Positive impacts of rangeland abandonment on dung beetle functional diversity

We assessed the effect of rangeland abandonment on dung beetle biodiversity and functional diversity in an African semi-desert region. Dung beetles were sampled on farms that were abandoned either over 10 years ago, abandoned one year ago, or not abandoned. We sampled from tree dominant landscape features including dry riverbeds, flatlands, and hills. We hypothesised that rangeland abandonment would decrease dung beetle biodiversity and functional diversity, also testing whether this pattern holds true across the dominant landscape features. Preference experiments revealed that all dung beetle species preferred dung resources other than sheep dung. Contrary to expectations, dung beetle biodiversity and functional richness was higher on abandoned rangelands. The landscape features that were particularly significant in sustaining high dung beetle diversity and functional diversity in this ecosystem were the flatlands and dry riverbeds, the main corridors of movement of animals. We speculate that rangeland abandonment improved conditions for most dung beetle species, due to decreased pressures on remaining native mammal populations. Despite this, larger species that need greater dung resources for development became rare after abandonment. Reintroductions of native mammals should therefore be encouraged to promote dung beetle biodiversity and functional diversity in this semi-desert ecosystem. •Rangeland abandonment may affect dung beetle bio- and functional diversity.•This was evaluated in the overexploited African semi-desert Nama-Karoo biome.•Remarkably, bio- and functional diversity increased after rangeland abandonment.•This was likely driven by decreased pressures on native mammals on abandoned land.•Large beetle species became rare and native meso-herbivores should be reintroduced.