Earthworm abundance and distribution pattern in contrasting plant communities within a tropical wet forest in Puerto Rico
Plant communities may impose strong control on soil fauna properties. We examined the abundance and distribution pattern of earthworms in two contrasting plant communities within a tropical wet forest in Puerto Rico. The Dacryodes community occurs in well-drained soils and is dominated by Dacryodes excels, Manilkara bidentata, Guarea guidonea, and Sloanea berteriana. The Heliconia community occurs in poorly-drained soils and is dominated by Heliconia caribaea and Prestoa montana. Earthworm biomass and density in Dacryodes community were twice those in the Heliconia community. Earthworm distribution was clumped in both communities, but was more aggregated in the Heliconia community. Soil pH in the Heliconia community was higher than in the Dacryodes community and correlated negatively with earthworm density after pooling the data from both communities. However, soil pH alone could not explain the observed differences in worm abundance and fresh biomass across the Luquillo Mountains. Soil water content in the Heliconia community was higher than in the Dacryodes community, but did not correlate with earthworm density or biomass. Forest litter biomass did not differ between the two communities. Pontoscolex corethrurus dominated the density and biomass of earthworms on both communities, and these data are comparable to other wet tropical regions. Our results indicate that variation in plant species composition and soil properties between plant communities can trigger differences in earthworm abundance and distribution pattern within a tropical wet forest.