Effects of tropical rainforest roads on small mammals: edge changes in community composition

In the wet tropics of north-eastern Queensland, the composition of the small-mammal community close to the edge of an unsealed rainforest road differed from that of the forest interior. During the first of two trapping series, mark-recapture trapping demonstrated that the abundance of Melomys cervinipes increased near the road and that significantly more Rattus sp. resided further from the road. At sites lacking canopy closure where the road clearing width measured 20 m, these edge effects were more noticeable than where canopy closure was maintained across narrower (12 m) clearings, with greater proportions of M. cervinipes occurring near wider clearing edges. During the second trapping series, edge effects also clearly occurred at the narrower clearings: M. cervinipes again preferred edge habitats and Rattus sp. preferred the forest interior. However, no significant effect of clearing width or distance from the edge for individual species was found during the second trapping series. The proportions of Rattus sp. and M. cervinipes had altered due to an influx of juvenile M. cervinipes into the trappable community during and after the breeding season, together with more individuals of Rattus sp. colonising the previously under-utilised habitat near the road. Edge avoidance by Rattus sp. appeared to be linked to preference for undisturbed habitat, while M. cervinipes was more of a generalist. Road verges with grassy habitat allowed the occasional intrusion of Rattus sordidus and Melomys burtoni - species alien to the rainforest.