Conserved responses of nutrient resorption to extreme drought in a grassland: The role of community compositional changes

The frequency, duration and magnitude of drought are projected to increase in the next few decades, with consequences for community composition and nutrient utilization of plants. Nutrient resorption, a process facilitating plant nutrient conservation, is a crucial driver for ecosystem nutrient cycling. It remains unknown how would extreme drought affect nutrient resorption of plant communities through changing community composition. We examined the contributions of different processes (richness and identity effect of species losses and species gains, as well as the context dependent effect) related with community compositional changes to the alterations of community-level nutrient resorption efficiency after 4-year treatments of chronic drought (66% rainfall reduction from May to August) and intense drought (100% rainfall reduction in June and July) in a temperate steppe in Hulun Buir, Inner Mongolia, China. Both chronic and intense drought significantly reduced nutrient resorption efficiency in most of the common species, but did not affect that at the community level. Drought-induced losses of species made positive contribution to the community-level nutrient resorption, as they generally had lower nutrient resorption efficiency. Such positive contribution balanced the negative effect of drought on the nutrient resorption of the common species. Our results indicate that drought-induced changes in community composition, especially those species being lost, were important in mediating the community-level responses of nutrient resorption to extreme drought in grasslands. Read the free Plain Language Summary for this article on the Journal blog.