DISTINGUISHING AREA AND HABITAT HETEROGENEITY EFFECTS ON SPECIES RICHNESS - BIRDS IN VICTORIAN BULOKE REMNANTS

Resolving whether area per se or habitat heterogeneity has the greater influence in controlling species richness remains a controversial yet important question. Here we show that avian species richness of same- sized transects (1 ha) is independent of the remnant area (of buloke w oodland) within which a transect is positioned. We also show chat avif aunal similarity of pairs of transects randomly placed within the larg est remnants (greater than or equal to 48 ha) is not consistently rela ted to either proximity (i.e. being within the same remnant) nor to ph ysiognomic characteristics of the transects. We believe that much of t he controversy over area/habitat heterogeneity effects is probably rel ated to scalar issues and propose a protocol by which some resolution of the question might be reached. The protocol involves 'zoom' samplin g in which successively larger transect sizes are used, and measures o f faunal richness and habitat heterogeneity are made at these differen t grains of resolution. One of our intentions is to stimulate discussi on on how heterogeneity might be measured when grains increase from ty pical transect sizes (ca 1 ha) up to much larger grains (ca 128 ha).