Belowground C Sources and Sinks in Arctic Tundra Ecosystems

本项目旨在描述气候和环境对冻土带土壤地下碳输入和冻土带土壤碳平衡的控制。该项目的具体目标包括：1)量化湿苔草苔原的根产和根源碳固定；2)评估全球变化如何影响地下碳源向土壤的碳输入速率以及这些碳输入在北极生态系统中的命运；3)描述当前和预计气候条件下土壤-水-大气界面上根源碳的通量。这里提出的碳标记实验将允许测量植物在地下生产中的碳分配，细根周转量，从植物到土壤和大气库的碳转移率，以及在几天到几年的时间尺度上的土壤碳周转率。如果没有这样的地下碳动态研究，就很难对北极生态系统对气候和环境变化的反应做出现实的预测。

ABSTRACT OPP 9615942 NADELHOFFER MARINE BIOLOGICAL LABORATORY This project is designed to characterize climatic and environmental controls on carbon inputs to tundra soils from belowground sources and on carbon balances in tundra soils. Specific objectives of this project include 1) quantifying root production and root-derived carbon fixation in wet sedge tundra, 2) assessing how global change influences both rates of carbon inputs from belowground sources to soils and the fate of these carbon inputs in arctic ecosystems, and 3) characterizing the fluxes of root-derived carbon across the soil-water-atmosphere interface under current and projected climatic conditions. The carbon-labeled experiments proposed here will permit measurements of plant carbon allocation to belowground production, fine root turnover, rates of carbon transfer from plants to soil and atmospheric pools, and rates of soil carbon turnover over timescales of days to years. Without such research on belowground carbon dynamics, it will be difficult to develop realistic predictions of arctic ecosystem responses to climate and environmental change.