Soil fauna and sustainable land use in the humid tropics

Abstract

It has been long claimed that soil fauna are key actors in sustainable land use. Long after Aristoteles caIled earthworms the 'intestine of the earth', Darwin (1881) said that'It maybedoubted whether there are manyotheranimals which have played so important a part in the history of tile world, as haue tflese lowly organized creatures'. Since that time, considerable efforts have been made to substantiate these statements and extend them to the whole soil fauna community. Their importance and role in energy cycling has been widely studied during the IBP Programme (Petersen and Luxton, 1982). These studies reinforced the feeling that they had significant impacts on major soil processes. During the last decade, considerable efforts have been made to describe and quantify these effects and assess the influence of land use on their communities (see e.g. Veeresh et al., 1991; Andren et al., 1988 and syntheses by Lee, 1985; Anderson and Flanagan, 1989; Lavelle et al., 1992b). . Processes whereby soil fauna may affect the dynamics of soil fertility have been described and quantified, mostly at the 'micro' and 'rneso' scales at which these organisms operate. These studies gave a clear understanding of the processes involved; none the less, the lack of experiments at the scale of a farmer's plot have not so far aIlowed the evaluation of the exact role of these processes, and the potential to manipulate them to improve soil fertility. This chapter gives an overview of the effects of land management practices on soil fauna communities in tropical soils. The effects of soil fauna on processes relevant to sustainability are discussed, and finally, recent results of manipulative experiments are presented.