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

据估计，北极圈和亚北极泥炭地覆盖了地球表面3.46亿公顷的土地。它们目前是大气二氧化碳的净汇，也是一种重要的温室气体--大气CH4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现在的功能。沿着通往阿巴拉契亚山脉的中轴线，可以发现许多相对较小的、以Sphagnum为主的泥炭地，远至南边的西弗吉尼亚州。阿巴拉契亚泥炭地属于第四纪，大多数泥炭地在9000-13000年前就开始了泥炭积累。在阿巴拉契亚地区，随着纬度的降低，泥炭沉积的数量变少，面积变小，变薄，并且更加高度分解。阿巴拉契亚泥炭矿床在几千年的气候条件下形成，气候条件通常比北方和亚北极地区的条件更温暖。因此，我们的研究方法建立在这样的前提下，即对北部(较凉爽的气候)和南部(较温暖的气候)泥炭地地点的比较将提供对在预测的全球气候变化情景下北方泥炭地潜在变化的洞察。这项研究的具体目标是：通过对从北向南梯度采集的210个泥炭岩心的化学分析来确定泥炭长期积累期间，估计北部和南部地点光合作用固定的14C的周转，以评估有机质质量和当地气候条件对有机质矿化的影响，比较北部和南部地点泥炭有机质矿化的时空模式，确定地点内年龄/深度关系的空间变异性的大小，并利用实验室中观研究评估根分泌物和根周转作为不稳定有机质的潜在来源，为CO2和CH4的产生提供燃料。这些研究的结果将提供对全球气候变化预测情景下的碳平衡、泥炭积累/降解以及与大气的温室气体交换的见解。

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.