Converting forests to agriculture decreases body size of Carabid assemblages in Zambia

Body size affects both intraspecific and interspecific competition. Land‐use affects such interactions within assemblages of species and should, therefore, also change the size structure of these assemblages. In particular one expects a decrease of mean body size with disturbances. We compared interspecific size structure of carabid assemblages between agricultural fields (frequent disturbances) and forests in Zambia using pitfall traps operated across 1 year. Mean body length across species co‐occurring within sites in agricultural fields was significantly smaller than in natural forests. Furthermore, in both habitats, we found evidence for ecological clustering in respect to body size, although in forests, body size differences between adjacent‐sized species tended to be overdispersed. We also found a positive relationship between log₁₀‐transformed body length and log₁₀‐transformed activity abundance in forests, suggesting competitive asymmetries between large and small species. Overall, these observations suggest that the size structure of carabid assemblages depends on disturbances as well as competitive interactions. Such interactions seem to be, however, of lower importance within agricultural fields.