Reptiles and habitat fragmentation in the box-ironbark forests of central Victoria, Australia: predictions, compositional change and faunal nestedness

Abstract

There are few published accounts addressing the impact of habitat fragmentation on biodiversity of terrestrial reptiles. Here we provide information on the saurofaunas of fragments of box-ironbark forest of central Victoria, south-eastern Australia, gathered over three years. Data for fragments of four size classes (10 ha, 20 ha, 40 ha, 80 ha) are compared with similar information for 'reference areas', which are sites of the same range of areas but set within large blocks of continuous forest (>10,000 ha). These comparisons are used to differentiate fragmentation effects from normal species–area relationships. Two sets of data are presented. One is an 'extensive' set based on 68 fragments and reference areas surveyed by using transect counts and area searches. The other 'intensive' set also included pitfall trapping, but was restricted to just 17 fragments and reference areas. The reptilian fauna generally was both depauperate and of low abundance. Differences in capture-rates and species richness between fragments and reference areas collectively are minor, but there are significant differences in species richness between area classes. While fragmentation does not seem to be influential on total numbers and richness, there are important differences in the occurrence of certain species. The two most abundant species in reference areas were very rare in fragments, while a number of species were either in much greater numbers or only occurred in fragments. Many of the observed distributions were consistent with predictions made prior to the study on differences in vulnerability between species. We show that the saurofaunas are 'nested subsets' by area, with strongest nesting apparent in the intensive data-set for reference areas.