Effects of anthropogenic disturbances on ground beetle (Coleoptera, Carabidae) communities in Afromontane forests: a comparison between habitats with different levels of disturbance in Amani Nature Reserve, Tanzania.

Abstract

The family of ground beetles (Coleoptera, Carabidae) is one of the most species-rich coleopteran families. Ground beetles are good indicators of habitat disturbances, and could provide valuable information for sustainable management planning. Most studies are, however, restricted to temperate regions, even though tropical forests have the highest potential biodiversity loss. This study aimed to investigate effects of land-use change on the ground beetle communities in northeastern Tanzania. The study area was located in Amani Nature Reserve, a reserve that is situated in a biodiversity hotspot. The original tropical montane forest habitat in this reserve has been reduced due to historical logging activities. Currently, a few primary forest habitats coexist with several secondary forest habitats, plantation forests, and agroforestry land. Six sites, located in habitats with different disturbance degrees, were chosen: undisturbed forest, secondary forest that was moderately logged in the past, secondary forest that was heavily logged in the past, riverine secondary forest that was moderately logged in the past, an agroforestry habitat, and a recently logged part of the secondary forest that was heavily logged in the past. In total, 157 ground beetles, representing sixteen morphospecies, were collected during eight sampling weeks, using pitfall traps. The results of this study showed that all sampled sites had a significantly different ground beetle composition. An increasing ground beetle abundance was found with an increasing disturbance degree, while the species richness, species evenness, and the diversity decreased. The agroforestry site had a significant higher abundance compared to the undisturbed forest site, the moderately disturbed forest site, and the riverine forest site. The logging site had a significant higher abundance compared to the moderately disturbed, and the riverine forest site. No significant differences in observed species richness were found across the sampled sites.