Flora & Fauna
About 1.2% of the Local Government Area is parkland managed by Hawkesbury City Council.
Plans of Management are being developed for all community land managed by Hawkesbury City Council. This land is categorised as Bushland, General Parkland, Sportsground or Playgrounds. It is anticipated that these Plans of Management will be available for public comment by December 2008.
Community participation in the management of Council's parks and reserves is invaluable. Over 10 "People for Parks - Bushcare" Groups conduct works such as weed control and bush regeneration within our parks. In September 2002, Council employed a Community Bushcare Officer to provide support to these community groups. If you are interested in participating in any of these activities, or would like to find out more, please contact Councils Bush Care Officer on (02) 4560 4525.
The vegetation of the Hawkesbury area is diverse and complex, reflecting the diversity of environments with regard to influences such as the Hawkesbury-Nepean River, geology, and climate.
With respect to vegetation in the Hawkesbury, this range may generally be categorised into three main groups:-
- Cumberland Plain and associated ecosystems
- Hawkesbury Nepean River floodplain and associated ecosystems
- Hawkesbury sandstone and associated ecosystems.
These groups are briefly described below: -
1. Cumberland Plain vegetation
Cumberland Plain vegetation occurs as far north as Wilberforce (Robinson, Fairley and Moore), and can be recognised by the dominant species Eucalyptus moluccana, E. tereticornis and E. fibrosa. The topography is undulating, uniformly between 20 and 100m ASL (Benson), and consists of low hills and boggy depressions. Generally soils are poorly drained and poorly aerated, and are heavy clay soils. Cumberland Plain vegetation also contains vegetation on poorly consolidated Tertiary alluvial deposits.
Benson describes the vegetation as generally Grey Box woodland on the flat Cumberland Plain 'core' country where rainfall is low and temperature ranges are high. Grey Box - Ironbark woodland occurs on the hilly margins of the Cumberland Plain.
Two regionally significant areas of vegetation are also found on the Cumberland Plain. These are the Castlereagh woodlands and the Agnes Banks sand deposit.
The Castlereagh woodland is a Tertiary alluvial deposit of sandy clay supporting an open woodland of Angophora bakeri, Eucalyptus sclerophylla and E. parramattensis which occurs between Windsor Downs and Castlereagh.
The Agnes Banks sand deposit is a deep almost pure windblown set of stable east-west dunes of Pliocene or Pleistocene age. The area now consists of approximately 300ha and the vegetation is unique to the Hawkesbury area. Banksia serrata, B. aemula and Angophora bakeri are the dominant canopy species.
2. Hawkesbury Nepean River and associated floodplain features
The underlying sediments here consist of Holocene alluvium, which result in River Flat Forest and Freshwater Reed Swamps, both vegetation communities are directly related to the river. Generally there is very little of the native vegetation remaining as this sediment represents one of the most fertile of the Hawkesbury. Small patches remain at Agnes Banks, Ebenezer, Cattai with larger areas along Roberts Creek and the Colo and MacDonald Rivers. Eucalyptus tereticornis is the dominant tree along the upper reaches of the Hawkesbury.
There are a number of Bushcare/Landcare or vegetation restoration groups working along the Hawkesbury aiming to restore or regenerate vegetation. However there are inherent problems in that they are weed infested, and the weeds are difficult to control due to the mobility of seed stock etc.
3. Hawkesbury sandstone and associated ecosystems
This area is very distinctive in both topography and vegetation. Benson (1992) explains Hawkesbury sandstone vegetation in terms of two major vegetation associations:- Sydney Sandstone Gully Forest, which is the moist forest type associated with sheltered hillsides and moist gullies, and Sydney Sandstone Ridge top Woodland which is associated with dry plateaus and ridges.
The Sydney Sandstone Gully Forest occurs extensively around Kurrajong Heights and along creeks flowing southward to the Grose River. High rainfall and steep sheltered gorges foster the development of this vegetation association, as well as nutrient enrichment from shale soils or ridges. Changes in floristic and vegetation structure are related to increased moisture, shelter and soil fertility.
The Sydney Sandstone Ridge top Woodland is ubiquitous across the LGA, occurring in dry and exposed sandstone country. Variation also occurs within this association with regard to rainfall and soil texture, particularly changes in sand and clay content (Benson, 1992).
As for other areas of the Greater Sydney Metropolitan area, areas that are good agricultural land and/or easily utilised for urban development have been extensively cleared. Even where some canopy species remain the understorey and herbaceous layers have generally been removed by clearing and grazing. Those areas that represent a challenge in terms of development (due to flooding or steep topography etc) are those that retain significant areas of vegetation.
The Hawkesbury Local Government Area has had the advantage that urban development has been slow because of factors such as distance from the city so that some quite large discrete areas have been retained. These areas tend to be isolated in terms of proximity to other vegetation, especially the areas of Castlereagh and Agnes Banks woodland. There may be some potential for vegetation corridors.
Large areas of vegetation are generally under the management of NPWS in Blue Mountains National Park, Wollemi National Park, Yengo National Park and Cattai National Park.
For the purpose of vegetation management in natural areas, a weed is regarded as any non indigenous plant. Measures are to be implemented to control and manage existing and future processes leading to weed invasion and sources of weeds which are invasive of natural areas. An important element of weed control is an understanding the causes of weed invasion and taking measures to minimise these causes.
Weeds create management problems in that they have ongoing maintenance requirements, which remove scarce resources from other areas of management. They also make it difficult for the community to perceive a natural area as a viable land use where the land in question is weedy and overgrown.
There are two different areas of responsibility with regard to weeds, in that noxious weeds are dealt with by the Hawkesbury River County Council and environmental weeds are dealt with by contractors or day labour.
Weed control is implemented in such a way as to minimise negative environmental impacts. Different techniques are required in varying situations, especially along watercourses, which are very sensitive to pollution impacts. An important part of control is the regular monitoring of weeds in natural areas on an ongoing basis.
The Hawkesbury River County Council manages Noxious Weeds in the Hawkesbury LGA.
Impacts on wildlife and habitat need to be taken into consideration whenever any management activity is proposed (such as bushland regeneration, weed control, bushfire hazard reduction, recreation activities, etc)
The control of feral animals (foxes, wild dogs, feral cats, etc) may need to be undertaken within natural areas.
In addition, the use of natural areas for exercising or training of domestic animals (eg horses, dogs, cats, etc) is an activity which is incompatible with the protection and management of native fauna and habitat.
Management aims to take measures to prevent damage to life and property from bushfires, and to ensure that as far as possible, bushfire management is compatible with the other objectives of plans of management.
Bushfire hazard reduction shall be undertaken where there is an identified high hazard to improvements on the land or on surrounding land, but only in accordance with the guidelines as set out in the management plans. As far as possible, bushfire hazard reduction shall be by mechanical means and will be undertaken along property boundaries. Hazard reduction programs are to include an adequate environmental assessment and will be implemented in a manner which protects the biological diversity.
Where appropriate, specific parcels of community land will have a fire management plan prepared and adopted.
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