Does habitat structure mediate the effects of forest fragmentation and human-induced disturbance on the abundance of Antechinus stuartii?

Abstract

Surveys were conducted among 30 remnants of differing size and degree of disturbance to examine the effects of forest fragmentation and human-induced disturbance on the abundance of a small, carnivorous marsupial, Antechinus stuartii. The underlying aim of the study was to evaluate the role of habitat structure in mediating the changes associated with fragmentation and anthropogenic disturbance on A. stuartii. The direct effects of remnant area and disturbance on the abundance of A. stuartii were marginal. Rather, the species responded more strongly to structural components of the remnant habitat, including understorey height and complexity, litter depth and the abundance of logs. In turn, these structural characteristics were, to some extent, influenced by the remnant size and the degree of remnant disturbance. The argument is therefore made that A. stuartii generally responded to area-dependent changes in habitat structure, rather than area per se, and that changes to habitat structure were the primary mechanism by which remnant area and disturbance regulated changes in the abundance of A. stuartii. It appears that A. stuartii may form a functional ‘metapopulation’ among the system of remnants at Tomago, New South Wales. The Tomago metapopulation may be responding to habitat structure across this heterogeneous landscape rather than being locally constrained within isolated remnants, as the theory of island biogeography might predict.