Mosman is fortunate to enjoy a substantial amount of bushland within its boundaries, much of it on Commonwealth Government land and in Sydney Harbour National Park. These large tracts of bushland at Middle Head, Georges Heights and Bradley’s Head are supplemented by a range of smaller bushland sites and unmade road sites that Council manages. Whilst generally small in comparison to the larger areas at Middle Head and Bradley’s Head these areas form an important part of the overall fabric of bushland in the local area and significantly add to the aesthetic value of the suburb.
The dominant vegetation community represented in Mosman’s bushland sites is a subclass of the Sydney Sandstone Gully Forest (SSGF 10ag) that being Regrowth SSGF. There are sites of Undisturbed Sydney Sandstone Gully Forest still found within the LGA. The other main vegetation community type is Coastal Sandstone Heath (CSH 21ag) which is predominantly found at Bradley’s Bushland Reserve.
Council undertook a bushland management review in 2000 and 2001 and it was resolved to undertake a flora and fauna survey to assist in setting priorities and determining specifications for future bushland management. This flora and fauna survey was conducted over the summer of 2000/2001 by Oculus. Council received the final report which was reported to Council on 12 June 2001. A part of the review process and MOSPLAN objective was to replicate this study in five years time to assess the effectiveness of the program and scheduled works.
The 2006/2007 Flora and Fauna Survey was completed by the ecological consultancy company Total Earth Care (TEC). The field survey was conducted from September 2006 to April 2007 and included a comprehensive flora survey and a late Spring and early Autumn nocturnal and diurnal fauna survey. Fauna was also noted when surveying each site for vegetation. Fauna census data (recorded sightings and records from Taronga Zoo Wildlife Clinic, DECC Wildlife Atlas, Barry Lancaster) for the LGA from 2001 to 2006 was also utilised.
Managing bushland in Mosman
When managing bushland Mosman Council ensures that weed management has clear conservation outcomes that follow three main principles:
- Retain relates to letting nature take its course and simply involves leaving healthy weed free bushland alone or if necessary applying minimal human intervention. Retain also relates to ensuring adequate fauna habitats are maintained and often the rate of weed removal in these situations will be dictated by the creation of suitable habitats in close proximity.
- Regenerate relates to using high level human intervention to help recreate natural processes in a bushland site and involves the removal and control of weeds in an area to assist the recolonisation of native plants. This is only possible in areas where native propagules are stored in the soil and therefore the site has resilience.
- Revegetate refers to the planting of locally sourced plant tubestock in areas where no regeneration of the bushland is possible. This is generally in areas that no longer have any natural soil profile and have either been heavily disturbed or have had fill placed on them and are usually devoid of any soil stored native propagules and therefore resilience.
Council has implemented Bushland Restoration Contracts for the vast majority of its bushland work. Bushland Restoration Contracts started in October 2001 and finished at the end of 2011.
Australian Bushland Restoration (ABR) works on bushland contracted sites. Bradley’s Bushland Reserve which was until recently managed by the Friends of Bradley’s Bushland Reserve (FBBR) is now managed by Council in consultation with the FBBR.
Overall Council actively manages 19 of its 22 large bushland sites. The sites not currently under regular active management include Rawson Park, Little Ashton Park and an unnamed site found on the southern side of Rosherville Reserve.
In the period from 2001 to 2006 there has been an overall increase in the percentage of native vegetation cover across all of Mosman’s bushland and unmade road sites that are currently actively managed. The total area of bushland with greater than 90% native vegetation cover is 45%. This is an increase of 20% from 2001.
In relation to weed cover there has been an overall reduction in the weed percentage classes at the vast majority of the sites between the previous and current surveys. The most significant reductions have been in areas of greatest resilience and this includes some areas previously assessed as in a high weed percentage cover that are now in a low category. This is significant as it shows that the contractors are targeting the right areas and are working from good bushland areas to bad. Also another significant positive finding in relation to weed cover was a large reduction in percentage cover of woody and vine weeds (plants that severely alter a natural ecosystem’s ability to regenerate).
In recognition of its successful bushland management program Council nominated for a Biodiversity Management Award through the Local Government and Shires Association of NSW Excellence in Environment Awards. These awards recognise initiatives in conserving and enhancing biodiversity on public and private land in urban and rural areas. This includes community involvement in protecting and conserving natural environments and wildlife habitat, rehabilitating and restoring degraded areas, and the improvement of wetlands management. Mosman Municipal Council was Highly Commended in Division B for its Bushland Management Program Flora and Fauna Survey 2006/2007.
Bushland Restoration Contracts review
The current Bushland Restoration Contracts 2001–2011 expired on 30 September 2011.
These contracts were introduced concurrently with the Community Environmental Contract (CEC) and were innovative in regard to duration, catchment based approach, and performance measurement criteria.
Given the need to review the outcome of the existing contract performance and to have any new contract commence at the best time of year, an extension of the existing contract until April 2012 was sought and accepted by Council. It is considered prudent to start the new contracts at a time of year when vegetation and especially weed growth is slowing and mid-autumn is considered a good time to abate this effect. This start date would allow contractors time to become familiar with sites prior to the high vegetation growth period in the following spring.
Current impacts on bushland areas
Although Council is investing a significant amount of funds to restore bushland sites there are several issues Council needs to be mind-full of in the future management of bushland areas in Mosman. Most of the bushland areas are still suffering from stormwater impacts, although the size of these areas has decreased significantly due to the completion of projects such as the Lawry Plunkett Integrated Stormwater Management Project, Balmoral Oval Contamination Capping and Creek Works and Beauty Point Stormwater Containment Project through Council’s Community Environmental Contract (CEC). Also, long standing encroachments from private residences are still evident.
The fragmented nature of the total bushland area, vandalism, dumping of garden waste, past neglect of these areas and the position and shape of individual sites mean that most sites have a high edge to area ratio. This means they are greatly exposed to disturbances and impacts of urbanisation which can lead to the progress of increasing native vegetation cover slower than what would be liked.
Feral and domestic animals are also negatively impacting on the biodiversity of Mosman’s bushland sites. Feral rabbits, even though they are controlled annually, are eating fresh tips of both planted and regenerating native plants. Domestic animals such as cats and dogs are responsible for the direct predation on possums and other native fauna. The community needs to be aware of this and take proactive steps to prevent their pets killing native wildlife. Many possums are also run over by cars and killed.
Unmade Roads Restoration Program
Mosman has 101 sections of unmade road. Unmade roads are those small (some are actually quite large) parcels of land that are classified as public roads but are not accessible to cars and are actually areas of soft landscape. Seventeen of these sites are already maintained as open space under the Parks and Gardens Management Contract. The remaining 84 unmade roads were identified by the Flora and Fauna Survey 2001 and Council staff as having significant value to the biodiversity of Mosman, acting as habitat corridors by providing fauna with safe travelling paths. Thirty six of these 84 unmade road sections are maintained under the Bushland Restoration Contracts (as they directly join a larger contracted bushland site) or the Volunteer Bushcare program.
Council has also been able to work on a further 24 unmade road sites guided by the Unmade Roads Restoration Strategy adopted by Council on 18 June 2002. Through this program Council is currently actively managing the large majority of the unmade road sites identified as having high and medium conservation values as defined by the Oculus Flora and Fauna Survey in 2001.
Fire management in bushland areas
Bushland within Mosman is largely made up of Sydney Sandstone Gully Forest (SSGF). This vegetation generally requires a burn every 10-12 years to maintain a high level of diversity. Conversely, burning more than twice within this period and then again before a further 12 years would seriously and irreversibly cause a decline in diversity. Over the last century Mosman’s bushland has suffered from very long inter-fire periods. This has, in many areas, lead to a mesic shift (a move towards a more closed monoculture canopy forest) away from fire-dependent species toward less fire-tolerant species. This mesic shift results in a greatly reduced level of flora diversity. Therefore by using fire as a tool to manage the bushland we can reverse this trend and create highly diverse natural areas.
Fire management is also important as Council has statutory responsibilities in relation to fire hazard reduction in bushland areas under its control. A program of hazard reduction burns is annually prepared by Council and submitted to the Manly Mosman District Bushfire Management Committee. Once the Committee is satisfied with each Land Manager’s proposed burn programs for the year the list is then sent to NSW Fire Brigades and the burns are completed throughout the year when weather conditions are suitable and resources are available. Mosman Council’s hazard reduction program is partly based also on weed removal locations where weed debris is piled from bush regeneration activities. This program has been extremely effective in the last couple of years with fire hazard reduction and ecological burns regularly and successfully carried out in many bushland sites.
As mentioned above many native plant species found in Mosman rely on fire for their seeds to germinate. Undoubtedly there is remnant native seed lying dormant in the soil in all bushland sites in Mosman waiting for fire to start the germination process. Using fire has increased native plant species numbers in all bushland sites, increased there density and in general has significantly improved the health and amenity of these sites. Also the threatened plant species Acacia terminalis spp terminalis, is now found at more sites and in greater numbers, most likely as a result of the use of fire throughout Council bushland sites.
Tree dieback – Phytophthora cinnamoni management
Since Phytophthora cinnamoni (Pc), was first identified as a potential threat to bushland in Mosman, Council has been actively pursuing measures to minimise the spread of Pc through its bushland sites. To date these measures have involved implementation of protocols in all Bushland Restoration Contracts and bushland volunteer activities. Similar protocols have been implemented in construction projects where bushland sites are involved. The next stage of Council’s strategy involved identifying reserves where Pc may exist and conducting an annual soil sampling program to establish the extent of Pc in Mosman Local Government Area (LGA).
Testing is generally carried out in late summer after significant rain (so that soil is wet and above 20 degrees Celsius) and that for the short term testing be directed to high usage areas where formal/informal tracks and drainage lines are evident and areas where significant dieback is observed. Sites that will be tested in the summer of 2008 include Beauty Point, Rosherville Reserve and The Spit Bushland Reserve.
Although sites have been sampled at random locations, the presence of Pc does not necessarily mean that dieback will occur as empirical data suggests that tree dieback and the presence of Pc are not directly correlated as sites with no dieback recorded the presence of Pc, whilst sites showing dieback recorded no Pc.
Tree injection to combat effects of Pc-related dieback
Council has injected trees with a Phosphonic acid (AGRI-FOS® 600 a systemic fungicide recommended to limit the effect of Pc on trees) in February 2005. The results indicate that injecting the trees with phosphonic acid has had little to no effect on Angophora costata trees and in the cases where the canopy cover had increased, other trees that had not been injected within close proximity also appeared to be healthier. The trees which were initially healthier have remained the same as prior to injection. Those trees which contained less than 10% canopy cover prior to injection generally appear to be dying, or are severely sick.
The results of the tree injecting would support the soil test results and again reiterate that Pc may not be directly responsible for the dieback that is occurring on Mosman lands. The phosphonic acid injected into the trees would certainly reverse the effects of Pc if it was solely responsible for the dieback condition. This was clearly not the case.
Bushland walking tracks
An important part of managing our bushland remnants is being able to actually enjoy them. A great way for everyone to be able to utilise and enjoy our natural environment is through bushwalking. Council is fortunate that the majority of its bushland areas have long established and well worn walking tracks that allow a walker spectacular views of the harbour and bushland. They also provide useful access to facilities such as wharfs, dinghy racks and beaches.
- Bushwalking tracks within Mosman (PDF 1MB)
In 2006 a university student undertook a project throughout Mosman which involved the GPS mapping of all bushland tracks that exist on Council land. This field data has since been transferred to Council’s GIS (Geographical Information System – digital mapping system) which will help us to produce maps showing the location and type of all bushland walking tracks and observe any gaps in these throughout the Mosman area. Tracks have been categorised as primary or secondary and track surfaces and features have also been recorded. Features include location of stairs, boardwalks and drainage lines.
To ensure these tracks are useable and safe Mosman Council undertakes upgrades through a maintenance program on all of its primary tracks. Part of this program involves closing off any minor secondary tracks and stopping unauthorised tracks being built on Council Land. With a limited budget, a priority listing has been developed and with help from grant funding under the ‘Sharing Sydney Harbour Access Program’ additional works have been possible. These funds have allowed Council to work through this program to ensure continued public access to all our foreshore areas are improved and maintained.
When undertaking improvements on existing tracks, or when creating new ones, every attempt is made to only use natural products that compliment the existing natural environment and reduce potential impacts. Construction is specified to minimise any disturbance to surrounding areas and products such as sandstone blocks for stairs, crushed sandstone for path surfaces and hard woods for board walks and bridges are used.
Some other issues that need to be taken in consideration when improving and maintaining bushland walking tracks include, water drainage, phytophthora, erosion and aboriginal heritage.
In addition to maintaining existing tracks Mosman Council has, over the past 7 years, established 5 new walking tracks in bushland areas. These include the track through Lawry Plunkett Reserve from Mulbring Street through to The Esplanade; a walking track at Quakers Hat South, from Bay Street playground to the foreshore and dinghy racks; a new foreshore access track through the recently purchased Joel’s Reserve; a walking loop at Balmoral Reserve; and more recently a walking track from Parriwi Road to the foreshore through Parriwi Lighthouse.
It should also be noted that in addition to the numerous tracks scattered throughout Council land there are also a number of very popular walking tracks within NPWS, Sydney Harbour Federation Trust and Taronga Zoo land around and throughout Middle Head and most are well connected to Council’s bushland walking tracks.