Linear strips of rain forest vegetation as potential dispersal corridors for rain forest insects

The potential of linear strips of vegetation to act as corridors to facilitate dispersal is examined for three taxa of insects in lowland rain forest in northeastern Australia. The taxa selected were ants, butterflies, and dung beetles, all of which are taxonomically well known and could be considered bioindicator groups. The sampling design encompassed four habitats, namely rain-forest interior, rain-forest edge, rain-forest linear strip (corridor), and arable land. Ants and dung beetles were sampled using baited pitfall traps, and visual surveys were used to census butterflies. Potential increase in dispersal was examined by first identifying those species that specialized on the rain-forest interior habitat and then determining whether these species were present in the linear strips as opposed to the surrounding arable land. Two species of butterfly and two species of dung beetle were identified as rain-forest interior specialists, and two of these species were found in the linear strips but not in the arable habitat. The result supports the concept that the presence of corridors can increase the potential for dispersal of these species. But the remaining rain-forest interior species did not occur in the linear strips, which suggests that corridors will not increase dispersal for these species.