RII Track-4:NSF: Amplification of drought effects on vegetation by anthropogenic warming

RII Track-4：NSF：人为变暖对植被的干旱影响放大

• 批准号: 2131853
• 负责人: Matthew Dannenberg
• 金额: $ 22.05万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2131853&HistoricalAwards=false
• 关键词: RII; Track; NSF; Amplification; drought

Droughts are among the world’s costliest natural disasters, causing severe damage to both social and ecological systems. Human-caused warming increases the “dryness” of the atmosphere and, all other things being equal, increases evaporation rates from plant and soil surfaces, which in turn increases the loss of soil moisture and worsens naturally occurring precipitation deficits. Drought reduces the photosynthesis and productivity of plants, including in both natural and agricultural ecosystems, but the extent to which human-caused ecological change has amplified the effects of drought on plant productivity still remains unclear. This EPSCoR RII Track-4:NSF Fellowship will combine state-of-the-art satellite and ground-based plant observations with observed and modeled climate data to examine how much the past century of climate change has worsened drought effects on plants, focusing specifically on the relative contributions of natural- vs. human-caused effects during two recent severe droughts: the 2012-2015 California drought and the 2012 Midwest drought. The project will improve our understanding of the extent to which the effects of drought on Earth’s ecosystems are amplified by climate change, and it will also improve educational outcomes through training of a postdoctoral researcher and development of new climate change-related laboratory exercises for courses at the University of Iowa.Droughts are among the world’s costliest natural disasters, causing severe damage to both social and ecological systems. Anthropogenic warming exacerbates natural precipitation deficits through heat-induced increases in evaporative demand, which further dries soils and stresses vegetation. Anthropogenic increases in the frequency and severity of droughts likely exert large, but still poorly constrained, impacts on ecosystem function, including photosynthesis and growth of plants (“primary production”). While drought clearly reduces vegetation health and primary production, the relative contributions of natural variability and anthropogenic forcing remain unknown. Using the severe 2012-2015 California and 2012 Midwest droughts as case studies, this project will quantify the proportion of drought-induced primary production loss that was directly attributable to anthropogenic climate change, including attribution to specific climatic drivers (temperature, vapor pressure deficit, soil moisture, and solar radiation). The primary hypothesis of this proposal is that anthropogenic contributions to drought-induced loss of primary production were even greater than anthropogenic contributions to loss of soil moisture due to the direct negative effects of higher temperatures and evaporative demand on stomatal conductance and photosynthesis. This hypothesis will be tested using state-of-the-art remote sensing techniques (e.g., solar-induced chlorophyll fluorescence) and climate change attribution methods. The ultimate goal of this research is to develop an empirical “global change ecology” attribution framework that will be portable to other ecological systems and other impacts of climate change, including follow-up work focused on the effects of climate change on nationwide changes in primary production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

干旱是世界上代价最高的自然灾害之一，对社会和生态系统造成严重破坏。人类造成的气候变暖加剧了大气的“干燥”，在其他条件不变的情况下，增加了植物和土壤表面的蒸发速率，进而增加了土壤水分的流失，加剧了自然发生的降水不足。干旱降低了植物的光合作用和生产力，包括在自然和农业生态系统中，但人类造成的生态变化在多大程度上放大了干旱对植物生产力的影响仍不清楚。EPSCoR RII Track-4：NSF奖学金将把最先进的卫星和地面植物观测与观测和模拟的气候数据结合起来，研究过去一个世纪的气候变化在多大程度上加剧了植物的干旱影响，特别关注最近两次严重干旱：2012-2015年加州干旱和2012年中西部干旱期间，自然和人为造成的影响的相对贡献。该项目将提高我们对气候变化放大干旱对地球生态系统的影响程度的理解，还将通过培训一名博士后研究员和为爱荷华大学的课程开发与气候变化有关的新实验室练习来改善教育成果。干旱是世界上代价最高的自然灾害之一，对社会和生态系统都造成了严重破坏。人为变暖通过热量引起的蒸发需求的增加来加剧自然降水不足，从而进一步干旱土壤并对植被造成压力。人为增加的干旱频率和严重程度可能对生态系统功能产生重大影响，包括光合作用和植物生长(“初级生产”)，但影响仍然很小。虽然干旱明显降低了植被健康和初级生产力，但自然变异性和人为强迫的相对贡献仍不清楚。以2012-2015年加州和2012年中西部严重干旱为例，该项目将量化干旱造成的初级生产损失的比例，这些损失直接可归因于人为气候变化，包括特定气候驱动因素(温度、水汽压差、土壤水分和太阳辐射)。这一建议的基本假设是，由于高温和蒸发需求对气孔导度和光合作用的直接负面影响，人类对干旱导致的初级生产力损失的贡献甚至大于对土壤水分损失的人为贡献。这一假设将使用最先进的遥感技术(例如，太阳诱导的叶绿素荧光)和气候变化归因方法进行验证。这项研究的最终目标是开发一个可移植到其他生态系统和其他气候变化影响的经验性“全球变化生态”归因框架，包括关注气候变化对全国初级生产变化的影响的后续工作。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。