Resolving the Dust Bowl paradox of grassland responses to extreme drought

作者：Alan K. Knapp, Anping Chen, Robert J. Griffin‐Nolan, Lauren E. Baur, Charles J. W. Carroll, Jesse E. Gray, Ava M. Hoffman, Xiran Li, Alison K. Post, Ingrid J. Slette, Scott L. Collins, Yiqi Luo, Melinda D. Smith · 发表于：Proceedings of the National Academy of Sciences · 年份：2020 · DOI：10.1073/pnas.1922030117 · 被引用次数：112 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Ecology and Vegetation Dynamics Studies

Significance During the Dust Bowl drought, central US grasslands responded unexpectedly to a decade of hot, dry conditions. Grass species adapted to high temperatures with higher water use efficiency (C 4 grasses) decreased, while those preferring cooler climates (C 3 grasses) increased. We reproduced this surprising response by experimentally imposing extreme drought in two native grasslands. Analysis of historical climate records revealed that during extreme drought years, the proportion of annual precipitation that occurs during cooler months increases. This previously unidentified shift in seasonal precipitation patterns during extreme drought years provides a mechanism for C 3 grasses to increase despite overall hot, dry conditions. Thus, alterations in precipitation seasonality may be as important as reduced precipitation amount when forecasting ecosystem responses to extreme drought.