Wild Herbivore Grazing Enhances Insect Diversity over Livestock Grazing in an African Grassland System

Abstract

Southern Africa’s grassland biodiversity is threatened by habitat transformation such as commercial forestry. Ecological networks (ENs) have been instigated to alleviate the pressure of habitat transformation on local biodiversity. ENs are large scale webs of corridors and patches of natural vegetation criss-crossing production landscapes that can simulate conditions in protected areas (PAs). Many ENs have lost many native large mammal species, which have been replaced by domestic livestock to retain natural grazing dynamics, which could have an impact on the long-term value of ENs for insects. Here we compared dung beetle, butterfly and grasshopper diversity in ENs across a landscape mosaic of timber plantations, where 1) wild megaherbivores were maintained, 2) in ENs where these herbivores were replaced by livestock and, 3) in a nearby World Heritage PA which retained its natural complement of megaherbivores. Sites in the PA far from any plantation were similar in composition to those in the wild grazed EN. Presence of the wild grazers improved the alpha- and beta-diversity of all focal insect taxa when compared to domestic grazing. Furthermore, species composition shows significant differences between the two grazing systems indicating that an assemblage of native large mammals facilitates insect diversity conservation. We support the maintenance or introduction of large native mammals in ENs or similar conservation areas in production landscapes to simulate the ecological conditions and natural heterogeneity in nearby PAs.

Primary productivity and habitat protection predict elevational species richness and community biomass of large mammals on Mt. Kilimanjaro

“…In addition, we expected the presence of domestic mammals to have a negative effect on wild mammals, either directly via competition for the same resources and space, or indirectly via the transmission of diseases (Pryke, Roets, & Samways, ). However, we found a positive effect of the community biomass of domestic mammals on the species richness of wild mammals.…”

Dung beetle diversity and functions suggest no major impacts of cattle grazing in the Brazilian Pantanal wetlands

“…The absence, and even the reduction, of grazing and/or the abandonment of previously grazed grasslands has been reported to negatively affect dung beetle communities in other regions (Tonelli et al, 2017;Numa et al, 2009;Verdú et al, 2007Verdú et al, , 2000Lobo et al, 2006). However, Pryke et al (2016) found higher dung beetle diversity in areas grazed by wild animals when compared with areas grazed by domestic animals in Africa. Dung beetles depend on the vertebrate fauna (Estrada et al, 1999), especially large mammals (Barlow et al, 2010), for their food resource, so differences among regions as to the impact of cattle grazing on dung beetle communities may result from differences in the diversity of wild herbivores.…”

Shrub encroachment is not always land degradation: Insights from ground‐dwelling beetle species niches along a shrub cover gradient in a semi‐arid Namibian savanna

“…In contrast to these vertebrate taxa with large home ranges, ground-dwelling beetles have been shown to be particularly sensitive to subtle habitat changes, even at local and small scales (Liu et al, 2016;Pryke, 2016). For example, tenebrionid diversity responded significantly to small spatial changes in plant diversity in a semi-arid, agricultural landscape in Israel (Yaacobi, Ziv, & Rosenzweig, 2007).…”