Drought conditions reorder plant communities through expansion of spatially sparse and temporally intermittent species

Authors: WATKINS, CARMEN - University Of Oregon; AGUIRRE, BEATRIZ - Cornell University; CHUNG, ANNY - University Of Georgia; BELL-DERESKE, LUKAS - Czech Academy Of Sciences; HALLETT, LAUREN - University Of Oregon; Hoover, David; GHERARDI, LAUREANO - University Of California Berkeley; DUDNEY, JOAN - University Of California Santa Barbara; WILCOTS, MEGAN - The Nature Conservancy; RUDGERS, JENNIFER - University Of New Mexico; SMITH, MELINDA - Colorado State University; ISBELL, FOREST - University Of Minnesota; FUKAMI, TAD - Stanford University; FARA, HANAN - University Of Minnesota; PORTALES-REYES, CRISTINA - St Louis University

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Droughts pose a significant threat to grasslands globally, and are increasing in frequency and intensity. There is uncertainty in how plant communities will respond to drought, but rare species are expected to be more vulnerable than more common species. We examined the responses of plant communities across six ecosystems in the US Great Plains to four years of experimental drought followed by a recovery period. We found that contrary to our predictions, rare species increased in abundance, while common species declined with drought. The responses of rare species to drought were consistent across the six sites and were related to plant traits. The rare species persisted even four years after drought, suggesting that multiyear droughts may have lasting impacts on grassland plant communities.

Technical Abstract: The frequency and severity of droughts are increasing in grasslands globally. Forecasting changes in community composition is challenging due to direct and indirect effects of drought as well as varied species ecologies. Rare species are typically assumed to be more susceptible to perturbations, but extreme drought may also disproportionately reduce more common species that are well-adapted to modal environmental conditions. Resolving these contrasting effects is key to predicting species re-ordering in response to extreme drought. We explored how species drought responses varied by their spatial and temporal abundances at six sites across a gradient of mean annual precipitation and found that in general both spatially sparse and temporally intermittent species responded positively during and after drought, while common and persistent species declined. Responses were similar at four of the six sites across a gradient of mean annual precipitation, but did not align with the precipitation gradient as expected. Instead, patterns depended on characteristics of common species such as life history and photosynthetic pathway. Finally, positive responses of rare species persisted for four years after experimental drought was lifted, suggesting that this extreme drought resulted in lasting shifts to community composition. This finding highlights the important role of rare species in maintaining productivity under extreme drought as well as the importance of assessing species recovery to periodic environmental disturbances.