Plant and litter influences on earthworm abundance and community structure in a tropical wet forest

Plant communities differ in species composition and litter input. To examine the influence of plant species on the abundance and community structure of soil fauna, we sampled earthworms in areas close to and away from the bases of Dacryodes excelsa and Heliconia caribaea, two distinct plant communities within a tropical wet forest in Puerto Rico. We also carried our a litter manipulation experiment to examine the short-term responses of earthworms to litter removal and litter addition treatments. We found that: (1) the density and biomass of both soil-feeding endogeic and litter-feeding anecic worms did not differ between areas close to and away from Dacryodes trees (in contrast, the density and biomass of anecic worms was higher in areas away from Heliconia plants despite the lack of differences for endogeic worms); and (2) total dry weight of earthworms tended to be higher in the litter addition treatment than in the control within the Heliconia community. Our results suggest that Heliconia caribaea has a strong negative influence on anecic earthworms and that earthworms in the Heliconia community are more sensitive to litter input than in the Dacryodes community.