Effect of N Deposition on Forest C Balance: Long-term Responses at Stand and Regional Scales

氮沉积对森林碳平衡的影响：林分和区域尺度的长期响应Nadelhoffer9815990该项目将测试和改进计算机模型，该模型旨在预测森林对大气污染引起的氨(NH4)和硝酸盐(NO3)沉积的响应。研究人员将确定增加的氮(N)投入如何影响森林生长、森林对大气二氧化碳的吸收和释放以及森林在十年时间尺度上的N保持。这将通过对20世纪90年代初标记有15N(非放射性同位素)示踪剂的森林进行重新采样，并通过比较马萨诸塞州中部试验田预测的15N再分布与示踪剂的测量来测试模型。修改后的模型将预测缅因州一片森林上的15N示踪剂移动。在第二轮测试后，改进的模型和地理信息系统(GIS)软件将用于预测N沉降如何影响美国东北部的森林生长和森林-大气C交换。

Effects of N Deposition on Forest C Balance: Long-term Responses at Stand and Regional ScalesNadelhoffer9815990This project will test and improve computer models designed to predict forest responses to deposition of ammonium (NH4) and nitrate (NO3) due to atmospheric pollution. The investigators will determine how increased nitrogen (N) inputs influence forest growth, the uptake and release of atmospheric CO2 by forests, and N retention by forests at decadal time scales. This will be done by resampling forests that were labeled with 15N (at non-radioactive isotope) tracers in the early 1990s and testing models by comparing predicted redistribution of 15N on experimental plots in central Massachusetts with measurements of tracers. The revised models will then be to predict 15N tracer movements on a forest in Maine. After a second round of testing, the improved models and GIS (Geographic information systems) software will be used to predict how N deposition is influencing forest growth and forest-atmoshphere C exchanges in the northeastern U.S.