Collaborative LTREB Renewal: Long-Term Ecosystem Response to Chronic Atmospheric Nitrate Deposition

随着地球气候在下个世纪变暖，整个北半球的生态系统将暴露在大气氮(N)沉降率上升的环境中。理解这一复杂的环境变化是我们能够预测森林将在多大程度上从大气中隔离人类产生的二氧化碳的核心。一个跨学科的科学家团队将通过在北美东部常见的以糖枫为主的森林生态系统中进行长期、地区性的野外实验，来调查气候变暖和模拟的大气氮沉降之间的相互作用。在过去的18年里，模拟的大气氮沉降以预计到2050年发生的速度增加了树木的生长，减缓了枯叶和树根的腐烂，增加了这个广泛分布的生态系统中储存的碳量。然而，目前还不确定，随着大气氮沉积的增加，碳储存是否会在长期内达到更高的平衡，或者预期的变暖是否会抵消这一影响。这项拟议的研究将量化未来十年覆盖层树木、森林地面和土壤中储存的碳量，使这个科学家团队能够测试关于气候变暖和大气氮沉积对生态系统碳封存的相互作用的假说。利用美国国家科学基金会的支持，该团队将继续开展年度全球变化教师研究所。通过讲座和实地学习，初中和高中教师将继续发展对全球环境变化的原因和生态影响的理解，从而将这些信息纳入科学课程。

As the Earth's climate warms over the next century, ecosystems throughout the northern hemisphere will be exposed to elevated rates of atmospheric nitrogen (N) deposition. Understanding this complex environmental change lies at the heart of our ability to anticipate the degree to which forests will sequester human-produced carbon dioxide from the atmosphere. An interdisciplinary team of scientists will investigate the interaction between climate warming and simulated atmospheric N deposition using a long-term, regional-based, field experiment located in a sugar maple-dominated forest ecosystem common over eastern North America. During the past 18 years, simulated atmospheric nitrogen deposition at rates expected to occur by 2050 have increased tree growth and slowed the decay of dead leaves and roots, increasing the amount of carbon stored in this wide-spread ecosystem. However, it is uncertain whether carbon storage will attain a higher equilibrium over the long-term as atmospheric nitrogen deposition increases or whether expected warming will counteract this effect. The proposed research will quantify the amounts of carbon stored in overstory trees, forest floor and soil over the next decade, allowing this team of scientists to test hypotheses regarding the interaction of climate warming and atmospheric nitrogen deposition on ecosystem carbon sequestration.Using NSF support, this team will continue conducting the annual Global Change Teachers Institute. Through lectures and field-based learning, middle and high school teachers will continue to develop an understanding of the causes and ecological impacts of global environmental change, thereby bringing this information into science curricula.