Grassland ecosystems resilience to drought: The role of surface water ponds

Currently, grassland ecosystems' stability is facing severe challenges due to climate variability and the increased frequency and intensity of extreme droughts. In many grasslands worldwide, closed-basin ponds supply various ecosystem services by collecting rainfall and runoff. These ponds may provide a significant opportunity to mitigate climate change pressures and improve the resilience of grasslands. Nevertheless, their conservation is hampered by problems auditing these small and dynamic features. Understanding the dynamics that characterise the interactions of ponds and grassland vegetation with climate changes is, therefore, a priority for better quantifying future impacts of climate change on managed-land systems. This study investigated variations of grassland vegetation quality from 2001 to 2021 in Lessinia Regional Park, a pre-alpine historical rural landscape in northern Italy. We combined multi-source data, weather information, and satellite-derived vegetation quality indices. The work focuses the analysis using a 'pond landscape dominance' index, calculated as a proxy of hydrologic connectivity, to illustrate the function of ponds in regulating vegetation. We provided an unprecedented mapping of 459 ponds across the whole area. The results show a progressively decreasing vegetation quality in Lessinia, following rainfall and temperature variability. Overall, however, the analysis highlighted the benefit of water extent and closeness to ponds in providing higher resistance of grasslands against drought, especially during the driest study years. These results demonstrate that this approach has great potential for monitoring the resistance of grasslands in response to drought over large regions. This study supports the importance of identifying multiple co-benefits and ecosystem services related to ponds, which can help communities cope with climate change and environmental challenges.