RUI: Peatlands and Global Climate Change: Continued Comparative Studies of Northern and Southern Sites

北纬和亚北极泥炭地覆盖了地球陆地表面约3.46亿公顷。目前，它们是大气中二氧化碳的净汇，也是大气中甲烷（一种重要的温室气体）的重要来源。鉴于气候变暖将在北纬地区最为明显的预测，这项研究的主要目标一直是并将继续是深入了解泥炭地的碳平衡以及泥炭地与大气之间的碳气体交换。将进行实地和实验室研究，以评估泥炭地的历史发展和目前的功能。沿着阿巴拉契亚山脉的轴线，南至西弗吉尼亚州南部，可以发现大量相对较小的泥炭地，泥炭地以泥炭石为主。阿巴拉契亚泥炭地为第四纪泥炭地，大部分泥炭在9000 - 13000年前开始堆积。在阿巴拉契亚地区，随着纬度的降低，泥炭沉积物的数量越来越少，面积越来越小，厚度越来越薄，分解程度越来越高。阿巴拉契亚泥炭沉积物在气候条件下发展了数千年，气候条件通常比北方和亚北极地区温暖。因此，我们的研究方法建立在北部（气候较冷）和南部（气候较暖）泥炭地地点的比较的前提下，这将为在全球气候变化预测情景下北方泥炭地的潜在变化提供见解。本研究的具体目标是：通过对沿南北梯度采集的210个pb年代泥炭岩心的化学分析，确定长期泥炭积累过程；估算北部和南部站点光合作用固定14C的周转量，评估有机质质量与当地气候条件对有机质矿化的影响；对比北部和南部站点泥炭有机质矿化的时空格局；确定年龄/深度关系的站点内空间变异性的大小，并通过实验室中尺度研究评估根系渗出物和根系周转量作为促进CO2和CH4生产的活性有机质的潜在来源。这些研究的结果将有助于深入了解全球气候变化预测情景下的碳平衡、泥炭积累/退化以及温室气体与大气的交换。

Wieder Boreal and subarctic peatlands cover an estimated 346 million ha of the earth's land surface. They presently function as a net sink for atmospheric CO2 and as a substantial source of atmospheric CH4, an important greenhouse gas. Given predictions that climatic warming will be most pronounced in northern latitudes, the main goal of this research has been and will continue to be to gain insights into carbon balance in peatlands and gaseous exchanges of carbon between peatlands and the atmosphere. Field and laboratory studies will be undertaken to assess the historical development and the present function of peatlands. Numerous, relatively small, Sphagnum-dominated peatlands can be found along the axis to the Appalachian Mountains as far south as southern West Virginia. The Appalachian peatlands are of Quaternary age, with most having initiated peat accumulation 9,000-13,000 years ago. Within the Appalachian region, with decreasing latitude peat deposits become fewer in number, smaller in areal extent, thinner, and more highly decomposed. The Appalachian peat deposits have developed over thousands of years under climatic conditions that have been generally warmer than conditions in boreal and subarctic regions. Therefore, our research approach has been founded on the premise that comparisons between northern (cooler climate) and southern (warmer climate) peatland sites will provide insights into potential changes in boreal peatlands under predicted scenarios of global climate change. Specific objectives of this research are: to determine during long-term peat accumulation through chemical analysis of 210 Pb-dated peat cores collected from sites along a north to south gradient, to estimate turnover of photosynthetically fixed 14C in northern and southern sites to evaluate the effects of organic matter quality versus local climatic conditions on organic matter mineralization, to contrast spatial and temporal patterns in organic matter mineralization in peat in northern and southern sites, to determine the magnitude of within-site spatial variability in age/depth relationships, and to evaluate root exudation and root turnover as potential sources of labile organic matter fueling CO2 and CH4 production using laboratory mesocosm studies. Results obtained from these studies will provide insights into the carbon balance, peat accumulation/degradation, and exchange of greenhouse gases with the atmosphere under predicted scenarios of global climate change.