Biodiversity boosts productivity most during extreme drought in drier grasslands

Biodiversity boosts productivity most during extreme drought in drier grasslands Gaby Clark Scientific Editor Andrew Zinin Chief Editor When extreme drought strikes, drier grasslands receive the greatest productivity benefit from biodiversity. By contrast, forests did not show the same context-dependent pattern under drought, according to a new global synthesis of 75 biodiversity experiments. Researchers from Yokohama National University published their results in Nature Ecology & Evolution on July 15. Biodiversity has been studied long before it received its catchy name, though fully exploring all it entails is a never-ending process. Other studies have established that biodiversity plays a significant role in an ecosystem's productivity. Less well known is where biodiversity matters most when climate extremes take their toll. "Our ultimate goal is to move away from a broad ecological insight to a practical basis for climate adaptation," said Takehiro Sasaki, professor of the Faculty of Environment and Information Sciences at Yokohama National University and first author of the study. With intense heat waves and droughts becoming more commonplace, this question has become crucial in climate science. A global synthesis of 75 biodiversity experiments sought to answer this question, along with whether these benefits persist, weaken or intensify during periods of drought or extreme heat and whether the benefits of biodiversity apply equally across different ecosystems. Drought sharpened differences in grasslands In more-arid grasslands, plant diversity had its strongest positive effect on productivity during years of extreme drought. This effect was driven mainly by stronger complementarity among species, consistent with species contributing in more functionally distinct and/or mutually supportive ways under water limitation. In less-arid grasslands, by contrast, drought was associated with stronger selection effects, indicating a greater contribution from a few highly productive species. Forests did not show comparable context dependence under extreme drought, although this does not mean that biodiversity is unimportant in forests. Heat extremes likewise did not produce clear context-dependent changes in biodiversity effects across ecosystem types or aridity gradients. Across both grasslands and forests, soil nutrient conditions did not detectably modify biodiversity effects under either drought or heat extremes, suggesting that water limitation may become a more important constraint on productivity than soil nutrient supply as climatic stress intensifies. How the global synthesis was built The study synthesized data from 75 biodiversity experiments in grasslands and forests spanning broad climatic gradients, with experiment durations ranging from 2 to 23 years. These data were linked to long-term daily precipitation and maximum-temperature records, as well as site-level aridity and soil data. The analysis assessed whether aridity and soil nutrient conditions modified biodiversity effects under drought and heat extremes. Results showed that biodiversity effects on productivity were strongest under extreme drought in drier grasslands, whereas forests showed no comparable context dependence under the same conditions. Gaps remain in forest evidence Further exploration is necessary to fully unpack where biodiversity will make the biggest difference when climate extremes hit. Researchers hope to improve their forest evidence by increasing study durations, developing more sensitive drought indicators for forest ecosystems and testing whether biodiversity effects are slower to emerge in forests than in grasslands. Examining tree health indicators and forest crown conditions years after extreme climatic anomalies might better indicate ecosystem health and the importance of forest biodiversity. Another goal of this research is to make the science more predictive for use in geographic blind spots in biodiversity experiments. This type of insight would help ecosystems better adapt to a warming climate and, ideally, make conservation efforts a top priority in preserving the varied environments present on this planet. Publication details Biodiversity effects under climate extremes intensify with aridity in grasslands but not forests, Nature Ecology & Evolution (2026). DOI: 10.1038/s41559-026-03130-1 Journal information: Nature Ecology & Evolution Key concepts biodiversityeffects of climate changebiological productivitydroughtsspecies diversityforest ecosystemsgrassland ecosystemslong-term ecological monitoringProvided by Yokohama National University