Long droughts decrease tiger- and ground-beetle’ beta diversity and community body size in savannas of the Gorongosa National Park (Mozambique)

Abstract

We assessed the Caraboidea communities of Gorongosa National Park (GNP) in Mozambique. Influence of tropical rainfall, after a long period of drought, was evaluated on alpha and beta diversity of tiger- and ground-beetles in the main habitat types of the park: miombo forests, mixed forests, transitional forests, and grasslands (open savannas). Tiger- and ground-beetle communities were sampled by pitfall traps set up in 25 sites of each habitat type along three sampling periods, comprising the transition of dry season to the wet season. After the first rainfall, an increase in alpha diversity was observed across GNP habitats, particularly in grasslands. Higher values of beta diversity were observed between the dry and wet sampling periods, particularly in grasslands. In contrast, community dissimilarities between sampling periods were not significant in the transitional forests. Community body size in grasslands increased after the rainfall, partly due to the occurrence of caraboid species that were exclusive of forest habitats during drought. Transitional forests, as ecotone habitat areas, appeared to support grassland species during drought, serving also as a source of forest species that may colonize the open areas in the wet season. Forest species will probably be more threatened by climate aridification and future landscape changes due to climate change.