Examining the impacts of agricultural drainage on carbon cycling of northern peatlands

北方泥炭地储存了全球约30%的土壤碳(C)，容易受到气候和土地利用变化的影响。它们已经并仍在通过排水转化为农业和林业用地。土地利用变化和其他人类干扰可能与气候变化的直接影响一样大，甚至更大，是全球碳循环中的关键不确定因素。这些被排干的泥炭地与原始泥炭地具有不同的水文和植被组成，它们是如何在碳循环方面发挥作用的？迫切需要研究这些变化，因为自2012年以来排水的影响必须在国家温室气体清单中加以考虑，因此将成为未来土地管理的一部分。然而，泥炭地C循环模型不能模拟排水，因为它们只被参数化来模拟自然条件下的C循环。要将排水纳入泥炭地生态系统C模型，需要更好地了解被排水的泥炭地的水文、生态和生物地球化学过程，并将这种理解纳入模拟模型。*我的研究计划的长期目标是了解北部泥炭地的碳循环是如何因气候和/或土地利用变化而改变的，并最终将这些知识纳入泥炭地生态系统生物地球化学模型中，用于气候和土地利用变化研究。农业是全球最广泛使用的泥炭地，大部分被用作草地和牧场。加拿大拥有世界上面积最大的农业用泥炭地。在这项研究中，我们主要对泥炭地退耕还草感兴趣。这项为期5年的研究计划的短期目标是研究排水对北部泥炭地生态和生物地球化学过程以及碳循环的影响，并在麦吉尔湿地模型(MWM)中对这些排水影响进行参数化。最初，我将使用我的新的原始的和排水的废弃草场泥炭地作为我的第一个测试案例，但随着时间的推移，我的研究将扩展到其他土地利用的变化。在我的研究计划中将采用现场测量和建模，其中现场测量将帮助对新开发的排水-MWM进行参数化和测试。*本研究对全球变化科学，特别是湿地C循环科学具有重要的参考价值。该测量将为我们提供来自原始泥炭地和排干泥炭地的二氧化碳和甲烷通量的严格和连续的数据，以供模型参数化和评估。此外，这项研究将为气候变化和土地利用政策制定者提供一个模拟工具，用于研究农业排水如何在碳循环方面潜在地影响北部泥炭地的生态系统功能。第一个确定的结果将与加拿大关于泥炭地排水和将泥炭地用作牧场的政策有关。

Northern peatlands, storing about 30% of global soil carbon (C), are susceptible to climate and land-use change. They have been, and are still being, converted into agricultural and forestry lands through drainage. Land-use change and other human disturbances, which can be as large as, or larger than, the direct effect of climate change, are key uncertainties in the global C cycle. How do these drained peatlands, with different hydrology and vegetation composition from pristine peatlands, function with respect to C cycling? There is an urgent need to study these changes because the effects of drainage since 2012 have to be accounted for in national greenhouse gas inventories and therefore will become part of land management in the future. However, the peatland C cycling models cannot simulate drainage as they are only parameterized to simulate C cycling under natural conditions. To include drainage in the peatland ecosystem C models requires a greater understanding of the hydrological, ecological and biogeochemical processes of the drained peatlands, and an incorporation of that understanding into the simulation models. *** The long-term objective of my research program is to understand how the C cycling in northern peatlands is altered by climate and/or land-use change, and eventually to incorporate that knowledge into peatland ecosystem biogeochemical models for climate and land-use change studies. Agriculture is the most widespread use for peatlands globally, the majority being used as meadows and pasture. Canada has one of the largest areas of agriculturally used peatlands. In this study, we are mainly interested in peatlands converted to pastures. The short-term objectives of this 5-year research program are to examine the impacts of drainage on ecological and biogeochemical processes and C cycling of northern peatlands, and to parameterize these drainage impacts in the McGill Wetland Model (MWM). Initially, I will use my new pristine and drained-abandoned pasture peatland sites as my first test case, but my research will expand to other land-use changes over time. Both field measurements and modeling will be employed in my research program, where field measurements will assist in parameterizing and testing the newly developed Drainage-MWM. *** This study will be of great value to global change science, especially wetland C cycling science. The measurement will provide us with rigorous and continuous carbon dioxide and methane flux data from both pristine and drained peatlands for model parameterization and evaluation. Moreover, this research will provide climate change and land-use policy makers with a simulation tool for examining how agricultural drainage could potentially affect the ecosystem functions of northern peatlands in terms of carbon cycling. The first definitive results will be pertinent to policy on peatland drainage and use of peatlands as pasture in Canada.********