Functional diversity and stability of litter-invertebrate communities following land-use change in Sumatra, Indonesia

Abstract

Tropical land-use intensification is rapidly increasing in regions that harbour high levels of biodiversity, thus posing a serious threat to the stability and resilience of tropical ecosystems and the important ecosystem services that they provide. We compared functional group richness and functional dispersion in litter-invertebrate communities among four different land-use systems, ranging in intensity from primary degraded lowland forest to oil-palm agriculture in two landscapes on Sumatra, Indonesia. We then investigated the consequences for functional stability and community resilience by calculating functional redundancy and response diversity of sampled communities. From primary degraded forest to intensively managed oil-palm systems, we found a 46% decrease in species richness and a 48% reduction in density, but weaker effects on functional group richness and an increase in functional dispersion. Although we detected no significant alteration of response diversity, functional redundancy of litter-invertebrate communities decreased clearly by losing 37% of functionally redundant species due to land-use change. Our results indicate that land-use change, from tropical rainforest to oil-palm agriculture, can alter both taxonomic and functional diversity of litter-invertebrate communities, resulting in the loss of functional redundancy and thus functional stability of these ecosystems. However, we also show that land-use systems of intermediate management intensity, such as jungle-rubber agroforestry, could serve as reservoirs of functional diversity and stability in monoculture-dominated production landscapes.