Collaborative Research: Alternative leaf water use strategies in hot environments

合作研究：炎热环境下的替代叶水利用策略

• 批准号: 2140427
• 负责人: Kevin Hultine
• 金额: $ 64.33万
• 依托单位: Desert Botanical Garden
• 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: 2022-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2140427&HistoricalAwards=false
• 关键词: Collaborative; Research; Alternative; leaf; water

Heat waves are impairing global forest productivity, ecosystem biodiversity and crop yields. In hot environments where leaf functioning is vulnerable to high temperatures, plants must cool leaves to avoid heat damage. This cooling might occur even when plants cannot photosynthesize, which is counter to the commonly understood benefit to plants of using water. However, the prevalence of these alternative water use strategies remains unknown, despite the important implications they have for understanding local, regional and global carbon and water cycles. This project will quantify alternative water use behavior across a broad range of species to determine whether this prioritization of cooling over photosynthesis is common. In turn, results will improve efforts to model vegetation responses to heat waves and identify species that are potentially best suited to cope with heat stress. The project will contribute to the training of early career scientists, graduate students, and undergraduate students in modern plant and environmental science research. Public outreach will focus on developing an outdoor exhibit for the Desert Botanical Garden, a public facility that receives approximately 500K visitors per year. The bilingual display will demonstrate to visitors the physiological and societal costs of heat waves on plants and the ways in which plants regulate their temperatures.Episodic heat waves that are increasing in duration, frequency and intensity will likely amplify plant thermal stress and mortality. Therefore, plants occurring in hot environments must cool leaves below a critical threshold that can result in permanent leaf damage. Contrary to stomatal regulation models, transpiration can achieve this cooling independent of changes in photosynthesis when conditions are thermally stressful. Recent studies have reported such alternative water use strategies in several species, which then do not maximize carbon gain for a fixed level of stomatal conductance or hydraulic risk. This project combines tightly controlled leaf gas exchange measurements with experimental manipulation of environments, and a hierarchical modeling framework in order to (1) determine the prevalence of alternative water use strategies across a diverse set of species, (2) determine the traits that best predict this behavior, (3) develop optimality theory to predict under what environmental conditions this behavior should occur, and (4) validate predictions along a broad desert – montane elevation gradient. Results will advance theory for stomatal regulation, a core topic in the fields of plant ecology and Earth system modeling. It will also provide one of the largest and most standardized datasets for plant responses to extreme environmental conditions, yielding a data resource of high value to other investigators. These findings can then be used to directly inform a revised representation of plant water use in Earth System Models. This representation will ultimately yield more useful predictions under climate change scenarios.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.

热浪正在损害全球森林生产力、生态系统生物多样性和作物产量。在炎热的环境中，叶片功能容易受到高温的影响，植物必须冷却叶片以避免热损伤。即使植物不能进行光合作用，这种冷却也可能发生，这与通常理解的植物使用水的好处相反。然而，这些替代用水战略的普遍性仍然未知，尽管它们对理解地方、区域和全球碳和水循环具有重要意义。该项目将量化各种物种的替代用水行为，以确定冷却优先于光合作用是否普遍。反过来，研究结果将改善植被对热浪的反应模型，并确定可能最适合科普热应激的物种。该项目将有助于培养现代植物和环境科学研究的早期职业科学家、研究生和本科生。公共宣传将集中在沙漠植物园的户外展览，这是一个每年接待约50万游客的公共设施。展览将以双语向参观者展示热浪对植物的生理和社会影响，以及植物调节温度的方式。持续时间、频率和强度不断增加的间歇性热浪可能会加剧植物的热胁迫和死亡率。因此，在炎热环境中生长的植物必须将叶子冷却到临界阈值以下，这可能导致永久性的叶子损伤。与气孔调节模型相反，蒸腾作用可以在热胁迫条件下独立于光合作用的变化实现这种冷却。最近的研究报告了几个物种的这种替代用水策略，然后没有最大限度地增加碳的固定水平的气孔导度或水力风险。该项目将严格控制的叶片气体交换测量与环境的实验操作和分层建模框架相结合，以便（1）确定不同物种的替代用水策略的普遍性，（2）确定最能预测这种行为的特征，（3）发展最优性理论来预测这种行为在什么环境条件下应该发生，（4）沿沿着广阔的沙漠-山地海拔梯度验证预测。结果将推进气孔调节理论，这是植物生态学和地球系统建模领域的核心课题。它还将为植物对极端环境条件的反应提供最大和最标准化的数据集之一，为其他研究人员提供高价值的数据资源。然后，这些发现可以用来直接通知地球系统模型中植物用水的修订表示。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。