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

这个CAREER项目将调查温度升高将如何影响泥炭地的碳循环。泥炭地是一种湿地生态系统，由于植物物质的分解非常缓慢，自然地储存了碳，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。密歇根州位于北方泥炭地范围的南端，这意味着密歇根州泥炭地将是最先受到气候变暖影响的地区之一。该项目将建立一个泥炭地气候样带，以帮助预测未来变暖将如何影响这些生态系统中储存的碳。该样带包含七个地点，从南部的波蒂奇到密歇根州上半岛的纽伯里。这些地点的平均温度跨度为5°C，大致相当于下个世纪的升温预期。该项目将利用这些自然温度差异来确定泥炭地的碳循环过程将如何随着变暖而变化。此外，将为一年级本科生开设一门新课程，主要内容是在开课前一周对泥炭地样带进行实地考察，以培养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（通过有机物的微生物分解）的净平衡决定。事实证明，预测未来碳平衡的变化是困难的，因为这两种通量预计都会随着变暖而增加。碳损失将通过测量土壤中二氧化碳和甲烷的排放以及凋落物袋分解实验来评估。由于泥炭地生态系统对氮的强烈限制，植物生长过程中碳输入的变化将受到氮有效性的调节。因此，将在整个样带的现场测量中评估氮矿化的温度敏感性。最后，利用密歇根州已经经历的1°C的升温，将利用地球化学方法评估变暖对净C积累的影响。长期积累速率将与近期积累速率进行比较，使用计算机建模来解释近期速率中仍在进行有氧分解的有机物。这将允许直接测试假设，即变暖已经开始减缓泥炭地在其气候窗口的南部边缘的泥炭地的泥炭积累。总之，这些方法将提供一幅完整的图景，说明泥炭地的碳输入和碳损失将如何响应未来几十年预期的变暖。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.