Chaco forest fragmentation effects on leaf litter decomposition are not explained by changes in litter fauna

Abstract

Forest fragmentation is a component of global change, with substantial impact on biodiversity and ecosystem functioning. Despite extensive evidence of forest fragmentation effects on aboveground ecological processes, little is understood about its belowground effects. Abundance and richness of leaf litter fauna can be affected by forest fragmentation and this can have cascading effects on the decomposition process. Here, we examine how fragmentation of a subtropical dry forest affects aspects of ecosystem structure and functioning, by unravel area and edge effects on leaf litter fauna and decomposition rates and testing whether changes in abundance or richness litter fauna mediated fragment area and edge effects on litter decomposition. We incubated litterbags filled with a common substrate, at the edge and interior of 12 fragments of Chaco Serrano forest in Central Argentina, for 180 days. We found that invertebrate abundance was higher at the forest edge but independent of fragment area, whereas decomposition declined with fragment size independently of edge or interior location. According to our results, the effect of forest size on decomposition was not mediated by changes in abundance or richness of leaf litter fauna, suggesting independent changes in ecosystem structure and functioning.