The spatiotemporal pattern of a tropical earthworm species assemblage and its relationship with soil structure: The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Abstract

The spatiotemporal pattern of a tropical earthworm assemblage (Lamto, Côte d'Ivoire) was assessed using a Partial Triadic Analysis (PTA). The abundance of earthworm species was estimated on five occasions covering two years within a single plot sampled with 100 sampling locations. The results showed that the earthworm community was highly structured in space and that the spatial pattern was stable through time. The Partial Triadic Analysis allowed extracting the earthworm community pattern that was common to all the dates. It was possible to identify which dates differed from the common model and which species were responsible for these discrepancies. The main pattern revealed by PTA was also submitted to spatial statistics to assess its significance. The results showed that the earthworm community is structured as a juxtaposition of patches dominated by different species. This pattern appeared to be constant during our 2-year study. When species were grouped following their impact upon soil structure dynamics the surveyed area appeared to be made of adjacent patches dominated either by compacting or decompacting earthworm species. The functional implications of this pattern are discussed and the spatial structure of the earthworm community was compared to soil bulk density distribution. The Mantel tests revealed a very strong relationship between soil bulk density and earthworm community structure.