Responses of ground-dwelling arthropods to long-term prescribed fire regimes in a savanna-protected area.

Abstract

In savanna ecosystems, fire is common, yet little is known on the direct and long-term effects of pre- scribed burns on arthropod abundance, richness, diversity, and composition. To understand the impact of fire on arthropods at Kruger National Park (KNP), standardized pitfall traps and active searches were used to collect arthropods at unburnt, annually burnt, and triennially burnt plots of the long-term experimen- tal burnt plots (EBPs). Abundance, richness, diversity, and assemblage composition of arthropods were compared across EBPs. Results showed that arthropods from the order Hymenoptera, particularly those in the family Formicidae, were the most abundant (76.4%), followed by Coleoptera (18.6%), Araneae (3%), Orthoptera (1%), and other small/less dominant orders (1%). However, the species richness of arthropods from Coleoptera was high (30.2%) compared with Formicidae (24.6%), Araneae (24.6%), and Orthoptera (4%). Abundance, richness, diversity, and assemblage composition of multitaxon and Formicidae were significantly different among EBPs. Although the abundance of multitaxon and Formicidae was signifi- cantly high at unburnt plot, species richness and diversity were low while the assemblage composition was unique at this plot compared with the annually and triennially burnt. Furthermore, the assemblage of arthropods in annually burnt EBP differed com pared with those collected at unburnt and triennially burnt EBPs. We conclude that the frequency of prescribed fires improves the richness, diversity, and as- semblage composition of arthropods with a significant reduction of abundances. Thus, fire can be used as a conservation tool for arthropods in the protected savanna of KNP.