Vegetation resistance to aridity thresholds depends on local environmental conditions in global drylands

Abstract

Abstract The crossing of specific aridity thresholds has been shown to trigger abrupt changes in multiple functional and structural ecosystem attributes across global drylands. While we understand the consequences associated with aridity thresholds, a significant knowledge gap remains concerning the key biotic and abiotic factors that influence the resistance of dryland vegetation when crossing them. Here, we used field observations from 55 dryland sites across six continents in combination with satellite remote sensing data from 2000–2022 to show that plant richness, precipitation dynamics, soil texture, and elevation are the most important variables contributing to dryland vegetation resistance when crossing aridity thresholds. Further, drought legacy, i.e., the frequency and magnitude of drought events in the years prior to crossing an aridity threshold, plays an important role in interaction with plant richness and soil texture. Interestingly, plant species richness was found to be negatively related to vegetation resistance, except at sites with moderate to high drought legacy, and in grasslands. Our results highlight that vegetation resistance depends on local environmental conditions and thus can vary within short distances. They also indicate that the use of global-scale gridded datasets for estimating vegetation resistance across larger geographic scales is challenging because of the limited quality and spatial resolution of available data for key biotic and abiotic modulator variables. Enhancing our comprehension of the factors important for vegetation resistance is an important step towards dryland conservation efforts and sustainable management strategies.