LTREB Renewal: Biogeochemical Mechanisms of Response in the Third Decade of Whole-Ecosystem Experimental Manipulations at the Bear Brook Watershed in Maine (BBWM)

在缅因州的贝尔布鲁克流域进行了超过25年的研究，研究气候变化下大气中硫和氮沉积对森林、土壤和溪流径流的影响。每个分水岭都有一条源头。一个流域每两个月由直升机处理一次（模拟大气中的硫和氮沉积），另一个是未经处理的参考。该项目将支持第三个十年的研究，探索新的生态响应机制，这些机制只能通过长期的、几十年的研究来研究。这个项目更广泛的影响包括培养本科生和研究生。这项研究还提供了模拟空气污染物的化学处理对整个生态系统反应的直接证据，提供了受控实验室研究无法获得的结果。这项研究已经确定并验证了控制森林对硫和氮沉积反应的关键因素，并揭示了我们在理解上的主要差距，这些差距对于确定《清洁空气法》当前和未来的影响是否成功至关重要。社会对酸沉降、活性氮和气候变化对森林生态系统服务的影响的关注越来越重要。这项研究直接解决了今天和未来的这些信息需求。

Research at the Bear Brook Watershed in Maine has been conducted for more than 25 years on the effects of atmospheric sulfur and nitrogen deposition on forest, soils, and stream runoff, in a changing climate. Each watershed includes a headwater stream. One watershed is treated bimonthly by helicopter (simulating atmospheric sulfur and nitrogen deposition) and the other is an untreated reference. This project will support the third decade of research, which explores new ecological response mechanisms that can only be investigated by long-term, multi-decadal research. The broader impacts of this project include the training of undergraduate and graduate students. This research also provides direct evidence of whole-ecosystem responses to chemical treatments that simulate air pollutants, providing results not possible from controlled laboratory studies. This research has identified and verified key factors governing forest response to sulfur and nitrogen deposition, and revealed major gaps in our understanding that are critical to determining the success of current and future influences of the Clean Air Act. Societal concerns about the effects of acid deposition, reactive nitrogen, and climate change on forest ecosystem services grow increasingly important. This research directly addresses those information needs for today and the future.