Grassy ecosystems need ongoing management in order to address threats to their biodiversity and heritage values. All the grassy ecosystems sites under the National Capital Authority’s management have a mixed history of use for human settlement, agriculture and recreation. Each of these uses has brought management issues that need to be addressed with long term investment. Furthermore, the current use and management of land surrounding the grassy ecosystems also has an impact, for example weed introductions.
The management principals and objectives identified in the Ecological Management Plan (EMP) for NCA Conservation Areas. The EMP provided management guidelines to be applied to those areas within the National Capital Estate that contain matters of national and territory ecological significance. There are four areas of significance. These are:
These areas include Natural Temperate Grasslands of the Southern Tablelands and White Box and Blakely's Red Gum Grassy Woodlands. These communities are declared endangered ecological communities under the CommonwealthEnvironmental Protection and Biodiversity Conservation Act 1999 (the EPBC Act). An important part of the natural heritage of Stirling Park is the second biggest surviving population of the nationally endangered Button Wrinklewort. The Perunga Grasshopper and the Striped Legless Lizard are also threatened species that rely on the ACT's natural temperate grasslands.
The key threats to grassy ecosystems are weed infestation, inappropriate fire regimes and soil disturbance.
Fire is an important management tool for grassy ecosystems, but inappropriate fire regimes can also be a threat. Fuel loads need to be kept low enough to prevent the risk of very hot wildfires, and this can be done by limited grazing, mowing, weeding, and conducting ecological burns. Designing and implementing appropriate fire management strategies that manage wildfire risk while allowing grassland species to regenerate is an important part of managing sensitive grassy ecosystems.
A Bushfire Operations Plan has been prepared in consultation with fire ecologists from the ACT Government, Friends of the Grasslands and ACT Rural Fire Service.
Exotic trees and shrubs are invading Stirling Park by seeds spreading from suburban gardens by animals, wind and illegal dumping. In this case the dense, bright green invading saplings are growing up around a eucalypt where perching birds have passed seeds. (C) J Pittock, 2010.
Weeds are the major threat to conservation values at all National Capital Authority managed grassland sites. The weeds include both woody weeds – such as Blackberry, Cotoneaster, Willow and non-Indigenous and unsuitable planted trees – as well as herbaceous weeds like Chilean Needle Grass, Paspalum, St John’s Wort, and Wild Oats. These species are highly invasive and degrade native grasslands. Initial control measures are required with strategically timed follow-up to prevent re-invasion. Weed control is undertaken using herbicides and physical removal as appropriate to the weed and the sensitivity of the site.
Weed seed introduction is an ongoing issue at many of the National Capital Authority managed grassland sites, with weed seeds being brought into the sites via drainage lines, mowers and other equipment, people, illegal dumping of garden waste, and by birds. This threat is further exacerbated where the water entering the sites also brings nutrients, or where soil is disturbed, providing favourable conditions for the weeds to establish. Cleaning maintenance equipment before entering the sites is an important preventative measure. Improving the quality of the water entering the site and minimising soil disturbance is needed to address this risk, along with targeting these areas for weed control. Healthy indigenous grasslands can resist invasion of many weed species.
Soil disturbance, compaction and erosion are threats to the multi-use grassy ecosystems under the National Capital Authority’s management. Erosion is caused by installation of infrastructure, poorly maintained tracks, vehicle movement, the scraping of the surface soil by mowers, wind and water. To mitigate these threats, guidelines need to be developed and adhered to by contractors and others accessing the sites, and illegal vehicle access of the sites – for example at Yarramundi Reach – needs to be prevented.
There is still much that is unknown about grassy ecosystem ecology so it is important that the effectiveness of management activities is carefully monitored, and the results are used to improve future decisions about managing the sites.
As the land manager, the National Capital Authority is responsible for ensuring that management plans are regularly reviewed, and that management actions are appropriate and monitored for effectiveness. Contractors are engaged by the National Capital Authority for large-scale works, while Friends of Grasslands volunteers are involved in fine scale work such as hand-weeding, particularly in sensitive areas.