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CURTAIN SQUARE SITE MANAGEMENT PLAN September 2011 Curtain Square Draft Site Management Plan 2011 CONTENTS 1.0 INTRODUCTION ............................................................................................................... 3 1.1 Purpose ......................................................................................................................... 3 1.2 Site Description ............................................................................................................. 3 1.3 Consultation ................................................................................................................... 3 2.0 MANAGEMENT ISSUES .................................................................................................. 4 2.1 Tree Management ......................................................................................................... 4 2.1.1 Irrigation ................................................................................................................ 4 2.1.2 Mulch .................................................................................................................... 5 2.1.3 Turf Control ............................................................................................................ 5 2.1.4 Compaction ........................................................................................................... 5 2.1.5 Elm Leaf Beetle (Pyrrhalta luteola) ....................................................................... 5 2.2 Possum Management ................................................................................................... 5 2.2.1 Population Surveys................................................................................................ 5 2.2.2 Population Density ................................................................................................. 6 2.2.3 Supplementary Feeding ........................................................................................ 6 2.2.4 Fertility Control ...................................................................................................... 6 2.2.5 Euthanasia ............................................................................................................. 7 2.2.6 Tree Banding ........................................................................................................ 7 2.3 Urban Wildlife Management in Yarra ............................................................................ 7 2.4 Heritage Issues .............................................................................................................. 8 3.0 CSCAC VISION ................................................................................................................. 9 4.0 OBJECTIVES .................................................................................................................... 9 4.1 Objective 1 ..................................................................................................................... 9 4.2 Objective 2 ..................................................................................................................... 9 4.3 Objective 3 ................................................................................................................... 10 4.4 Objective 4 ................................................................................................................... 10 4.5 Objective 5 ................................................................................................................... 10 4.6 Objective 6 ................................................................................................................... 10 4.7 Objective 7 ................................................................................................................... 10 5.0 IMPLEMENTATION......................................................................................................... 11 5.1 Actions for Objective 1 ................................................................................................ 11 5.2 Actions for Objective 2 ................................................................................................ 11 5.3 Actions for Objective 3 ................................................................................................ 11 5.4 Actions for Objective 4 ................................................................................................ 11 5.5 Actions for Objective 5 ................................................................................................ 12 5.6 Actions for Objective 6 ................................................................................................ 12 5.7 Actions for Objective 7 ................................................................................................ 12 APPENDIX 1 – PRELIMINARY COST ESTIMATE..................................................................... 13 2 City of Yarra Curtain Square Draft Site Management Plan 1.0 INTRODUCTION 1.1 Purpose 2011 The purpose of the Curtain Square Site Management Plan is to guide the future management of the Park to ensure a sustainable environment for all park users. The Plan makes environmental, vegetation, and wildlife management recommendations and actions for this heavily used and highly valued urban landscape. The Plan identifies a vision for Curtain Square, along with objectives to meet this vision, and actions for implementation. 1.2 Site Description Curtain Square is a 1.46 hectare park in Carlton North, and is one of the most popular neighbourhood parks within the City of Yarra. It is bound by Curtain and Newry Streets to the north and south respectively, with Rathdowne and Canning Streets forming its western and eastern boundaries. The area was originally a bluestone quarry before being converted to public open space in the 1870’s. Planting on the site originated in 1876 with additional planting taking place in 1884. A number of the trees in the park today are likely to be from these plantings. The area has undergone a number of changes from its original, strongly symmetrical layout which consisted of two paths running along the central north-south and east-west axis dividing the site into four quadrants. Perhaps one of the largest changes occurred during the post-war period where the emphasis of the use of Curtain Square changed from a meeting place for older men of limited means to a major children’s recreational centre. This change resulted in the loss of much of the late 19th century design, particularly the path network. Today Curtain Square still caters to children’s recreation with a fenced junior playground area, a second playground area catering to the needs of older children, hard-surfaced ball courts and open lawn areas. Other uses of Curtain Square include picnicking, dog walking, and leisure and recreation. 1.3 Consultation The management of trees and possums at Curtain Square has been an ongoing issue and matter of community friction for many years. More recently, a public meeting was held on 24 May 2010 to discuss issues around developing a Management Plan for Curtain Square to guide future management of the park. Following this meeting, Council determined at its Ordinary Meeting in October 2010 to establish the Curtain Square Community Advisory Committee (CSCAC) comprising members of the Community, Councillors and Council officers The role of the CSCAC was to contribute to the development of the Curtain Square Site Management Plan through stakeholders who represent the open space, flora and fauna interests of the wider Yarra community. The terms of reference for the CSCAC state that ‘A particular emphasis of the CSCAC will be on the identification, protection and preservation of the tree population in Curtain Square under the guidelines developed in Councils Urban Wildlife Management Plan, 2009’. The CSCAC met five times from February to April 2011 and developed a set of recommendations and actions which have informed this Plan. 3 City of Yarra Curtain Square Draft Site Management Plan 2.0 2011 MANAGEMENT ISSUES The studies conducted for Council by various consultants and the CSCAC concur that damage to trees at Curtain Square was not solely the result of possum browsing and that a multipronged approach was required to secure the future of the park including both tree and possum management. 2.1 Tree Management There are a number of factors affecting the health and vigour of the trees in Curtain Square including drought, compaction, senescence, disease, and grazing by Common Brushtail Possums. Management of these factors is vital if tree health and longevity is to be increased. The recent drought has taken its toll on many of the trees in Curtain Square. A comparison of assessments carried out by Homewood Consulting in 2005 and again in 2009 confirms this with a reduction in the number of established trees assessed as “good” and a corresponding increase in the number assessed as “poor”. New tree plantings have also taken place during this time including the replacement of a number of the trees removed in 2005. These juvenile trees currently make up almost 30% of the total tree population. Curtain Square therefore, lacks a variety of tree ages 10 and 100 years old that ensures the park will always have offer high levels of amenity for park users. The consequence is that when the most mature trees die it will be many years before the newly planted trees are able to provide the extensive green canopy valued by park users and wildlife in this Park, and for this reason the mature, aged trees must be protected to give them the longest life span possible. A tree planting and replacement strategy is needed to guide the planting of vegetation to replace senescent trees and to increase the amount of vegetation in Curtain Square. The CSCAC placed heavy emphasis on an increased diversity of both plant species and layers in Curtain Square, including more understorey / garden bed planting and a mix of exotic and indigenous species with a variety of flowering times. Management techniques available include: increasing the amount of moisture available to trees through irrigation; increased/more frequent mulching; turf control; a reduction of compaction around trees; control of Elm Leaf Beetle in the elms; a reduction of possum numbers to a more sustainable level; and implementation of a tree replacement programme. 2.1.1 Irrigation The amount of supplementary water needed to be applied to trees to secure their health and vigour will depend on a number of factors including temperature, rainfall, tree size and canopy coverage and the health of the trees’ root systems. Observations on the health of the trees including canopy coverage (in the absence of predation by pests), leaf size and colour are all good indicators of whether trees are receiving adequate water. Throughout the irrigation season, measurement of the moisture content of the soil should be undertaken to help with timing irrigation. This may involve digging a small hole with a shovel near the drip line of trees and observing and feeling the moisture content of the soil or alternatively moisture sensors could be used. Similarly, Homewood Consulting (2005) have suggested installing extra irrigation hose around the trees, particularly the avenue of Moreton Bay Figs and the Planes along Rathdowne Street to provide more effective and consistent irrigation over the root zone. 4 City of Yarra Curtain Square Draft Site Management Plan 2.1.2 2011 Mulch A mulch layer provides protection to the root system by reducing the amount of evaporation from the soil surface, reducing temperature extremes in the soil and reducing compaction of the soil surface as well encouraging soil microbial activity, providing nutrients as it decomposes, and suppressing weed growth. A number of trees in Curtain Square have a mulch layer applied around them including the Ficus Avenue, the Elm Avenue, the Plane trees along Rathdowne Street, some of the Elms along Newry Street and some of the newer tree plantings. Mulch layers should be extended to include all of the trees in Curtain Square with mulch applied to the dripline of the trees, where the majority of the tree’s feeder roots are situated. Homewood Consulting suggest a thickness of 150 mm and that mulch be reapplied to this thickness once it falls below 80 mm. 2.1.3 Turf Control Competition with turf for moisture is compounding the drought stress placed on trees. Turf should be removed at least out to the dripline of the trees and replaced with mulch. 2.1.4 Compaction Regular pedestrian traffic can cause compaction over the root zones of the trees, not only restricting root growth but also reducing water penetration into the soil. There is a number of methods available to help ameliorate compaction, such as shallow cultivation of the area and soil-lifting by blasting the soil with compressed air, however results vary. Improving soil structure through the application of compost and organic mulches, increasing irrigation and preventing further compaction by restricting public access can often mitigate the effects of compaction on trees. 2.1.5 Elm Leaf Beetle (Pyrrhalta luteola) The larvae of the Elm Leaf Beetle can severely defoliate elm trees, reducing their photosynthetic area and weakening the tree. Consecutive defoliations can eventually lead to tree death. A current preventative management program within the City of Yarra treats all Elm trees in parks on a three-year cycle through soil injection. This program will be continued, including Curtain Square. 2.2 Possum Management Common Brushtail Possums are well adapted to living in the urbanised environment of Curtain Square. Their ability to exploit various human and natural resources has enabled them to expand well beyond their normal density as found in natural environments. Although possums are a valued component of the biodiversity of Curtain Square, the high population density has lead to a number of issues within the park. 2.2.1 Population Surveys An average of 60 Common Brushtail Possum’s was recorded over the 16th and 29th of January 2011 in a survey by Ecology Australia. This is a density of approximately 42 possums per hectare (ha), which is consistent with previous surveys by Ecology Australia which recorded an average of 60 Brushtail Possum’s (42 possums per ha) during February 2010. Earlier surveys in September 2002 and April 2004 counted 29 animals, with an average of 51 and 50 animals recorded in September 1999 and July 2000 respectively. Curtain Square provides plentiful resources for possums, including high availability of dens and consistent supplementary feeding. The exceptionally high density (42/ha) of Brushtail Possums is ten times greater than that found in natural environments and three times greater than that found within the highest-density parks within the City of Melbourne. 5 City of Yarra Curtain Square Draft Site Management Plan 2011 Regular feeding of possums is creating an artificially dense population greater than the natural carrying capacity of the system. This is resulting in additional impacts to trees caused by browsing and long-term welfare issues for these animals, including potential nutritional deficiencies and increased territorial disputes. Whilst the survey was not intended to assess the health or welfare of possums, several of the individuals recorded were wounded and/or in poor condition indicative of competition and/or high density. Given the population level and damage caused by possum browsing, as assessed using DSE protocols, intervention and management is required for both the protection of the parks’ landscape and amenity values, and the sustainability and welfare of the resident possums. 2.2.2 Population Density Brushtail Possum densities in natural environments range from 0.2 to 4 individuals per hectare (Strahan 1995). Their numbers are regulated by resource availability, competition, predation, wildfire and disease. Brushtail Possums have readily adapted to modified urban environments, due to high food and den availability, lowered predation levels and absence of wildfire. Densities in other urban parks in Melbourne range from 6.9 / ha in Fitzroy Gardens to 13.5 / ha in Carlton Gardens South. The possum density at Curtain Square (42 animals per ha) is ten times greater than that found in natural environments and three times greater than that found within the highest-density parks within the City of Melbourne. The current density of 42 animals per ha at Curtain Square in 2010-2011 compares with 37 animals per ha in 1999 and 20.7 animals per ha in 2002 and 2004 (Harrison 2002, 2004). These results show a fluctuating possum population within the park, both seasonally and over time, but also an increase in the density over the last decade. The possum population at Curtain Square has increased to a level determined by the available resources, including plentiful den sites and consistent supplementary feeding, building up to a number not otherwise able to survive in such a natural environment. 2.2.3 Supplementary Feeding Feeding possums can lead to a dietary imbalance, and artificially high densities of possums (Temby 2005). Many visitors, some international, are attracted to Curtain Square to view possums. Some visitors feed possums without understanding the negative impact this has on native animals. This kind of supplementary feeding should be stopped by informing people through an education program of the damage of supplementary feeding and the protected status of native wildlife. Furthermore a local law banning supplementary feeding would allow Council to enforce a no-feeding rule and signage in Curtain Square. Because the possum population is accustomed to regular supplementary feeding, it is recommended that a feeding program be brought under Council control, with input from wildlife experts, and gradually reduced until all feeding can be completely stopped. Reduction of feeding would be based on increased availability of fodder in the form of vegetation planted in the park, and a reduced demand for food based on a controlled population reduction program based on two fertility control strategies. Public information about the feeding program should communicate the reasons and methods for Council supplementary feeding to discourage any other members of the public from feeding the possums. The recommended ongoing monitoring actions will allow the effects of population management to inform the appropriate reduction of the feeding program. 2.2.4 Fertility Control Fertility control is viewed as a preferred management option compared to euthanasia, and was recommended by the Curtain Square Community Advisory Committee and is supported by Council. Two types of control are available and have been tested on marsupials; these are 6 City of Yarra Curtain Square Draft Site Management Plan 2011 immunocontraceptive methods, and hormonal implants. The CSCAC was in favour of the hormonal implant as a more ethical option for possum management. Of hormonal implants, a contraceptive implant called deslorelin has been tested without any negative side effects or other adverse effects on Brushtail Possums, and could be an effective measure for management at Curtain Square. The implant was effective in preventing reproduction in the study for approximately one year, therefore such a program would need to be ongoing and reviewed on a regular basis to determine its efficacy and need for continuing. As part of the multi-pronged approach, regular monitoring of possum numbers to determine if control measures are having an impact on the population. Counts should be carried out biannually in late spring/early summer and late autumn/early winter, including diurnal assessment of den sites, nesting boxes, and tree damage, and nocturnal, spotlight assessments of possum numbers. It is proposed that this be reviewed by Council two years after it is commenced before continuing with the program. 2.2.5 Euthanasia While not endorsed by Council as the preferred method, it is proposed that euthanasia remains an option if the sterilisation program does not produce a meet the objective of reducing the existing possum population and show a demonstrable improvement after two years of the program. 2.2.6 Tree Banding Tree banding can prevent over-grazing of vulnerable trees by possums. The placement of bands should be done in a humane way to prevent injury to wildlife. Bands placed low on the tree trunk can leave possums subject to attack by predators such as dogs on the ground without the possibility of escape up the tree trunk. Where possible bands should be placed: above den sites, or if not possible above the first fork of the tree If the tree structure does not allow placement in these locations, all hollows of the banded trees should be checked for possums prior to banding and any possums present possums should be removed from the tree and placed in a nesting box provided for this purpose. Banded trees should either be isolated from adjoining trees by pruning branches of the surrounding trees to leave a 1.5 – 2 m gap between canopies or if this is not possible, surrounding trees should also be banded. Existing banding on higher branches of six Elms has led to improvements in foliage density. These bands were placed on higher branches mean to ensure possums are able to access dens lower in the tree without grazing on the upper canopy. However it is accepted that the majority of trees in Curtain Square do not have a similar vertical branching structure which would allow this kind of banding to be effective. Banding of trees is likely to increase grazing pressure on non-banded trees, particularly while the possum population is high and needs to be monitored closely to prevent over-grazing of these trees. Bands will need to be rotated between trees to ensure that trees have a chance to recover from grazing whilst still providing some dens and food for possums. Rotation frequency will depend on the recovery time of banded trees and all banded trees should be given sufficient time for new leaves to emerge and harden and for the tree to manufacture and store carbohydrate reserves before any band is removed. Bands should therefore remain on trees for at least 8 weeks after the tree has developed new leaves. 2.3 Urban Wildlife Management in Yarra In December 2009, the City of Yarra adopted an Urban Wildlife Plan prepared by Ecology Australia. One of the key recommendations in the plan is to: 7 City of Yarra Curtain Square Draft Site Management Plan 2011 “investigate the need for a pest animal policy, or develop site vegetation management plans for sites where the health of vegetation is threatened by over-feeding by native species like possums and bell miners and noisy miners” The Plan also identifies that: Problematic fauna are not only those classified as feral exotic animals such as foxes but may also include those native animals that are often highly abundant, out-competing many other native species through aggressive behaviour. Fauna species that may be considered problematic have been separated below into possum and native/exotic bird management. In order to direct the allocation of resources for fauna management, the study area has been divided into three Area Types: (a) Area Type 1 – Waterways and remnant vegetation. The primary focus for land management should be the conservation of flora and fauna values, with additional values and uses being managed to compliment urban bushland and wildlife habitat; (b) Area Type 2a – Urban Parks (Urban Bushland plantings). The primary aim for land management should be to maintain and extend urban bushland plantings where possible, maintain exotic planting where appropriate and provide for passive recreation; (c) Area Type 2b – Urban Parks (predominantly exotic parks and sporting ovals). The primary focus for land management should be on the recreational values with conservation of fauna habitat as a secondary purpose; and (d) Area Type 3 – Street Trees (provide landscape amenity and low values as fauna habitat). Curtain Square has been identified as an Area Type 2b – Urban Parks. The following is an extracted summary of the general management actions recommended for Area Type 2a and b: urban parks with bushland plantings/sporting ovals/golf courses. Details of each action are outlined within Plan Elements, Section Recommendations for Area Type 2 include: (a) maintain recreation focus; (b) consider adopting a policy to plant native species (preferably indigenous and local provenance where possible) for plantings, noting that restrictions in regards to heritage controls and adopted precinct planting plans may determine the actual species planted. Planting indigenous flora of local provenance within areas in close proximity to the waterways is particularly important (Moderate – high priority) (Section 5.1.3); (c) remove environmental weeds from existing planting guides (High priority); (d) retain all hollow bearing trees and stags (High priority) (Section 5.1.1); (e) investigate use of nest boxes to augment habitat and where already present engage volunteers to monitor fauna use and exclude exotic species (Low priority) (Section 5.1.4); and (f) monitor health of trees for signs of possum damage. Install possum bands where the overall health of tree is determined to be endangered (High priority, on-going management required) (Section 5.1.9). 2.4 Heritage Issues Curtain Square Conservation Analysis prepared by John Patrick Pty Ltd in February 2000 identified the significance of Curtain Square within the City of Yarra and enumerated each component element as of primary, contributory and no significance to the place. Elements of primary significance included the principal 19th century tree plantings including: The Moreton Bay Fig Avenue; The mature avenue and row plantings of Elms, many of which have since been replaced; Other mature tree plantings including boundary oaks and the since-removed Camphor Laurels and Grey Poplar. The Camphor Laurels are of particular note as these trees were noted as being under severe possum browsing stress, though possum damage to other trees was also noted in the document. The key considerations of this plan in terms of heritage are: 8 City of Yarra Curtain Square Draft Site Management Plan 2011 the principal extant tree plantings identified as of primary significance should be protected and managed to maximise their amenity value within the landscape; and replacements should be selected from the same palette and located according to historical precedent. Opportunities potentially exist within the scope of the tree replacement strategy to re-establish some of the early form of Curtain Square, including re-aligning the main western axial path through the middle of the site which has recently been replanted with Elms, including at least partial removal of the central mound. 3.0 CSCAC VISION The following ten-year vision for Curtain Square was developed by the CSCAC. The Curtain Square of 2020 will: be a sustainable and healthy community and environment. offer a variety of mainly passive activities for people of all ages and abilities, and provide a welcoming, and comfortable space without conflict between users, which is treasured by the community. have an increased number of large, healthy trees (including a large number of 9-year old plantings) providing increased canopy and shade for all park users, as well as increased layers of diverse planting such as groundcovers, grasses and shrubs. be a part of a broader, interconnected open space network joined by streetscape planting and tree canopy, contributing to wildlife corridors. be a park which is self-sustaining in some small way, through the use of : o treated and harvested stormwater o diversity of species for habitat generation o mulching and improved tree health. 4.0 OBJECTIVES Objectives resulting from the vision and the desired outcomes are listed below. 4.1 Objective 1 An increased quantity and variety of healthy trees and vegetation in Curtain Square Outcomes to measure success for this objective will include: The implementation of a tree strategy to guide planting in the park The presence of a diversity of vegetation including indigenous and exotic species which will also provide a sustainable food source for wildlife The presence of healthy trees of different ages within the park to plan for senescence and replacement of older trees A variety of plant flowering times and layers, including upper tree canopy, and middle and lower storey planting including garden beds New plants are able to establish due to protection from possum browsing 4.2 Objective 2 The gradual decrease and cessation of supplementary feeding of Brushtail Possums Outcomes to measure success for this objective will include: A council-managed feeding program will provide appropriate amounts and types of supplementary food for possums until a stable population level is reached and adequate vegetation is available as a food source. In the long-term there is no supplementary feeding of Brushtail Possums in Curtain Square 9 City of Yarra Curtain Square Draft Site Management Plan 2011 The community are educated about the value of native wildlife and the danger and penalties of feeding them in the Park. 4.3 Objective 3 Establish a sustainable and stable possum population Outcomes to measure success for this objective will include: A possum population which is at a sustainable level for the size of the Park and its available natural food sources. The use of humane population control measures, such as fertility control, rather than euthanasia, which should be considered a last resort measure. A carefully monitored program to understand the possum population. 4.4 Objective 4 The protection of vulnerable trees Outcomes to measure success for this objective will include: Trees at risk from over-browsing are protected by the use of tree bands until they show signs of improvement. Mature trees experience an extended life-span to cover the ‘gap’ in tree ages. Banding is implemented in a humane way to avoid endangering or trapping possums. 4.5 Objective 5 Management of nesting boxes to encourage a diverse native wildlife Outcomes to measure success for this objective will include: A number of Brushtail Possum boxes appropriate to the stable population level, including some surplus boxes. An increased diversity of species are able to live in Curtain Square. 4.6 Objective 6 Improved environmental quality and management Outcomes to measure success for this objective will include: Improved health of flora and fauna through enhanced environmental management actions, including water and soil. A park environment which has some self-sustaining qualities and relies on renewable and recyclable resources. 4.7 Objective 7 Ongoing monitoring of park management Outcomes to measure success for this objective will include: Regular monitoring and reporting against success of objectives Adjustments to management actions based on results of monitoring 10 City of Yarra Curtain Square Draft Site Management Plan 5.0 2011 IMPLEMENTATION The following implementation plan identifies the required actions, resources and timing to achieve the objectives of the Management Plan. An estimate of costs by year can be found in Appendix 1. 5.1 Actions for Objective 1 An increased variety and quantity of healthy trees and vegetation in Curtain Square Action Develop a Tree Strategy to identify appropriate species and locations of planting over time Consult on Tree Strategy and obtain Council endorsement Implement Tree Strategy and planting through ongoing annual program 5.2 Timing Immediate Responsibility Open Space & Arboriculture Soon Open Space & Arboriculture Open Space & Arboriculture Ongoing Actions for Objective 2 The gradual decrease and cessation of supplementary feeding of Brushtail Possums Action Develop a feeding program including dietary criteria appropriate to circumstance Carry out feeding per program Timing Immediate Responsibility Open Space, with expert advice Ongoing Develop an education program to discourage public from feeding and littering, including informational signage and literature Enact a local law to ban feeding Enforce local law Removal and replacement of any non possum-proof bins Soon Contractor to City of Yarra Open Space & Communications 5.3 Soon Ongoing Immediate Community Amenity Community Amenity Open Space Actions for Objective 3 Establish a sustainable and stable possum population Action Develop a fertility control program using previously tested hormonal implants Carry out fertility control program using services of a qualified veterinarian Monitor effect of program and determine ongoing annual retention or removal of implants 5.4 Timing Immediate Soon Ongoing Responsibility Open Space, with expert advice Open Space, with expert advice Open Space, with expert advice Actions for Objective 4 The protection of vulnerable trees Action Implement tree banding to protect trees most vulnerable to over-browsing. Rotate bands between trees as they recover Develop guidelines for humane banding, including placing bands above dens where tree structure allows or if not, above the first fork where tree structure 11 Timing Immediate Responsibility Arboriculture Ongoing Arboriculture Ongoing Arboriculture City of Yarra Curtain Square Draft Site Management Plan 2011 allows or if not remove possums from the tree into nesting boxes. 5.5 Actions for Objective 5 Management of nesting boxes to encourage a diverse native wildlife Action Provide a nesting box for each possum removed from trees (due to banding or tree removal) Introduce nesting boxes of different sizes (larger and smaller) to encourage diversity of species Inspect brushtail boxes (at times of possum survey) and if there is evidence they are not in use, numbers to be reduced (while maintaining some surplus above population number) 5.6 Timing Ongoing Responsibility Arboriculture Soon Arboriculture Ongoing Arboriculture Actions for Objective 6 Improved environmental quality and management Action Assess existing irrigation system and add lines if required. Asses soil moisture and irrigation regime – increase irrigation at required times. Investigate sustainable irrigation sources, such as treated stormwater through WSUD initiatives in the Park. Install mulch layer to drip line of all trees where it does not exist. Top up mulch to 150mm depth when it falls below 80mm depth. Reduce compaction by aeration of soil Pruning of trees to remove dead and dangerous branches 5.7 Timing Immediate Responsibility Arboriculture Immediate Arboriculture Soon Open Space Immediate Arboriculture Ongoing Arboriculture Ongoing Ongoing Arboriculture Arboriculture Timing Ongoing Responsibility Open Space Immediate Arboriculture Actions for Objective 7 Ongoing monitoring of site management Action Survey possum population and use of nesting boxes on a six-monthly basis to determine feeding and fertility control program adjustments. Survey mature tree health two times a year to identify trees at risk and inform tree band rotation. 12 City of Yarra Curtain Square Draft Site Management Plan 2011 APPENDIX 1 – PRELIMINARY COST ESTIMATE Note: all costs are preliminary estimates to be confirmed following expert advice on areas of management 13 City of Yarra