School of Biology and Ecology, University of Maine, Orono, ME 04473-5722, USA.
Environ Monit Assess. 2010 Dec;171(1-4):83-92. doi: 10.1007/s10661-010-1532-2. Epub 2010 Jun 10.
The Bear Brook Watershed in Maine (BBWM) is a long-term, paired watershed experiment that addresses the effects of acid and nitrogen (N) deposition on whole watersheds. To examine stream response at BBWM, we synthesized data on organic matter dynamics, including leaf breakdown rates, organic matter inputs and standing stocks, macroinvertebrate secondary production, and nutrient uptake in treated and reference streams at the BBWM. While N concentrations in stream water and leaves have increased, the input, standing stocks, and breakdown rates of leaves, as well as macroinvertebrate production, were not responsive to acid and N deposition. Both chronic and acute increases of N availability have saturated uptake of nitrate in the streams. Recent experimental increases in phosphorus (P) availability enhanced stream capacity to take up nitrate and altered the character of N saturation. These results show how the interactive effects of multiple factors, including environmental flow regime, acidification, and P availability, may constrain stream response to chronic N deposition.
美国缅因州的熊溪流域（BBWM）是一个长期的、配对的流域实验，旨在研究酸沉降和氮（N）沉降对整个流域的影响。为了研究 BBWM 的溪流响应，我们综合了有关有机物质动态的资料，包括叶片分解率、有机物质输入和储量、大型无脊椎动物的次级生产以及处理和参照溪流中的养分吸收。虽然溪流水中和叶片中的 N 浓度增加了，但叶片的输入、储量和分解率以及大型无脊椎动物的生产对酸和 N 沉降并没有反应。慢性和急性增加的 N 供应已经使溪流中的硝酸盐吸收饱和。最近增加的磷（P）供应增强了溪流吸收硝酸盐的能力，并改变了 N 饱和的特征。这些结果表明，多种因素的相互作用，包括环境水流模式、酸化和 P 供应，可能会限制溪流对慢性 N 沉降的响应。
