Land Management Program

Our land management program focuses on managing the Hawkesbury’s natural areas through bushland regeneration and restoration. 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:-

  1. Cumberland Plain and associated ecosystems
  2. Hawkesbury Nepean River floodplain and associated ecosystems
  3. Hawkesbury sandstone and associated ecosystems.

These groups are briefly described below: -

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.

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, and excess nutrient which favours weed growth.

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).

Page ID: 162106

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