Soil Fungi and Macrofauna in the Neotropics
Decomposition is a critical ecosystem function that decomposes dead organic materials, removes wastes, recycles nutrients and renews soils fertility. In natural ecosystems most nitrogen (N) and phosphorus (P) required for plant growth are supplied through the decomposition of detritus, relying therefore on the activities of soil microbes and microfauna. Decomposition is a consequence of interacting physical and chemical processes occurring inside and outside of living organisms in an ecosystem (Chapin III et al. 2002). The two major processes include fragmentation, breaking larger pieces of organic mater into smaller ones, and chemical alteration, the change of chemical elements of dead organic mater into others. Fragmentation is largely a consequence of feeding activity of soil macrofauna and chemical alteration is primarily associated with the activity of bacteria and fungi. Land conversion from forests to pasture or agricultural land alters the belowground ecosystem and decomposition process, and depletion of soil organic C (Doran and Zeiss 2000). Degradation processes such as losses in soil C, nutrient depletion and reduced water holding capacity often lead to considerable change in soil microbial community and macrofauna (Bever et al. 1996, Picone 200, Thomas et al. 2004). In the Neotropics, land conversion from tropical forest to agricultural land and then pasture is the most common kind of land practices (Fearnside 1193, Thomlinson 1996, Cleveland et al. 2003). Studies of the dynamics of microbes and macrofauna following land conversion are thus particularly of importance for establishing effective strategies of post-agriculture recovery and forest ecosystem restoration because soil microbial community and soil macrofauna play a key role in successional pathways.