Within the city of Adelaide, state and local government authorities have recently removed, or plans to remove, some of the city’s more iconic trees. The Adelaide Law School’s Paul Leadbeter considers the relaxation of South Australia’s urban tree removal controls that have facilitated these removals.

Media reports indicate some recent controversies have arisen in the City of Adelaide regarding trees growing within the confines of the city. First there was the axing of an avenue of 105 year old White Cedar trees behind the Adelaide Oval redevelopment to make way for a carpark. Now debate is raging about the proposal to remove the shade trees from Rundle Mall to facilitate a redevelopment of the Mall to open it up to encourage people to come and shop there more often. Trees will play an increasingly important role in Australian urban environments particularly given the predicted increase in temperatures as a consequence of climate change. Australian cities receive a significant amount of solar radiation. Adelaide, capital city of the driest State in the driest inhabited continent on earth now experiences long hot summers and relatively dry winters. With climate change the city and State as a whole will face significant adverse impacts including less rainfall, more extreme weather events such as sudden violent storms and flash flooding and more hot days each year.

Based on a trajectory of mid-range greenhouse gas emissions in 2030, the average number of days a year over 35 degrees C is projected to increase to 21-26 and the average number of days a year over 40 degrees C is projected to increase to 3-5.[1]

Urban trees are and will be important because they provide shade and aesthetic improvements to our streetscapes, privacy, shelter for fauna and humans during inclement weather and contribute to biodiversity and the overall maintenance of a healthy ecosystem. They also help address what has been called the ‘urban heat island effect’.[2] Urban areas are hotter than the surrounding unbuilt and undeveloped areas for a range of reasons. There is a significant heat release from human activities within those urban areas from building heating and cooling systems, public transportation systems, vehicular traffic and energy use within commercial and residential buildings. There is less of an albedo effect which results in shortwave radiation being absorbed within the dark surfaces of roads and buildings rather than being reflected back into the atmosphere resulting in a build up of heat within the urban area. The greater preponderance of impervious surfaces results in less natural soil and vegetation thereby reducing evapotranspiration and latent heat cooling.[3]

With the exception of urban trees listed or protected under State heritage legislation few cities in Australia have regulatory controls to simply protect trees. South Australia was an exception. In April 2000 the State Government introduced the concept of a ‘significant tree’ into the land use planning system controlled under s 4 of the Development Act 1993 and made ‘tree damaging activity’ within the area of metropolitan Adelaide a form of development for which development approval under the Act was required. These changes were accompanied by a Ministerial policy amendment to all council Development plans to ensure that there were provisions in place against which proposals for tree damaging activity could be assessed.[4] Outside of Metropolitan Adelaide there are no controls over the pruning and removal of non-indigenous vegetation although there are strong vegetation clearance controls for indigenous vegetation through the provisions of the Native Vegetation Act 1991. Thus substantial exotic trees outside the metropolitan Adelaide area are not protected unless given designation as a State or local heritage place under either the Heritage Places Act 1993 or by a development plan. There are, for example some magnificent species of fig trees in a number of South Australian country towns which if unprotected can be removed without any approvals or community consultation. A good example are the massive old but still very healthy fig trees in the public squares in the historic heritage townships of Wallaroo and Moonta on Northern Yorke Peninsula. Similar examples can be found in many other SA country towns.

The original significant tree controls designated trees as significant either because they were listed as such in a council development plan[5] or if they met prescribed criteria, namely, that they had a trunk with a circumference of 2 metres or more or, in the case of trees with multiple trunks, that they have a total circumference of 2 metres or more and an average circumference of 625millimetres, measured at a point 1 metre above natural ground level.

The provisions worked reasonably well given the intention was to stop developers removing perfectly healthy suburban trees simply to facilitate development without any consideration of alternative design solutions that might have resulted in the tree’s preservation. There were some issues. If the tree was a healthy specimen and posing no unreasonable risk to persons or property it was often very difficult to obtain clearance approval, particularly when the tree made an important contribution to the character or amenity of the local area.[6] Furthermore, councils were increasingly requesting that applicants seeking development approval for tree removal and pruning provide expensive reports from arborists and landscape specialists in support of their application. The existence of trees which were classified as significant trees on existing residential allotments under the previous controls would often be seen to hamper the redevelopment of those allotments for more intensive forms of development or create significant costs for developers as they sought alternative design solutions to accommodate those trees. Increasing the density of residential development in the Metropolitan Adelaide area is part of the State government’s overall strategy for development in South Australia[7] and there was an obvious inconsistency between the two policy positions. There is also a perception that the State Labor government (particularly under the leadership of former Premier Mike Rann) was beholden to the development industry which can be seen to have had particularly favourable treatment in a number of areas of State planning policy and legislative enactments.[8]

It was therefore a combination of factors which lead to the enactment of major changes to the significant tree provisions, the Development (Regulated Trees) Amendment Act 2009, which came into operation in November 2011. These changes have relaxed the controls potentially facilitating a much greater level of urban tree removal. At the time the controls came into operation the Planning Minister, The Hon. John Rau said:

The changes are designed to balance protection of trees with the need to remove inappropriately located trees and inappropriate tree species for reasons such as public safety. The intention is to provide greater clarity for people wanting to undertake reasonable and expected development or to remove inappropriate trees for legitimate reasons, while also providing appropriate protection for trees that give Adelaide much of its character.[9]

What do the changes do? First they create a concept of ‘regulated trees’ which are trees with the 2 metre circumference requirements previously applying to ‘significant trees’. Significant trees will in future be trees declared as significant by a council’s development plan or trees with a circumference of 3 metres measured at a point 1 metre above natural ground level. Development now includes any tree damaging activity to a regulated tree. Tree damaging activity includes the killing or destruction of a tree, tree removal, severing of branches, limbs, stem or trunk of a tree, ringbarking, lopping or topping of a tree and any other substantial damage to a tree. At times excavation work associated with building construction, such as for a pool or dwelling may sever significant roots of trees and therefore come within that definition on the basis it comprises ‘other substantial damage to a tree’. Acceptable pruning of regulated trees which is excluded from the definition is pruning that does not remove more than 30% of the crown of the tree; and is necessary to remove dead or diseased wood, and branches posing a risk to life or property.

On first glance the changes might appear acceptable. However, there are a range of exceptions which in my opinion significantly undermine the efficacy of these planning controls as an urban tree protection mechanism. First, unless trees are Willow Myrtles or of a Eucalypt species, even if they meet the measurement criteria, they will not be regulated trees if they are located within 10 metres of an existing dwelling or an existing in-ground swimming pool. Secondly, there is a list of exotic tree species, many which have been traditionally grown in the Adelaide area since European settlement in 1836 which can also be removed or pruned without approval, as can trees effectively listed as pest plants under the provisions of the Natural Resources Management Act 2004,[10] even though they may meet the measurement requirements for regulated trees.

All development applications have to be assessed against the relevant development policy contained in council development plans. With the initial introduction of significant tree controls, the Planning Minister authorised an amendment to all council development plans to introduce policies against which applications for approval to undertake tree damaging activities could be assessed. With the changes to the legislation he introduced a Development Plan Amendment to add to, and, in some places, alter those existing policies. The Regulated Trees Development Plan Amendment came into operation on an interim basis on 17 November 2011. Public consultation followed and on 15 November 2012 the Development Plan Amendment (DPA) was authorised without any apparent changes despite many representations, some of which made sensible suggestions for changes to the policy. During that interim period the policy provisions were operative and planning applications for tree damaging activities had to be assessed against the new policies. Query whether the fact the DPA was finally authorised by the Minister without any changes means public consultation on planning policy in South Australia is a largely perfunctory process these days. If so, it does not augur well for future planning in the State and the right of the community to have input to how the areas within which they live, work and recreate are developed.

The Regulated Trees DPA continues the previous policy criteria for the removal of significant trees. Thus tree damaging action in relation to significant trees should not be undertaken except in circumstances where the tree, is diseased and its life expectancy is short; or it represents an unacceptable risk to public or private safety; or it is within 20 metres of residential tourist accommodation or an otherwise habitable building and is a bushfire hazard within the relevant development plan’s Bushfire Protection Area or it is shown to be causing or threatening to cause, substantial damage to a substantial building or structure of value; and all other reasonable remedial treatments and measures have been determined to be ineffective. Further, it must be demonstrated that all reasonable alternative development options and design solutions have been considered to prevent substantial tree-damaging activity occurring.[11]

For the new category of regulated tree the policy provisions are similar although there is more emphasis on the balancing of development (presumably of the built form) and preservation of regulated trees. However, in the new policy there is a significant variation from the significant trees criteria in terms of when regulated trees can be removed or damaged in Principle of Development Control 2 (d). It provides that removal or damage may be appropriate when ‘development that is reasonable and expected would not otherwise be possible’. It is not clear what this means. There appears to be no objective criteria for determining what is ‘reasonable’ development. Nor does the policy explain by whom or what the development is expected? Perhaps it is meaning development that the development plan expects within a particular zone or policy area. This would be extremely broad criteria. The policy as expressed gives planning authorities a very broad discretion as to when they authorise the removal or damage to a regulated tree. The protection ultimately afforded to trees classified as regulated trees and not significant trees is minimal.

The South Australian government’s 30 Year Plan for Greater Adelaide included climate change Policy No 13 which says:

Create a more liveable urban environment through the establishment of a network of greenways, tree-lined streets and open spaces, which will have a cooling effect on nearby new neighbourhoods and new buildings.[12]

The drafters of the DPA said:

The DPA supports this policy by protecting trees that would be likely to have a tall height or large canopy. This in turn could result in an increased cooling effect in areas prone to the urban heat island effect. The legislation’s allowance for the establishment of urban tree funds also facilitates the creation of designated areas (potentially greenways and open spaces) for the planting of replacement trees that will be legally protected.[13]

These comments are correct, however the DPA also enables a greater number of urban trees to be removed, which cannot help to minimise the urban heat effect. It contemplates replacement trees which will, in time, also help with mitigating the urban heat effect, nevertheless there is a period of time after removal of the original trees during which the effect is likely to be more pronounced. Furthermore, where large trees have been removed from land and replaced by more intensive built form, replacement trees are rarely likely to provide the same level of canopy coverage.

The changes to the significant trees controls have increased the complexity of the rules and requirements in this area of land use planning law. Somewhat ironically, despite that increased complexity they afford less protection to trees in the urban landscape. In particular many of the exotic trees commonly planted on the Adelaide plains and in the foothills are no longer protected by law. An example is the London Plane tree, a popular street tree planted by many metropolitan local government authorities since colonial times. These trees currently make a significant contribution to the character and amenity of the Metropolitan Adelaide area as well as contributing to a reduction in the city’s urban heat bank. While in the longer term, climate change adaptation requirements will require us to plant more climate and water sensitive indigenous trees and vegetation rather than exotic foreign species, there should still be protection mechanisms in place for such species for the time being. Under the new regulated trees provisions it will be easier to obtain development approval for the removal of many trees in that category. Without careful management in the longer term, if tree removals increase accompanied by increased urban densities we will have a future metropolitan area that is warmer and less attractive.

In terms of reducing energy use for artificial cooling of buildings and reducing the overall output of urban generated heat preventing urban tree removal is a modest yet worthwhile measure for mitigating and adapting to the effects of climate change. Urban tree protection controls in South Australia were originally driven by a desire to protect habitat and for character and amenity reasons. However, with the increased awareness and knowledge of climate change and its predicted impacts the role that urban trees play in moderating temperatures within urban areas and buildings has become increasingly apparent and accepted. It is therefore a retrograde step for the State government to undertake major amendments to the controls on urban trees which facilitate a greater level of urban tree removal.

Paul Leadbeter is a Senior Lecturer at the Adelaide Law School. He has written a chapter on the relaxation of urban tree removal controls in Adelaide in an upcoming book celebrating the work of Emeritus Professor Adrian Bradbrook, which will be published by the University of Adelaide Press later this year.