Tropical grassy biomes are resilient to disturbances with which they evolved. Changing the nature of disturbances, e.g. replacing diverse herbivore communities with single domestic grazers, should change plant community structure and ecosystem functioning. Furthermore, projected future climate will increase the frequency and severity of drought events, which will intensify disturbances such as overgrazing. Understanding the combined effects of drought and herbivory on species diversity and function is important to inform restoration strategies. Forbs contribute most to herbaceous diversity in grassy biomes, although their contribution to resilience is poorly understood. In a drought-affected semi-arid savanna, we linked forb species and functional diversity across land-use types representing opposite herbivore diversity and intensity. Herbivore intensity significantly affected forb species, but not functional trait composition. Several forb species tolerated drought conditions at both sites, although only a few could maintain their dominance after drought release. Others were not recorded during the drought but responded significantly to drought release. Certain plant functional traits dominated during the drought but failed to persist after the drought. Drought-tolerant forb species and traits were limited and dissimilar across herbivore diversity and intensity sites. Our results suggest that species and functional traits are equally important for drought-tolerant forb communities, although the identification of species and traits suitable to understand the combined effects of herbivory and drought remains poorly understood, even in systems that evolved with such disturbances. Narrowing down the species and traits adapted to herbivory under increasing drought events, is believed to inform restoration attempts in dynamic semi-arid ecosystems.
Audio/Video, Conference Presentation, SER2019
Pre-approved for CECs under SER's CERP program
Society for Ecological Restoration