Climate change limits aboveground primary production and exacerbates post-abandonment woody encroachment in mountain grasslands

Abstract Context Mountain grasslands support diverse plant communities and multiple ecosystem services, but they are increasingly threatened by changes in land use and climate. Understanding how they respond to these drivers is essential for their sustainable management and conservation. Objectives This study investigates the long-term (1984–2023) dynamics of aboveground primary production and its stability in response to climate and land-use change in mountain grasslands of the Spanish Pyrenees. Methods We analyzed the climate-NDVI relationships and assessed stability components (resistance, resilience and temporal stability) in three grasslands types: grazed subalpine, grazed alpine and abandoned subalpine grasslands. Results We found that the impacts of climate change on grassland primary production were modulated by land use. Specifically, climate change had a net negative effect on aboveground primary production in alpine and subalpine grazed grasslands, probably due to increased hydric stress, but a net positive effect in abandoned grasslands, possibly due to the lengthening of the growing season. Nevertheless, a long-term increase in primary production was observed across all grassland types, suggesting the pervasive effects of carbon and nitrogen fertilization and plant succession. Primary production in alpine grasslands showed resistance to precipitation variability, whereas subalpine grazed grasslands were highly sensitive to changes in temperature and precipitation. In abandoned grasslands, woody encroachment decoupled primary production from climatic drivers, leading to increased resistance and higher temporal stability, but reduced resilience. Conclusions Our results highlight the dual threat that climate change poses to managed mountain grasslands, hindering their productivity while exacerbating post-abandonment woody encroachment.