Impacts of rainforest logging on non-volant small mammal assemblages in Borneo

Abstract

As logging activity increases in tropical rainforests, it is crucial to better understand the extent to which changes in species assemblages and species interactions with the environment affect the function of rainforest ecosystems. The overall objective of this study was to determine how non-volant small mammal assemblages are affected by rainforest logging in the rainforest in Borneo: Do species diversity and assemblage variability of small mammals differ in undisturbed and logged rainforests? Do logging-induced habitat differences influence habitat use and movement trajectories? What are the characteristics of movement and ranging patterns of the rat Leopoldamys sabanus in different forest types? Do these trajectories differ at different scales? Do parasitic helminthes assemblages differ in small mammals? Are these helminth assemblages affected by logging? The study emphasizes the importance of local ecological interactions and within-habitat dynamics in contributing to the spatial dynamics of small mammal assemblages in dipterocarp rainforests. The variability in spatio-temporal habitat use within local assemblages and the large variability in individual movement patterns tended to be greater between sites than differences induced by logging, demonstrating the difficulty in predicting the effects of logging. The high level of forest heterogeneity in both forest types may help to explain the weak effects of logging on small mammal assemblages. The reduced species richness in logged forests clearly shows that some species are vulnerable to severe population reductions or extinction by logging-induced changes. The inconsistent responses of several small mammal species to logging with regard to movement trajectories and composition of parasitic helminth assemblages prevent general predictions about the effects of logging. It became clear with this study that multiple sets of environmental and intrinsic features unique to a species determine the outcomes of logging.