The Effect of Habitat Utilization on Species-Area Curves: Implications for Optimal Reserve Area

The biological reserves in the wheatbelt of Western Australia form islands of native vegetation in a sea of arable farmland. Subdivision of the species in three vertebrate taxa (mammals, passerine birds and lizards) into species retained only in reserves (u species) and those also surviving outside the reserves in disturbed areas (d species) show conflicting requirements for reserve area. In each taxon u species are lost disproportionately with a reduction in area. The d species are favoured by more smaller reserves while u species, those most in need of conservation, are favoured by larger reserves.