Landscape design with indigenous Landscape
design with indigenous
vegetation in New Zealand – preliminary results
Glenn Stewart
Glenn
Stewart
Department of Environmental Management
Lincoln University
Christchurch, NEW ZEALAND
IALE, Beijing, China, 20 August 2011
New Zealand – isolated history
>85 % plants, frogs, lizards and birds endemic – Global
biodiversity “hotspot”
Prior to Polynesian settlement (c. 800 yrs BP) no terrestrial
mammals except bats. Polynesians introduced dog, rat; Sealers/Whalers &
Captain Cook (1770’s) introduced pigs, goats; early settlers (1820’s) cattle,
horses, sheep
22 of the 54 mammal and 90 of the 138 bird species introduced 1860—1880.
Eventually 33 sp. mammals and 43 sp. birds successfully established
2300 sp. native plants, c.2400 naturalised exotic sp. plants, c. 30,000 – 40,000
exotic sp. in cultivation and 1 exotic sp. becomes naturalised every 3 months.
Now 30
30,000
000 to 40
40,000
000 sp
sp. exotic plants in cultivation in NZ
New Zealand Urbanization
New Zealand Urbanisation
85 % of New Zealand population live in an urban environment Largest cities: Auckland (1.3million),
Wellington (Capital, 450,000),
(
)
Christchurch (375,000)
Data on species diversity of selected urban plant communities –
Christchurch Lawns1
Walls2
Urban Forest
Woodland
W
dl d3
Parkland
P
kl d3
Linear
Li
Parkland3
Number of
sites
327
70
128
65
60
Total species
richness (S)
127
117
416
200
116
Mean S per
site (+/- SD)
12.5
(3.3)
N.A.
20.6 (8.9)
12.0 (6.1)
7.5 (2.8)
% of native
species
13%
15%
25%
16%
16%
1
Stewart et al 2009a, 2 De Neef et al 2008, 3 Stewart et al 2009b Urban Landscape Design
• Historically emphasis has been on vibrant plant colour and texture which has favoured exotic plant species (colonial history?)
• Indigenous species until recently (last 20 years) were not popular as they were perceived as dull and unexciting
• However, the last 20 years has seen a marked increase in indigenous planting, especially in residential gardens and in native restoration projects (new and colourful cultivars)
projects (new and colourful cultivars)
• I ask 3 questions in relation to tree species used in design
1. What is the mixture of exotic vs indigenous species used?
2. Specifically, what indigenous species are planted?
3 What is the potential for enhancing indigenous biodiversity?
3.
h i h
i lf
h i i di
bi di
i ?
Objectives – preliminary data on trees
1. What has been planted and by whom? Summarise indigenous /exotic species used in:
• Commercial and residential design (landscape practitioners)
• Residential gardens (property owners)
• Urban street tree planting (city authorities)
p
g( y
)
• Restoration projects (government & non‐government agencies)
2. What is readily available for planting?
3. What could/should be planted to increase biodiversity?
What could/should be planted to increase biodiversity?
Landscape designs
Residential gardens
Urban street trees
Restored native woodlands
Lincoln University
Wi
Wigram
D t ti B i
Detention Basin
Matawai Park
Methods
1. What has been planted and by whom? What has been planted and by whom?
• Landscape designs (field survey)
• Residential garden survey data (Stewart et al. 2009b, UF&UG)
• Urban street trees (Christchurch City Council database)
Ub
(Ch i h h Ci C
il d b )
• Restoration projects (planting lists/field sampling)
2. What is readily available for planting?
• Nursery catalogues/manuals
3. What could/should be planted to increase biodiversity?
• Species traits, ecosystems services, etc
Current plantings ‐ landscape design
47 designs, 17 native spp, 27 exotic spp.
Most abundant exotic genera – Quercus 38%, Betula 36%, Magnolia 36%, Fraxinus 28%, Prunus 23%
Most abundant exotic spp – Quercus palustris, Q. robur, Betula
pendula, Magnolia grandiflora, Fraxinus, Prunus (several spp.)
Most abundant native genera – Sophora 34%, Pittosporum 32%, Plagianthus 30%, Cordyline 24%, Pseudopanax 18%
Most abundant native spp – Sophora tetraptera, Pittosporum
eugenioides, P. tenuifolium, Cordyline australis, Plagianthus regius, Pseudopanax
p
crassifolius
f
Current plantings – residential gardens (woodlands)
98 native dominated gardens
98 native dominated gardens
Most abundant genera:
Hoheria Pittosporum Plagianthus Podocarpus Olearia
Hoheria, Pittosporum, Plagianthus, Podocarpus, Olearia
Most abundant species
Pittosporum eugenioides, Plagianthus
eugenioides Plagianthus regius, Pittosporum
regius Pittosporum crassifolium, crassifolium
Hoheria populnea, Olearia paniculata, Podocarpus totara
28 exotic dominated gardens
28 exotic dominated gardens
Most abundant genera:
Betula, Fagus, Fraxinus, Magnolia, Prunus, + 3 others
Betula, Fagus, Fraxinus, Magnolia, Prunus, 3 others
Most abundant species
Betula p
pendula, Prunus
,
cerasifera, Prunus
f ,
yyedoensis, Acacia melanoxylon, ,
y ,
Azara microphylla, Fagus sylvatica, Fraxinus excelsior, Magnolia grandiflora, Malus domestica.
Current plantings ‐ urban streets and urban parks
• 5 exotic genera – Quercus (10.4) Fraxinus (10.3), Prunus (8.7), Betula (5.9), Acer (5.1) comprise 40.4% of all trees
• 19 exotic species – Betula pendula (5.0), Quercus palustris (4.1), Fraxinus ornus
(4.1), Liquidambar styraciflua (2.6), Quercus robur (2.5), Prunus cerasifera (2.5) comprise 38.8% of all trees
• The remaining 458 exotic species comprise 43.6% of all trees
• 4 native genera –
i
Plagianthus
l i h (3.7), Sophora
( )
h
( )
(3.7) Cordyline
d li (3.2), Pittosporum
( ) i
(2.8) comprise 13.4% of all trees
• 5 native species –
native species Plagianthus regius (3.7), Cordyline
(3 7) Cordyline australis (3.2), Sophora
(3 2) Sophora
tetraptera (2.1), Pittosporum eugenioides (1.6), Sophora microphylla (1.6) comprise 12.2% of all trees
• The remaining 56 native species comprise only 6.0% of all trees
Current plantings ‐ indigenous restoration projects
3 sites, a snapshot typical of most recent restoration projects
Species richness
16 years – 24 (native 20, exotic 4)
20 years – 20 (native 16, exotic 4)
40 years –
y
32 (native 28, exotic 4)
(
)
Most dominant species (relative basal area)
16 years –
y
Pittosporum
p
eugenioides, Aristotelia
g
,
serrata, Dodonea
,
viscosa, Pseudopanax arboreus
20 years – Pittosporum eugenioides, Cordyline australis, Hoheria
angustifolia, Pittosporum tenuifolium
angustifolia, Pittosporum
40 years – Nothofagus solandri, Podocarpus totara, Plagianthus
regius, Pittosporum tenuifolium
Most commonly planted tree genera
Landscape Landscape
designs (47)
Residential
gardens (126)1
Street/park Street/park
Restoration
Restoration plantings plantings (13)3
(94,889 trees)2
Native species
p
17
50
61
33
Exotic species
27
151
477
4
% native/exotic spp.
37/63
25/75
18/82
89/11
Hoheria
Pittosporum
Plagianthus
Podocarpus
Cordyline
Pittosporum
Plagianthus
Sophora
Hoheria
Pittosporum
Plagianthus
Cordyline
Betula
Fagus
Fraxinus
Magnolia
Prunus
Betula
Acer
Fraxinus
Quercus
Prunus
Sambucus
Acer
Most abundant genera
native
Sophora
Pittosporum
Plagianthus
Cordyline
Exotic
Betula
Quercus
Fraxinus
Magnolia
Prunus
1Stewart et al. 2009b 2CCC database 3Stewart et al. in prep. Quercus
Prunus
Most abundant native species planted
Landscape designs Residential
gardens
Street/park plantings Restoration plantings
Pittosporum eugenioides
Pittosporum tenuifolium
Plagianthus regius
Cordyline australis
Sophora tetraptera
Pittosporum eugenioides
Pittosporum tenuifolium
Plagianthus regius
Pittosporum eugenioides
Pittosporum eugenioides
Pittosporum tenuifolium
Plagianthus regius
Cordyline australis
Plagianthus regius
Cordyline australis
Sophora tetraptera
Hoheria angustifolia
Podocarpus totara
Hoheria angustifolia
Sophora micropyhlla
8 species
8 species
P. tenuifolium
C. australis
P. eugenioides
What is readily available for planting? ‐ nursery catalogues (all species)
catalogues (all species)
• 71 plant nurseries in the Christchurch region (not including garden centres)
• Majority sell mixtures of exotic and native species, <5 provide native species only
• Typical nurseries – exotic/native spp (%) – 62/38, 64/36, 88/12, 54/46
• Over 2500 species (including cultivars), excluding cultivars, correcting naming errors, etc reduces the list to c. 1200 species.
• Trees for Canterbury (Council), Wai Ora (Trust), Motukarara (Department of Conservation) ‐100 % native spp.
• Greatest variety offered for sale
Exotic – Acer (36), Prunus (19), Fraxinus (18)
Native – Pittosporum (55), Pseudopanax (27), Hoheria (18)
Further analysis is underway..........................
What could/should be planted to increase biodiversity? • The Department of Conservation nursery in Christchurch sells 39 native tree and 56 small tree and shrub species local to the region, many of which are rarely planted.
many of which are rarely planted.
• Many of these genera/species are/or attract important food for native birds:
native birds:
Alectryon excelsus (F), Aristotelia (F; I), Astelia (F; I), Carpodetus serratus (F; I; L), Clematis (N), Coprosma
),
( ), p
((F), Cordyline
),
y
((F; N; I), Corokia
; ; ),
cotoneaster (F), ( ),
Dacrycarpus dacrydioides (F; I), Elaeocarpus (F, I, I), Fuchsia excorticata (F), Griselinia littoralis (F; N; I; L), Hebe salicifolia (I) Hebe strictissima (I), Hedycarya arborea (F, I), Hoheria (F; I), Kunzea ericoides (N; I), Lophomyrtus
obcordata (F), Melicope simplex (F), Melicytus lanceolatus (N; I; L), Metrosideros umbellata (N), Myrsine (F; I), Myoporum laetum (F; I), Olearia
(N; I), Phormium (F; N), Pittosporum (F; I), Plagianthus (F; I), Podocarpus (F), Prumnopitys
i taxifolia
if li (F; I), Pseudopanax (F; N; I; L), Sophora
( I)
d
(
I L) S h
(
(F; N; I)
I)
(F) ‐ Fruit/seed, (N) – Nectar, (I) – Insects, (L) ‐ Foliage Which is better for biodiversity?
Do we continue with this?
Or move
more to this?
References
De Neef, D., Stewart, G.H., & C.D. Meurk (2008). URban Biotopes of Aotearoa New Zealand (URBANZ) (III): Spontaneous urban wall vegetation in Christchurch and Dunedin. Phyton (Horn, Austria) 48: 133‐
154.
Stewart, G.H., Ignatieva, M.E., Meurk, C.D., Buckley, H., Horne, B., & T.Braddick (2009a). URban Biotopes of Aotearoa New Zealand (URBANZ) I: Composition and diversity of temperate urban lawns in
(URBANZ) I: Composition and diversity of temperate urban lawns in Christchurch. Urban Ecosystems 12: 233‐248. Stewart, G.H., Ignatieva, M.E., Meurk, C.D., Buckley, H.L., Magueur, A, Stewart
G H Ignatieva M E Meurk C D Buckley H L Magueur A
Case, B.S., Hudson, M., & M. Parker. (2009b). URban Biotopes of Aotearoa New Zealand (URBANZ) (II), Florisitics, biodiversity and conservation values of urban residential and public woodlands. Urban p
Forestry & Urban Greening 8: 149‐162.
Stewart, G.H., Meurk, C.D., & J. Chang (in prep.). URban Biotopes of Aotearoa New Zealand (URBANZ) (VI): New Zealand urban forest futures. Plant Ecology.
Acknowledgments
My colleagues Sue McGaw, Maria Ignatieva and Colin Meurk.
Meurk
The New Zealand Foundation for Research, Science & T h l
Technology funded this research.
f d d hi
h