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Agricultural expansion and logging are resulting in habitat degradation and fragmentation, especially in tropical regions. In Southeast Asia oil palm agriculture and commercial logging are the main threats to rainforest biodiversity, and I assessed the impacts of forest disturbance and land-use change on species composition and ecosystem functioning. I explored the role of the High Conservation Value (HCV) approach for biodiversity conservation in tropical agricultural landscapes and concluded that better knowledge exchange between scientists and HCV users is needed to improve biodiversity conservation in managed landscapes. I carried out a meta-analysis to examine the responses of birds, ants and beetles to the conversion of rainforest to oil palm which revealed that species in plantations were generally small-bodied species from lower trophic levels that had low abundances in forest. I collected new field data from Sabah(Malaysian Borneo) on dung beetle diversity and ecosystem functioning in undisturbed forest, selectively logged forest and forest fragments (5-3,529 ha). Dung beetle diversity was adversely affected by forest fragmentation, but not by selective logging. Larger fragments with better quality forest supported similar species assemblages to continuous forest, including functionally important dung beetle species. Dung removal, seed burial and seed dispersal were maintained in selectively logged forest, but were reduced by >50% in forest fragments. Dung removal in forest fragments was dependent on a few large, disturbance-tolerant species, which resulted in highly variable rates of functioning in fragments. Consistently high rates of dung removal and seed dispersal required high species richness as well as high biomass of dung beetles. Overall, forest fragmentation adversely affected diversity and ecosystem functioning, although fragments >100 ha maintained some dung beetle diversity and ecosystem functions. By contrast, degraded logged forest was functionally similar to undisturbed forest and thus should receive higher protection. |
