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Culturally Significant Trees Assessment& Management Guidelines

Assessment and Management Guidelines - Culturally Significant Tree Project - Prepared by Symatree Pty Ltd

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Culturally Significant Trees Assessment& Management GuidelinesIntroduction and Background

Culturally Significant trees are a special class of trees that can provide a wide range of historical, cultural, aesthetic and scientific benefits over and above the accepted values of trees.

Many remnant native trees have significance for local Aboriginal communities, some of these trees are obvious, such as shield or canoe trees, but others may be less conspicuous. Most other communities have planted trees or gardens to commemorate a person or important event. These plantings help define communities and are a living reminder of significant local history. .

From a local government perspective many of these important trees are located on public land or roadsides, and may either be at risk from adjacent development or maintenance activities, or may through age, proximity to other structures or neglect be a hazard themselves.

The following guidelines have been developed to assess individual trees, group of trees or avenue of trees that may be considered culturally significant. These guidelines are based upon the information obtained as a result of a literature review completed as part of the Culturally Significant Tree Project. This project has been instigated by District Council of Mount Barker, in partnership with TREENET, and with funding support from the LGA (Local Government Association of South Australia).

Heritage Charters and Conventions

A number of heritage charters and conventions exist to help professionals and others define and manage items of cultural significance for present and future generations. Heritage charters and conventions act as frameworks to help the decision making process when dealing with culturally significant items. From a review of the heritage charters it was determined to use the Australian ICOMOS, Burra Charter (Australian ICOMOS 1999) and the Australian Natural Heritage Charter for the places of natural heritage significance (Natural Heritage Charter 2002) as the primary charters with supporting reference to the Florence Charter for Historic Gardens (ICOMOS-IFLA 1982).

These charters appear to be the most applicable to trees of cultural significance. The Burra Charter provides guidance for the conservation and management of places of cultural significance (cultural heritage places), and is based on the knowledge and experience of Australia ICOMOS members (Australian ICOMOS 1999). The Burra Charter is the favoured Charter in use by Australian heritage professionals.

Trees create a unique challenge when one applies an architecturally driven approach such as the Burra Charter to what is in essence a biological system. Trees have vastly different management needs to buildings. However the terms, definitions and processes outlined within the Burra Charter can be adapted. Melding of these approaches will provide the best possible methodology to conserve and manage culturally significant trees. The conservation of trees and avenues really means applying the best appropriate care so that they are enjoyed for present and future communities.

The Burra Charter lacks recognition of natural processes that define what a tree is and how it grows. For conservation processes to clearly be applicable to urban tree management certain terms and guidelines must reflect trees as biological (living) systems. By adapting Article 2, from the Florence Charter the unique characteristics of trees and other plants can be defined: Trees are living, which means they are perishable and renewable. Thus their health and stability reflects the perpetual balance between the cycle of the seasons, the growth and decay of nature and the desire of the arborist/ horticulturalist to keep them permanently unchanged once maturity has been reached.

Definition

The Australian ICOMOS, Burra Charter uses the concept of cultural significance to justify the conserving of places, including trees. Cultural significance means aesthetic, historic, scientific or social value for past, present and future generations (Australian ICOMOS, Burra Charter Article 1.2, 1981).

Culturally significant trees are a special class of trees that have exceptional values in terms of their contribution to our environment. These values are over and above the accepted values of trees. Trees that are likely to be of cultural significance are those that help us understand the past or enrich the present, and which will be of value to future generations.

The charter describes the four values used in the definition as encompassing all other values. These values include historical, cultural, aesthetic and scientific.

Assessment and Management Guidelines - Culturally Significant Tree ProjectPrepared by Symatree Pty Ltd

Heritage Charters and ConventionsThe meaning of these values in the context of culturally significant treesis discussed below:

Cultural: Trees play an important role in elements of towns and cities such as approach roads, showgrounds, transport links, residential areas, important buildings, access roads, parks and nature strips. Trees help identify special places. They may have associations with individual people and communities or tell stories of other times and places.

Historical: Trees are often associated with important eras, buildings, events or people. Trees may reflect specific epochs in garden design or landscape architecture.

Scientific: Trees could be rare, vulnerable, endangered or of a great age. Remnant trees from former natural ecological communities may retain valuable habitat and faunal corridors for other endangered and dependent species.

Aesthetic: Trees are of aesthetic value if they reflect important features in townscapes. These trees often visually dominate a place by their size, scale and visual impact.

Cultural, Historical, Scientific and Aesthetic values are the principal values applied to culturally significant trees. However, more precise values may be included for specific specimens or situations.

The Burra Charter and Guidelines (Australian ICOMOS 1999) have been used as the basis for this definition of culturally significant trees. Part of the definition developed by the National Trust of South Australia was also incorporated.


Terms and Principles For the purposes of these guidelines the following terms that could be used in the conservation of culturally significant trees have been listed below. Please note specific Arboricultural terminology is beyond the scope of this policy.

Place: means the site, area, land, landscape and may include elements, spaces and views that are part of this place. The concept of place should be broadly interpreted. The elements include memorials, individual and avenues of trees, gardens, parks, places of historical events, urban areas, towns, industrial places, archaeological sites, spiritual and religious places.

Fabric: means all the physical material of the place. Species, age, location, biology, growing zone are considered to be the fabric of a tree.

Protection: may include conservation management measures that are either direct or indirect. The aim of protection is to prevent or minimise impacts that may be detrimental to the individual tree’s, group of trees’ or avenue of trees’ long term health and/or stability. Any alteration to the tree’s physical environment which will endanger tree health must be prohibited. This protection is applicable to all aspects of the tree’s physical growing environmental (e.g. soil type, pH, wind patterns) or adjacent infrastructure (e.g. drainage, irrigation systems, roads, car parks, fences etc).within a tree’s designated “Tree Protection Zone”. The TPZ is based upon the Australian Standard for the Protection of Trees on Development Sites AS 4970 method.

Conservation: means all the processes of managing an individual tree, group of trees or avenue of trees so as to retain its cultural significance Conservation should include the provision for the tree’s security, its maintenance and its future. Conservation is based on a respect for the existing fabric. It requires a cautious approach of changing as much as necessary but as little as possible.

Maintenance: means the continuous protective care of an individual tree, group of trees or avenue of trees. This may include minor pruning, weeding, mulching, fertilising and irrigation undertaken to prolong the health and life expectancy of a tree. Culturally Significant individual trees, group of trees or avenues of trees must be preserved in appropriate surroundings.

Reinstatement: is appropriate only if there is evidence that an individual tree or avenue that is to be reintroduced once existed there at a previous time. Returning the individual tree or avenue contributes to the cultural significance of that place. Reinstatement is only possible if the processes that have threaten an individual tree, group of trees or avenue that once existed at that place have been discontinued.

Restoration: is appropriate only if there is sufficient evidence of an earlier state to guide the conservation process and if returning an individual tree, group of trees or avenue of trees is consistent with a previous time. An illustration of restoration for a culturally significant tree is major pruning to regain a tree’s structural integrity or the interplanting of new trees of the dominant species to complete an avenue planting.

Reconstruction: is appropriate only where a place is incomplete through significant tree damage or removal, and only where there is sufficient evidence that replanting a tree, group of trees or avenue will return the site back to an earlier era. This is the most applicable of the conservation terms for culturally significant trees, along with the idea of maintenance. Reconstruction most accurately reflects the ongoing nature of scheduled arboricutlural practices given the ongoing continually changing nature of living trees. Tree replacement most readily approximates this process. It can include the introduction of a new species to replace the old if sufficient justification exists and no or minimal impact to the significanceof the place occurs.

Use: While any culturally significant tree is designed to be seen, access to it may need to be restricted to the extent demanded by its vulnerability or risk factors, so that its physical fabric and cultural significance may be preserved or to provide a sufficient level of risk management by excluding people or removing property from under the canopy of thesubject tree. The application of a fenced tree protection zone would illustrate best the intention of this term.


Specific StepsThe specific steps relevant to determining significance for trees that are possibly culturally significant are as follows:

1. Gathering information2. Assessing against criteria3. Preparing a statement of significance

Gathering information

The following are possible sources of information:

• Undertake a broad survey to identify areas likely to contain important or significant trees. A number of information sources are available to assist in this process

• Check if any trees have been formally recognised on the Register of the National Estate, State National Trust Registers or listed under specific local government or state registers

• Focus on specific areas or sites of interest

• Undertake a tree survey of specific areas or sites. Tree surveys must be undertaken by suitably qualified arboricultural consultants, botanists, landscape architects or other experienced environmental scientists. A list of data requirements has been provided in Appendix A.

• Involve the public/community groups and other interested parties in the survey and assessment process, whether the assessment method has an objective (scientific) or subjective (aesthetic) basis.

Useful sources of information include; the National Trust, RSL, historical societies, public libraries, conservation/ community groups. Local histories, maps and plans, land records, drawings, sketches or paintings, plant catalogues, wills, sale notices, conservation studies, student theses, photographs, journals, books and other archives are also useful. Oral histories from elderly members of the community may also be able to provide valuable information.

Once the historical or other relevant information, physical description and features of the tree/s are collated an assessment as to the individual tree’s, group of trees’ or avenue of trees’ significance can be conducted.

Assessing Significance

Assessment methods must be rigorous as they provide strategic justification for protection and will be the basis of decisions. Broad categories that have been proposed for use are as follows.

• Any tree which is of horticultural or genetic value and could be an important source of propagating stock, including specimens that are particularly resistant to disease or exposure.

• Any tree which occurs in a unique location or context and so provides a contribution to the landscape, including remnant native vegetation, important landmarks, and trees which form part of an historic garden, park or town.

• Any tree of a species or variety that is rare or a very localised distribution.

• Any tree that is particularly old or venerable.

• Any tree outstanding for its large height, trunk circumference or canopy spread.

• Any tree of outstanding aesthetic significance.

• Any tree which exhibits a curious growth form or physical feature such as abnormal outgrowths.

• Any tree commemorating a particular occasion (including plantings by Royalty) or having associated with an important historical event.

• Any tree associated with Aboriginal activities.

These categories

have been derived

from those used by

the National Trusts

of Victoria and South

Australian. A full list

of the categories and

sub-categories has been

listed as part of Appendix B.

In general, nominations can be made and assessed using two or more of the categories listed. Each nominated treemust also have a background summary in order to define the reason(s) why it should be consideredas a culturally significant within the local environment.


Once a tree has been nominated as being culturally significant it is recommended the tree or avenue should be assessed by an expert panel of Council. The expert panel is required to assess information on the tree’s nominated as culturally significant to determine their suitability. People nominated on the panel must have experience and or qualifications to assess significance. Relevant skill sets could include Arborists, Town Planners, Heritage Officers, members of local historical groups or others shown to have relevant skills for this group.

Both local government staff members and relevant community representatives should be involved. If the community is involved, there is a greater likelihood the outcomes will be understood and supported.

Statement of Significance

A statement of significance must be developed for each tree, group of trees or avenue deemed culturally significant. The statement will guide the level of protection and therefore management inputs and other conservation measures an individual tree, group of trees or avenue is required. The statement must be succinct, expressing simply why the tree, group of trees or avenue planting is culturally significant or important. The statement should encapsulate the intent of the planting and detail what makes these trees valuable. This judgement should be based on studies that try and reveal these values.

The statement should explicitly comment on the value(s) in relation to each criterion and be based upon the research results and any relevant secondary data. Photographs, location maps and all other appropriate information should be included. It should also include known or foreseen threats and potential problems such as threats to the tree’s growing environment or changes to government policy .

It should not restate the physical attributes collected as part of the tree survey or the historical documentary evidence discovered but should be cross-referenced to it. Statements of significance may be prepared for individual or groups of trees such as avenue plantings.

Whatever may be considered the principal significance, other lesser values should be given consideration and recorded as part of the statement process. The statement of significance should be available through an overlay via Councils’ GIS system or Tree Inventory Register or similar computerised system.

General Principles Tree Protection

Trees under councils’ care and control are protected under specific sections of the South Australian Local Government Act 1993 and State and Federal Acts. A list of relevant Local State and Federal Acts has been provided as part of Appendix B. Specific protection measures may be required given the importance of this special class of trees.

If it is proposed to protect trees via a planning scheme it must be supported by strategic justification and identified within council strategic policies. These policies should clearly articulate objectives for protecting trees, strategies for achieving the objectives and practical implementation measures. The objectives should state why these trees should be protected, what level of protection is being sought and what the desired outcomes are for protecting trees drawing on strategic work.

The community should have ownership of the objectives by being involved in formulating the strategic vision. If the community is involved, there is a greater likelihood the outcomes sought by the planning scheme will be understood and supported. Objectives for protecting trees may be related to other objectives such as protecting significant landscapes, valuable habitats or the character of a place or area and the Significant Tree Legislation 1993. Local policies should explain and inform planning and management decisions. They should reinforce and emphasise broader strategic objectives.

In some areas, where tree protection is important to council’s broader planning objectives, the preparation of a specificpolicy for vegetation protection may be preferred (such as a type of land management agreement). Typical local policiesmay reinforce the need to protect a particular avenue of trees or emphasise the significance of mature vegetation.In some instances, a local policy may be all that is required to achieve a particular objective.


Management Plans

In addition to the statement of significance and supporting data, a management plan to ensure the long term significance is safeguarded is required. The management plan must optimise tree longevity by using two strategies; developing a stable physical tree structure and developing a stable growing environment.

Management plans assure a continuity of direction throughout a period of time. However, they should be seen as dynamic rather than a static instrument, responding to new information as it becomes available The cultural significance of a tree and level of significance should be the basis of what management programming and action is chosen. This would help determine the level of protection and therefore maintenance input and other conservation measures an individual tree or avenue required.

The tree’s fabric - species, age and biology will determine the selection of particular conservation action(s). Such action programs or plans commonly include a combination of general aims or objectives and/or specific strategies and detailed actions. Good tree management programs/plans integrate species and site differences into both general approaches and specific actions. These actions must be clear, logical and straightforward.

Having a basic knowledge of species history, an arborist may approach the care and management of Culturally Significant trees many of which are aging by focusing preventative care on two objectives:

• Avoiding entry into a mortality spiral ,and

• Preventing death from acute causes. Maintenance Activities

The maintenance of mature trees involves the application of cultural treatments in the context of tree biology which change with time. Since the biology of a tree changes over time so must its management. Arborists can play a central role in the maintenance of mature trees by providing stable growing conditions. They identify routine and remedial treatments, as well as assess the ability of a tree to respond to such treatments.

As previously documented maintenance is defined as continuous protective care. For trees this may include minor pruning, weeding, mulching, fertilising and irrigation undertaken to prolong the vigour and life expectancy of a tree.

The maintenance procedures involved must be clearly identified and scheduled as part of an overall, management plan. It must be viewed in the long term with preventative maintenance being the main focus. A few of the important techniques when maintaining culturally significant trees have been defined below.

• Prune mature trees conservatively to avoid excessive thinning and wounding;

• Observe target pruning to minimise decay development;

• Irrigate and fertilise judiciously considering the trees natural environment and past history;

• Protect the tree from environmental degradation, such as soil compaction, root damage, or mechanical damage and attempt to eliminate these via management.

• Develop species-appropriate programs for pest management.

These maintenance techniques aim to create a strong, stable tree structure, minimise unfavourable environmental changes and minimise insect and disease attack.

Maintenance programs for aging trees need to be considered carefully with a focus on preventative not reactive maintenance. As a tree matures it becomes increasingly affected by stress and responds slowly to treatment. Problems observed must be treated quickly. The management of these trees requires expertise and specialised equipment.

The tree’s growing environment must be maintained to protect it from undue stress and the structural integrity of the tree in public locations must be maintained to ensure public safety. Aging trees do not necessarily pose a higher risk of whole tree of branch failure. Aging trees in appropriate locations that are well-managed and healthy may be considered low risk.


Tree ReplacementIndividual Trees

Trees have a finite life span and eventually senesce and die so that they require removal and replacement. The replacement of trees is one of the more complex, emotive and pressing issues of managing culturally significant trees.

The emphasis throughout the whole tree replacement process should be on planning so as to preserve, if possible, what is considered to be culturally significant. Any tree removal and replacement needs to be planned to ensure a staged process is implemented and the removal of the tree does not detract from the quality of the place.

Over-mature culturally significant trees can represent a risk should they be in decline or stressed. The difficulty for managers comes as culturally significant trees age and decline and decisions need to be made on their future. It may be necessary to retain a tree beyond its peak aesthetic value because of its age, dimensions, rarity or association with a particular historical event or person. However this is subject to risk, historical and social significance, aesthetics and cost.

Tree regeneration should be considered in the first instance if tree health and species response are conducive to this method of regeneration. Should these techniques not be possible then it may be necessary to remove and replant with a young tree.

Retention of a dead tree could also be considered as an alternative approach. The dead tree would act as a memorial. Risk, historical and social significance, aesthetics issues and community support must also be considered as part of this approach.

Individual Council tree removal policies and procedures should dictate at what stage of a tree’s life cycle removal and replacement is appropriate.

The following Tree Replacement approaches can be considered for individual tree plantings:

• Single Tree Rotation – Remove and replace before or as the tree enters decline

• Manage for as long as possible then remove when the tree is no longer safe or attractive and replace. It is necessary to consider that arboricultural techniques aimed at prolonging the life of trees will improve vigour and slow the rate of senescence by providing an ideal growing environment, however they cannot halt or reverse decline.

• Dual Tree Rotation – Plant a young replacement tree adjacent to the existing tree as close as practical for a number of years prior to removal. If successful this will soften both the aesthetics and functional blow of mature tree replacement.

• Continuous Tree Rotation – the process is applicable for extensive features such as woodlands, it may be possible to develop a mix of age classes by carrying out a continual replacement program.

The method of replacement that can be applied to an individual situation depends on the specifics of the tree, its level of significance, location, resources available and community response. Culturally significant trees in public places are managed by council’s on behalf of the community and are recognised as important living assets. As such the community should be consulted (in accordance with the Local Government Act SA) in all major tree replacement projects.

Individual Council policies and procedures including requirements under the Development Act if the tree is deemed to be Regulated or Significant should be used to dictate the level of consultation required. A report submitted to Council for consideration and endorsement for the request for tree removal is the minimum level of consultation required before any tree removal occurs. It is strongly recommended that the wider community be consulted as part of any tree replacement process. Development approval may also be required if the tree is deemed to be regulated or significant as defined under the South Australian Development Act 1993.


Avenues and Rows

There are a number of approaches that can be applied to avenues and rows of trees if replacement is required. These approaches are summarised below:

• Remove and replant the entire avenue.

• Remove and replace sections at a time

• Replace each tree as it dies

• Remove and replace every second or third tree

Each of these methods has positive and negative implications. The replacement of each tree as it dies or the removal and replacement of every second or third may seem appropriate, but these approaches are rarely effective of efficient as the fundamental characteristics of an avenue - conformity in size and age are not retained. It is recommended that removal and replanting of the entire avenue of trees or replace sections at a time are the preferred approaches.

In may be necessary to plant a reduced number of trees or find a new similar planting location (i.e. main road for main road, park frontage for park frontage) if the original physical growing environment (Fabric) of a place has been reduced in area or become unsuitable for long term tree growth. All attempts should be made to use the same species, number of trees (if possible) and spacing as the original planting. Although not ideal at least some reinstatement of the original avenue may be possible.

No matter what method of replacement is selected it is important that the chosen method retains the fundamental characteristics of an avenue - symmetry created by consistency of age, species and size - and that key stakeholders are consultant and encouraged to participate.

As with individual tree replacement Council’s tree removal policies and procedures should dictate at what stage removal and replacement occurs and the method of replacement selected. Development Approval may also be required if the tree is deemed to be regulated or significant as defined under the Development Act 1993.

Replacement Species and Groupings

The replacement species should be limited to the species, varieties or hybrids available at the particular period when the subject tree or avenue was initially planted. However circumstances may dictate an alternate species, variety or hybrid that is better suited to the available growing environment. An example of clear justification for the use of an alternate species is the original species is defined as a pest plant under the Animal and Pest plant Control (Agricultural Protection and Other Purposes) Act 1986 or the place in which the tree was originally located has been modified to such an extent only a different variety or species would suit.

If the exact species is not available then an approximation will have to be made from what is known to have been in general cultivation at the time. Modern cultivars should be avoided and preference given to historic forms which were once used if those forms are suited to the available growing environment.

If these trees are unavailable then propagation from original trees on site or other sites planted at the same time, or simpler forms could be considered. If vegetative propagation is used then an identical genetic copy or clone of the original tree is derived.

There are exceptions allowing the use of modern varieties or cultivars. For instance modern cultivars are desired because they could require less maintenance, or may be better adapted to extended periods of drought once established.

Modern philosophies of tree groupings should be ignored in favour of those used in earlier periods if space permits. Storage of Information

Once individual trees have been assessed and required information collected it needs to be stored and maintained. This should be achieved through computerised databases. Key requirements of these systems include:

• Storage of information

• Data manipulation – generating lists, summarising data

• Computer Mapping (GIS) – visually display the location of the tree, useful for future referencing

The system should be user friendly, have good documentation and support and permit easy updating of data.

General or specific software packages are available to fulfil these requirements.


Appendix A 1. Horticultural value

Any tree which is of horticultural or genetic value and could be an important source of propagating material including specimens that are particular resistant to disease.

2. Location or context

Any tree which occurs in a unique location or context and so provides a contribution to the landscape, including remanet native vegetation, important landmarks, and trees which form part of an historic garden, park or town.

2.1 Location or context2.2 Historic garden or Park2.3 historic cemetery2.4 Important landmark2.5 Remnant Native Vegetation2.6 End of Natural Range2.7 Contribution to the landscape 2.8 Historic Town2.9 Historic Planting style

3. Rare or Localised

Any tree of a species or variety that is rare or of very localised distribution

3.1 Rare Or Localised3.2 Only Know Species3.3 1 To 10 Know Species3.4 10 To 50 Know Species3.5 Natural Vegetation3.6 End Of Natural Range3.7 Disjunct Community

4. Particularly Old

Any tree that is old or venerable.

No sub-categories

5. Outstanding size

Any Tree outstanding for its large height, trunk circumference or canopy spread

5.1 Outstanding Height5.2 Height5.3 Circumference5.4 Canopy And Spread5.5 Height And Circumference5.6 Spread And Circumference5.7 Height And Circumference And Spread

6. Aesthetic value

(dimensions, age, character, physical features, landmark/landscape qualities):

6.1 Outstanding Aesthetic Beauty 6.2 Outstanding Dimensions In Height, Or Trunk Circumference, Or Canopy Spread 6.3 Very Old Or Venerable 6.4 Occurs In A Unique Location Or Context, And Thus Provides A Special Contribution To The Landscape, Or Is A Landmark 6.5 Excellent Example Of Topiary 6.6 Curious Growth Forms Or Physical Features Either From Natural Causes, Or Pruning 6.7 Other, (Please Describe)

7. Historical Value

Any tree commemorating a particular occasion (including planting by Royalty) or having an association with an important historical event.

7.1 Historical Value7.2 Cultural Group7.3 Public Feature7.4 World War 17.5 World War 27.6 British Royalty7.7 Non-British Royalty7.8 Visiting Dignitary7.9 Australian Public Figure7.10 South Australian Public Figure

8. Aboriginal Culture

Any tree associated with Aboriginal activities

8.1 Scarred Tree8.2 Corroboree Tree

9. Outstanding Examples of Species

Any tree that is an outstanding example of its species

No sub-categories


Appendix B Legislative Requirements The management and care of Urban Trees under the care and control of Council’s is subject to various Legislative requirements and regulations.

Local Government Act 1999

• Sections 196 to 199 Community land management plans

• Section 213 Recovery of costs of roadwork

• Section 221 Alteration of road

• Section 232 Trees

• Section 233 Damage

• Section 244 Liability for injury, damage or loss on community land

• Section 245 Liability for injury, damage or loss by certain trees

• Section 299 Vegetation clearance

• Councils existing Policies including Public Consultation which reflects the requirements of the Local Government

Act 1999 State and Federal Acts

• Development Act 1993

• Commonwealth Environment Protection and Biodiversity Conservation Act 1999

• Electricity Act 1996

• Heritage Act 1993

• Water Resources Act 1997

• Environment Protection Act 1993

• Animal and Pest plant Control (Agricultural Protection and Other Purposes) Act 1986

• Sewerage Act 1929.

• Aboriginal Heritage Act 1988

• Native Vegetation Act 1991


Assessment and Management Guidelines - Culturally Significant Tree Project - Prepared by Symatree Pty Ltd

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