Effect of livestock and vegetation structure on Carabidae (Coleoptera) diversity in dehesas of the Iberian Peninsula

The response of carabid beetles to extensive livestock farming and vegetation structure in two traditionally managed 'dehesa' ecosystems was investigated. From March 2011 to January 2012, sampling was done, using pitfall trapping, on two forestry farms located in the Sierra de Hornachuelos Natural Park (Crdoba, Spain), both with hunting use, but one of them also with a heavy livestock load. On each forestry farm, two sampling plots were selected according to the vegetation structure. Faunal differences were proved through the ecological indices, and the faunal uniqueness was checked by the Coldwell and Coddington Complementarity Analysis. To identify the most influential factor on the carabid biodiversity, a Generalised Linear Mixed Model (GLMM) was performed. Results show that abundance and richness are higher in the plots with open vegetation, similarly like the number of recorded tribes. Nevertheless, the ecological indices do not reflect any significant differences. The complementarity between different vegetation structures exceeds that of the exploitation types. In fact, the GLMM analysis indicated that the livestock itself does not have a significant effect on the fauna. In addition, all exclusive, rare or endemic species came from the closed vegetation plots, suggesting that these areas may act as a reservoir of unique species in terms of biodiversity.