CONSERVING BIODIVERSITY AND THE RECOGNITION OF HETEROGENEITY IN ANCIENT LANDSCAPES - A CASE-STUDY FROM SOUTH-WESTERN AUSTRALIA

Subdued topographical relief is a conspicuous feature of the temperate High Rainfall Zone (HRZ) of Western Australia, where biotic assemblag es are dominated by regionally common eucalypt taxa. These two feature s have led to the perception of this area as a relatively homogeneous forest, and the establishment of broad-scale management regimes. Exami nation of the biota at a different scale reveals both exceptional land scape richness, and local endemism of vulnerable taxa. We consider pat terns of distribution of a range of the biota including widespread dom inants and local endemics. The ancient south-western landscape harbour s pockets of refugial habitat and relictual taxa that are dependent on fine-scale hydrological patterns persisting at a local level, These s ites are not always predictable from current knowledge of the biota. T his suggests a need to reconsider both conceptual frameworks, and cons ervation priorities in the temperate HRZ. The maintenance of microhabi tats that are dependent on moisture, and an even hydrological regime s hould be key features of management practice. The loss of heterogeneou s environments and the difficulty of reconstructing ecosystem function s in the nearby Transitional Rainfall Zone (TRZ) urges a pro-active ap proach in the prevention of ecosystem decline rather than post-hoc att empts at reconstruction. Thus the interactions between various agents of disturbance must be recognised, in conjunction with a cautious appr oach to management in the HRZ. Many elements, particularly local endem ics, will only survive if complex interactions between agents of distu rbance are recognised, and high value is placed on vulnerable, locally endemic taxa.