Trophic structure of a tropical soil- and litter-dwelling oribatid mite community and consistency of trophic niches across biomes.

The trophic positions of the most abundant soil- and litter-dwelling oribatid mite species in a tropical monsoon forest in Dong Nai (Cat Tien) National Park, southern Vietnam, were estimated using stable isotope analysis. Previously published data and Layman's metrics were used to compare the structure of the 'isotopic trophic niches' and the range of resources used by Oribatida in the tropical forest to those observed in temperate forests. The range of trophic levels occupied by oribatid mites, as reflected in their nitrogen isotopic compositions, did not differ between tropical and temperate forests. In contrast, the range of δC values of oribatid mites in the tropical community was smaller than that typically observed in temperate forests. This was due to the lack of C-enriched species with strongly calcified integuments. The diversity of trophic niches and the range of resources consumed did not differ between temperate and tropical communities of Oribatida. Moreover, similar δN values were observed for oribatid mite families across temperate and tropical ecosystems, suggesting that the taxonomic system of soil- and litter-dwelling Oribatida is ecologically consistent and supporting the 'taxonomic sufficiency' principle.