SGER: Biogeochemical Response Mechanisms Controlling Nitrogen Export from Defoliated Forests in the Eastern US

EshlemanSGER：控制美国东部落叶森林氮素输出的生物地球化学反应机制昆虫落叶森林中溶解氮(N)的过量泄漏会对小的酸敏感溪流以及下游水域(如切萨皮克湾)造成水质影响。受控实验室实验已经对这些机制有了一些了解，但它们对实际森林生态系统的适用性有限。很少进行实地研究，主要是因为落叶暴发的相对不可预测性。这个用于探索性研究的小额赠款项目的目标是利用最近预测的在马里兰州西部再次发生大范围吉普赛蛾落叶的机会。研究人员将对该地区受干扰森林氮素渗漏的生物地球化学控制机制进行详细的、基于过程的研究，方法是比较受吉普赛蛾落叶的林地和未落叶的林地中控制氮素渗漏的关键生物地球化学过程的比率。此外，调查人员打算比较排放落叶流域和参考流域的溪流中溶解N物种的浓度，并使用遥感图像来探测、绘制地图和估计2001年生长季期间吉普赛蛾落叶的区域范围和强度。

Abstract0119581EshlemanSGER: Biogeochemical response mechanisms controlling nitrogen export from defoliated forests in the Eastern U.S.The excessive leakage of dissolved nitrogen (N) from forests defoliated by insects has water quality ramifications for small acid-sensitive streams as well as for downstream receiving waters such as Chesapeake Bay. Controlled laboratory experiments have shed some light on these mechanisms, but they are of limited applicability to actual forest ecosystems. Few field studies have been conducted, primarily due to the relative unpredictability of defoliation outbreaks. The goal of this Small Grant for Exploratory Research project is to take advantage of the recently-forecasted reoccurrence of extensive gypsy moth defoliation in western Maryland. The investigators will conduct a detailed, process-based study of the biogeochemical mechanisms controlling N leakage from disturbed forests in this area by comparing rates of key biogeochemical processes controlling N leakage in forested plots subjected to gypsy moth defoliation with rates in plots not defoliated. In addition, the investigators intend to compare concentrations of dissolved N species in streams draining defoliated and reference watersheds and use remote sensing imagery to detect, map, and estimate the regional-scale extent and intensity of gypsy moth defoliation during the 2001 growing season.