CAREER: A network-oriented research and education plan to explore links between forest cover and temperature in the eastern United States

职业：一项面向网络的研究和教育计划，旨在探索美国东部森林覆盖率与温度之间的联系

• 批准号: 1552747
• 负责人: Kimberly Novick
• 金额: $ 75.14万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1552747&HistoricalAwards=false
• 关键词: CAREER; network; oriented; research; education

While the vast majority of the surface of the earth has warmed over the past century, in much of the eastern United States the air temperature has failed to rise or has even declined. At the same time, forest cover over the region has increased dramatically, driven by abandonment of poor quality agricultural lands. This project will test the hypothesis that reforestation in the eastern U.S. provides the explanation, in that it affects the surface energy balance in ways that lead to cooling and thus obscures long-term warming from climate change. Just as human bodies are cooled by sweating or by a fan, forests may be cooled by greater rates of evapotranspiration and wind-driven movement of heat energy when compared to the croplands and grasslands they have replaced. Looking forward, the rate of reforestation will decline over time as available space is filled, but the types of trees that fill in naturally or are planted will likely change. Notably, drought-tolerant oaks are currently declining, while drought-sensitive maples and pines are proliferating. So this work will also test a second hypothesis that ongoing regional shifts in tree species promote a reduction in evapotranspiration, particularly during periods of drought, that will tend to warm the surface. The research will inform the development of sustainable agro-ecosystem management strategies that mitigate damaging effects of drought on ecosystem productivity and function. A series of workshops will be developed, along with a citizen science program aimed at training young scientists in effective approaches for leveraging and analyzing network data.The research will be enabled by interactions with a range of environmental observation networks, which aggregate meteorological and ecological observations from many ecosystems and thereby enable a big data approach to environmental science. Project outcomes are relevant to ongoing modelling efforts to reproduce historic climate trends and predict future conditions with more confidence. This work will advance network-driven environmental science by generating a rich collection of leaf- to ecosystem scale observations that will be shared with existing networks. The research is motivated by the recognition that, within the study region, ongoing management activities are driving a transition from forests dominated by species that are more anisohydric in their water use to forests dominated by more isohydric species. The concept of isohydry has received much attention in recent years, and this project will advance this body of knowledge by classifying important eastern U.S. species along the isohydric-anisohydric continuum, and developing a model for stomatal conductance that incorporates the isohydric-anisohydric framework. While this project is focused on ecosystem energy balance, the project outcomes will also be relevant for efforts to understand regional carbon and water cycling, and for the development of forest management strategies that mitigate deleterious effects of drought on ecosystem functioning

虽然地球表面的绝大多数地区在过去一个世纪里变暖了，但在美国东部的大部分地区，气温没有上升，甚至下降了。与此同时，由于放弃了质量较差的农田，该地区的森林覆盖率大幅增加。这个项目将检验这样一种假设，即美国东部的重新造林提供了解释，因为它影响了地表能量平衡，导致气温下降，从而掩盖了气候变化对长期变暖的影响。就像人体通过汗水或风扇降温一样，与被它们取代的农田和草原相比，森林可能会通过更高的蒸散率和风力驱动的热能运动来降温。展望未来，随着可用空间的填满，重新造林的速度将随着时间的推移而下降，但自然填充或种植的树木类型可能会发生变化。值得注意的是，耐旱橡树目前正在衰落，而对干旱敏感的枫树和松树却在激增。因此，这项工作还将检验第二个假设，即树种正在进行的地区性变化促进了蒸散的减少，特别是在干旱时期，这将倾向于使地表变暖。这项研究将为制定可持续的农业生态系统管理战略提供信息，以减轻干旱对生态系统生产力和功能的破坏性影响。将开展一系列研讨会，以及旨在培训年轻科学家有效利用和分析网络数据的公民科学计划。这项研究将通过与一系列环境观测网络的互动来实现，这些网络汇集了来自许多生态系统的气象和生态观测，从而使环境科学的大数据方法成为可能。项目成果与正在进行的模拟工作有关，这些工作旨在更有信心地再现历史气候趋势和预测未来条件。这项工作将通过产生丰富的从树叶到生态系统尺度的观测来推动网络驱动的环境科学，这些观测将与现有的网络共享。这项研究的动机是认识到，在研究区域内，正在进行的管理活动正在推动从以用水更加各向异性的物种为主的森林向以更多等水物种为主的森林过渡。等湿的概念近年来受到了很大的关注，这个项目将通过沿着等湿-各向异性连续体对美国东部的重要物种进行分类，并开发一个包含等湿-各向异性框架的气孔导度模型来推进这一知识体系。虽然该项目的重点是生态系统能量平衡，但项目成果也将与了解区域碳和水循环的努力有关，并有助于制定森林管理战略，以减轻干旱对生态系统功能的有害影响。