High trait diversity among soil arthropods allows their survival in a heterogeneous eco-agricultural mosaic

Abstract

Studies examining changes in functional diversity and trait composition for soil arthropods are limited yet crucial for understanding the effects of land-use change. To determine whether plantation forestry drives functional homogenization of soil biota, we compared the taxonomic and functional diversity of ants and springtails between natural (indigenous forests and grasslands) and transformed (Eucalyptus plantations) biotopes. The prevalence of morphological and ecological traits in natural vs. transformed biotopes was also assessed. The study was conducted in two environmentally contrasting regions: high elevation areas with clay soils and coastal areas with sandy soils, in KwaZulu-Natal, South Africa. Surprisingly, the Eucalyptus compartments generally had similar levels of taxonomic and functional diversity as indigenous forests and/or grasslands. However, there were shifts in traits between the three biotopes, with each biotope supporting arthropods with traits suited to the environmental conditions in the biotope. Some traits were representative of the natural biotopes, and others of the plantation compartments. As a functionally diverse component of soil biodiversity is present in the plantations, it is indicative that these plantations have seemingly high levels of ecosystem stability and functioning. Arthropod traits compatible with the different environments appear to allow them to persist in high diversity across the landscape mosaic. These results suggest that enhancing landscape heterogeneity in a production landscape increases taxonomic and functional diversity of soil arthropods by creating a large-scale, spatial mosaic of complementary conditions for species with different habitat requirements.