Subsequently the Council obtained a further report from horticultural consultant Nigel Turner. The report dated 8 April 2002, was accompanied by 6 photographs of various aspects of the Norfolk Island pine trees, and provided a further assessment of them, including that they were both only in "fair" condition, together with the following recommendation:

"Removal I believe is indicated and is recommended, in relation to the decline and hazardous limb drop to both the street and garden of No. 7."

This recommendation was premised on his opinion that the trees were in decline due to lack of water, and would continue to decline, given the last two "low moisture" summers in Adelaide. The Court heard expert evidence from one witness with respect to the trees, namely Mr Marcus Lodge, an arboriculturalist, who operates a business under the name Arborman Tree Solutions.

The dimensions of the trees varied slightly across the 4 reports, but the differences are not material. The approximate dimensions of each tree are as follows:

Circumference 1m above ground level: approximately 2.27m

Circumference 1m above ground level: approximately 2.2m

Mr Hosking estimated both trees to be about 70 to 90 years old, while Mr Lodge estimated both trees to be around 50 years old, with a life expectancy of greater than 150 years and a "useful life expectancy" of greater than 100 years.

Both trees have dead foliage and limbs in the canopy, with the southern tree having a significantly higher percentage of dead foliage and limbs within the canopy. Neither tree exhibits evidence of disease. The current health of the trees was described by Mr Lodge as "good" in the case of the northern tree and "good to fair" in the case of the southern tree.

The subject land is located in the Residential B350 Zone, close to where the zone abuts the Neighbourhood Centre Zone, in which the Black Forest Primary School is located. Both Norfolk Island pine trees can be seen in Kerta Weeta Avenue (but the jacaranda trees were without leaves and flowers when we viewed the locality), and from the properties opposite the subject land, Forest Avenue, and glimpses may be obtained from the Black Forest Primary School grounds, the reserve located to the rear of the appellant's and other allotments having frontage to the eastern boundary of Kerta Weeta Avenue, and South Road to the west.

In City of Mitcham v Freckmann & Ors [1999] SASC 234; (1999) 74 SASR 56, the Supreme Court spelt out the task facing a planning authority when assessing an application for provisional development plan consent, under the Development Act. The first task of the authority is to determine the nature of the proposal. In this case the nature of the development is clear; it is the removal of the two trees, which comes within the meaning of "tree-damaging activity" in the Development Act.

The second task is to identify the provisions of the development plan that are relevant, and having done that, to assess the proposed development against those provisions. In Freckmann, the Court suggested that the first step was to establish the zone in which the subject land was situated and then to turn to the zone provisions, to determine the desired character or purpose and intent of the zone, by reference to the objectives and principles of development control for the zone.

Given the nature of the development proposed, in this case the zone provisions which the Development Plan states are "additional to those expressed for the whole of the Council area" do not assist greatly. The statement of Desired Character for the zone includes the following:

"This Zone is intended to continue as an attractive and established living area with limited infill development."; and

Under the sub-heading "Streetscape", the following:

"A wide variety of mature vegetation in private gardens and street reserves is evident in the Zone. Landscaping associated with development should complement and enhance existing planting thereby improving the established character of the area".

Possibly relevant is Zone Principle of Development Control 5 as follows:

"5 Development should provide for attractive front garden landscaping, including the planting of at least one tree per dwelling."

Principle of Development Control 6 indicates those kinds of development which are complying in the zone. "Tree-damaging activity" is not included in the list. Principle of Development Control 7 indicates that "tree-damaging activity" is a kind of development which is not a non-complying kind of development in the zone. Thus "tree-damaging activity" is neither a complying or non-complying kind of development in the zone.

Both the zone provisions and the introduction to the Development Plan make clear that reference should be made to all parts of the Development Plan to ascertain the relevant policies "applying to any site".

Some of the general provisions of the plan are relevant, such as the following:

"Objective 3: The establishment of urban development which provides models in the conservation and management of resources and the natural environment ...".

"Objective 5: The amenity of localities not impaired by the appearance of land, buildings and objects".

"Principle 23: Existing substantial landscaping should be retained in conjunction with any development ...";

"Principle 25: Species selected in the landscaping of a development should require minimal maintenance."

Objective 47: The conservation, preservation or enhancement of, scenically attractive areas...",

"The watercourses with their natural vegetation are the most significant natural features on the Adelaide Plains. The trees and natural vegetation can add to the attractiveness of suburban areas and, wherever possible, these features should be incorporated in the layout of residential areas."

"Principle 165: Development should be undertaken with the minimum detrimental effect upon natural features, land adjoining water or scenic routes or scenically attractive areas."

"Principle 166: Substantial vegetation should be preserved, wherever possible, ..."

Objective 54: The conservation of significant trees in Metropolitan Adelaide which provide important aesthetic and environmental benefit.",

"Trees are a highly valued part of the Metropolitan Adelaide environment and are important for a number of reasons including high aesthetic value, conservation of bio-diversity, provision of habitat for fauna, and conservation of original and remnant vegetation.

While indiscriminate and inappropriate significant tree removal should be generally prevented, the conservation of significant trees should occur in balance with achieving appropriate development."

(a) makes an important contribution to the character or amenity of the local area; or

(b) is indigenous to the local area and its species is listed under the National Parks and Wildlife Act as a rare or endangered native species; or

(c) represents an important habitat for native fauna; or

(d) is part of a wildlife corridor of a remnant area of native vegetation; or

(e) is important to the maintenance of biodiversity in the local environment; or

(f) forms a notable visual element to the landscape of the local area;

"Principle 199: Significant trees should be preserved and tree-damaging activity should not be undertaken unless:

(1) (i) the tree is diseased and its life expectancy is short; or

(ii) the tree represents an unacceptable risk to public or private safety; or

(iii) the tree is within 20 metres of a residential, tourist accommodation or habitable building and is a bushfire hazard within a Bushfire Prone Area; or

(iv) the tree 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."

In my view it would be in error to look solely at those provisions of the Development Plan under the heading of "Significant Trees", in assessing a development which comprises solely the removal of one or more significant trees. It would be contrary to the provisions of the Development Plan itself, and to the way in which the Supreme Court has indicated in Freckmann that the assessment required in Section 33 of the Development Act, is to be carried out. In addition, it must be remembered, consistently with the approach taken in South Australian Planning Commission v Dorrestijn & CR Dorrestijn Nominees Pty Ltd (1984) 36 SASR 355, Town of Walkerville v Adelaide Clinic Holdings Pty Ltd (1985) 38 SASR 182 and City of Unley v Hall & Ors [2002] SASC 337 that the development plan cannot of itself, prevent development. The development plan is an important guide; indeed, a relevant authority may not grant consent to a development that it has assessed as being seriously at variance with the relevant provisions of the development plan (Development Act, Section 35), but the language is advisory. The relevant authority must make a planning decision, based on the provisions of the development plan.

The Development Plan clearly encourages the retention of mature vegetation in private gardens and street reserves in the Residential B350 Zone. It is part of the character of the area. However, that does not mean that no existing vegetation should be removed. The Development Plan was created with certain objects in view, including the facilitation of sustainable development and the protection of the environment, and the encouragement of the management of the environment in an ecologically sustainable manner (see: Development Act Section 3). The Development Plan also encourages the conservation and management of resources, which, in relation to vegetation would include encouragement of the retention and planting of those species of vegetation which are particularly adapted to the dry conditions prevalent in the Adelaide region. In Adelaide, where the average annual rainfall (1977-1997) is 880mm, and South Australia generally, water is a resource to be conserved and its use managed in an ecologically sustainable manner. This is perhaps reflected in Objective 3 and Principle 25 of the General provisions of the Development Plan.

The preservation of trees and natural vegetation is encouraged in residential suburban areas: Objective 47. In some respects, Objective 54 could be seen as reinforcing Objective 47 by encouraging the conservation of significant trees. However a plain reading of Objective 54 suggests that it is directed only at those significant trees which provide "important aesthetic and environmental benefit" (my emphasis).

Principle 197 is curiously couched. At first blush it would appear not to be relevant to development which consists of removal of the significant tree. However, it is appropriate to take one step at a time. Does either of the Norfolk Island pine trees fulfil the attributes set out in paragraphs (a) to (f) (inclusive) in Principle 197? The evidence of the only expert witness before the Court, Mr Lodge, was that the Norfolk Island pine trees have the characteristics set out in paragraphs (a) and (f), only. While Mr Lodge is a qualified arboriculturist, and therefore has an expert knowledge of trees with respect to their natural habitats and propensities, their care and cultivation, I am not persuaded that he has specialist expertise with respect to issues of character and amenity of an area. I do not accept that it follows from his qualifications and experience that his opinion on these issues should be accorded more weight than that of any other person. However, even if I am wrong in this decision, his evidence was flawed.

Mr Lodge's evidence was that both the Norfolk Island pine trees make a contribution to the character or amenity of the local area. He did not indicate whether it was character or amenity. He spoke of them having a higher "amenity value" than the sugar gum. This term has a special meaning with respect to trees, and is used in the context of the assessment of damages in the case of loss of a tree through the negligent action of another, or otherwise. The "amenity value" is the value of the tree to the landowner who has suffered, or will suffer, its loss. It is the value of the tree itself. That is a different concept from that of the contribution a tree makes to the amenity of the local area. Care must be taken in the use of "amenity value" as a determinant of the contribution a tree makes to the amenity of a local area. It could never be the sole determinant. Herein lies the problem with asking an arboriculturist to assess a tree having regard to the provisions of Principle 197. Every tree, vegetation, building and object in the local area, and the inter-relationship between them, will contribute to the amenity and character of an area, as will the uses of land, the volume of traffic on the roads, and so on.

The Norfolk Island pine trees undoubtedly contribute to the character of the local area. The evidence of the appellant was that the trees are barely visible in Kerta Weeta Avenue when the jacaranda trees are in full bloom or full leaf. They are visible from other locations from time to time, as I have indicated above. The question is as to the importance of the trees' contribution to that character.

Do the trees make an important contribution to the amenity of the local area? They provide shade, but not the dappled shade preferred by the appellant. They contribute to a green and leafy environment, desired for aesthetic reasons, as would a fully developed sugar gum, or many other trees. However, the Norfolk Island pine trees currently need attention; they appear to be suffering from insufficient water in some years and root compaction damage (southern tree) and further effects of inadequate water supply are likely to manifest in the future. Their health is considered by Mr Lodge to be merely "good" (northern tree) and "fair-good" (southern tree) while others have uniformly described the condition of both trees as only "fair".

In Mr Lodge's view, "probably about 30-40% of the Araucarias in Adelaide are similar to the southern tree" and in that context, he described the southern tree as a standard, normal or average example in the Adelaide context. Given the trees' preference for "abundant rainfall evenly distributed throughout the year" and their "large spreading root system" with "the majority of (moisture and oxygen) absorbing roots ... found in the top 300mm of soil even extending to the soil surface ...", perhaps it is almost inevitable that these trees in the Adelaide area, where the rainfall is less than the optimum for them by a factor of 2 or 3, will suffer dieback in many cases as a result of our long dry summers [the quotes are from Mr Lodge's statement of evidence: Exhibit R2]. Mr Lodge conceded that the trees are not optimally suited to Adelaide, although he proffered that it is a very adaptable species. I do not accept that the appropriate standard against which to measure the condition of the trees is the condition of other Araucaria heterophylla species growing in the Adelaide region. However, my opinion in this regard has no bearing, in the circumstances, on the decision of the Court.

In Mr Lodge's opinion, the trees need ongoing attention, both for remedial purposes and to reduce the potential for limb failure. That includes:

pruning to clear out the dead wood (both for visual amenity and the health of each tree);

replacing existing ground coverings with suitable composted organic mulch to cover as much of the critical root zone (7m radius, northern tree and 6.8m radius, southern tree) as possible;

replanting beneath the trees with suitable understorey plants, namely different types of conifers;

providing water to the critical root zone over the dry periods of the year;

ensuring that there is no disturbance to the lateral roots.

His evidence was that the pruning could be achieved at a monetary cost of roughly $500-$600, and might need to be repeated in 5 years' time. Mr Lodge informed the Court that additional water during summer would have to be provided both to the trees and any understorey planting. By law, no work could be undertaken in the vicinity of the trees which could result in damage to them, without the consent of the relevant planning authority under the Development Act first having been obtained.

The appellant informed the Court that the southern tree has had no water (apart from rainfall) for about the past decade, while the only additional water available to the northern tree has been that provided to the garden beds and citrus trees north and north-east of the tree. He does not plan to water the trees in the future, nor does he systematically clear the trees of dead wood, but has removed dead branches which have been overhanging the footpath in Kerta Weeta Avenue.

On the face of Principle 199 of the "Significant Trees" provisions of the Development Plan every tree, regardless of species, characteristics, benefit provided, contribution to amenity, should be retained, unless it is diseased and will die, presents a safety risk to persons, buildings or valued structures and remedial treatments and measures will not be effective. That cannot be the intended consequence of the Development Plan provisions; one can readily imagine examples to show how ridiculous such a result would be, and it would fly in the face of the objects of Development Plans. Common sense demands that Principle 199 be read in the context of Objective 54. Thus, it is desirable that certain significant trees not be removed, unless they fall within the provisions of Principle 199(a)(1). How does one identify the significant trees that it is desirable to preserve? Objective 54 states that it is those which provide aesthetic and environmental benefit. Objective 54 must be interpreted in light of the commentary or explanatory paragraphs which follow it, and the Principle 197, which appears to address the attributes which render significant trees worthy of preservation.

Following this line of reasoning, a significant tree which has any one of the attributes listed in Principle 197, should not be removed, unless it fulfils one of the criteria in Principle 199(a)(1) and "all other reasonable remedial treatments and measures have been determined to be ineffective." In so concluding, I have read the Development Plan as a planner's document, not a legal document, and thus have ignored the apparently conjunctive requirement in Objective 54 for the significant tree to provide both important aesthetic and environmental benefit, to be worthy of conservation.

Both of the Norfolk Island pine trees make a contribution to the character of the local area, of course. They are part of the existing character of the local area, which in the absence of any evidence, I determine to include Kerta Weeta Avenue and the land abutting both sides, the reserve abutting the northern boundary of the subject land and portion of the Black Forest Primary School grounds.

I do not accept that the trees make an important contribution to the character of the local area. In so determining, I have had regard to their condition, and the limited views of them that are obtainable.

The trees contribute to the amenity of the area, but perhaps less importantly than would an indigenous species given a few years in which to grow. Given their existing problems, which are likely to continue, and that the appellant no longer wants the trees growing there and is not prepared to provide additional (and expensive) water to them, I cannot accept that they do now, or will in the future, make an important contribution to the amenity of the local area. Perhaps their greatest contribution in this regard, is in respect of the shade they provide on Kerta Weeta Avenue, probably in the morning.

However, once the jacaranda trees in the footpath adjacent the subject land reach a reasonable height, they will be able to provide street shade. It was suggested by the appellant that the jacarandas on the footpath adjacent the subject land are stunted in their growth because of the presence of the extensive root spread of the Norfolk Island pine trees and the consequent root competition. The evidence was inconclusive although root competition was agreed by Mr Lodge to be a factor. I accept it is a possibility, but this has played no part in my decision.

In addition the existing sugar gum is likely to be able to provide shade, should the Norfolk Island pine trees be removed. Mr Lodge had concerns about the future prospects of the sugar gum, given its structure, but agreed that it could be managed, with difficulty. He also conceded that the sugar gum is in a climatic environment which is closer to its optimum conditions than is the case for the Norfolk Island pine trees. The sugar gum does not require water in addition to rainfall.

As I have earlier indicated, the provisions of the Development Plan with respect to significant trees must be read together with other relevant provisions. However, before I consider the significant tree provisions in context, it is worthy of note that these provisions do not seek to preserve significant trees at the cost of development. The Development Plan acknowledges that trade-offs will have to be made. That is clear in all principles under the Significant Tree heading. Of course "development" has specific meanings according to the Development Act, but it would be a nonsense if an appropriate building could proceed at the expense of a significant tree, in accordance with the Development Plan, while the removal of a significant tree in order, for example to preserve and promote the growth of, or to plant and nurture another tree, perhaps more suitable in the conditions, could not be countenanced, simply because the latter is not "development".

Thus is made clear one of the difficulties of bringing "tree damaging activity" within the concept of "development". It perhaps has become easier to remove a tree to facilitate a building in the interests of urban consolidation, than it is to remove a tree in the interests of planting or facilitating the growth of an alternative species, better suited to the climatic conditions of Adelaide and potentially making a greater contribution to the amenity of the local area without drawing on our precious water resources for its good health and survival.

The Development Plan provisions for the zone seek "attractive front garden landscaping". While this is sought in the context of development, it is clearly part of what is desired for the zone (see: Streetscape under the zone heading "Desired Character"). Mr Summers told the Court, when we viewed the subject land, and repeated it in Court, that he is trying to make a more natural, bush garden across that part of the front yard nearest the Kerta Weeta Avenue boundary, as he has commenced to do in the south-western part of the land with the planting of eremophila species. The establishment of a garden as envisaged by the appellant, would, in my opinion make a greater contribution to the immediate local area, namely Kerta Weeta Avenue, particularly given the existence of other trees on the appellant's land, and of the jacaranda trees in the street, than would the retention of the existing Norfolk Island pine trees. This kind of garden would also be consistent with general Objective 3 and Principle 25, which look to the conservation and good management of resources and landscaping using species which require minimal maintenance.

The only other attribute in Principle 197 which could possibly be applied to the Norfolk Island pine trees, according to the respondent is:

"(f) forms a notable visual element to (sic) the landscape of the local area."

The trees of course are a visual element in the streetscape. They also form a visual element of the local area landscape. They may be a notable element, too, from one or more parts of the local area, in that by their height, they are noticeable and therefore, noteworthy or notable. However, if the trees do not make an important contribution to the character, which logically includes a consideration of the interplay between the elements of an area, including landscape, physical and social[1], should they be retained, simply because they are a notable element, visually, in the local area? I think not. An item can be a notable element in the landscape in both negative and positive senses. It would be inconsistent with Objective 54 to retain a significant tree on the sole ground that it forms a notable element in the landscape because it presents a negative aesthetic element or otherwise stands out as a jarring element in the generally uniform landscape character of the local area.

Thus, I determine that Principle 197 must be read in the context of Objective 54, which seeks the conservation of significant trees providing important aesthetic and environmental benefit (my emphasis). Since I have decided that the Norfolk Island pine trees do not make an important contribution to the character of the area, it follows that they are not a notable visual element, in a positive sense in the local area landscape.

Before I conclude, it is appropriate that I comment on the expert evidence. It seems to me that the Court would be assisted by hearing from landscape architects in these "significant tree" cases, to assist in the assessment of the contribution a tree makes to the character and amenity of an area. The evidence of an arboriculturist is of value when consideration has to be given to whether the tree is diseased and its chances of returning to a healthy state, and the nature of the tree in the context of safety issues. On some other matters addressed by Principle 199, engineering evidence may be appropriate. What is clear is that an arboriculturist is not an expert in all aspects requiring assessment in relation to significant trees.

A similar message has been given by this Court, in respect of expert planning witnesses, in the past. Expertise in one field does not qualify one to comment in other fields and it is unfair for an authority to expect this from its experts.

In so saying, the Court is not insisting on hearing from a panoply of experts, but reminding parties of the worthlessness of having an expert in one field comment on matters beyond his or her expertise. Mr Lodge did not greatly assist this Court. I rejected much of his evidence. As to evidence within his expertise, I was assisted by that about the species (both Araucaria heterophylla and Eucalyptus cladocalyx) generally, but did not accept his assessment of the Norfolk Island pine trees. That Mr Lodge did not significantly assist the Court was not entirely his fault. He was perhaps asked to do more than he should have been, but pride in his professional integrity should have caused him to take care.

Having considered the application against all relevant provisions of the Development Plan, I have concluded that, on balance, the appeal should be allowed, and the decision of the Council reversed. An order will be made, granting provisional development plan consent to the appellant, for the removal of the 2 Araucaria heterophylla trees presently growing on his land at 7 Kerta Weeta Avenue, Black Forest.

[1] Lester Townsend, "The Evolution of Neighbourhood Character," Landscape Australia 23(4) (4-2001): 11-14.