Co-occurrence of earthworms in Lamto savanna: A null model analysis of community structure

Diamonds assembly rules predict that competitive interaction leads to a non-random cooccurrence of patterns. Earthworms were sampled in three sites of vegetation of Lamto savanna to test the reducing level of co-occurrence of species among earthworm communities. Null model and spatial method were used as cokriging to generate patterns expected in the absence of species interactions. Three indices of null model showed that species co-occurrence in the three sites was less than expected by chance. Furthermore the cokriging revealed positive association between Stuhlmannia porifera and Chuniodrilus zielae and negative association between Millsonia omodeoi and the two other species. This study indicates that the non-random selection observed in the three sites of vegetation is due to an interaction between species close to the same ecological category.

► Spatial structure of the three earthworms species was opposite.
► The semivariance showed that the structure of earthworms species was distinct.
► Null model indices indicated that earthworms were randomly distributed.