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Development of a evaluation method of environmental effect on a forested ecosystem using a biogeochemical model based on stream-water hydrochemical processes

利用基于溪流-水水化学过程的生物地球化学模型开发森林生态系统环境影响评价方法

基本信息

批准号：
15310029
负责人：
YOSHIOKA Takahito
金额：
$ 9.22万
依托单位：
Research Institute for Humanity and Nature
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Studies on environmental changes in forested ecosystems caused by perturbations have been summarized. Among simulation models for biogeochemical material cyclings, we considered the applicability of the PnET model, which has been developed for northern American forests, for simulating the long-term environmental changes in forests in Japan. Observational results obtained in the forested watershed, where periodic logging has been conducted, were input to the PnET-CN model to simulate the water qualities of the streamwater. The model was well reconstructed the changes in the nitrate (NO_3^-) concentration among small catchments having different tree ages, although there were some difference in the level of concentrations between the observation and simulation. Effect of the logging on stream NO_3^- concentration can be found for 20 years after logging, coinciding with observations. It was suggested that logging rates up to 40% did not change the NO_3^- concentration level in the streamwa … More ter. The patterns of the long-term change in the woody biomass and the decrease in the leaf nitrogen content were successfully simulated. However, there were large gaps between observational and simulated values. It suggests that the careful setting of parameters included in the model should be done from viewpoints of water and nutrient conditions and the development of the rizosphere. Forest renewal and hydrologic processes should be taken into considerations to improve the simulation results.In order to clarify the relationship between stream water qualities and watershed environmental conditions, we conducted the nationwide survey on the stream hydrochemistry in Japan. We collected stream waters from more than 1270 sites and analyzed the ionic concentrations. It was suggested that the stream NO_3^- concentration was largely governed by the atmospheric nitrogen deposition to the watershed. From the comparison with previous survey in 1950's, the stream NO_3^- concentration in Japan increased during 50 years. Geologic characteristics in the watershed affected the phosphorus (PO_4^<3->) concentration. Less

综述了扰动引起的森林生态系统环境变化的研究。在生物地球化学物质循环模拟模型中，我们考虑了北美森林的PnET模型在模拟日本森林长期环境变化方面的适用性。在森林流域进行周期性采伐的观测结果输入到PnET-CN模型中，模拟径流水质。该模型较好地再现了不同树龄小流域硝态氮（NO_3^-）浓度的变化，但观测值与模拟值存在一定差异。测井后20年对水体NO_3^-浓度的影响与观测结果一致。结果表明，录井率达到40%后，水体NO_3^-浓度水平不会发生变化。成功地模拟了木本生物量的长期变化规律和叶片氮含量的下降规律。然而，观测值和模拟值之间存在很大差距。建议从水、养分条件和对流层发育的角度仔细设置模式参数。为了改进模拟结果，应考虑森林更新和水文过程。为了弄清河流水质与流域环境条件之间的关系，我们在日本进行了全国范围的河流水化学调查。我们从1270多个地点收集了溪水，并分析了离子浓度。表明河流NO_3^-浓度在很大程度上受大气氮沉降的控制。与20世纪50年代的调查结果相比，日本的NO_3^-浓度在50年间呈上升趋势。流域地质特征影响了磷（PO_4^<3->）浓度。少