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

氮沉降对森林碳平衡的影响：林分和区域尺度的长期响应Nadelhoffer 9815990本项目将测试和改进计算机模型，用于预测森林对大气污染引起的铵（NH 4）和硝酸盐（NO3）沉降的响应。 研究人员将确定增加的氮（N）输入如何影响森林生长，森林对大气CO2的吸收和释放，以及森林在十年时间尺度上的氮保留。 这将是通过在20世纪90年代初用15 N（非放射性同位素）示踪剂标记的恢复森林和通过比较预测的15 N在马萨诸塞州中部的实验地块上的再分配与示踪剂的测量来测试模型。 修订后的模型将预测15 N示踪剂在缅因州的森林运动。 经过第二轮测试，改进的模型和GIS（地理信息系统）软件将用于预测氮沉降如何影响美国东北部的森林生长和森林-大气碳交换。

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.