Abandoned croplands show higher insectivorous bat species and functional diversity than forest fragments in a communal land area of the Eastern Cape, South Africa

Deagrarianisation (cropland, field abandonment) is a widespread global phenomenon with high potential for carbon sequestration and for reversing biodiversity extinction debt thus promoting environmental sustainability and conservation. To date, much work on this topic has focused on plant succession and associated plant diversity, but few studies have considered faunal communities, particularly in Africa. Here we used passive acoustic monitoring to record insectivorous bat communities within forest fragments and former fields under communal land tenure in the Transkei region (Eastern Cape) of South Africa. Insectivorous bat diversity of fields, abandoned in the 1960s to 1980s, resembling late stages of succession, were compared to fragments of Transkei Coastal Scarp forest embedded within the landscape. We found that former fields hosted 14 species from 11 genera, comprising greater species richness, activity, Shannon-Weiner diversity, and functional diversity, irrespective of age, as compared to the forest fragments. Furthermore, the former fields exhibited comparable species richness to, and higher functional diversity than, three large neighbouring intact Transkei Scarp forests. Interestingly, the time since cultivation had ceased (35—64 years ago) had no measurable effect on species and functional diversity. Former fields are dominated by the invasive alien shrub Lantana camara and the indigenous pioneer tree Vachellia karoo , but nonetheless in terms of insectivorous bats, these landscapes have a conservation value as they are diverse both in terms of species and function. Mutual mechanisms to enhance both biodiversity conservation and the utility of the land to local communities should be further considered.