Impact of tree loss on the character of the area
The Hybrid
39The retention or removal of the Hybrid was a significant issue in the proceedings. A decision on whether the Hybrid should be removed also impacted on whether the relief offered by cl 44(6(b), in relation to whether there is "no practicable alternative is available in terms of the design, type and site coverage of the proposed development" should be available. The retention the Hybrid was also a common theme in the evidence given by residents on-site and the submissions provided to the council when the development application was advertised.
40The Hybrid is located towards the southern part of the site. It is a large and mature specimen with the crown extending approximately 20 m x 20 m, effectively limiting any development to the northern part of site, if development was restricted to the area outside the canopy. A large branch has dropped and is currently being supported by an existing Red Bloodwood located on the site. The health and vigour of the tree was the subject of considerable conflicting evidence by the experts.
The Hybrid - the evidence
41Dr McDonald and Mr Janes rely on two separate and independent arboricultural reports prepared by the applicants and submitted to the council as part of the development application. The first report was completed in May 2008 and the second report in September 2010. Both reports investigate the viability of the tree, and in both cases include a Picus Sonic Tomograph test that is used to detect decay and cavities in standing trees by measuring the velocity of sound in wood, that is a function of the elasticity and density of the measured wood.
42The 2008 test concluded that there was a considerable percentage of internal decay and recommended that the tree be removed if the site was to be developed. The 2010 test concluded that there is very little sound wood remaining in the base of the tree due to the large percentage of decay in the lower trunk area. Also, it was noted that tree has many defects from decay to the base in at least two of the three main trunk of the tree; one of which is being supported by an adjoining tree. The report also described the tree as being mature to over mature and requiring substantial remedial care and only being suitable for retention in the short term. The recommendation of the 2010 report was that the tree be removed and replaced with another long living Eucalypt species.
43Dr McDonald states that the tree has reasonable vigour when based on a visual assessment however its structural condition, near the base, is poor based on the two Tomograph tests. He notes that some interspecific plant hybrids, like the Hybrid, are weaker and this may explain why the tree is not excessively old yet is starting to fail structurally. Also, Dr McDonald states it is difficult to determine the likely longevity of hybrid individuals.
44Mr Janes states that the tree may not fall down as a whole tree, but over time the large limbs will fail due to the size and weight of these limbs. This can be seen from one branch of the tree that is resting on another younger tree on the site. Mr Janes is of the opinion that the tree should be removed as the impact of the development on the tree will be significant through firstly, the construction of two-storey home, and secondly the ground disturbance during construction of the two buildings and their services. He states that the risk of leaving this tree, in a residential situation, would be high with the likelihood of damage or injury through branch or tree failure. In his opinion, it would be appropriate, at present, to fence off the area under the tree canopy to avoid potential danger to persons who may be underneath the tree canopy.
45Ms Hobley comes to a different conclusion. She does not concur with the findings of both Tomograph tests. In her opinion, the tree is a healthy, mature specimen of very large dimensions. It has a full crown with no signs of major dieback. Its structural condition is considered good for such a large old tree, and in the context of the site; it still has all its primary lateral branches and the branch losses that have occurred, in terms of secondary and tertiary branches; are typical of the attrition that occurs due to intra-canopy competition associated with tree growth and development. Its major branch unions appear healthy and structurally sound. While one branch is interacting with a nearby tree, the situation needs to be monitored but the failure zone for this branch is the low use landscape zone of the nature strip. Ms Hobley states that old trees of this genus typically contain large cavities and this does not mean they are likely to fall over and die in the near future. Ms Hobley is also of the opinion that it may be possible for a dwelling to be constructed outside the area of the canopy or even under the canopy, subject to specific engineering requirements to protect the root system and monitoring of the condition of the Hybrid.
The Hybrid - findings
46In balancing the different evidence of Dr McDonald and Mr Janes and Ms Hobley, I agree that the Hybrid can be removed for three main reasons. First, and while the provisions of DCP 9 must be considered as a fundamental element in, or a focal point to, the decision-making process ( Zhang v Canterbury City Council (2001) 115 LGERA 373) it does not necessarily follow that the tree should be retained under any circumstances. DCP 9 is silent on how to address trees that are potentially dangerous or unhealthy although cl 6 provides the opportunity to "cut down...any tree listed on the Register of Significant trees" but with the consent of council.
47Second, and accepting that the Hybrid adds to the scenic quality of the site and the surrounding area, this benefit needs to be balanced against the likely longevity of the tree and its health. In this case, I have little trouble in concluding that the balance falls in favour of the removal of tree. The conclusions of the two Tomograph tests and the evidence of Dr McDonald and Mr Janes, and supported by the council officer, leave little doubt as to the appropriate outcome. I do not accept that the retention of the tree, irrespective of the scenic quality links to the area, should be preferred when there is a serious and legitimate question over the safety of the tree. In my view, the overwhelming expert and scientific evidence clearly suggests that the tree is dangerous and presents an unsafe situation for future occupants of the site.
48Third, and even if a dwelling is constructed outside of the area covered by the tree canopy, I am not satisfied that is sufficiently overcomes the potential danger from the tree. It would be clearly impractical to fence off the area under the canopy, given the limited area remaining for a dwelling on the site and the need to provide ancillary matters such as private open space and buildings setbacks. The suggestion by Ms Hobley that a dwelling could be located underneath the three canopy is misconceived, given the weight of evidence for branch failure and which is supported by the obvious example where an existing branch has failed and only remains because it is held up by another tree on the site. I am not satisfied that Ms Hobley has given proper consideration to the potential for injury in her assessment of the tree.
The rare species of flora
49Clause 44(b) provides that any buildings and works shall be designed and sited so as to have no adverse environmental impact on "any rare species of flora". Exemptions are provided where an adverse environment impact cannot be avoided (and subject to the satisfaction of the matters identified in cl 44(5)(a)-(c)) and subject to the matters in cl 44(6).
50There was agreement by Dr McDonald, Mr Janes and Ms Hobley that the site contains 7 groups of Faulconbridge Mallee Ash ( Eucalyptus burgessiana ), of differing maturity, which fall within the definition of a "rare species of flora" in cl 44(4)(c). There was also agreement that four groups were affected by the proposed building while three groups will located in the setback areas of the proposed development. Importantly, there was also agreement that the loss of four groups was not necessarily a reason to refuse the application providing that the three groups unaffected by building work were retained and additional Faulconbridge Mallee Ash were included on any new landscaping on the site.
51Pursuant to cl 44(5), I accept that an adverse environmental impact cannot be avoided however I am satisfied that the proposed development has been designed and sited to minimise any impacts through the retention of 3 groups of Faulconbridge Mallee Ash and the inclusion of the same species in the additional planting required for the site. In coming to the conclusion that the adverse environment impact cannot be avoided, I am satisfied that there is no practicable alternative in terms of design, type and site coverage, having regard to the permissibility of the proposed development (including compliance with the relevant zone objectives but subject to the provision of an acceptable landscape plan) and significant compliance with the development standards in Schedule 2 Part 1. While a different design could retain all 7 groups (or even a lesser number) of Faulconbridge Mallee Ash, I am satisfied that such a design would significantly reduce the opportunity for the development of the land for a purpose for which it was to be intended that it could not be deemed to be a "practicable alternative".
Rock outcrops
52Clause 44(4)(g) provides that any buildings and works shall be designed and sited so as to have no adverse environmental impact on " any significant natural features, including rock outcrops, rock ledges and cliffs".
53The site contains a number of rock crops however there was agreement by Dr McDonald, Mr Janes and Ms Hobley that the proposed design adequately addresses the retention of rock outcrops with the most significant outcrop being retained between the two proposed dwellings.
54Pursuant to cl 44(5), I accept that an adverse environmental impact cannot be avoided however I am satisfied that the proposed development has been designed and sited to minimise any impacts on the number rock outcrops on the site through the retention of the most significant outcrop and other minor outcrops. In coming to the conclusion that the adverse environment impact cannot be avoided, I am satisfied that there is no practicable alternative in terms of design, type and site coverage, having regard to the permissibility of the proposed development (including compliance with the relevant zone objectives) and significant compliance with the development standards in Schedule 2 Part 1. While a different design could retain all rock outcrops, I am satisfied that such a design would significantly reduce the opportunity for the development of the land for a purpose for which it was to be intended that it could not be deemed to be a "practicable alternative".
55Pursuant to cl 52(1), I am satisfied that the detailed environmental assessment undertaken as part of these proceedings adequately addresses the requirements in cl 44.
56Pursuant to cl 53, I have had regard to the question of vegetation retention, including vegetation that contributes to the streetscape character (but subject to the provision of an acceptable landscape plan) of the locality and I am satisfied that the vegetation to be removed is reasonable in the circumstances of this application.
Habitat/loss of vegetation
57While not raised as a contention in proceedings, Dr McDonald and Ms Hobley addressed the question of potential loss of vegetation and consequent loss of habitat. Dr McDonald states that the site has a similar habitat to be habitat that is abundant in the wider area, including the Blue Mountains National Park. Many invertebrate fauna, fungal species and microorganisms are dispersed by the wind and as similar habitat occurs in the wider area, these species are also highly likely to occur widely in the area. Dr McDonald also states that the site does not function as a corridor, apart from a "stepping stone" for birds.
58Ms Hobley states that the level of vegetation removal is significant in terms of impacts on the sites existing ecological values but that it is only of low significance in terms of impacts on habitat resources in the locality although she states that the significance of tree loss, in terms of its role in any ecological corridor, is not be established.
59On this matter, I did not understand Dr McDonald and Ms Hobley to be so far apart in their positions that the loss of vegetation and the consequent loss of habitat was an issue that warranted the refusal of the application.