Landscape heterogeneity shapes taxonomic diversity of non-breeding birds across fragmented savanna landscapes

Abstract

There is an ongoing need to integrate agricultural production with wildlife conservation to maintain biodiversity, especially in developing countries. The landscape heterogeneity hypothesis identifies a potential means for promoting biodiversity in agricultural landscapes by emphasizing that increasing heterogeneity can increase biodiversity. However, the importance of landscape heterogeneity relative to habitat amount and vegetation structure is poorly understood, particularly regarding the relative importance of different components of landscape heterogeneity. We investigated how taxonomic, functional, and phylogenetic diversity of non-breeding birds responded to two components of landscape heterogeneity, compositional and configurational heterogeneity, and compared the importance of the landscape heterogeneity hypothesis relative to the habitat amount hypothesis and vegetation structural heterogeneity hypothesis. To do so, we conducted point counts at 80 plots across 16 landscapes during June–July 2016 in northeastern Swaziland, a sub-tropical savanna. We found a positive effect of landscape heterogeneity on taxonomic diversity, but no effect of habitat amount or vegetation structure. In contrast to taxonomic diversity, we found a positive trend between the amount of savanna habitat and phylogenetic diversity. In agricultural mosaics in subtropical savannas, conservation value may be created if landscape compositional heterogeneity, landscape configurational heterogeneity, and large areas of habitat are incorporated into land planning. Our findings show that it is important to use multiple measures of diversity in conjunction with various landscape and habitat measures when designing conservation management strategies.