CAREER: Detecting warming impacts on carbon accumulation across a climate transect of Michigan peatlands

这个职业项目将研究气温升高将如何影响泥炭地的碳(C)循环。泥炭地是湿地生态系统，由于植物材料分解非常缓慢，它们自然地储存碳，因此现在以有机物的形式储存了大量的碳。随着气候变暖，这些泥炭地的碳循环将如何变化尚不清楚。密歇根州位于北部泥炭地范围的南端，这意味着密歇根州的泥炭地将是最先受到气候变暖影响的地区之一。该项目将建立泥炭地气候样带，以帮助预测未来变暖将如何影响储存在这些生态系统中的碳。横断面包含七个地点，从南部的波蒂奇到密歇根州上半岛的纽伯里。这些地点的平均气温为5摄氏度，大致相当于下个世纪预计的升温。该项目将利用这些自然的温度差异来确定泥炭地的碳循环过程将如何随着气候变暖而变化。此外，还将为一年级本科生开发一门新课程，重点是在上课前一周对泥炭地样带的地点进行实地考察，以培训和激励下一代环境科学家。泥炭地生态系统的净碳平衡由碳输入(来自植物生长)和碳损失(通过微生物分解有机物)的净平衡决定。预测未来碳平衡的变化已被证明是困难的，因为这两个通量预计都会随着气候变暖而增加。将通过测量土壤中的二氧化碳和甲烷排放量以及垃圾袋分解实验来评估碳损失。由于泥炭地生态系统对氮的强烈限制，通过植物生长引起的碳输入的变化将受到氮(N)有效性的调节。因此，氮矿化的温度敏感性将在整个样带的野外测量中进行评估。最后，将利用密歇根州已经经历过的升温1摄氏度的地球化学方法，评估气候变暖对碳净积累的影响。长期积累速率将与最近的积累速率进行比较，使用计算机建模来解释仍在进行有氧分解的近期速率中包含的有机物。这将允许对气候变暖已经开始减缓气候窗口南缘边缘泥炭地泥炭堆积的假设进行直接测试。总而言之，这些方法将提供泥炭地碳输入和损失的完整图景，以应对未来几十年预期的变暖。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This CAREER project will investigate how increases in temperature will affect the carbon (C) cycle in peatlands. Peatlands are wetland ecosystems that naturally store C due to very slow decomposition of plant material, and thus now store a massive amount of C as organic matter. How the C cycle in these peatlands will change as climate warms is unknown. Michigan is positioned at the southern end of the range of boreal (northern) peatlands, which means that Michigan peatlands will be among the first to be affected by warming. This project will establish a climate transect of peatlands to help predict how future warming will affect the C stored in these ecosystems. The transect contains seven sites, from Portage in the south to Newberry in Michigan’s Upper Peninsula. The sites span 5°C in average temperature, which is approximately equivalent to the warming expected over the next century. The project will exploit these natural differences in temperature to determine how C cycle processes in peatlands will change with warming. In addition, a new course for first-year undergraduate students will be developed, centered around a field trip to sites on the peatland transect in the week before the start of classes, to train and inspire the next generation of environmental scientists.The net C balance of the peatland ecosystem is determined by the net balance of C inputs (from plant growth) and C losses (through microbial decomposition of organic matter). Predicting future changes in the C balance has proved difficult because both of these fluxes are expected to increase with warming. C losses will be evaluated by measuring carbon dioxide and methane emissions from the soil, as well as litter bag decomposition experiments. Changes in C inputs via plant growth will be mediated by nitrogen (N) availability, due to the strong N limitation of peatland ecosystems. Therefore, the temperature sensitivity of N mineralization will be assessed in field measurements across the transect. Finally, the effects of warming on net C accumulation will be assessed using a geochemical approach, taking advantage of the 1°C of warming that Michigan has already experienced. The long-term accumulation rate will be compared to the recent accumulation rate, using computer modeling to account for organic matter included in the recent rate that is still undergoing aerobic decomposition. This will allow direct testing of the hypothesis that warming has already begun to slow down peat accumulation in marginal peatlands at the southern edge of their climate window. Together, these approaches will provide a complete picture of how C inputs and losses from peatlands will change in response to the warming expected over the coming decades.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.