2024-01-29 カリフォルニア大学サンタバーバラ校(UCSB)
◆この国際的な乾燥実験（IDE）は、1年間の極端な干ばつが世界中の草原と低木地帯の植生生産性をほぼ40％減少させる可能性があることを示しました。これらの生態系が占める地球表面の40％に及ぶ範囲での植物生産性の損失は、過去に報告されたものを大きく上回ります。これにより、気候変動の影響や将来のストレスが最も顕著な地域が明らかになりました。
＜関連情報＞
- https://news.ucsb.edu/2024/021337/extreme-drought-hits-grasslands-and-shrublands-harder-anticipated
- https://www.pnas.org/doi/10.1073/pnas.2309881120#:~:text=This%20drought%2Dinduced%20loss%20in,severity%20have%20been%20substantially%20underestimated.
極端な干ばつによる草原や低木林への影響は、世界的に過小評価されている Extreme drought impacts have been underestimated in grasslands and shrublands globally
Melinda D. Smith, Kate D. Wilkins, Martin C. Holdrege, +169, and Xiaoan Zuo
Proceedings of the National Academy of Sciences Published:January 8, 2024
DOI:https://doi.org/10.1073/pnas.2309881120
Significance
Drought has well-documented societal and economic consequences. Climate change is expected to intensify drought to even more extreme levels, but because such droughts have been historically rare, their impact on ecosystem functioning is not well known. We experimentally imposed the most frequent type of intensified drought—one that is ~1 y in duration—at 100 grassland and shrubland sites distributed across six continents. We found that loss of aboveground plant growth, a key measure of ecosystem function, was 60% greater when short-term drought was extreme (≤1-in-100-y historical occurrence). This drought-induced loss in function greatly exceeds previously reported losses for grasslands and shrublands, suggesting that the global impacts of projected increases in drought severity have been substantially underestimated.
Abstract
Climate change is increasing the frequency and severity of short-term (~1 y) drought events—the most common duration of drought—globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function—aboveground net primary production (ANPP)—was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought.
