A survey of tropical earthworms : taxonomy, biogeography and environmental plasticity

A worldwide survey of earthworms in the humid tropics revealed that 51 exotics and 151 native species are commonly found in tropical agroecosystems. On the basis of frequency records and climatic and edaphic ranges, 21 exotics and 27 native species have been selected as possible candidates for manipulation. A multivariate analysis separated these species into four groups: (i) native species with wide edaphic and medium climatic tolerances; (ii) exotic species with wide climatic and edaphic tolerances; (iii) native and exotic species with narrow edaphic tolerances but more resistant to climatic variations; and (iv) native species with limited tolerance for climatic and edaphic variations. Regarding management, species of group (ii) seem to be the most adaptable. both at regional and locallevels (multipurpose species); group (i) can be managed for specific climatic conditions whereas group (iii) should be managed in specific soil environments. Species of group (iv) may only be managed at a very local scale.