Comparison of the abundance and composition of litter fauna in tropical and subalpine forests

Abstract

In this study, we quantify the abundance and composition of the litter fauna in dry and wet tropical forests and north- and south-facing subalpine forests. We used the same litter species contained in litterbags across study sites to standardize for substrate conditions, and a single method of fauna extraction from the litter (Tullgren method). Fauna densities were calculated per gram of dry litter. We found a higher density of total litter fauna and a higher taxonomic diversity in the tropical wet forest (80 individuals and 4 orders per g of dry litter and) as compared to the tropical dry (6 individuals and 1.5 orders per g of dry litter) and the subalpine forests (6–11 individuals and 2 orders per g of dry litter). Oribatid mites (Cryptostigmata) were the most abundant group of fauna across the study sites. The abundance of both micro- and macroinvertebrates was significantly higher in the tropical wet forest than all other sites. Taxonomic diversity (number of orders) was positively correlated with plant litter decomposition across all the sites. We conclude there is a significantly higher density of litter fauna and a greater taxonomic diversity per gram of litter in the tropical wet forest than in the tropical dry and the subalpine forests. Both of these factors can contribute to the differences in litter decomposition rates among the tropical and the subalpine sites.