ECOLOGY

Habitat values

Some Acacia communities serve as particular habitats. For example, in Victoria the Pink Robin (Petroica rodinogaster) breed in the damp shade of Acacia dealbata stands (Keast, Recher,Ford & Saunders 1985), while the Double Bar Finche (Peophilia bichenovii) has frequently been observed nesting in the dense prickly stands of Acacia paradoxa and A. triptera.

Acacias are particularly valuable in their natural habitat for the part they play in soil conservation and in stabilising sandy soils. It has been observed (Lavery 1978) that the clearing of mulga (Acacia aneura) scrub leads to an increase in termite activity following the invasion of grasses, and this in turn results in increased erosion during dry times. Similarly, the clearing of gidgee (Acacia cambagei) from some red brown earths has resulted in greater soil erosion (Cunningham, Mulham, Milthorpe & Leigh 1986). The augmentation of the soil nitrogen by acacias through the symbiosis with the nitrogen-fixing bacteria Rhizobium is substantially beneficial for other plants of the community, particularly in arid areas. For the establishment of native plant communities in arid areas, the prior establishment of Acacia aneura may be necessary to provide a ground mulch and nutrient source, and give shelter and protection to small plants, as well as to many of the native animals.

Acacia longifolia subsp. sophorae performs an important sand stabilising role on coastal foredunes, often growing as a distinct zone.

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