Seasonality in the coleoptera community in two Caatinga phytophysiognomies

Abstract

Temporal variations in climatic conditions and trophic resources have strong influence on the abundance of insects in the xerophilous environments of Caatinga, being this tropical semiarid region characterized as having a long dry season and also a long rainy one. Two characteristic habitats in this region were investigated regarding the seasonal variation in the beetle’s fauna, near an evergreen riparian forest and at a deciduous xerophytic vegetation in Paraíba state, in northeastern Brazil. The aim of this study was to compare the seasonal variation in abundance, composition and richness of Coleoptera species in these two phytophysiognomies, evaluating possible evidences that mesic habitats serve, at least for some species, as refuges during the dry seasons. Weekly samples with malaise trap were carried out uninterruptedly in each area, during four years. There was a strong seasonal variation in the community of beetles in the xerophilous vegetation, with differences in the average number of individuals and species between rainy and dry season samples. However, no significant differences were recorded near the riparian forest. The species turnover was the component that contributed the most to beta diversity in both phytophysiognomies. The results regarding variation in richness and abundance of the species between dry and rainy seasons corroborate the previous evidences of the strong seasonality of the community of beetles in the Caatinga xerophilous vegetation, but the absence of such variation in the riparian forest is interpreted as an indicative of the importance of the mesic habitats as refuges during the dry season, at least for some species. Each species group must be studied in order to confirm the role of these areas in the population dynamics and in the permanence of active adult individuals during dry season.

Keywords:
Dry tropical forest; Mesic environments; Species richness; Abundance; Malaise