25th May 2011
ARBORIST REPORT
Tree (Safety) Management Plan
Commissioned by:
Little Sisters of the Poor
Randwick NSW
Site address:
Little Sisters of the Poor
70 Market Street,
Randwick
Produced by:
Enviro Frontier Tree Management Pty Ltd
Peter Dubiez
Ph; 1 300 077 233
Email; [email protected]
Website; envirofrontier.com.au
Little Sisters of the Poor /Tree Management Plan.
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25th May 2011
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SUMMARY
Enviro Frontier Tree Management was engaged by Little Sisters of the Poor
(Randwick) to produce this tree safety management plan. Little Sisters of the Poor
will herein be referred to as, the client.
The subject site was located at 70 Market st, Randwick NSW. Site usage is for an
aged care services. The subject site boundaries are Avoca & Market streets and
Clovelly road. The site was located within the Local Government Area of Randwick.
The local consent authority is Randwick Council.
The client has requested this tree management plan as part of a pro-active
approach to tree health and safety management for the subject site.
No written brief outlining the client’s objectives was supplied for the purpose of
producing this report. A meeting at the subject site was conducted with the client’s
representative, Mr Brian Gagin. Mr Gagin is the client’s onsite trade services
manager. The client’s representative outlined the brief verbally during the onsite
meeting.
The client’s representative raised concerns regarding the health and condition of
the tree population at the subject site. The client’s representative requested that
tree management issues relating to public safety/ liability, reduction of maintenance
costs, suitable replacement species, site amelioration and appropriate tree
placement be addressed.
The purpose of this tree management plan is to address client concerns and
provide a reference guide for “best arboricultural practice” at the subject site for a
five year period.
A site inspection for the purpose of gathering field notes was carried out by
consulting arborist James Vivian of Enviro Frontier Tree Management through the
month of May 2011
Seventy seven trees were surveyed for the purpose of producing this tree
management plan. The client’s representative informed me that several of the
subject trees were listed on the local consent authorities Significant Tree Register.
A number of the subject trees exhibited high landscape significance due primarily to
the subject site history.
A tree management safety plan is a moderate to long term project where the initial
capital outlay is rewarded with significantly reduced maintenance costs in the
moderate to long term, and an open space area that is greatly enhanced in the
areas of, safety, reduced maintenance costs, aesthetic appeal and ecological
biodiversity.
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TABLE OF CONTENTS
Page
1.
Summary
2
2.
Methodology
5
3.
Assumptions
6
4.
Observations
6
5.
Findings and Budget
7 - 10
6.
Discussion
11 - 18
7.
Recommendations
18 - 23
References
Bibliography
Appendix 1 - (SULE) Safe Useful Life Expectancy
Appendix 2 - Glossary
Disclaimer
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MAP 1. Site Location Map: The subject site. Not to scale. (Google Maps
2011.)
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1.
METHODOLOGY
1.1
Site Inspection Methodology:
Page 5
A site inspection for the purpose of gathering field notes was carried out by
consulting arborist James Vivian of Enviro Frontier Tree Management over
several days in the month of May 201. Approximately 16 hours was spent on
onsite gathering field notes.
Field notes were recorded electronically on a PDA (Personal Digital
Assistant). The summary of observations (table 1) was produced on an
Excel® spread-sheet and is a duplicate of notes gathered whilst in the field.
1.2
Tree Survey Methodology:
My verbal brief from the client requested that trees be surveyed for the
purpose of producing this tree (safety) management plan.
The subject trees were inspected from the ground only using VTA (Visual
Tree Assessment).
The hazard rating, significance rating and retention value awarded the
subject trees were calculated off site by utilising field notes.
Tree height and average crown diameter were estimated without the use of a
clinometer. The DBH (Diameter at Breast Height) of the subject trees was
measured with a metric measuring tape at 1.3 metres above ground level.
Multi-stemmed specimens were measured at the widest stem.
I did not carry out drilling or Resistograph® assessment to assess
stem/buttress structural integrity. I did not collect and send tissue samples
for pathology testing. I did not conduct aerial inspections of the subject
trees.
1.3
Research Methodology:
Information relating to the site and tree maintenance regimes was obtained
in conversation with the client’s representative.
Site specific local government and other planning instruments relevant to the
subject site and it’ tree population were referenced online.
Every effort was made to obtain information from reliable sources.
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2.
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ASSUMPTIONS
The comments and recommendations in this Tree Management Plan assume the
following:
2.1
Any safety concerns relating to the existing health and condition of the
subject trees needed to be identified.
The amenity of adjoining neighbours needed to be considered.
The retention of the subject trees and preservation of the streetscape and
landscape character was desired.
Removal of trees is considered a last resort option.
Consideration for potential wildlife habitat and related ecological issues was
to be considered.
Federal, state, local, cultural heritage and environmental planning
instruments needed to be addressed.
Information obtained from the client’s representative and sourced information
was accurate.
3.
OBSERVATIONS
3.1
The Site:
The site was located within the Local Government Area of Randwick. The
local consent authority was Randwick Council.
3.2
Site Usage:
Site usage is for an aged care facility.
3.3
Relevant Planning & Environmental Instruments:
The following planning and environmental instruments were relevant to the
subject site;





Local Government Act (1993)
EPA Act (1989)
Randwick Council LEP (1989)
Randwick Council Tree Preservation Order (2006)
Randwick DCP 2002
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4. Age of Surveyed Tree Population as a Percentage (0-100%):
4.1
Tree Age:
Details the age class awarded to the relevant number and percentage of
trees surveyed:
Dead – 2 trees or 3% of the tree population surveyed
Juvenile/Young – 17 trees or 22% of the tree population surveyed
Semi-mature - 21 trees or 27% of the tree population surveyed
Mature - 37 trees or 48% of the tree population surveyed
4.2
Tree Health:
Details the health exhibited by the relevant number and percentage of trees
surveyed:
Good health - 39 trees or 51% of the surveyed tree population.
Fair health - 26 trees or 34% of the surveyed tree population.
Declining health - 12 trees or 15% of the surveyed tree population.
4.3
Works outline
Details the required works as per assessment by the relevant number and
percentage of trees surveyed:
Canopy lift (includes buildings) – 16 trees or 21% of the surveyed tree
population
Canopy lift & deadwood – 14 trees or 18% of the surveyed tree population
Crossed limbs – 1 tree or 1% of the surveyed tree population
Deadwood – 19 trees or 25% of the surveyed tree population
Mulch & weed – 3 trees or 4% of the surveyed tree population
Removal – 17 trees or 22% of the surveyed tree population
No work or completed – 7 trees or 9% of the surveyed tree population
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TABLE 1. Summary of Observations, Comments & Recommendations:
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5.
DISCUSSION
5.1
The Management of Mature Trees:
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48% of the surveyed trees were mature specimens.
Mature trees develop differently to their younger counter-parts. Their rate of
growth is less, they are less vigorous and are less likely to adapt successfully
to changes made within their immediate environment.
It is the norm for mature trees to develop a number of wounds,
compartments and become more susceptible to wood boring insects.
Yet it is often these mature specimens which are held in high regard due to
their physical presence and aesthetic contribution to a site. Arborists’ are
often called on to provide tree management plans to care for and maintain
these highly valued mature trees.
When preparing a tree management plan for mature trees it is necessary to
consider several issues. These issues include the average life span, the
process of decline and death and our ability to enhance longevity whilst
considering relevant safety issues.
Firstly each tree genera has an average life span and in nature tree life
spans range from decades to millennia.
It is difficult to tell with absolute certainty how long the subject trees may be
safely retained. Mattheny and Clarke have noted that the life-span of a tree
will generally be shorter when trees are removed from their natural
environment.
Secondly, trees generally die in a predictable manner. In developing
management plans for mature trees it is necessary to understand the
mortality spiral of the species concerned.
Thirdly, and this issue relates directly to the subject species, for many
species death is as likely to occur due to structural failure as any other
reason. The decay and heart rot that often occurs as a natural process in
older trees is a precursor to failure. The loss of large sections of the tree as
a consequence of this natural process further compounds the mortality spiral
and decline of a tree. (Harris, Clarke & Mattheny 2004)
5.2
Management Strategies:
The management of mature trees has two goals:


Maintaining health
Stabilising structure
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In order to achieve these goals it is necessary to have a thorough
understanding of the subject species and characteristics of its mortality
spiral.
If tree health and structural integrity is established it is then possible to
incorporate a variety of techniques including monitoring, cultural and
chemical treatments to enhance tree longevity. With regard to maintaining
tree health the specific treatments will vary depending on tree species,
affecting issues and site considerations however may include the following;





5.3
Supplemental irrigation
Fertilisation
Removal of competing vegetation
Mulching
Pest management & control
Pruning:
Excessive pruning or the removal of a significant amount of biomass can
lead to tree death. An understanding of the natural habit (form) of a tree and
the area required both below and above surface required to accommodate
the trees mature physical dimensions prior to planting may negate the need
for this type of pruning.
To understand how a tree is affected by excessive biomass reduction via
root disturbance or canopy pruning it is important to understand how a tree
functions. It is also necessary to understand the symbiotic relationship that
exists between the root system and foliage of a tree.
“In a sense, a tree is like an oscillating pump or seesaw. One part moves the
other part so long as energy is supplied. There is no perpetual motion
machine. Any machine or pump that does not receive fuel will eventually
stop. In a tree, one part of the pump traps energy [C6H12O6] and the other
part supplies the water and the essential elements [H2O & 13E]. The top
cannot function without
the bottom and the bottom cannot function without the top. The living
network – symplast – and the transport systems – xylem, phloem – maintain
connections between the top and bottom. The top and bottom move as a
seesaw or as an oil pump – up and down, up and down. The pump
maintains a dynamic equilibrium. This means that it appears to be balanced
when any observation is made at any one time. Yet, the pump is constantly
in motion meaning that one part – top, bottom – is always up or down and
away from the other part. When movement stops or becomes balanced, life
stops. Again, balance is the equalization of opposing forces.
Balance means that motion stops. When movement ceases, the system
stops - death. The balance of nature is a myth. Natural systems survive
because the keep moving as dynamic equilibrium and dynamic oscillation.
When one part-top or bottom – is threatened or made smaller, the other part
will adjust if the injury is not beyond the limits of the system and if there is
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enough time. Now comes the part that most people do not, and cannot
understand. As the pump adjusts to a smaller mass, the energy in the parts
that are shed is first transferred to the parts that will remain.
When the “balancing act” – removing top to compensate for killed roots – is
tried by tree workers, the living parts are removed BEFORE they have had a
chance to return their energy system. Then the imbalance is made worse,
not better. After parts die, then remove them, never before. “(1)
Understanding this principle of energy dynamics and equilibrium may then
pose the question, “how much of a trees canopy or root area may be
removed without killing the tree?”
DIAGRAM Pruning Dose or How Much to Remove. (Shigo .A. 1999)
5.4
The bottom horizon X axis shows age increasing [A]. The vertical Y axis
shows percentage of wood removed increasing. When trees are young [Y]
great amounts of living wood [L] can be removed. As the tree matures [M]
less living wood should be removed and dead wood removed should
increase [D]. As the tree approaches over maturity [OM] very little living [L]
wood should be removed, and great amounts of deadwood [D] should be
removed.
Assessing Tree Age:
In a planning context it is necessary to accurately assess the age of existing
tree assets to help minimise the impacts associated with tree removal/
pruning and effectively address the issue of succession planting.
“Mature trees are those being close to maximum height and exhibiting
reduced extension growth elongation, (either as decreased elongation or a
reduced number of flushes per year. At maturity the degree of apical control
frequently lessens and a rounded crown results.
Mature trees generally possess sound structure, even though inherent
structural problems and numerous internal compartments may be present.
They appear healthy and vigorous and may persist in this condition for long
periods of time, indeed for much of their life span. In contrast, declining or
senescent trees appear less vigorous, because of adverse environmental
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stress, structural failures or simple old age. Their growth rates may be slow
or non existent. Indeed, they may experience reductions in size and mass
due to the loss of large branches.
The development of irregular crowns does not necessarily lead to structural
instability, and trees in this condition may live for some time. However, the
potential life span of trees in a state of decline seems more limited, and the
likelihood of death is much greater. Even with outside intervention, a state of
decline may be irreversible.” (2) (See Table 2.)
Table 2. Characteristics of Mature & Declining Trees. (Clarke and Matheny
1994.)
Character
Mature Tree
Declining Tree
Shoot elongation - extent
normal for species
greatly reduced
Pattern
normal for species
single flush only
Crown form
normal – some loss of apical control
stag-headed, dieback
Foliage development
normal
reduced size and density
Foliage retention (evergreens)
normal
poor
Presence of epicormic shoots
generally absent
present
Compartmentalization response
normal for species
inhibited/reduced
Wound-wood formation
normal for species
inhibited/reduced
Integrity of bark
strong
weak
Susceptibility to parasites
normal for species
Increased
Reproductive behaviour
normal, may be cyclic
may produce stress crops
Stress response
normal
reduced
Autumn colouration
normal
premature
5.5
Tree Maintenance Cost to Amenity Benefit Ratio:
Dr. Hitchmough from Burnley College in Victoria presents the theory that as
a tree ages its aesthetic return decreases whilst its management cost
decrease. Diagrams 6, 7 and 8 illustrate the hypothetical relationships
between tree age, aesthetic return and between tree age and maintenance
costs.
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DIAGRAM 6. Relationship between time and the aesthetic return generated
by a hypothetical tree. (Fakes .J. after Hitchmough 1992.)
DIAGRAM 7. Relationship between time and the management costs
generated by a hypothetical tree. (Fakes .J. after Hitchmough 1992.)
DIAGRAM 8. Relationship between time, aesthetic return and management
costs generated by a hypothetical tree. (Fakes .J. after Hitchmough 1992)
Aesthetic
return
Management
costs
Remove tree
here.
These graphs show several things;
 Aesthetic returns decrease as the tree enters over maturity and this latter
phase may be twenty to thirty years before the biological death of the
tree.

The management costs illustrated in Diagram 7 are for a tree which is not
subjected to regular pruning for powerlines etc. If it was, the curve would
be steeper. The initial higher costs are associated with establishment.
Trees then enter a relatively low cost phase, the length of this phase
depending on the species. As the tree ages it requires more attention to
keep it in a safe and attractive condition.
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Aesthetic decline and maintenance cost would be greater with some trees
due to poor management techniques such as lopping. By overlaying
Diagrams 6 and 7 (diagram 8) you can see that there is a cross-over point
beyond which aesthetic return is decreasing and maintenance costs are
increasing. Where resources are limited, as with most schools it would be
difficult to justify such non-productive expenditure and therefore removal and
replacement would be a rational decision at this point.
Another result of doing nothing until the tree’s death is that those years of
non-productive decline, perhaps 20-30 years, could have been used to reestablish the aesthetic return by planting new trees. Therefore a key
objective of tree management should be the maintenance of a high level of
aesthetic return from trees for as long a time as possible (that is, ‘sustainable
amenity’), rather than a pattern of fluctuating highs and lows.
‘How do we know when aesthetic decline sets in and how much is it costing?
These questions need to relate to the specific site or plantings; that is, one
particular species may behave differently in different physical and
environmental conditions (soils, climate, space in which to grow,
maintenance practices). The answers will never be known without
systematic observation and record keeping. (Fakes .J. after Hitchmough
1992)
5.6
Tree Removal Strategies:
Tree removals are an unpopular but eventually essential part of managing a
population of trees. All living things have a genetically programmed life
span. Over-mature, senescing trees become more hazardous and require
more maintenance to keep them safe.
Dr Hitchmough has identified some of the reasons why those responsible for
tree management have failed to address the problems of tree replacement in
urban landscapes:
1.
There seems to be a desire to believe that trees, if not immortal, are at
least very long-lived. In Australia there is limited experience with the
useful lifespan of amenity trees. In some areas we still have the
original plantings. Apart from the relatively short period of European
occupation of Australia, the fact that some urban areas are still going
through major redevelopments blurs the picture of the longevity of
some species.
2.
The public veneration of trees, particularly “heritage” trees and
“memorial” trees has some positive and negative effects. On the
positive side, landscape managers need to operate in a professional
manner. On the negative side it can be difficult to achieve anything
because of public outcry.
3.
Fear by management authorities of adverse public reactions to tree
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replacement programmes. The public reaction is not always based on
aesthetic or heritage values but may relate to perceived decreases in
property values.
4.
The long term nature of the problem. Tree replacement strategies
require a commitment to planning as well as community education
and involvement. A major limitation for many authorities is that
budgets are linked to the financial year. The lack of staff skilled in tree
management also exacerbates this problem.
5.
The fear of significant cost associated with a serious tree replacement
programme. It may cost several thousand dollars to remove existing
trees. In the short term there is nothing cheaper than doing nothing
so understandably this is an attractive option for many managers.
If the do-nothing approach is taken, there are problems in the long term. As
trees decline and become more hazardous, there is a risk of liability if these
trees cause damage to people and property. As individual trees die and are
either replaced or not replaced, the character of the landscape changes and
becomes less cohesive as well as more difficult to manage on a systematic
basis. (Fakes .J. after Hitchmough 1992)
5.7
Reducing Hazards Associated with the Tree Population:
A hazard assessment of the subject trees was conducted as part of this tree
management plan. (Not all trees on-site were assessed.) Sometimes tree
hazards are obvious and at other times the hazard is not made apparent until
the tree has failed. It is therefore impossible to accurately assess the failure
potential of each and every tree.
“Although trees provide many benefits to people and environments, they also
pose risks. Property can be damaged and people injured or killed when
trees fail. Trees, however, cannot be neatly separated into hazardous and
non hazardous groups. Nearly every tree has some potential to fail,
particularly when exposed to a catastrophic storm. Complete tree safety
could not be attained without removing most trees. (Arboricultural managers
must not only be able to evaluate tree hazard potential, but also to convey
the relative risk of failure to the tree owners. Together the arborist and
owner can evaluate the situation and determine which treatment options
combine suitable reduction in tree hazard with an acceptable level of risk.)
A tree is considered hazardous if it is structurally unsound and there is a
target that would be injured or damaged if the tree failed, (see table 3). An
unsound tree in an area with no target is not considered a hazard; neither is
a sound tree in an area with a target.
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Typical Tree Defects & Factors That Increase the Potential for Failure. (Harris,
Clarke & Mattheny 2004.)
Location
Branch
Trunk
Root
Common Defects Leading to Failure
Excessive end weight
Decay
Poor attachment
Poor taper, low live crown ratio
Decay
Co-dominant stems with included
bark
Lean
Soil failure
Decay and disease
Root removal
Girdling roots
Possible Aggravating Conditions
Poor taper, weak attachment
Weight, exposure to wind
Weight, exposure to wind
Recent stand thinning
Heavy crown, exposure to wind
Heavy crown, exposure to wind
Restricted root system, cut or decayed
roots
Shallow wet soil
Heavy crown, exposure to wind
Heavy crown, exposure to wind, lean
Asymmetrical crown
Some of the defects that may result in tree failure are weak branch
attachments, decay of trunk and branches, excessive weight coupled with
poor taper, and root loss or root decay. Strong winds, snow, and ice can
place excessive loads on trees and can cause breakage even in the absence
of defects. Structures, vehicles, and people are possible targets. The
potential for property damage depends on the likelihood of a tree or a part of
a tree striking the property. Injury to people depends on the likelihood of a
tree striking a specific area when people are present.” (3)
6.
RECOMMENDATIONS:
6.1
Immediate:

Carry out pruning and dead wooding as specified in the summary of
observations schedule

Submit a Tree Application for the removal of tree assets as outlined in the
report. A Tree order provides works can be carried out within 12 months of
consent.

Take down and remove trees as per the approval.

Have all stumps on site ground to a minimum depth of 300mm. (Leaving
stumps in the ground is not only unsightly; it also creates a trip hazard and
promotes the breeding of destructive fungal pathogens. A schematic of
underground services should be supplied to the contractor prior to the
commencement of grinding works. The industry standard allows for stump
grindings to remain on-site unless specified otherwise.)

Where practical, leaf mulch or wood chip should be applied within the PRZ of
all trees on site. The inclusion of leaf mulch will avoid damage to tree
stem/roots, improve soil quality by the promotion of beneficial fungi subsurface, and reduce compaction thereby improving soil quality and tree
vigour. The application of mulch will also reduce maintenance costs via the
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reduction in mowing and water use. In short, it will reduce maintenance
costs and reduce the incidence of disease and associated tree removals.
(Mulch utilised should only be produced from native trees, be aged, free from
seed/pests and be spread at a depth of 75mm. Mulch should be kept away
from the stem of young plants.)

All dead wood with a stem diameter in excess of 20mm should be removed
from retained trees that is over public access frequently used areas.

All tree work should be carried out by a qualified arborist to AS4373.

The selected tree contractor should be a member of, or be eligible for
membership with, the Tree Contractors Association or The National Arborist
Association of Australia.
6.2
Reporting of Works
To have an appropriate Risk Management System for your tree inventory
requires the ongoing and follow up documentation.


Works undertaken, by what staff and qualifications
Supporting Work Method Statements and appropriate Public and Workers
Compensation Insurance

Forward plan of works to be undertaken

Documentation
Attached is an example summary of some of the documentation required by the
contractor performing the tree works
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Calender of Outcomes
Works Programmed Schedule
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Works completed and forward Plan
Works Undertaken
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Photo documentation
Having invested in a Risk Management Plan, the key is the ongoing actioning of the
plan supported by the appropriate company and documentation.
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TREE MANAGEMENT PLAN
REGULATORY Consult local ordinances and regulations including AS4373 (2007)
regarding any limitations on tree maintenance and succession planting.
Educate school employees & contractors about the biology of trees, their
life span, health and condition.
BIOLOGICAL
CULTURAL
CHEMICAL
6.3
Tree management plans are adopted as policy by local consent
authorities under their LEP. This tree management plan provides a
systematic best practice approach for the subject site and should be
adopted as policy for the management of tree assets.
Develop a thorough understanding of the life cycle of the tree assets and
the components of their individual mortality spiral.
Prune to remove dead, dying diseased and other structurally unsound
branches.
Monitor for insects and diseases (including soil borne fungal pathogens.)
Monitor for structural faults and defects.
Reduce the impacts of soil compaction, reduced drainage and evapotranspiration with the application of leaf mulch.
Provide species appropriate irrigation and irrigate in times of drought or
stress. (Do not over-irrigate.)
Remove trees as required. (The tree removal strategy, number of trees
removed and succession planting should be dictated by tree health,
condition and specific site situations.) Carry out community consultation
as required.
Selectively treat pests and diseases as required. (Determined via the
monitoring process.)
TABLE 5. TREE MANAGEMENT PLAN (Part B - Five year timeline.)
2011- 2012
2012-2013
2013-2014
2014-2015
2015-2016
Carry out recommendations as per report. (Tree removals to be tailored to suit specific
tree/site situations. Succession, additional planting & application of Seasol® to be
carried out during Autumn. Pruning works to be carried out to AS4373 2007 & as per
species and timing requirements.
Monitor all trees and carry out tree/remediation works as outlined. Succession planting
& application of Seasol® to be carried out during Autumn. Carry out formative pruning
of young plants and replace dead or underperforming succession plantings as required.
All pruning works to be carried out to AS4373 & as per species and timing requirements.
Monitor all trees carry out tree/remediation works as required & top up mulch as
required. Succession planting & application of Seasol® to be carried out during
Autumn. Carry out formative pruning of young plants and replace dead or
underperforming succession plantings as required. Pruning works to be carried out to
AS4373 2007 & as per species and timing requirements.
Monitor all trees carry out tree/remediation works as required & top up mulch as
required. Succession planting & application of Seasol® to be carried out during
Autumn. Pruning works to be carried out to AS4373 2007 & as per species and timing
requirements.
Monitor all trees carry out tree/remediation works as required & top up mulch as
required. Succession planting & application of Seasol® to be carried out during
Autumn. Carry out formative pruning of young plants and replace dead or
underperforming succession plantings as required. Pruning works to be carried out to
AS4373 2007 & as per species and timing requirements.
Yours sincerely,
PETER DUBIEZ Dip. Hort. (Arb.) Enviro Frontier Tree Management
(Member - National Arborists Association of Australia.)
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REFERENCES
(1)
Alex L. Shigo (1991), Modern Arboriculture, Shigo & Trees Associates –
USA. (Page 87)
(2)
Clark and Matheny, Abstract taken from – Management of Mature Trees.
Journal of Arboriculture ISA (Vol 17. Page 173)
(3)
Harris W. Clarke James R. Mattheny Nelda P. (2004), Arboriculture
Integrated Management of Landscape Trees, Shrubs and Vines. Prentice
Hall - New Jersey USA. (Page - 405)
BIBLIOGRAPHY
Native Plant List Port Jackson Catchment
(http://www.northsydney.nsw.gov.au/www/html/3267-native-plants-of-northsydney.asp)
Fakes .J. after Hitchmough (1992), Tree Care & Maintenance, TAFE NSW
Alex L. Shigo (1991), Modern Arboriculture, Shigo & Trees Associates – USA.
Mattheck and Breloer (1994), The Body Language of Trees. Forschungszentrum
Karslruhe GMBH.
Harris W. Clarke James R. Mattheny Nelda P. (2004), Arboriculture Integrated
Management of Landscape Trees, Shrubs and Vines. Prentice Hall - New Jersey
USA.
AUTHORS EXPERIENCE & QUALIFICATIONS:
Industry Experience:
 Manager – Enviro Frontier (all aspects of tree management) 2010-present
 Business Manager NSW – Citywide – Open Space Division 2009 - 2010.
 Manager Active Tree Services Residential/Commercial Division- 1990 2005.
Qualifications & Training:
 Tree Care & Maintenance Certificate - Ryde School of Horticulture - 1994
 Phil Hadlington Tree Course - 1989
 Working Committee for the first Amenity Tree Industry standards with
WorkCover
 Working Committee for the first AS4373
 Founding Member for Tree Contractors Association
Professional Association:
 Member - National Arborist Association of Australia
 Member – Tree Contractors Association
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APPENDIX 1
SULE (Safe Useful Life Expectancy)
Categories (after Barrell 1996, Updated 01/04/01.) The five categories and their sub-groups are as
follows:
1. Long SULE - tree appeared retainable at the time of assessment for over 40 years with an
acceptable degree of risk, assuming reasonable maintenance;
A. Structurally sound trees located in positions that can accommodate future growth.
B. Trees which could be made suitable for long term retention by remedial care
C. Trees of special significance which would warrant extraordinary efforts to secure their long term
retention.
2. Medium SULE- tree appeared to be retainable at the time of assessment for 15 to 40 years with
an acceptable degree of risk, assuming reasonable maintenance;
A. Trees which may only live from 15 to 40 years.
B. Trees which may live for more than 40 years but would be removed for safety or nuisance
reasons.
C. Trees which may live for more than 40 years but would be removed to prevent interference with
more suitable individuals or to provide space for new planting.
D. Trees which could be made suitable for retention in the medium term by remedial care.
3. Short SULE - tree appeared to be retainable at the time of assessment for 5 to 15 years with an
acceptable degree of risk, assuming reasonable maintenance:
A. Trees which may only live from 5 to 15 years.
B. Trees which may live for more than 15 years but would be removed for safety or nuisance
reasons.
C. Trees which may live for more than 15 years but would be removed to prevent interference with
more suitable individuals or to provide space for new planting.
D. Trees which require substantial remediation and are only suitable for retention in the short term.
4. Removal - trees which should be removed within the next 5 years;
A. Dead, dying, suppressed or declining trees.
B. Dangerous trees through instability or recent loss of adjacent trees.
C. Dangerous trees because of structural defects including cavities, decay, included bark, wounds or
poor form.
D. Damaged trees that are clearly not safe to retain.
E. Trees which may live for more than 5 years but would be removed to prevent interference with
more suitable individuals or to provide space for new planting.
F. Trees which are damaging or may cause damage to existing structures within the next 5 years.
G. Trees that will become dangerous after removal of other trees for the reasons given in (a) to (f).
H. Trees in categories (a) to (g) that have a high wildlife habitat value and, with appropriate
treatment, could be retained subject to regular review.
5. Small, young or regularly pruned - Trees that can be moved or replaced;
A. Small trees less than 5m in height.
B. Young trees less than 15 years old but over 3m in height.
C. Formal hedges and trees intended for regular pruning to artificially control growth.
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APPENDIX 2
GLOSSARY
Age Classes; (S) Semi-mature refers to a tree between immaturity and full size.
(M)
Mature refers to a full sized tree with some capacity for further growth.
(LM) Late Mature refers to a tree that is entering decline.
(O)
Over-mature refers to a tree already in decline.
Health; Refers to the tree’s vigour as exhibited by the crown density, leaf colour,
presence of epicormic shoots, ability to withstand disease invasion, and the degree
of dieback. Classes are Good (G), Fair (F), Declining (D), and Poor (P).
Condition; Refers to the tree’s form and growth habit, as modified by its
environment (Aspect, suppression by other trees, soils) and the state of the scaffold
(i.e. trunk and major branches), including structural defects such as cavities,
crooked trunks or weak trunk/branch junctions. These are not directly connected
with health, it is possible for a tree to be healthy but in poor condition. Classes are
Good (G), Fair (F), Declining (D), and Poor (P).
Diameter at breast height (DBH); Tree stem diameter at 1.3 metres above
ground.
Critical Root Zone (CRZ); Refers to a radial offset of five (5) times the trunk DBH
measured for the centre of the trunk, rounded to the nearest 0.5 metres.
Primary Root Zone (PRZ); Refers to a radial offset of ten (10) times the trunk DBH
measured from the centre of the trunk, rounded to the nearest 0.5 metres.
Visual Tree Assessment (VTA); Refers to visual inspection of tree only.
Aerial Inspection; Refers to climbing a tree to obtain more accurate information.
Remnant Stand or Tree; Refers to a stand of trees or tree which is a remaining
specimen/s from an area of previous woodland or forest community.
Crown; Refers to the position of the tree consisting of branches and leaves and any
part of the trunk from which branches arise.
Stem; Refers to an organ which supports branches, leaves, flowers and fruits.
Epicormic Growth; Refers to shoots produced by dormant buds within the bark or
stem of a tree as a result of stress, incorrect pruning or increased light.
Resistograph Drill; Refers to a specialised arboricultural tool used for drilling a tree to
ascertain structural integrity.
SAFE USEFUL LIFE EXPECTANCY (SULE); In planning context, the time a tree
can expect to be usefully retained is the most important long-term consideration.
SULE i.e. a system designed to classify trees into a number of categories so that
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information regarding tree retention can be concisely communicated in a nontechnical manner. SULE categories are easily verifiable by experienced personnel
without great disparity. A tree’s SULE category is the life expectancy of the tree
modified
first by its age, health, condition, safety and location (to give safe life
expectancy), then by economics (i.e. cost of maintenance: retaining trees at an
excessive management cost is not normally acceptable), effect on better trees, and
sustained amenity (i.e. establishing a range of age classes in a local population).
SULE assessments are not static but may be modified as dictated by changes in
tree health and environment. Trees with a short SULE may be at present by
making a contribution to the landscape but their value to the local amenity will
decrease rapidly towards the end of this period, prior to their being removed for
safety or aesthetic reasons. For details of SULE categories see Appendix A,
adapted from Barrell 1996. (Updated April 2001)
Hazard Rating: Refers to three separate categories; Failure Potential, Size of
Defective Part and Target Rating. A tree is given a score of 1 to 4 in each individual
category. A score of 12 would rate as an extreme Hazard Rating; a score of 3
would rate as a very low Hazard Rating. (Source; Matheny and Clarke 1994)
(Failure Potential) – Identifies the most likely failure and rates the likelihood that
the structural defect will result in failure.
1. Low - defects are minor (e.g. Dieback of twigs, small wounds with good
wound wood development)
2. Medium – defects are present and obvious (e.g. Cavity encompassing1025% of stem circumference).
3 High – numerous and or significant defects present (e.g. Cavity
encompassing 30-50% of stem circumference or major bark inclusions).
4. Severe – defects are very severe (e.g. heart rot fruiting bodies, cavity
encompassing more than 50% stem circumference.
(Size of Defective Part) – Rates the size of the part most likely to fail. The larger
the part that fails, the greater the potential for damage.
1.
2.
3.
4.
Most likely failure less than 150mm in diameter.
Most likely failure 150mm – 450mm in diameter.
Most likely failure 450mm – 750mm in diameter.
More than 750mm in diameter.
(Target Rating) – Rates the use and occupancy of the area that would be struck by
the defective part.
1. Occasional use (e.g. jogging/cycle track).
2. Intermittent use (e.g. picnic area/day use parking).
3. Frequent use, secondary structure (e.g. seasonal camping area/storage
facilities).
4. Constant use, structures (e.g. year-round use for a number of hours each
day/residences).
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Hazard Rating = Failure Potential + Size of Part + Target Rating. (Add each of
these categories for a rating out of 12).
Significance Rating: (Produced by Enviro Frontier Tree Management 2004.
Amended November 2006.) Refers to four separate categories; Streetscape
Significance, Landscape Significance, Ecological Significance and Special
Significance. A tree is given a score of 1 to 3 in each individual category. A score
of 12 would rate a tree as being of high significance and a score of 3 would rate a
tree as being of low significance.
(Streetscape Significance) - Assesses a tree within the streetscape and rates its
contribution to visual amenity and streetscape character.
1. Low - Refers to trees that have little influence on the streetscape character
and/or visual amenity.
2. Moderate to High - Refers to trees that have a moderate to high influence on
the streetscape character and/or visual amenity.
3. High - Refers to trees that have a high influence on the streetscape character
and/or visual amenity.
(Landscape Significance) - Assesses a tree within the landscape and rates its
contribution to visual amenity and landscape character.
1. Low - Refers to trees that have little influence on the streetscape character
and/or visual amenity.
2. Moderate to High - Refers to trees that have a moderate to high influence on
the streetscape character and/or visual amenity.
3. High - Refers to trees that have a high influence on the streetscape character
` and/or visual amenity or trees that ‘create a sense of place’.
(Ecological Significance) - Assesses a tree and rates its worth in ecological terms.
1. Low - Refers to species of exotic climatic origin that represents little
ecological value, generally for the purpose of providing habitat, or trees with
a low possibility of contributing in an ecological sense. (For example; an
isolated exotic specimen with no interconnecting canopy area or hollows
present.)
2. Moderate - Refers to endemic species that represent moderate ecological
value, generally for the purpose of providing habitat, or trees that offer a
moderate contribution in an ecological sense. (For example; an endemic
specimen which forms part of a stand with an interconnecting canopy area.
Please note; a specimen of exotic climatic origin which exhibits significant
habitat or ecological benefits may also be awarded a moderate significance
rating. )
3. High - Refers to endemic species which represent part of a wildlife corridor,
riparian zone or makes a significant contribution in an ecological sense. (For
example; a tree with hollows which may serve as habitat.)
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(Special Significance) - Details the significance of a tree with regard to its’
historical, aboriginal, protected local, state or federal significance. (For example;
trees listed on a significant tree register, trees listed as a threatened species, trees
that form part of an endangered ecological community or trees that are protected
under a heritage conservation plan as a landscape item etc.) (Special significance
does not refer to trees protected under a local consent authority’s Tree Preservation
Order.)
1. Low - Refers to trees that have no special significance at local, state or
federal level.
2. Moderate - Refers to trees of special significance as assessed by a local
consent authority.
3. High - Refers to trees of special significance as assessed by state or federal
government.
Significance Rating = Tree Species + Landscape Significance + Ecological
Significance + Historical Significance. (Add each of these four categories
together for a score out of 12.)
Glossary continued:
Retention Value: (Produced by Enviro Frontier Tree Management 2004.) Refers
to three separate categories; Health, Condition and Age. A tree is given a score of
1 to 4 in each individual category. A score of 12 would rate a tree as having a high
retention value and a score of 3 would rate a tree as having a low retention value.
(Health) - Refers to the tree’s vigour as exhibited by the crown density, leaf colour,
presence of epicormic shoots, ability to withstand disease invasion, and the
degree of dieback. (Matheny and Clarke 1994)
1.
2.
3.
4.
Poor.
Declining.
Fair.
Good.
(Condition) - Refers to the tree’s form and growth habit, as modified by its
environment (Aspect, suppression by other trees, soils) and the state of the scaffold
(i.e. trunk and major branches), including structural defects such as cavities,
crooked trunks or weak trunk/branch junctions. These are not directly connected
with health as it is possible for a tree to be healthy but in poor condition. (Matheny
and Clarke 1994)
1.
2.
3.
4.
Poor.
Declining.
Fair.
Good.
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(Age) - Refers to the age of a tree on a site and its potential for future growth taking
into account any physical restrictions, (e.g. position of house.)
1.
2.
3.
4.
Refers to a tree that is over-mature and senescing due to advanced age.
Refers to a tree that is late-mature and is in, or entering, decline.
Refers to a tree that is mature.
Refers to a tree that is semi-mature.
Retention Value = Health + Condition + Age.
categories together for a score out of 12.)
(Add each of these three
AS4373; Refers to Australian Standard for Pruning of Amenity Trees. This
certification commenced in 1996 and is a standard for correct arboricultural
techniques. The standard takes into account tree biology and tree worker safety
issues.
Co-Dominant Stems; Refers to stems on trunks of about the same size originating
from the same position from the main stem.
Catena; Refers to the physical location of a site on a slope.
Endemic; Refers to locally indigenous species.
Significant Tree; Refers to mature trees assessed as having either high landscape
significance or playing a significant role in the structure or ‘playability’ of the course.
Senescing Trees; Refers to trees that are in full decline.
Mycelium; Refers to fungal presence as exhibited by a floury white vein.
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25th May 2011
(VTA) Methodology Model; (Mattheck and Breloer 1994.)
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DISCLAIMER
Limits of Scope Statement:
“I am not a solicitor,” There is no substitute for current professional litigation
consulting agri-horticultural matters and legal advice. This publication is not
intended as, and does not represent legal advice and should not be relied upon to
take the place of such advice. Although every effort has been made to assure the
accuracy of the information included in this publication as of the date on which it
was issued, laws, court and arbitration decisions and governmental regulations in
Australia and New South Wales are subject to frequent change. To be included in
all the standards and duties of evaluation, investigations, interpretations,
methodology and contradictions in determining the failure for claims and litigation.
Assumptions:
Care has been taken to obtain information from reliable sources. All data has been
verified insofar as possible, however, Enviro Frontier Tree Management, can
neither guarantee nor be responsible for the accuracy of information provided by
others.
Unless Stated Otherwise:
Information contained in this report covers only the tree/trees that were examined
and reflects the condition of trees at the time of inspection.
Little Sisters of the Poor /Tree Management Plan.