Development of advanced evaluation method for terrestrial CO2 budget by improving nitrogen-cycle processes

在日本的一个森林生态系统中进行了温度和氮素调控试验，以了解生态系统功能和结构对温度和氮沉降变化的响应。还利用日本和亚洲各种生态系统的长期CO2通量数据研究了生态系统与大气之间CO2交换的环境控制。此外，还对一个陆地生物圈模型进行了升级，以根据从各种生态系统观测到的数据考虑氮循环过程。该模型成功地模拟了冠层叶片C/N比的季节变化以及生态系统碳收支。利用该模式估算了日本周边陆地生态系统碳、氮收支，并从生态系统对大气氮沉降变化响应的角度分析了其时空变化。

Temperature and nitrogen manipulation experiments were conducted in a forest ecosystem in Japan to understand the responses of ecosystem function and structure to the changes in temperature and nitrogen deposition. Environmental control on the CO2 exchange between ecosystems and the atmosphere was also investigated using long-term CO2 flux data over various ecosystems in Japan and in Asia. In addition, a terrestrial biosphere model was upgraded to consider nitrogen cycling processes based on the observed data from various ecosystems. The model successfully simulated the seasonal patterns of C/N ratio in the canopy leaves as well as the ecosystem carbon budget. The carbon and nitrogen budgets in terrestrial ecosystems around Japan were estimated by the model with a spatial resolution of 1km, and the temporal and spatial variations were analyzed in the viewpoint of responses of ecosystems to the changes in the atmospheric nitrogen deposition.