Long droughts decrease Caraboidea beta diversity and community body size in savannas of the Gorongosa National Park (Mozambique)

Abstract

In the aftermath of the 2019’ tropical cyclones Idai and Kenneth, we assessed the Caraboidea communities of Gorongosa National Park (GNP) in Mozambique. Influence of the wet season, after a long period of drought, was evaluated on alpha and beta diversity of Caraboidea in the main habitat types of the park: miombo forests, mixed forests, transitional forests, and grasslands (open savannas). Caraboid 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 seasons, particularly in grasslands. In contrast, dissimilarities in caraboid communities between seasons were not significant in the transitional forests. A higher proportion of xerophilous species, with smaller body size and higher dispersal ability (winged species) was found in grasslands whereas bigger sized and more moisture-dependent caraboid species were found in forested habitats, particularly mixed 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 forests species that may colonize the open areas in the wet season. Hygrophilous forest species will probably be more threatened by climate aridification and future landscape changes due to climate change.