Relationships between invertebrate communities, litter quality and soil attributes under different cacao agroforestry systems in the south of Bahia, Brazil

This study was undertaken to investigate the relationship between soil and litter attributes to soil and litter fauna, and further to determine which of these attributes would be most significant in explaining the distribution of faunal communities in cacao agroforestry systems in the south of Bahia, Brazil. Soil and litter samples were collected in five cacao agroforestry systems: a cacao system renewed under Erythrina sp. (CRE); a cacao system renewed under natural forest (Cabruca-CRF); a cacao system under Erythrina sp. (CE); a cacao system under a natural forest system (Cabruca-CNF) and a cacao germplasm collection area (CGC). Soil and litter samples were also collected from natural forest (NF) near the agroforestry systems. The path analysis was used to evaluate the interdependencies among a set of variables including direct and indirect test effects that can be mediated by an intermediary variable. An average of 1367 (+/-126.5) individuals m(-2) and 10 (+/-0.3) taxa per sample were found under these areas. Soil attributes and litter quality under different cacao agroforestry systems affected the diversity of the soil and litter fauna, and these attributes are potential regulators of the fauna functional groups. The chemical components related to acidity, nutrition, and palatability are most decisive for abundant and diverse soil and litter fauna. Attributes which affected soil fauna in cacao agroforestry systems included mainly pH and bulk density in soil and polyphenols and lignin content in the litter. The faunal communities were more sensitive to litter quality than soil quality. Litter management could be a good practice to maintain healthy activities of the faunal community and to maintain improved ecosystem functioning in cacao agroforestry systems. (C) 2010 Elsevier B.V. All rights reserved.