Fragmentation of a Small-mammal Community by a Powerline Corridor through Tropical Rainforest

Abstract

Trapping was used to investigate small-mammal community composition of a cleared powerline corridor compared with that of surrounding tropical rainforest in the wet tropics of north-eastern Queensland and to determine whether movements from the rainforest across the corridor were inhibited. The dense exotic grassland of the cleared powerline corridor supported a small-mammal community composed mainly of the grassland species Melomys burtoni (73·3%) and Rattus sordidus (15·0%) with rainforest small mammals being restricted to woody-weed thickets along the rainforest–powerline corridor edge. The rainforest species Rattus sp. (80·3%), Melomys cervinipes (10·9%) and Uromys caudimaculatus (8·8%) comprised the small-mammal community of the forest interior. These rainforest species also inhabited rainforest edge habitat and regrowth rainforest connections across gullies. Movements of rainforest species across the grassland corridor were almost completely inhibited even under bait inducement, a result attributable to the substantial structural and microclimatic habitat differences within the clearing and to interspecific competition with the better-adapted species of the grassland community. Rainforest species used regrowth connections along gullies to cross the powerline corridor. Mitigation of the fragmentation effects caused by powerline grassy swathes can best be achieved by strengthening extant canopy connections in regrowth gullies, and by establishing new connections across the clearings.