhack
Blackberry
Canary Grass
Cut Grass
Plantain
Common Dandelion
Clover
Creeping Buttercup
Sitka Sedge
Cusik.' s Sedge
Alder
Birch
Hemlock
Coyote
Raccoon
Voles
Red-winged BlackbITd
American Robin
Northern Harrier
Sharp-shinned Hawk
Starling
Cliff Swallow
Barn Swallow
Northwestern Crow
Savannah Sparrow
Chipping Sparrow
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LINEAR ALONG A STREAM OR DRAINAGE DITCH
Physical Appearance
The linear grass land habitats bordering on urban waterways exhibit a great degree
of variability in physical appearance due to variables such as soil moisture, fertility,
disturbance and competition. One of the most important factors determining the type
of linear environment bordering the waterway is the size and type of water channel.
Areas bordering on rivers and large streams tend to have larger transition zones
between the water's edge and the grass banks lining the waterway above the
maximum flood level. This larger area gives rise to a distinct set of sub-zones capable
of accommodating a greater diversity and plant species.
Smaller streams and drainage ditches may not have a gradual or a well defined
transition zone between the water's edge and the grass bank borders. Often, as in the
case with most drainage ditches, the change is usually very abrupt. The distance
between the water's edge and the grass bank may only be a few, (almost vertical),
feet, and thus the habitat's capacity to support a greater diversity of species is
reduced.
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Location
These habitats occur along the banks of almost every type of waterway flowing
through or within urban environments. In large urban centres these habitats are
often part of a linear park system and is usually subject to heavy pressure from
recreational use and from management by park maintenance staff.
Drainage ditches and their associated grass bank habitats are less likely to occur in
larger metropolitan areas because they are usually replaced by a more sophisticated
drainage system, or the water flow is contained in and directed by a network of
culverts. Drainage ditches and small run-off streams are thus more likely to be found
in less well developed municipalities and poorer semi-suburban centres. Most ditches
in urban areas often occur in floodplain areas.
General Description
The linear grassland habitat along rivers, streams or ditches is often composed of
three distinct sub-zones. The extent of differentiation into the different zones is
directly related to the size and type of water channel. Rivers and large streams tend
to have discrete zonation patterns, whereas smaller streams and ditches have less
well defined sub-zones. Thus there is a great degree of variability in the complexity
of the various waterside habitats.
The three major zones are:
1)
The mud flat or foreshore areas which are subject to periodic cycles of
flooding and dryness due to tidal effects, variations in flow rates due to
precipitation run-off, or flood or drainage control programs.
2)
The transition zone between the water channel and the maximum flood
height. This area often lies on a moderate to steep gradient (30-60°),
which rises from the water's edge and is not subject to regular flooding.
Along rivers or larger streams, dykes, rubble mounds and other flood
control modifications are usually incorporated into this area.
3)
The grass bank area above the maximum flood level, which is often
characterised as an urban meadow community dominated by grasses,
shrubs, and less often (depending on the degree of disturbance), by a few
scattered trees, although scattered trees and shrubs occur along the
banks, only rarely do they form a closed woodland (Gilbert 1989).
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125
The complexity of these grassland zones above the maximum flood level
are also affected by such factors as proximity and type of adjacent
development, land use, management, accessibility, human activity, and
other forms of disturbance.
Soil
In the upper grass bank area the surface substrate is usually composed of mineral
soil with little or no layer of organic material or detritus. Soil pH is generally slightly
acidic and well drained, and this is usually favourable to a wide variety of grasses
and flowering herb species. Since the area is generally level and above the maximum
flood level of the waterway, the threat of soil erosion or flooding is usually minimal.
In the transition zone between the water channel and the maximum flood height the
soil is often the same composition as the grass bank area above it, but with
increasing amounts of sand, silt and mud as you approach the water's edge. These
conditions are also favourable for a variety of grass species and especially to
horsetails. Because this portion of the grass bank habitat usually lies on a gradient
leading down to the water, it is more susceptible to soil erosion, landslides, and
flooding in the lower portions. Frequently on larger waterways, embankments
consisting of large amounts of scree, and talus which are formed into dykes may be
incorporated into this area as a means of flood control.
The surface substrate of the mud flat and foreshore areas consists primarily of mud,
clay, silt and tidal flat deposits. Eel grass and other similar species tolerant of
frequent submersion are characteristic of this zone.
Water
The proximity of water to the linear bank habitats greatly increases the wildlife
values of these areas. Again, the size and type of watercourse greatly influences, not
only the type of linear grass bank habitat, but also the extent and diversity of both
flora and fauna. Thus rivers and large streams with their more extensive transition
areas usually attract a greater amount of wildlife than do drainage ditches.
The proximity of flowing water to these habitats also increases the use of the areas
by wildlife in transit, either via the waterway or along the foreshore areas. Thus
these habitats serve as corridors for wildlife in transit between different areas.
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Flora and Fauna
Rivers and large streams attract larger numbers of wildlife species and because of
their more gradual ecotones they also support a greater diversity of plant life. Some
typical examples of wildlife might include various waterfowl such as Canada geese,
or Great Blue herons in the foreshore areas, and frogs, raccoons, moles and various
songbirds in the other areas.
The typical plants such as the grasses, clover, berry bushes and shrubs provide an
abundance of cover, nesting and perching sites along with food and forage to support
wildlife. A few trees such as the Black Cottonwood and Birches which favour damp
and wet conditions are also characteristic of these locations.
Smaller waterways do not exhibit as much species diversity because of the smaller
habitat areas. Some typical wildlife examples from these areas may include
muskrats, frogs, foraging ducks, and raccoons. The plant species associated with
these areas are almost always limited to grass species and smaller shrubs. Horsetails
and ferns are also typical examples of other water loving vegetation in these areas.
Disturbance
Waterside habitats are subject to a variety of stresses, both natural and man made.
Natural disturbances include floods, fire, or landslides due to natural processes. The
most significant disturbances to these habitats, however, are caused by man. These
include various forms of pollution (air, water, and ground), traffic stress, industrial
activity, and other forms of human activities. Sites which have higher wildlife
potentials tend to be those which are isolated from industrial and other human
disturbances, and which are relatively inaccessible.
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Flora
Fauna
Clover
Thistle
Plantain species
Tansy
Vetch
Buttercup
Yarrow
St. John's Wort
Dandelion
Scotch Broom
Fescue spp.
Stinkweed
Blackberry spp.
Horsetail
Fern species
Various grasses
Black Cottonwood
Raccoon
Muskrat
Canada Goose
Herring Gull
Great Blue Heron
Mallard
Mole
Northwestern Crow
American Robin
Various songbirds
Invertebrates
Banana Slug
Black Cottonwood
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BOULEVARDS AND STREET TREES
Physical Appearance
Boulevards are usually only several metres wide but this affords enough habitat to
support a rich array of tree and shrub life. These are highly manicured sites that do
not have an understory.
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Location
Boulevards usually occur along many major roads throughout a city. In Vancouver
boulevards of note occur along Cambie Street, 16th Avenue, and 25th Avenue.
Street trees are planted alongside sidewalks in narrow grass patches or in small pits
in the ground with only the trunks coming through the sidewalk.
General Description
A good review of the trees which may be seen in Vancouver is given by Straley (1992).
Although native vegetation occurs along boulevards, it is not particularly common.
There may be large broadleaf maples, Douglas-firs or western redcedar, but most of
the tree and shrub growth is exotic.
The boulevards create the atmosphere of an urban forest. The trees and shrubs form
a unique ecosystem which is markedly different from that of the bioregion. In the
Lower Mainland the dominant tree and shrub growth in the wild would be red alder,
broadleaf maple, vine maple, Douglas-fir, western hemlock and western redcedar.
What do we have in the boulevards? There is the deodar cedar which appears to grow
very well in our climate. This is a true cedar (unlike our native redcedar), and has
needles instead of scales on its branches. The deodar cedars grow to be large and lush
and add a beautiful texture to the urban landscape.
There are several varieties of European beech trees are also common. The large,
copper variety forms a large canopy with a thick trunk and a stunning monument of
colour. A different cultivar of the European beech has green leaves and grows straight
and tall - there is no spreading canopy.
The "urban forest" of boulevard trees also regularly contains sycamores (London plane
trees), related to the native sycamores of eastern North America, but a different
species. They have a characteristic peeling bark and a maple-leaf shape to the leaf.
Tulip trees are frequently planted with them. The tulip trees have a lovely bark.
Other broad leaf trees seen along roads, perhaps in people's yards, include the
Lombardy poplar, white poplar, European sweet chestnut, and arbutus. Ornamental
cherry and plum trees which do not bear fruit are commonly used to line streets in
residential parts of the city.
Conifers that occur as street trees include the Lawson cypress which looks very much
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like a cedar. The Lawson cypress has many forms and it can vary in size and shape
from a low shrub to a tall tree. Other conifers seen as street trees or in small parks
include junipers and Giant sequoia.
There are also the really unusual looking trees such as the monkey puzzle tree which
looks like it is from another time or era. The monkey puzzle tree is actually from
South America and is native to Argentina and Chili. It is related to the Norfolk
Island pine which is a common house plant.
Common shrubs planted in boulevards and with street trees are English holly and
Scotch broom.
A majority of the trees and shrubs are introduced species and this can be a problem
in certain cases. Scotch broom and English holly are regular escapees from gardens
and can displace native shrubs. They may also be vectors of disease which can
devastate native tree populations (for example, Dutch elm disease was brought to
North America through introduced plants).
Street trees have their disadvantages with people too. They can break sidewalks and
building foundations, and their roots may clog sewers. Limbs and trunks may fall in
storms and damage property or potentially can injure people. They may block a scenic
view, and can drop sap and needles on cars or houses.
Nevertheless, street trees add beauty to a neighbourhood and can add to the value
of a property. Property values can increase 15-18% if large trees are present
(Zukowski 1990). In the same article Zukowski maintains that for every 2,500 trees
planted, the overall net value of property in a community increases $1 million. Trees
also ameliorate climatic extremes, and by absorbing airborne pollutants (Moll 1989).
Disturbance
Disturbance problems for street trees are summarized by Watson (1991). Street trees
can be subject to considerable disturbance. They are placed under stress from higher
temperatures, drought (little soil or little infiltration on the site), sporadic care,
damage to their limbs and trunks from vehicles and vandalism, exposure to toxic
chemicals (usually petroleum products from cars) and pollutants (including air-borne
particulates and noxious gases), and wind (which can even cause wind-burns on trees
next to busy highways).
Street trees are frequently planted improperly. Often the wrong species are selected
for the conditions of a site. The species may not tolerate the local conditions. Also,
they may be planted close to power lines, buildings, and pathways where they do not
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have enough space to grow to maturity.
Even if the species is correct for the site it may be improperly planted in a hole much
too small for its needs. Root growth is restricted and the tree can die of malnutrition,
or the roots will encircle the tree in the pit, strangling the stem (a form of girdling).
Extensive or improper pruning adds to these problems. Typically a tree root system
in the city is only 15% of the volume the tree would normally produce in a forest soil.
This imbalance in the ratio of the root and shoot systems stresses the tree and makes
it more susceptible to secondary insect and disease problems.
For all of the above reasons street trees often live less than 20 years.
Flora and Fauna
Street trees attract a large variety of birds and mammals. They act as linear
corridors for warblers, chickadees, and other canopy feeders to pass through a city
from the surrounding forests. They are also home to squirrels and raccoons.
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RAILWAYS
Physical appearance
Railroads are easily identified by the two parallel rails on a bed of course gravel and
wooden ties. These habitats are linear and continue for hundreds of miles, the regions
of interest here are the sections of track that transects urban areas. The two major
forms of track found in urban areas are yard track and active track. Active track is
the typical single set of rails between two points while yards are large agglomerations
of track used for storing, switching, and maintaining rolling stock.
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Location
Railroads are used for the transportation of industrial, agricultural and resource
products and can be found in areas where these products are manufactured, grown,
harvested, trans-shipped, or delivered. Most tracks in urban areas are used by
transfer trains, and most transfer tracks are found in industrial areas. Yards are
collection centres for rolling stock and can be found in central locations throughout
urban centres.
General Description
Railway rights-of-way can be classified into two distinct regions:
A)
Main and Transfer tracks: These tracks are generally used for direct
movement between two points with little or no switching of cars in
between.
B)
Yards and Sidings: These tracks are used as marshalling and storage
areas with frequent switching operations taking place.
The main difference between these two forms of track, from a habitat point of view,
is the amount of switching. Switching involves violently crashing cars together to
couple them. This crash often knocks seeds loose from the car's undercarriage. The
habitat difference is caused by these seeds. Trains travel great distances across the
continent and pick various seeds along the way. When these cars enter a yard, many
of these seeds from afar fall and take root in the yard. This seeding of foreign plants
is not as common on main and transfer tracks ..
Plants that grow on railway rights-of-way are short lived. Most foreign plants do not
propagate (Gilbert 1989) and those that do, along with native plants, are killed by
maintenance crews using either herbicides or steam. The plants are destroyed to
prevent soil formation on the right-of-way because soft soil destabilizes the tracks.
Soil
There is no soil on the rail bed, any that is formed is actively removed to prevent
track destabilization. The rail bed is made of a layer of cinder under a heavy layer
of large gravel. The gravel is up to two feet deep with sloping sides.
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Flora and Fauna
A distinction must be made between the animal species that inhabit the track bed
and those that use the tracks opportunistically to feed or move. No large vertebrates
can inhabit the track because of the frequent maintenance and lack of soil; only the
hardiest of invertebrate species can survive, feeding mainly on grain spillage. This
grain spillage does attract a range oflarger animals to feed on the tracks, however.
Canada Geese can be especially bold, even entering railway maintenance shops in
search of spilled wheat. As well, pigeons, ring-necked pheasants, rats and mice risk
the tracks in search of food. In winter, larger creatures like bears, deer, and moose
are common on tracks, using them as a trail because deep snow is cleared from the
tracks creating a snow-free path. Road kill damage is a major concern for railroads
and in attempts to prevent accidents like this, runaway lanes are now ploughed to
allow animals to get off the tracks rather than running along the tracks until the
train catches them. In urban areas, railway tracks act as trails for larger mammals
between isolated habitats, possibly enhancing genetic diversity and certainly allowing
access to otherwise inaccessible areas, like the Pacific National Exhibition grounds
in Vancouver.
Plants that can tolerate the conditions on the tracks must either be adapted to being
run over regularly or live well outside the tracks. The clearance between rail bed and
the train is as low as four inches at the locomotive's front, meaning that any plant
that survives on the tracks must be shorter than four inches or be extremely flexible.
Some of the plants that can survive here are plantain, fireweed, vetch, clover,
creeping buttercup, dandelion and St. John's Wort. Outside the tracks,on the rail bed
verge alder saplings can start along with blackberry runners and goldenrod. Most
plants here do not reach maturity and very rarely do they reproduce.
Disturbance
Disturbances on railway tracks are regular and extreme. Herbicides and steam trains
attempt to kill plants, scheduled trains run over animals and destroy maladapted
pants, and trains spill or leak fuel oil, lubrication oil and gearcase grease. Further,
passenger trains dump raw sewage on rail lines and some freight trains still use
polyethylene bags for catchment on toilets. Train crews do not like keeping these used
bags on board and often toss them overboard.
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Comments
As an urban habitat, railways offer a harsh environment. Few species are able to
exploit this region but those that do, do so quite successfully. Pigeons never had it so
good.
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Flora
Fauna
Alder
Horsetail
Plantain
Creeping Buttercup
St. John's Wort
Fireweed
Common Dandelion
Vetch
Goldenrod
Thistle
Bindweed
Sheep Sorrel
Canada Goose
House Sparrow
Ring-necked Pheasant
Rock Dove
Norway Rat
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The Private Landscape
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LAWNS
Physical Appearance
Lawns occur in residential areas and manicured parks for landscaping and playing
surfaces. They typically consist of only a few species (fescues and blue grass) of
grasses that are mowed regularly to an approximate height of2.5 cm (one inch). The
soil is generally compacted because of use. There is little to no cover for wildlife. In
the United States it is estimated that lawns cover 2% (8.0 million ha) of the land area
(Garber 1987). Thirty plant species and one hundred species of insects are commonly
found in urban lawns (Garber 1987).
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Location
Lawns are found around residences, often taking about 30% of the lot area or 180 m 2 •
They can also be found around schools, public institutions, businesses, or being used
as playing fields, and golf courses. Lawns tend to be more extensive away from the
city core. Lawns frequently are the only type of open space found in the central core.
General Description
Lawns are generally flat with no standing water and good drainage. They occur in
several discreet forms:
A)
Highly fragmented: Divided by driveways, gardens, roads and other forms of
land use.
B)
Continuous, uniform management: Playing fields, golf courses, playgrounds,
picnic area, continuous urban lawns and other large tracts that receive uniform
maintenance throughout.
C)
Continuous, mixed management: Residential lawns without barriers where
different householders apply varying amounts of care and maintenance.
Highly fragmented lawns are common to urban neighbourhoods where driveways cut
across the lawn for road access or are intersected by gardens or hedges. This
fragmentation can restrict the movement of smaller species. The fragmentation is
usually the result of small plots of land with differing ownership. Each owner is
responsible for maintenance of only a part of the lawn so maintenance is spotty. If
one owner allows weed species to invade all adjacent properties become vulnerable,
but if a property is surrounded by heavily maintained properties weeds will have a
harder time colonizing.
An example of the continuous, mixed management lawn is where many residential
back yards come together. The lawn may be divided on the surface by a narrow fence
but the lawn itself is virtually continuous. Without driveways, gardens or hedges are
the major obstructions. Again, due to multiple ownership, maintenance on differing
areas of lawn is variable.
The continuous, uniformly maintained lawn is best represented by playing fields and
park lawns. These lawns are usually larger than two acres and owned by the city,
although some more affluent neighbourhoods may have continuous, private lawns this
large. The maintenance is uniform because only one owner is responsible.
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Flora and Fauna
Lawns possibly contain a higher bird density than deciduous forests (Gilbert 1989).
Clover in lawns also attracts various nectar feeding insects including bees and
butterflies. Flocking birds such as European Starlings which have a broad diet forage
the lawns areas for worms, larval insects, and flying insects. The presence of any
perching sites or cover through landscaping or buildings greatly increases the
diversity and abundance of fauna. The presence of water near the site will attract
ducks and geese which will then feed on the grass. Lawns contain a variety of soil
invertebrates that attract birds and moles. In particular, large earthworms and
Tipulid larvae. The species diversity here is low but the biomass found can be
surprisingly high. The only resident vertebrates are moles, the rest are transient.
Weeds, such as the creeping buttercup, plantain, and dandelions, can be found in
lawns. This increases the availability of nectar and attracts a wider variety of
transient insects. Clover fixes nitrogen, naturally fertilizing the lawn. Weeds survive
by adapting to the lawn environment. Dandelions have very deep roots that are
difficult to remove and can reproduce through rhizomes. Plantain has adapted their
leaf growth form to allow them to lie flat, avoiding the blades of the lawnmower.
Native plants such as the creeping buttercup and trailing yellow violets can invade
lawns using runners. As well, poorly drained, acidic, shaded sites tend to encourage
mosses.
Less management means more species.
Disturbance
Pesticides, fertilizers, and the frequent use oflawnmowers all act to disturb the site.
Pesticides tend to eliminate more than just the pest species and leads to a
simplification of the food chain. Urban lawns frequently receive 10-40 times the
amount of pesticide used on comparable areas of agricultural land (Stats. Can. 1992).
This causes a reduction in species number and unstable species relationships.
Fertilizers can affect adjacent sites through leaching. They change the Nitrogen,
phosphorus, and potassium content of soils affecting the plant and animal community
in indeterminate ways. The frequent mowing of lawns compacts the ground and
decreases oxygen availability and water holding capacity. People walking across
lawns also compacts the soil.
Pets, such as dogs, urinate and defecate on lawns creating a spot of dead grass due
to over fertilization surrounded by a ring oflush growth. Waterfowl feces can lead to
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a coliform problem m surrounding waterways forcing closures of some public
swimming areas.
Comments
Lawns are perhaps the most common urban habitat and represent much of the area
in residential neighbourhoods, meaning that species common on lawns are often the
only wildlife people see on a daily basis.
Flora
Fauna
Fescue sp.
Bluegrass
Clover
Moss
Common Dandelion
Creeping Buttercup
Plantain
Mushroom sp.
Trailing Yellow Violet
Moles
Robin
European Starling
Canada Goose
Mallard
Barn Swallow
Cliff Swallow
House Sparrow
Invertebrates
Crane Fly
Nightcrawlers
Beetles
Slugs
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EXOTIC LANDSCAPES
Physical Appearance
Landscaping is the formal or informal planting of vegetation surrounding residences.
Land design varies with each site but the overall affect is one of esthetic appeal.
Native or exotic species of plants are incorporated into fencing, rockery, and
pavement layout in numerous ways, depending on the flare of their designer and
intended function.
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Location
Landscaping, in one form or another, occurs throughout urban centres. Discussed
here are the most common areas of landscaped lots in cities: residential properties
and ornamental gardens.
General Description
Landscape design may be subdivided into categories dependent on vegetation type:
1)
Native species: Gardening using plants that grow wild in the same local
regIon.
2)
Exotic species: Gardening which uses plants that have been removed
from their native setting elsewhere in the world.
Owners of residential properties typically combine native and exotic species for three
reasons. First, native species tend to be less expensive than those of exotic types and
so make up the bulk of a landscaped yard. Second, climatic conditions may not be
suitable for non-natives and they often require more care and special cultivation
techniques. Third, exotics add a distinctive feature to grounds, often inviting different
species of fauna which are attracted to their unique colors, scents and nectars.
Different climatic, soil, and water conditions ultimately determine the quality of the
species used in landscaping. However, plant traits such as size, form, flowers, foilage,
and ease of propagation may be initial reasons for choosing a particular species.
Ornamental gardens typically display a large variety of exotics and these plants are
the feature attraction. As mentioned above, unique traits of exotic species invite
many visitors, both human and animal alike. For example, the Botanical Garden at
the University of British Columbia features plants from our own province but also
includes exotics from around the world such as Asia and England.
Soil
Soil requirements will vary with the species planted and landscape designers will
often provide the proper subsoil and topsoil prior to planting. Most westside soils are
slightly acidic with pH ranging between 4.5 and 6.9, and so these soils are poor in
calcium and potassium (Kruckeberg 1982). Also, landscaping usually occurs on soils
which have been severely disturbed and are of poor quality. It becomes necessary to
modify the site by adding nutrients or new mixtures of soils in order to provide
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proper water drainage and aeration. Plants with deep root systems may be
jeopardized if underlying subsoil contains rock or construction debris and they are
unable to penetrate such compaction.
Both native and exotic species require special attention when they are being
trallsplanted into a soil which differs in chemical compostion or structure. Although
natives grow better with sufficient amounts of nutrients, they are capable of thriving
in less than optimum conditions; unlike their exotic counterparts.
Flora and Fauna
Floral variety will vary on the climatic conditions and individual taste of the
landscaper. Combinations of annuals and perennials are common in residential and
ornamental garden landscaping. Perennials, plants with a duration of three or more
years, include herbaceous and bulb varieties and are considered mainstays of a
garden (Musteg 1980). Species of daffodil, iris, lupine and crocus are examples of
plallts that are commonly used in landscape design because they are easy to grow and
do llOt need to be replanted.
Annuals are a favorite in all types of landscaping. These include plants with a
max:imum lifespan of one year and are usually exotic species which have been bred
for their color, foilage texture, full flowers, and ease of propagation. Ornamental
gardens typically replant annuals as the seasons change because some varieties of
these plants have lifespans of only a few weeks and then wither and die. Examples
include tulips, petunias, and marigolds.
By introducing a variety of native and exotic species into a garden, one inevitably
invites a diversity of fauna. Trees, hedges, and shrubs provide cover, perching and
nesting sites for birds and squirrels. They also serve as a food source by way offruits,
berries, nuts, and seeds. Different species of insects are attracted to the colors, scents
and nectars of flowering plants and herbs. Ornamental gardens in particular entice
a variety of species of butterflies and dragonflies. Attracting bees is also important
in that their pollination is essential to a number of plants including apple and cherry
trees.
Disturbance
Disturbance may take many forms in landscaped gardens. These include sudden
changes in weather, improper care, animal and insect damage, and plant diseases.
Sudden frosts or hail storms can damage plant leaves and fruit beyond repair,
animals and insects may feed on and damage foilage, and diseases may kill off a
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plant completely and have the potential of spreading. Although plants are difficult
to protect from weather, the use of pesticides and herbicides help to control other
unwanted infestations.
Perhaps more damaging to sections of landscaped property is that of improper care
where neglect and lack of skill make for an unhealthy garden. Ignoring a landscaped
lot may lead to a weed infestation, and competition for existing water and nutrients
potentially chokes out surrounding vegetation. Over- or underfertilizing may result
in soils which are too acidic or basic and so cannot adequately provide the plants with
their nutritional requirements.
Unskilled gardeners may also inhibit vegetative growth if they are not aware of
important plant interactions. For example, a young Douglas fir will not be able to
survive in shade and so cannot be planted in an area of little light. Allelopathy, the
adverse effect of one plant's chemistry on another plant's growth, also plays an
important role. Species such as the vine maple and Western red cedar produce
inhibitory chemicals and may alter the growth potential of neighbouring plants if
these compounds are washed off and enter the soil (Kruckeberg 1982). Other factors
such as overcrowding and overtopping of trees and shrubs may also prove deleterious
to plant vitality.
Comments
Landscape architecture serves a multitude of functions but ultimately provides a
welcomed habitat for a diversity of bird and insect species. Ornamental gardens in
particular invite species that are uncommon in urban areas and residential properties
can do the same by introducing exotic species into their landscape design.
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Flora
Fauna
Trees
various butterflies
various dragonflies
Mole
Western Bluebird
Brown Creeper
Bushtit
Hairy Woodpecker
Downy Woodpecker
Common Flicker
Chipping Sparrow
Stellar's Jay
Fox Sparrow
Tree Sparrow
Purple Finch
Rufous Hummingbird
Calliope Hummingbird
American Goldfinch
Red wing Blackbird
White-crowned Sparrow
Roufous-sided Towhee
Dark-eyed Junco
Black-headed Grosbeak
Evening Grosbeak
Wilson's Warbler
Yellow Warbler
Incense Cedar
Silver Dollar Gum
White Birch
Buckthorn
Goldenrain
Flowering Cherry
Hawthorn
Red Horse Chestnut
Apple
Linden
Silk Tree
White Mulberry
Norway Maple
Ginkgo
Chinese Elm
Shrubs
Azalea
Gardenia
Boxwood
Fuschia
Lilac·
Rhododendron
Hydrangea
Juniper
Perennials
Yarrow
Daylily
Delphinium
Primrose
Phlox
Geranium
Peony
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Annuals
African Daisy
Hollyhock
Marigold
Nasturtium
Iceland poppy
Impatiens
Petunia
Aster
Cosmos
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ORNAMENTAL SHRUBS AND THICKETS
Physical Appearance
Ornamental horticulture depends upon a wide variety of shrubs to add texture,
colour, form and structure to the urban landscape. Ornamental shrubs are used to
define paths, borders, and outline garden areas in both public parks and residential
settings. Screen hedges are used as living walls to provide privacy on residential
property and are often manicured into decorative shapes in public parks and gardens.
The physical appearance of ornamental shrubbery depends on the particular species,
the use made of it in the landscape setting, and the amount of management
(manicuring), it receives. The general growth forms include tall shrubs, woody ground
covers and woody climbing vines.
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Location
Most ornamental shrubbery can be found in public parks, gardens, private residential
property, and to an increasing extent indoors in various types of atriums located in
the public areas of larger buildings and office towers.
In some old gardens and public areas which are no longer being extensively used or
managed some forms can also be found growing wild.
General Description
Ornamental shrubs can generally be categorized into three distinct types:
1)
Coniferous Needle Leaf Shrubs: e.g. Common or dwarf juniper.
These types of shrubs are dwarf or shrubby cultivars of coniferous trees
and are most often used in rock gardens and low border type vegetation
in such applications as defining or outlining pathways or forming
borders around flower beds.
2)
Broad Leaf Evergreen Shrubs
Approximately fifty species of this type qualify as ornamental shrubs,
and over half of these are members of the heather family. Examples
include Evergreen Huckleberry, Pacific Rhododendron and Salal.
Depending on the type of species these shrubs can be used for a variety
of purposes ranging from ground cover, shade, borders, screening
hedges, highway plantings on embankments, replacing lawn on steep
and hard to mow slopes, and many other decorative uses.
3)
Broad Leaf Deciduous Shrubs
Common examples of this type include such species as Serviceberry,
Sitka Spruce, Mountain Ash and Red Osier Dogwood. As in 2 above
similar uses are made of these species in landscape architecture. Some
other uses may include soils conservation , especially in areas
undergoing ecological restoration.
Soil and Water
Ornamental shrubs thrive in a variety of soil and moisture conditions. Generally any
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area with moderate shade, slightly acidic and well drained soils will suffice for the
majority of ornamentals. Some species such as the Common or dwarf junipers prefer
well drained soils low in calcium and high in magnesium. Others such as Labrador
teas, Bog laurels, Evergreen huckleberry and California Wax Myrtle favour cool,
moist peaty, and slightly acidic soils. A few such as the prickly pear cactus, the
hedgehog cactus, and Sagebrush do better in drier, sunnier areas and are very
drought tolerant.
Flora and Fauna
Most ornamental shrubs occur in well maintained public and private settings, and
the resulting intensity of management often precludes the coexistence of many
wildlife species, which would normally utilize the wild growth forms for cover, nesting
sites, food, and forage. However, some of the denser and more isolated growth forms
such as hedges and sculptured bushes may accommodate such nesting birds as robins
and house finches. Many flowering species can also provide copious amounts of food
in the form of nectar and berries for a variety of birds and butterfly species.
Ornamental shrubs rarely support any other forms of larger wildlife species, and in
general, the less well managed and the more isolated ornamentals provide the
highest wildlife values.
Disturbance
In well managed areas, great emphasis is placed on neatness and tidiness and the
resliltant disturbance is often very high.
Stress resulting from human recreational activities and human traffic is usually very
high in public parks and gardens. Great emphasis on aesthetics also determines the
kinds of growth forms and may also favour one particular shrub species over others.
In particular if herbicides are widely used certain intolerant species may be
eliminated thus favouring others.
Comments
The majority of ornamental shrubs are very hardy and resilient species, unusually
tolerant to a wide spectrum of stress which makes them particulary suited for use in
urban environments. Their utility in the urban landscape is not solely limited to
improving the aesthetic value of a particular area, but also by the potential of the
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varying species to attract wildlife, and by the diversity of the species themselves.
Since the objective of most landscape architects is to enhance visual beauty of an
urban greenspace area, a little knowledge of the ecology of the ornamental shrubs can
pay great dividends both in terms of aesthetics and in the enhancement of
greenspace for wildlife use.
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Flora
Fauna
Common Dwarf Juniper
Western Yew
Salal
Manzanitas
Kinnikinnik
Bog Rosemary
Labrador Teas
Bog Laurel
Western Leucothoe
Kalimiopsis
Pacific Rhododendron
Evergreen Huckleberry
Pipsissewa
Twinflower
California Wax Myrtle
Sagebrush
Oregon Box
Oregon Grape
Buckbrush
Evergreen Oak
Serviceberry
Deer Brush
Red Osier Dogwood
Oceanspray
Mock Orange
Shrubby Cinquefoil
Red Flowering Currant
Western Azalea
Sitka Mountain Ash
Red Huckleberry
American Robin
House Finch
Various butterflies
Red Huckleberry
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ORNAMENTAL FORESTS
Physical Appearance
Ornamental forests are comprised of one or more groves of mature trees which may
be of a variety of species. The trees are often surrounded by lawn and other
landscaping such as gardens.
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Location
These forests may be found incorporated into the landscape design of residential and
institutional properties, and also along road edges or medians.
General Description
Although the habitats may be somewhat similar, ornamental forests may be divided
into three categories according to location:
1)
Forests located on residential property: These forests are located in the
front and back yards of homes in residential neighbourhoods. As with
institutional properties, these forests are also surrounded by lawn but
in comparison, this landscaping style is on a smaller scale.
2)
Forests located on institutional property: Groves of native , mature trees,
often in combination with ornamental exotics, are incorporated into the
landscaping. Such areas are often noted for their large areas of lawn
and high degree of maintenance.
3)
Boulevard forests: This category includes ornamental landscaping along
roadways or medians and are maintained on a regular basis.
The essential function of ornamental forests is aesthetic appeal but there are other
advantages in having woodland within the city. For example, in terms of
environmental value, trees contribute to removing toxins in the air and they
moderate temperature by absorbing heat throughout the day and releasing it during
the night. Trees also act as wind breaks, sound buffers, and help to protect land from
erosion. (Harper 1984). Of course, trees also provide habitat for a diversity of animal
species that may not otherwise exist in a city.
Homes that have maintained a grove of mature trees are generally long-established
residences. These residential ornamental forests may provide the best wildlife habitat
because they are not as disturbed as the forests of institutional properties.
Maintenance is typically not as high and with less disturbance, the number of
potential habitats increases.
Boulevard trees are planted in areas of public rights-of-way along roadsides and
medians. This type of landscape design adds depth and texture to otherwise sterile
surroundings. Such areas are typically planted with one species of tree (monolithic
planting) and they too provide small habitat islands for a variety of birds (Harper
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1984).
Soil
Soil quality is generally of the same type in residential and institutional properties
and in the areas where boulevard trees are planted. Initially, regions displaying
monolithic street trees were an afterthought of development and were provided with
rich topsoil prior to planting. Areas with mature, native trees typically have only the
surrounding lawn maintained. Soil changes are most evident when the lawn has been
extended all the way to the base of the tree. Native soil supporting the tree will
ultimately change in chemical composition and structure as a result of pesticide and
fertilizer application and compaction. Changing the pH of a soil to make a lawn lush
and green may have an adverse affect on surrounding trees which may require
different amounts of nutrients. Soil degradation due to human and mechanical traffic
eventually leads to compaction of soil particles and creates problems with drainage
and aeration.
Flora and Fauna
Floral diversity of ornamental forests depends on location but tree species are usually
mature and native to the area. Our cool and moist climate supports a variety of
coniferous and deciduous species. However, mature groves are typically composed of
conifers such as Western hemlock and Douglas fir due to their longevity but slower
growing deciduous species such as apple and Black Hawthorn are also found. As
previously mentioned, monolithic planting is characteristic of boulevard and median
landscape design. The species chosen is one that is suited to the environment and is
typically slow growing such as oak. This keeps tree maintenance low and serves as
a cost-effective measure and safety consideration (Harper 1984). '
Faunal diversity will generally be greater in areas of less disturbance such as
residential properties. Ornamental forests always welcome a wide variety of avifauna
because of their cover, perching, and nesting opportunities. Depending on the size of
grove, density of canopy, and proximity to the city, species will range from small
songbirds such as the Chipping Sparrow to large predatory birds, including Barn owls
and Red-tailed hawks. Larger mammals such as opposum, raccoon, and deer may
frequent the site but such areas are usually too small and disturbed too often to
sustain these creatures as long-term residents. Of course, availability of food may
ultimately decide which animals are capable of inhabiting these environments.
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Disturbance
Disturbance may take many forms. For example, frequent site management changes
soil pH and results in compaction. Intervention, such as the removal of coniferous
needles which provide the tree with a preferred acidic soil, may have negative effects
on tree vitality. The removal of underbrush and leaf litter also robs the tree of
essential nutrients provided by humus. Of course, physical destruction, including
vandalism and pest infestations affect the health of a tree and may destroy an entire
mature woodlot.
Comments
Ornamental forests, because of their size, may be developed around and still provide
an ideal habitat for a variety of species. However, it is important to recognize the
necessary conditions that these mature groves require in order to thrive. Minimum
intervention will ultimately maintain longevity and protect potential wildlife habitat.
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Flora
Fauna
Red Maple
Flowering Dogwood
White Ash
Juniper
Larch
Tulip Tree
Douglas-fir
Black Locust
Western Redcedar
Western Hemlock
Oregon Grape
Moraine Locust
Norway Maple
Silver Maple
Holly Oak
Coast Live Oak
Chinese Elm
Apple
Linden
White Mulberry
Flowering Cherry
Incense Cedar
White Birch
Chipping Sparrow
Steller's Jay
Brown Creeper
Bushtit
Hairy Woodpecker
Yellow-bellied Sapsucker
Red -winged Blackbird
Swainson's Thrush
Song Sparrow
Fox Sparrow
White-crowned Sparrow
Purple Finch
Rufous-sided Towhee
American Goldfinch
House Finch
Black-headed Grosbeak
Evening Grosbeak
Wilson's Warbler
Northern Flicker
Downy Woodpecker
Douglas Squirrel
Gray Squirrel
Raccoon
Deer
Oppossum
Rabbit
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CLIMBING PLANTS ON BUILDINGS
Physical Appearance
This habitat is one of the most distinctive in the modern urban environment as it is
rare. Any building or portion thereof including roofs blanketed by a layer of
vegetation easily stands out from adjacent and often more sterile structures. Plant
covered walls are the most common occurrences in urban areas with sloping roofs
second and entire buildings a distant third.
The density of the growth may vary as a result of the location upon the structure,
type of vegetation, the exposure to sun, and the amount of management and
manicuring it receives. The colour and density of the vegetative cover may also vary
depending on season, flowering potential, and type of vegetation, e.g. deciduous or
evergreen.
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Location
Since climbing vegetation on buildings is becoming increasingly rarer in modern
urban settings, it may be difficult to locate outstanding examples of this type of plant
community. In some older urban areas, or the older sections of evolving urban
centres a few buildings may exist which still sport a complete blanket of vegetative
growth on their exterior structure, including their roofs. More common, however, are
structures which are partially covered, such as green concrete walls or chimmney
areas.
One factor contributing to the rarity of urban structures clothed in vegetation is the
prohibitive cost associated with the management and upkeep of these vertical
gardens. As a consequence of this, they are most likely to be found on older, more
wealthier urban residential quarters, or in public or commercial establishments which
can afford the costs associated with the upkeep and management. Occurrences of this
habitat are very rare in the inner cities of larger urban centres.
General Description
Climbing plants are generally comprised of two types: shrubs and vines. While the
climbing potential of vines is obvious, some shrubs can also be pruned and managed
causing them to ramble, trail and climb like vines.
Climbers, depending upon species, have a number of different applications ranging
from "roofing", framing doorways and windows, and curtaining walls. They can also
be employed by the landscape architect to soften building lines, clothe pillars with
living green, transform ugly concrete walls and lend colour to dull fences (Lenanton,
1980).
In order to facilitate and support the climbing potential of these plants, a general
knowledge of the requirements of the different types is necessary, since they all do
not climb using similar means. English ivy is capable of attaching itself directly to
walls, wood posts and masonry by means of modified roots called, appropriately
enough, holdfasts. Boston ivy clings to most surfaces by means of discs on its stems.
Since neither of these types require any special structural support they are usually
found on structures which do not possess extensive surface texture or support. Other
types of climbing species such as clemantis or climbing rose, require varying degrees
of structural accommodation to allow them to fully express their climbing potential.
Fine support structure such as wires, small diameter runners, or even stems from
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other vegetation will allow clemantis, which twines its leaf stems around these
supports to climb and spread along a structure. Other heavier climbers such as
Climbing rose and Wistarias will require stronger and more substantive support to
accommodate their greater weights and to prevent collapse under the strain of
mature growth. These climbers must also be trained to grow onto those supports.
Finally, some vines and shrubs can be manicured to grow in distinctive patterns
against walls, fences and other structural supports. These are the espaliers, (from the
French epaulet or shoulder; i.e. branching at right angles from the main body or stem
), and are used to create decorative shapes and designs, save space, and to provide
growth in narrow places where there is insufficient room for larger plants. Examples
include fire thorn and the evergreen pear (Lenanton 1980).
The majority of climbing shrubs and vines occurring in the urban environment have
a wide tolerance for the various soil types common to these areas. Many of the urban
ornamental shrubs and climbing vines prefer slightly acidic, well drained soils with
lots of sun. Some climbers such as ivy have rootlets at every joint, which are termed
aerial roots or adventitious roots. These roots are mainly for support, but they are
capable of absorbing moisture and nutrients which may be unavailable to the more
conventional root system in the supporting soil.
Flora and Fauna
A well established community of climbing vines or shrubs has the potential to support
a limited variety of mostly bird species. The density and proliferation of the growth
and the management regime are the primary factors in determining the capacity of
the this type of habitat to accommodate any wildlife. Structures with well developed
growth have good cover, nesting, and perching site potential for many songbird
species such as house finches, sparrows, and robins. Since the higher areas on walls,
along rooflines (overhangs), and eavesthroughs afford more protection from exposure
and disturbance, these areas are highly prized urban bird habitats. The wildlife value
of these habitats also increases greatly if the climbing plant species can also provide
a food source such as berries or nectar producing flowers. Butterflies and other
insects attracted to the nectar may then become food for the resident bird community.
Sites with less dense growth and more management in the form of frequent
manicuring will not be as attractive to the many species because of the corresponding
thin cover and frequent disturbance.
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Disturbance
Although many climbing shrubs and vines are aesthetically pleasing when properly
managed and manicured, some can be destructive. Ivy cover can be very attractive,
but its holdfasts can also insinuate themselves into the supporting structure and
cause damage. Some of the climbers can cause cracks in concrete, stucco, masonry,
and tiled lined structures. Ivy holdfasts can split wooden shingles and tear them off
roofs. Dense growth on roofs can lead to soil and detritus accumulating an these
structures and the resulting increase in weight may pose a threat to the building
structural integrity. Accumulation of the acid based soil material may also cause
damage not only to roofs, but erosion to walls and other supporting structure.
These disadvantages generally outweigh any of the aesthetic benefits and thus
climbing shrubs and vines are not widely tolerated. They are eliminated or controlled
by a variety of means ranging from herbicides to weeding or uprooting.
Comments
Green walls and buildings clothed in a layer of vegetation due to cultivated and
manicured climbing plants are increasingly becoming rarer in today's urban
landscape. Such factors as routine painting, building maintenance and damage to
exterior structure caused by rooting and erosion limit the viability of this aspect of
urban landscape architecture.
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Flora
Fauna
English Ivy
Boston Ivy
Clemantis
Clinbing Rose
Wistaria
Firethorn
Evergreen Pear
House Finch
Sparrows
American Robin
Various butterflies
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163
ROOFTOPS
When people think of rooftop, they envision flat hard or gravelly with tar and where
access is often rescticted for safety reasons. Rooftops offer tremendous views and
vistas overlooking busy and bustling streets, and the neighbourhood as a whole. Wind
channels through corridors of buildings swishing up to the rooftops. Those urban
residents that are fortunate enough to have access enjoy the many pleasures of being
high above the city.
Ecologically, rooftops can be considered as harsh habitat for many plants and wildlife.
With human intervention, however, this can be converted to a viable habitat such as
a rooftop garden.
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Location
They can be found every where in urban areas and including suburbans. A best
example of where to find a rooftop habitat is in a penthouse. Plants are carefully
planted in containers whether terracota clay or wooden.
General Description
It is generally hotter and drier on rooftops. The materials used to construct roof-tops
usually tar and gravel absorb heat from the sun and reflecting it to othe surfaces. In
dense urban centres, rooftop gardens play an impportant role in climate modification
similar to ground level vegetation. As discussed above, rooftops are hostile
environments. An experiment conducted by Hough et al. (1977-9) on a flat roof of an
old industrial building in the city of Toronto to explore the alternative uses of rooftops. The experiments showed that plants readily adapt to the hostile climatic
conditions. Futher, the vegetation growing on peat moss media had kept the ambient
air temperature above freezing throughout winter. This then suggests another way
to prevent heat loss throughout winter.Furthermore, rain water is easily drained by
drainpipes down to the streets below. Many roofs are not as easily drained as desired
by the owners. They collect pools of water which may cause structural stress.
Rooftop gardens are becoming increasingly popular in apartment, condominiums and
office towers. Not only they are aesthetically pleasing but they also help cool the
ambient air. The gardens usually consist of boxes, different types of containers as
described in the section on CONTAINER HABITATS. The containers or boxes are
placed along the walls to obtain maximun sunshine and most importantly shelter.
Interestingly, a community garden initiated by McGill University ona community
centre roof in downtown Montreal was proven productive and a practical· way to
utilize an open space (obtained from Hough 1984). Luxuarious penthouses may have
swimming pools and hot tubs or jacuzzis with a beautifully constructed patio and
benches.
Rooftops of older buildings may seem unsightly at a first glance, but may present
some interesting habitat types. Patches of grasses may colonize an area where soil
formation process has initiated by the weathering process oflichens and moss. Pigeon
cages are common on some rooftops in New York.
Flora and Fauna
Pigeons are common user of rooftops. They roost in large flocks on the ledges and
build their nest in nooks and crevices. Old rooftops may succeed into a naturalized
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165
habitat over the years of weathering process and colonization. Combined with
standing pool of water, a wetland habitat may be formed. This may attract birds both
residents and those onroute to their wintering or breeding habitats. Rats and mice
are common here as well exploiting the openness without human interferrence. Flat
rooftops on large buildings may be used by nesting nighthawks. The eves of roofs and
the undersides of corner roof tiles are common nesting sites for the European
Starling.
Naturalized plants such as grasses grown from wind-blown seeds, moss and some
flowers or flowering weed are common on old rooftops. On the other hand, garden
plants in pots and boxes add colour and variety to the ordinary.
Disturbance
Disturbance of the naturalized habitats are usually from man. Old buildings are
frequently demolished and replaced with new ones. Wild grasses and weeds are
usually pulled out in order to make room for planters and pots. On newer rooftops,
herbicide is usually applied to control weed problems.
Comments
The Urban Landscape Task Force highly encourages the use of rooftops as gardens
and plces for people to gather and relax. Rooftops offer a world of wonders adove the
busy streets. The views and vistas are exhilirating and often refreshing. Garden
landscapes on rooftops can contribute to climate amelioration.
Flora
Fauna
Grass spp.
Vegetable crops
Moss
Lichen
Flower weeds
Willow sapling
Nighthawk
European Starling
rats
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The Public Landscape
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167
RECREATION PARK
Physical Appearance
City parks range in appearance from highly maintained and manicured to natural
and undeveloped. Depending on size, location and monies available, a park provides
various activities for people. Large parks may contain courts or playing fields for
sports, petting zoos, or swimming areas. Smaller parks may only provide a
playground or picnic area.
In general, city parks remain horticulturally based and are maintained to whatever
degree keeps them aesthetically pleasing. Gilbert (1989) states that town parks retain
a particular style, "landscape gardening-- in which an enlarged corrected, refined, and
idealized portrayal of nature is presented at an aesthetic level."
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Location
Parks may be found anywhere within an urban centre. A city may develop around an
extensively wooded site, allowing the park to become a green oasis. A park may also
be created on an abandoned industrial lot or in an area unsuitable for development
due to soil instability or gradient such as a ravine.
General Description
Parkland may be divided into categories depending on the activities that occur:
1)
High maintenance: These parks are typically large and provide
recreation opportunities for the public.
2)
Low maintenance: These parks emphasize nature and usually have
footpaths and trail systems.
City parks that are continuously maintained and manicured typically display areas
of mown grass containing scattered trees and are supported by areas of woodland.
Ornamental landscaping such as formal beds of roses, annuals, herbaceous plants and
rockeries tend to occupy small regions as they are expensive to maintain (quote).
Low maintenance parks typically represent nature in an undisturbed manner. Dense
shrubbery and trees which may be a safety hazard are removed and sawdust trails
and footpaths are provided. Maintenance is minimal except for picking up garbage
and keeping the trails clear of overgrown vegetation.
Soil quality depends on the type of park and the degree of management it receives.
High maintenance parks undergo high disturbance in the form of fertilizer and
herbicide application. Soil pH, whether acidic or basic, is maintained at ideal levels
for the vegetation which is planted on site. For example, rhododendrons, which prefer
acidic soils are often supplemented with bark mulch.
Soil compaction is typical of high maintenance parks and also of parks containing
walking trails and footpaths. Compaction may occur due to human and vehicle traffic
or with the addition of extra soil layers for landscaping purposes. Such activities
result in high bulk densities and so reduce porosity of a soil. Bullock and Gregory
(1991) explain that if the soil is in a very dense state or is severely compacted, it may
be virtually impenetrable to roots and worms and unlikely to undergo structural
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169
recovery. Compaction results in restricted soil aeration and increased soil strength
which may slow down root growth and affect the vegetation.
Flora and Fauna
Faunal diversity is also dependent on the degree of park maintenance. Parks in
which the upkeep is minimal and emphasis is on keeping a site in its natural state
may provide the largest species diversity. Habitat value to wildlife also depends on
size, structure, and availability of shelter. Bird abundance and diversity is especially
dependent on shelter as it provides cover, nesting and perching sites. If not sufficient
in number, these factors may limit the population size of certain species and allow
for others to dominate the existing niches.
Wildlife diversity is greatly influenced by the type of plant community it supports.
Vegetation controls food supply by providing seeds, roots, fruits and insects. Of
course, humans also playa role in contributing to the food chain in parks. By handfeeding or leaving garbage, animals such as squirrels and raccoons learn to
'supplement' their regular diets of berries, seeds and nuts.
Disturbance
Extensive management operations of a park playa significant role in disturbing its
environment. Use of herbicides, fertilizers, and growth retardants may keep species
diversity low. Their intent is to encourage growth of some species of plants and slow
down or halt the growth of others thus limiting floral diversity. Growth retardants
are generally applied in areas where mowing is difficult such as the slopes of banks,
path edges, or areas of .obstruction. A problem arises when the retardant works on
a particular species but may allow for other weeds to spread because of reduced
competition.
In terms of other forms of disturbance, Gilbert (1989) indicates "the presence oflarge
numbers of exotic plants, close mowing, disturbance by people and dogs, litter and
vandalism are less detrimental to urban wildlife and may encourage it."
Comments
Parks provide a variety of habitats depending on their size, structure, and function.
Ideally, the most successful parks are those that provide recreational opportunities
for the public yet remain sensitive to keeping the natural habitats of the flora and
fauna that previously existed.
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170
Flora
Scotch Pine
Pacific Willow
Douglas Maple
Black Cottonwood
English Hawthorn
Broadleaf Maple
Horse Chestnut
Apple
Cherry
Plum
Pear
Pacific Dogwood
Vine Maple
Douglas-fir
Lodgepole Pine
Walnut
American Holly
W €stern Hemlock
W €stern Redcedar
Ornamental Plum
W €stern Daisy
Sedge sp.
White Birch
Sword Fern
Bracken Fern
Lady Fern
Salmonberry
Huckleberry
Red Elderberry
Wild Lily-of-the-Valley
Periwinkle
Foxglove
Urban Habitats
Fauna
Raccoon
Voles
Red-winged Blackbird
Woodpeckers
Rufours-sided Towhee
Savannah Sparrow
Chipping Sparrow
Northwestern Crow
American Robin
Canada Goose
Cliff Swallow
Barn Swallow
Mallard
Black-capped Chicadee
Steller's Jay
House Finch
Rabbit
Mole
Grey Squirrel
Black-tail Deer
171
GOLF COURSES
Physical Appearance
Golf courses areas of large expanse of highly maintained lawns termed as greens,
fairways, and roughs. They are beautifully designed by prominent golfers and
architects. The lay-out of the fairways varies depending on the flair of the designs
and to challenge the golfers on the course. The fairways are usually lined with trees
and tall shrubs to separate from other fairways. The putting green located at the end
of fairways are especially very well groomed, to maintain a smooth surface for the
precision putting. The older and well established courses are often popular mainly
because of the attractiveness of the landscape of the facilities as well challenging the
game of the golfer.
Golf is increasing in popularity as a sport, attracting players both young and old. In
the British Columbia alone, 11% of the population over the age of twelve play some
golf. This is among the highest level in Canada and the United States (GVRD, 1991).
Golf courses are a valued commodity in the Lower Mainland of British Columbia.
Some of the golf courseshere are considered to be world-renowned and attract golfers
from all over the world. The mild maritime weather of the southwest coastal region
enable the game to be played all year round.
((
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•
j
I
172
Location
The existing 18 hole and Championship Golf Courses have been constructed on lowlying areas with convenient road access. There are several courses that have been
constructed at the periphery of agricultural lands. As documented in "Golf Courses
of the Lower Mainland" (1991), almost all of applications for golf course development
are for land in the Agricultural Land Reserve. The Agricultural Land Reserve
designates lands with productive capacity; that is lands with highly organic soils for
farming.
General Description
Golf course facilities vary in size, design and the number of golfers the facilities can
handle.
The club houses are the common meeting areas where golfers relax from a
challenging game and begin a round of golf. The grounds are usually lawned and
planted with various ornamental flowers to beautify the structure. A car park area
is usually located close-by for the convenience of the visitors. Also near-by are the
driving-range and a practice putting green for those who wish to improve in their
swing and putting. At the driving range, golf balls rented by-the-bucket from the club
house are hit onto a large field of approximately 350 yards in distance. The balls are
later collected by specialized collector operated by staff. The practice putting green
resemble closely to other individual greens but has at least twelve holes for improving
the putting techniques.
The fairways are lawns with variable distances and challenges. Par 3 fairways have
usually short distances and are considered easy to those with an exceptional
handicap. Par 5's are challenging fairways requiring skills in "driving" the ball as far
as possible. To make the game more interesting and challenging, sand bunkers,
ponds, islands, and streams whether natural or man-made are incorporated in the
design of the course.
Trees and shrubs are planted along each fairways and at some of the edges of the
greens. The purpose of the vegetation is to divide the fairways as well as shade and
m()st importantly to take cover from the flying balls. The trees also add a sense of
peacefulness and relaxation often appreciated by the golfers. The ponds are manmade (refer to section PONDS) and planted with native and exotic plant which
increase the challenge of the game.
Golf courses on sloping lands may also have ravines with streams. These ravines are
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173
hazards to development and usually left undisturbed. The presence of ravines further
challenge the golfers. Lost balls are quite common here.
Soil
The soil is usully foreign to the site of the course. During construction soil is brought
in compliance with the design and architecture. The most common soil type is sand
and mineral soil. Lawn grass grows well in sand-mineral soil mixture.
Maintenance
As previously mentioned, golf is a money-generating business. The facilities are
managed and maintained to ensure the posperity of the business and to keep golfers
coming. The golf courses are especially devoted to professionally trained grounds
maintenance crew. Fertilizers and pesticides are applied regularly. However, the
chemicals employed here are not necessary environmentally-friendly. The extensive
environmental impacts are recently becoming a public concern. Several studies have
demonstrated that leaching and runoff of fertilizers and pesticides from golf courses
are toxic to wildlife and sterilize streams, creeks and other waterbodies.
Krause and Niemczyk (1989), and Watschke et al. (1989) reported that a well
managed turf produces negligible fertilizer and pestiside leaching and runoff which
will not endanger wildlife habitat. Westwood Plateau Golf Course is currently
employing an environmentally sensitive practices in turf management which include
conservative application of fertilizers and pesticides.
Flora and Fauna
Golf course construction will ultimately displace wildlife by removing the viable
habitat and range area. Large mammals such as black bears, cougars, and blacktailed deer are common in forested slopes of the north shore mountains of the Lower
Mainland. Westwood Plateau Golf Course are currently implementing a "large
mammal management plan" to minimize their encounters. For black bears, this plan
consist of regular monitoring, educating staff on bear habits, avoiding the planting
of their food types, regular removal of refuse from golf course and the clubhouse,
establishing a procedure for dealing with problem wildlife, and posting signs warning
of black bears. Once displaced, cougars do not remain in the area. The young cougars
may become a problem when they are trying to establish their territory. Coyotes are
easily adaptable to changes in their range areas. They most commonly return to the
adjacent forested areas exploiting the periphery of the golf course and fringes of
residential areas. Black-tailed deer remain residents in the forested areas along golf
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174
courses and may wander to the golf course to feed on the young leaves of the planted
trees and shrubs. Grass turf of golf courses are highly favoured by field mice and
voles. The roughs adjoining fairways and the forest edge provide an ideal habitat for
the voles and mice. Once the golf course becomes established with mature trees, one
can usually find squirrels running about in the trees. The sight does facinate the
tired and frustrated golfers!
A golf course at the forest edge is considered as edge habitat often exploited by birds.
The exotic vegetation such as fruit trees and colourful flowers planted throughout the
golf course is an attractant to birds. Fruits and berries provide food for many song
birds. These birds nest and roost in the trees and shrubs of the golf course groungs.
Installation of nestboxes further enhances the golf course as avian habitat. The boxes
will attract raptors such as screech owls, saw-whet owls and American kestrels.
The ponds and other wetland habitats are quite easily constructed into the design.
These habitats attract various waterfowl and marsh bird species such as mallards,
wood ducks, pintails, Great Blue Herons, red-winged blackbirds, and marsh wrens.
The types of plants in a golf course depends on the flair and knowledge of the
landscape architect. A golf course can be planted with either a mixture of native and
exotics or strictly natives. The trend nowadays is to use the already available
landscaping materials and incorporating them into the design.
Disturbance
The most important type of disturbance is the impact of golf courses to adjacent
habitats. such as streams, forests and farmlands. Golf courses are notorious for their
the abundant use of fertilizers and pesticides which leach and runoff into
groundwater systems, and streams. Golf courses that have water bodies, sreams or
creeks may compete for water usages. The large volumes of water are required in
order to keep the fairways and putting greens constantly green. With easy access to
water supply, golf courses quite commonly use the water from adjacent creeks and
streams. This ultimately will decrease the net summer water flows thus shrinking
fish habitat. Fisheries habitat is particularly vulnerable during golf course
construction (Golf Course Development Study 1991). Increase sedimentation is
common in streams after a heavy rainfall wich eliminate available habitat to wildlife.
The Fraser River delta is a critical stopover for migratory birds along the Pacific
Flyway. The migratory birds depend on the farmland habitats for food and shelter.
These lands are under great pressure for further urbanization and golf course
development.
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Comments
Golf is and enjoyable as well as a challenging sport that has gained tremendous
popularity. Golf plays an important role in enhancing British Columbia's tourism
industry by attracting not only golfers from a11 over the world.
Arbutus
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176
Flora
Fauna
Western redcedar
Lodgepole pine
Western hemlock
Douglas fir
Weeping willow
Cherry cultivars
Prune cultivars
Black hawthorn
Weeping willow
Lombardy poplar
Rhododendron spp
Jun.iper
Blue spruce
Vertebrates
Black bear
Cougar
Black-tailed deer
Field mice
Voles
Squirrel
Coyote
Great Blue Heron
Red-winged blackbird
Marsh wren
various song birds
crabapple
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177
COMMUNITY GARDENS
Physical Appearance
Just as the name says, community gardens are gardens shared by the people of the
community it serves. It is where you can grow anything as you please. The City of
Vancouver Urban Landscape TaskForce has identified these gardens as an important
and benificial initiatives in neighbourhood landscapes. Mount Pleasent and
Strathcona Community Gardens are among the larger gardens within Vancouver City
limits with more than three hundred gardeners.
At the Mount Pleasant Garden, the land is divided into fifty-five, 100 square feet
plots. Each gardener pays their yearly ten-dollar usage fees for a plot of land, tools,
manure, and water. The land is leased from Vancouver Parks and Recreation and
managed by a groug of keen volunteers.
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Location
There are a few of these gardens in Vancouver City, Mount Pleasant and Strathcona
being the larger and well established ones. Three small and experimental gardens
have been started in the Kitsilano area. Community gardens are easily initiatied; all
it takes is a group of enthusiastic people in a neighbourhood.
General Description
Many people value farm-fresh vegetables and fruits which tend to be quit pricy for
people with fixed incomes. Gardening is an economical as well as healthy way of
getting fresh produce. Community gardens are originally designed for those that do
not have ready access to a piece of land where they can garden. Over the years,
residents of urban centres are drawn to community gardens just to do so. Community
gardens can be successfully by knowledgable neighbourhood volunteers. The gardens
must be made available to their adjacent neighbours first.
Each plot may vary from the neighbours' simply because of the various choices
different gardeners make. Essentially, the soil must be fertile and productive; the
vegetables and flowers are watered and weeded regularly.
Flora and Fauna
Varieties of vegetables are commonly planted in community gardens. A gardener can
continuously garden the same plot of land all year of land depending on the plant
variety and hardiness to the climatic changes. Crops tolerant of slight frost are
spinach, broccoli, cabbage, turnip, rutabaga, onion, radish, and garlic.
Urban Habitats
179
Comments
Why do people garden? Not only it is economical, the fruits and vegetables you
harvest at peak maturity are the freshest with exceptional flavour and of course
higher nutritional value. Many people enjoy gardening not only for food but also as
a therapy or personal satisfaction. Success in gardening stirs a sense of pride and joy,
and not to mention achievement. Children often find gardening fun and an intersting
way to learn biology and nature. Community Gardens are especially importants in
urban areas where land base available for gardening is scarce. Further, it is a place
where people can get acquainted; share and compare ideas, successful techniques, and
plant materials. This feeling of comradery and neighbourliness will definitely soften
the cold and harsh exterior of an urban centre.
Urban Habitats
180
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