Department of Plant, Soil, and Environmental Science, University of Maine, 5722 Deering Hall, Orono, ME, 04469, USA.
Environ Monit Assess. 2010 Dec;171(1-4):149-61. doi: 10.1007/s10661-010-1524-2. Epub 2010 Jun 11.
The Bear Brook Watershed in Maine (BBWM), USA, and the Fernow Experimental Forest in West Virginia, USA, represent unique, long-term, paired, whole watershed, experimental manipulations focusing on the effects of nitrogen (N) and sulfur (S) deposition on temperate forests. Both watersheds began whole-ecosystem additions of N and S as (NH(4))(2)SO(4) in the fall of 1989, and both are entering their third decade of chronic enrichment of the treated watersheds, while the reference watersheds offer unique opportunities to evaluate forest watershed responses to recovery. Differences between BBWM and Fernow in the history of atmospheric deposition, soil properties, and forest composition all contribute to different response trajectories in stream chemical exports over time. The four watersheds represent a spectrum of N enrichment and retention, ranging from ≈98% N retention in the reference watershed in Maine, to ≈20% N retention in the treated watershed in West Virginia. Despite these differences, there is evidence that mechanisms of response in base cation leaching and other processes are similar among all four watersheds. In both cases, the history to date of two decades of research and monitoring has provided new insights into ecosystem response not evident in more traditional short-term research.
美国缅因州的熊溪流域（BBWM）和西弗吉尼亚州的费恩诺实验林是两个独特的、长期的、配对的、全流域的实验性操作，重点研究氮（N）和硫（S）沉积对温带森林的影响。这两个流域都在 1989 年秋季开始对整个生态系统进行 N 和 S 的添加，添加物为（NH4）2SO4，目前都已进入处理流域的慢性富营养化的第三个十年，而对照流域则为评估森林流域对恢复的响应提供了独特的机会。BBWM 和 Fernow 在大气沉积历史、土壤特性和森林组成方面的差异，都导致了随时间推移溪流化学输出的不同响应轨迹。这四个流域代表了氮素富集和保留的范围，从缅因州对照流域中约 98%的 N 保留到西弗吉尼亚州处理流域中约 20%的 N 保留。尽管存在这些差异，但有证据表明，基础阳离子淋溶和其他过程的响应机制在所有四个流域中是相似的。在这两种情况下，迄今为止二十年的研究和监测历史为生态系统响应提供了新的见解，这些见解在更传统的短期研究中并不明显。
