The effect of forest, wet land and pasture land on the solute dynamics in terrestrial to lake ecosystem.

为明确植被和土地利用对森林、湿地和农用地组合流域生物地球化学过程的影响，对日本北海道北部岛马里奈Rake流域的土地利用特征、植被格局、河流和湖泊的溶质化学和动态进行了研究。流域陆地植被格局影响着土壤水分状况，而土壤水分状况又与地形特征密切相关。分布在下坡区和河岸区的湿地和沼泽森林对河流化学的形成起着重要的作用，湿地的渗漏具有较高的溶解有机碳和氮，这些有机碳和氮是由土壤中分解的有机质产生的。另一方面，滨岸湿地地下水和河流中硝酸盐含量明显低于其他地区，表明固定和反硝化作用是湿地净氮汇的重要机制。草地向河流和湖泊生态系统释放了大量的养分（N和P）。整个流域牧草向河流和湖泊的年养分通量显著大于森林和湿地生态系统的年养分通量。通过对生物地球化学过程的综合监测、植被格局和过程的普查以及GIS的综合分析，为评价大型联合流域的生态系统功能和过程提供了新的工具。

To clarify the effect of vegetation and land-use on biogeochemical processes in combined watershed including the forest, wet land and agricultural land, analysis of land-use characteristics, vegetation pattern, solute chemistry and dynamics in stream and lake were investigated in the Shimarinai Rake watershed located in northern Hokkaido Japan. Terrestrial vegetation pattern in the watershed was affected the soil moisture condition which closely related to the topographic features. The wetland and swamp forest distributed in the lower slope and riparian area played a significant role on the formation of the stream chemistry, The seepage from the wet land has higher dissolved organic carbon and nitrogen which produced from the decomposed organic matters in the soil. On the other hand, nitrate in the groundwater and stream water in the riparian wet land significantly decreased than that in the other area, suggesting that the immobilization and/or denitrification were important mechanisms for net nitrogen sink in the wet land. Larger amount of nutrient (N and P) was released from the pasture land to stream and lake ecosystem. The annual nutrient flux from pasture to the stream and lake was remarkably greater than that from forest and wetland ecosystem in the whole watershed. Our analysis using integrated monitoring of biogeochemical processes, census of vegetation pattern and processes and GIS analysis for the synthesis could proposed the new tool to assess the ecosystem function and processes in the larger combined watershed.