Drought intensity and duration interact to magnify losses in primary productivity

As droughts become longer and more intense, impacts on terrestrial primary productivity are expected to increase progressively. Yet, some ecosystems appear to acclimate to multiyear drought, with constant or diminishing reductions in productivity as drought duration increases. We quantified the combined effects of drought duration and intensity on aboveground productivity in 74 grasslands and shrublands distributed globally. Ecosystem acclimation with multiyear drought was observed overall, except when droughts were extreme (i.e., ≤1-in-100-year likelihood of occurrence). Productivity losses after four consecutive years of extreme drought increased by ~2.5-fold compared with those of the first year. These results portend a foundational shift in ecosystem behavior if drought duration and intensity increase, from maintenance of reduced functioning over time to progressive and profound losses of productivity when droughts are extreme.

Research support was provided by the following: National Science Foundation (NSF) Research Coordination Network grant to M.D.S. (DEB-1354732); US Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA) Postdoctoral Fellowship grant to K.D.W. (2020-67034-31898); USDA-NIFA Conference grant to M.D.S. (2020-67019-31757); US Geological Survey John Wesley Powell Center for Analysis and Synthesis grant to K.D.W. and M.D.S.; US Geological Survey grant to M.D.S. (G21AC10266-00); Global Drought Synthesis Group grant to K.D.W. and M.D.S., funded by the NSF Long-term Ecological Research Network Office (LNO) and the National Center for Ecological Analysis and Synthesis, University of California-Santa Barbara. T.O. acknowledges NSF funding (DEB-2224662, DEB-2340606, and DEB-1748133). Additional funding for specific experimental sites within this synthesis paper came from the USDA Forest Service Rocky Mountain Research Station and the USDA Agricultural Research Service; the findings and conclusions are those of the authors and should not be construed to represent any official USDA determination of policy. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Funding for soil analyses was provided by the Colorado Agricultural Experiment Station. Additional funding includes grants from the NSF Long Term Ecological Research (LTER) program (DEB-2423861 and DEB-2426143); funding from the NSF LTREB program to O.S. (DEB-2326482); USGS Ecosystems Mission Area; University of New Hampshire’s Agricultural Experiment Station; Natural Sciences and Engineering Research Council of Canada; Canadian Foundation for Innovation; and Federal Ministry of Education and Research (BMBF) grants 031B0516C and 031B1067C. The Ciempozuelos DroughtNet site was established with funds from the European Research Council (BIODESERT, ERC grant agreement no. 647038). F.T.M. acknowledges support from King Abdullah University of Science and Technology; A.C. acknowledges support from the US Department of Agriculture National Institute of Food and Agriculture (grant no. 2024-67019-42396); R.P.P. acknowledges support from the Department of Energy (DoE) Environmental System Science (ESS) program (award no. DE-SC0021980); and L.Y., L.B., and V.F.B. acknowledge support FONCyT (PICT 2019-02324), CONICET (PIP 11220210100681CO), and UBA. Additional funding was provided by National Key R&D Program of China (2022YFE0128000 and 2022YFF1300603) and the National Natural Science Foundation of China (32171592 and 32061123005); New Hampshire Agricultural Experiment Station (accessions 1003450 and 1013351), Iola Hubbard Climate Endowment; Department of Biology at Kansas State University and NSF LTER program to Kansas State University (DEB-144048); FWF (Austrian Science Fund, grant P22214-B17), ÖAW (Austrian Academy of Sciences) grant ClimLUC; Swedish Research Council grants 2013-06395 and 2019-04779, Formas grants 2015-10002 and 2023-00361; Federal Ministry of Education and Research (BMBF) grant 01LL1802C; grants from the US NSF LTER (DEB-1234162 and DEB-1831944); DOE Office of Science Early Career Award DE-SC0015898 and NSF Geography & Spatial Studies grant no. BCS-1437591 to D.F.C.; and German Research Foundation (DFG) grant no. DU1-1/1688. K.M.B. acknowledges support from US Bureau of Land Management (grant no. L16AS00178) and California State University Agricultural Research Institute (grant no. 18-06-004), N.E. acknowledges support of iDiv funded by the German Research Foundation (DFG-FZT 118, 202548816); A.C.G. and G.M.W. acknowledges support from Australian National Landcare Program: DigiFarm-A digitally enabled durable agroecosystem, Hermon Slade Foundation; A.H. acknowledges the John Fell Fund, Ecological Continuity Trust, and Patsy Wood Trust; G.L. acknowledges Programa Atração de Jovens Talentos, CAPES/Brasil; R.O. acknowledges Manitoba Beef and Forage Initiatives Inc. and Canadian Agricultural Partnership; D.C., G.P., and J.M.Z. acknowledge support from PI-UNRN 40-C-1226and PIP-CONICET 402; C.P.C. was supported by the French government IDEX-ISITE initiative 16-IDEX-0001 (CAP 20-25); J.M.P.G. was supported by a postdoctoral fellowship of IAI (CRN3005) and ANPCyT (PICT 2827); M.P.S. acknowledges support from SCRDC-AAFC; K.T. and L.v.d.B. were funded by the German Research Foundation (DFG) Priority Program SPP-1803 “EarthShape: Earth Surface Shaping by Biota” (TI 338/14-1) and ANID PIA/ACT 210038; and C.W. was supported by the China Huaneng Group Headquarters Technology Project (HNKJ22-H48). This work has benefited from the equipment and framework of the COMP-HUB and COMP-R Initiatives, funded by the “Departments of Excellence” program of the Italian Ministry for University and Research (MIUR, 2018-2022 and MUR, 2023-2027). Additional funding includes: the Gottfried Wilhelm Leibniz Prize (Ei 862/29-1); DFG Research Grant DU1-1/1688 to M.D.; Australian Research Council grants (DP150104199 and DP190101968); Norwegian Research Council project (255090); Strategic Environmental Research and Development Program RC18-1322; Natural Sciences and Engineering Research Council of Canada; Federal Ministry of Education and Research (BMBF) grants 01LC1821A, 01LC2321A, 01LL1802C, and 01LL1304D; National Key R&D Program of China (2021YFD2200405) and Sino-Europe Cooperation Project (2023YFE0105100); National Key R&D Program of China (2021YFD2200403) and Sino-Europe Cooperation Project (2023YFE0105100); Teshio Experimental Forest Forest Research Station, Hokkaido University, Japan; Federal Ministry of Education and Research (BMBF) grant 01LL1304D; Estonian Research Council (PRG1065) and the Centre of Excellence AgroCropFuture (TK200); the CredoJ and CredoM Drought-Net sites are part of the Great Western Woodlands TERN SuperSite, supported by the Australian Government and the Western Australian Department of Biodiversity, Conservation, and Attractions; Texas A&M Savanna Long-Term Research and Education Initiative (SLTREI), Sid-Kyle Foundation, and Sonora Research Station personnel; Key Projects of Jilin Province Science and Technology Development Plan (20230303006SF); Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA28110303); National Natural Science Foundation of China (32371669); the Science and Technology Talent Project Distinguished Young Scholars of Jilin Province (20240602009RC); National Natural Science Foundation of China (32071627); National Natural Science Foundation of China (31870456) and National Research Foundation grant no. 116262; Generalitat Valenciana, Project R2D–Responses to Desertification (CIPROM/2021/001); Stengl-Wyer Endowment at University of Texas, Austin; and Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, grants 149862 and 185110.We thank CONAF La Campana and the agricultural community Quebrada de Talca for the access to their sites. A.S.M. was supported by the Environment Research and Technology Development Fund (JPMEERF15S11420) of the Environmental Restoration and Conservation Agency of Japan, with additional field support from the Teshio Experimental Forest, Hokkaido University. Further support came from the Advanced Studies of Climate Change Projection Grant, Ministry of Education, Culture, Sports, Science and Technology, Japan (JPMXD0722678534).

Peer reviewed