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Title: Soil and litter fauna of cacao agroforestry systems in Bahia, Brazil

Author
item SILVA MOCO, M - State University Of North Fluminense
item GAMA-RODRIGUES, E - State University Of North Fluminense
item GAMA-RODRIGUES, A - State University Of North Fluminense
item MACHADO, V - State University Of North Fluminense
item Baligar, Virupax

Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2008
Publication Date: 1/1/2009
Citation: Silva Moco, M.K., Gama-Rodrigues, E.F., Gama-Rodrigues, A.C., Machado, V.C., Baligar, V.C. 2009. Soil and litter fauna of cacao agroforestry systems in Bahia, Brazil. Agroforestry Systems. 76:127-138.

Interpretive Summary: Soil microorganisms (soil fauna) are the key components of biological processes in the soil that transform organically-bound plant nutrients into inorganic plant-available forms. These microorganisms are also responsible for the formation of soil organic matter. Therefore, soil fauna are vital components of the soil and serve as potential indicators of soil quality. Experiments were conducted in the state of Bahia, Brazil to investigate the effects of various agroforestry systems on soil fauna activities and this was compared to their activities under natural forest. We found only small differences among various agroforestry systems and native forests. These findings suggest that cacao agroforestry systems offer similar environmental conditions to that under native forests. Furthermore, agroforestry systems appear to be an excellent alternative for the preservation of forests and sustainable management of degraded soils. These findings will be used by researchers, extension people and farmers in Brazil and will have an impact on the sustainable production of cacao for US consumers.

Technical Abstract: Agroforestry systems deposit great amounts of plant residues on soil; and eventually, this leads to high levels of soil organic matter content and has increased soil biodiversity and improved its conservation. This study compares the distribution of meso and macrofaunal communities in soil and litter under cacao agroforestry systems and in a natural forest in the southern Bahia state of Brazil. Soil and litter samples were obtained during September 2003 (winter), February 2004 (summer) and August 2004 (winter) in five cacao agroforestry systems. The systems evaluated included: cacao renewed under Erythrina sp. (Erythrina poeppigiana) (CRE); cacao renewed under natural forest (Cabruca - CRF); an old cacao system under Erythrina sp. (OCE); an old cacao system under a natural forest system (Cabruca - OCF) and a cacao germplasm collection area (CGC). As a reference soil and litter under a natural forest (NF) was included. Organisms were collected over a 15 day period with a Berlese–Tullgren apparatus. Small seasonal variations were observed in density and richness of soil and litter fauna. The average faunal density in the cacao agroforestry systems studied was 626 ind/m2 (soil) and 2235 ind/m2 (litter), and in natural forest faunal density was 713 ind/m2 (soil) and 1388 ind/m2 (litter). Overall, average richness of faunal richness was 7.5 (soil) and 11.8 (litter) in cacao agroforestry systems, and 7.7 (soil) and 11.5 (litter) in natural forest. Only small differences were observed in functional groups among various agroforestry systems and natural forest. Functional groups with larger faunal density included microbial grazers (Collembola) and social insects (majority Formicidae).