Abstract ID: 3.11956 | Not reviewed | Requested as: Talk | TBA | TBA

Mountains are regions of high biological and cultural diversity, and the long-term conservation of these areas is a key strategy to improve biodiversity resilience to global warming. Mediterranean mountains are particularly vulnerable to the impacts of global change, and the whole Mediterranean is known to be a climatic hotspot. Some of the consequences of climate change challenge the mountain ecosystems of this region, such as the increase of summer droughts and the decrease of snow cover, both exacerbating water stress conditions. Understanding the ecophysiological responses to water availability of variables such as carbon dioxide exchange is critical to design conservation strategies for unfavourable scenarios. We evaluated the effects of soil water content on CO2 fluxes – net ecosystem exchange (NEE), ecosystem respiration (ER) and gross primary production (GPP) – in the high-altitude grasslands of the Levionaz valley in the Gran Paradiso National Park (GPNP) located in the Western Italian Alps. We compared flux responses to changes in soil water content by analyzing irrigated (IN) and non-irrigated (OUT) areas over three years with varying drought conditions (2022–2024). During 2022 the most severe drought event in the last 18 years was recorded, while wetter conditions characterized 2023 and 2024. Soil volumetric water content (VWC) was significantly higher in the irrigated plot on all measured dates and years, but carbon fluxes mean values showed no significant difference between plots in the wettest situations. Results from generalized linear mixed models (GLMMs) indicated different responses of ER and GPP to changes of soil water content. GPP was especially sensitive to VWC values, with a significant increase in sensitivity in the driest condition. We found that under drought stress, a relatively limited water input could maintain levels of CO2 fluxes equivalent to no stress periods, suggesting that low-intensity irrigation during droughts can be a valuable tool to sustain productivity, offering a conservation strategy to mitigate extreme drought impacts in key areas of high mountain grasslands.