Net ecosystem production (NEP) of boreal bogs in Finland under climate change scenarios - Using tree rings to reconstruct past NEP, C-flux measurements to estimate present NEP and General Circulation Models to project future NEP

气候变暖对本地泥炭地产生强烈影响，这些生态系统对气候产生反馈。重要的反馈是：1)在现有条件下，北方泥炭地的碳被储存，降低了大气CO2浓度（碳汇）2)北方泥炭地释放甲烷（CH4源）。温暖和干燥的条件可能会将北方泥炭地从碳汇转变为碳源，因为更高的分解速率可能会增加二氧化碳外排（反馈1）。然而，CH4外排（反馈2）可能会减少。目前尚不清楚这两种通量的相对重要性，而且缺乏对变暖情景下北欧泥炭地的全面评估。在这里，我提议研究芬兰北方沼泽的CO2、CH4和溶解有机碳的通量。与芬兰合作伙伴合作，我将结合五种方法：1)在地块水平上识别碳通量；2)研究这些通量的空间变异性；3)使用树木年轮重建净生态系统产量和水位（控制CH4/CO2外排）的近期变化；4)使用IKONOS图像扩大结果；5)最终使用一般循环模型的输出预测21世纪的碳通量。这种独特而有力的方法有望在空间上明确显示北欧北方沼泽的完全碳平衡及其在气候变暖下的当前和未来碳通量。

Climate Warming strongly affects boral peatlands and these ecosystems feed-back to climate. Important feedbacks are: 1) Carbon is stored under present conditions in boreal peatlands, reducing atmospheric CO2 concentrations (carbon sink) 2) Boreal peatlands release methane (CH4 source). Warmer and drier conditions might switch boreal peatlands from carbon sink to carbon source, because higher decoposition rates will likely increase CO2 efflux (Feedback 1). However, CH4 efflux (Feedback 2) will likely decrease. Te relative importance of both fluxes is unclear today and a comprehensive assessment of northern European peatlands under warming scenarios is missing. Here, I propose to study fluxes of CO2, CH4 and Dissolved Organic Carbon at boreal bogs in Finnland. Cooperating with Finish partners, I will combine five methods to 1) identify carbon fluxes at plot level, 2) investigate the spatial variability of these fluxes, 3) use tree rings to reconstruct recent change in net ecosystem production and water level (which controls CH4/CO2 efflux) 4) scale results up using IKONOS imagery and 5) ultimately project carbon fluxes for the 21st century using output from General Circulation Models. This unique and powerful approach promises spatially explicit results of the complete carbon balance of boreal bogs in northern Europe and their present and future carbon fluxes under climate warming.