Manuele Bazzichetto, Marta Gaia Sperandii, Caterina Penone, Petr Keil, Eric Allan, Jan Lepš, Daniel Prati, Markus Fischer, Ralph Bolliger, Martin Gossner, Francesco de Bello

How different biodiversity components underpin ecosystem resistance and recovery and thus stability under extreme climatic events is a timely question in Ecology. To date, most studies have focused on the role of taxonomic diversity, neglecting how community functional composition and diversity beget stability under exceptional climatic conditions. In addition, land use potentially modulates how biodiversity and ecosystem functions respond to extreme climatic conditions. Using an 11-year time-series of plant biomass from 150 permanent grassland plots spanning a gradient of land-use intensity, we examined how different biodiversity components affected resistance and recovery of biomass production under extreme drought. The association between biodiversity, land use, and biomass production varied across years, especially in the driest years. Species rich and functionally diverse communities buffered extreme droughts better, while species poor communities dominated by fast-growing species had higher recovery capabilities after a moderate to extreme drought. Our results show that plant community functional and taxonomic components determine grasslands resistance and recovery under severe drought. In turn, this points to the importance of designing landscapes with both extensively and intensively managed grasslands. Functionally and taxonomically rich communities (favoured under low land-use intensity) would preserve biomass production under extreme droughts, whereas species-poor, fast-growing communities (favoured by high land-use intensity) would restore biomass production after extreme droughts.