Changes of bat activity, species richness, diversity and community composition over an altitudinal gradient in the Soutpansberg range, South Africa

摘要

Bats are important indicator species which can help in identifying areas where conservation efforts should be concentrated and whether these areas are affected by ongoing climate change. To elucidate factors limiting and influencing the elevational distribution of bats in a recognised biodiversity hotpot, the Soutpansberg mountain range (in Vhembe Biosphere Reserve) of northern South Africa, we collected data in and around the Luvhondo Private Nature Reserve, by catching and acoustically monitoring bats over an altitudinal gradient from 900 to 1,748 m. A total of 18 different species could be recorded. Two species, namely Pipistrellus hesperidus and Chaerephon cf. ansorgei appeared to be present and dominant at all altitudes. Activity, species richness and diversity significantly decreased with increasing altitude, whereas community composition was not related to altitude and no endemics to either low or high altitude were detected. It is likely that the change of species richness and diversity over altitude is caused by other factors correlated with altitude such as vegetation type, area size, energy availability and climatic differences. Our research demonstrated that lower altitudes are richer and more diverse in bat species and since no highland endemics have been discovered, conservation efforts in the area, regarding bats, should not ignore these lower altitudes which are most susceptible to human impacts leading to habitat degradation due to over-grazing, bush encroachment, cultivation and denudation of large trees for firewood collection.