Wetlands in a changing world: processes, feedbacks and the climate benefits of wetlands

在湿地提供的众多生态系统服务中，从野生动物栖息地到水质改善，气候调节被认为是湿地对社会最重要的效益之一。湿地生态系统在全球碳（C）循环中发挥着重要作用；它们为碳封存和大气二氧化碳 (CO2) 的长期储存提供了理想的环境，但它们也是大气甲烷 (CH4) 的最大单一来源，甲烷是一种短期内比二氧化碳更有效的温室气体 (GHG)。气候变化有可能增加湿地的温室气体排放，然而，气温上升对湿地温室气体动态和碳循环的影响仍然不确定。此外，防止湿地进一步丧失和恢复湿地生态系统已被认为对于限制未来排放以帮助实现气候目标非常重要。虽然湿地有可能放大和减弱全球变暖，但人们对湿地对气候和土地利用变化的反应仍然知之甚少。该研究计划旨在通过改进对湿地碳和温室气体动态对气候变化和管理的响应的机制理解来解决这一知识差距。在接下来的五年中，我们将研究三个不同的自然和管理湿地生态系统之间的土地-大气相互作用，以量化和比较年度温室气体和碳预算，确定痕量气体通量的关键控制措施，并改进对湿地碳通量的预测。该研究计划的四个短期目标是通过相互联系的研究活动来实现的，这些活动结合了实地测量、遥感和建模，为湿地碳和温室气体通量在一系列空间和时间尺度上的控制和时间安排提供了新颖的见解。该研究计划的核心是对三个湿地的生态系统规模的二氧化碳、甲烷、水和能量通量进行新的、持续的涡流协方差测量。这些地点包括不列颠哥伦比亚省伯恩斯沼泽生态保护区的天然和修复沼泽，以及不列颠哥伦比亚省边界湾野生动物管理区的潮汐沼泽。通过对各个地点的痕量气体通量进行全年测量，我们将量化这些湿地生态系统的年度碳和温室气体预算，以评估和比较它们对气候的净变暖或变冷影响。我们还将研究每小时到年际时间尺度上湿地温室气体交换的主要控制因素，探索不同湿地类型以及自然和恢复地点之间的驱动因素如何变化，并表征痕量气体通量的场内空间变化。我们还将把遥感指数与通量塔测量联系起来，以模拟和升级恢复湿地和自然湿地中的碳通量。这项研究对于更好地预测湿地当前和未来对气候变化的贡献至关重要，这与旨在限制全球气温上升水平的政策高度相关。

Among the numerous ecosystem services provided by wetlands, from wildlife habitat to water quality improvement, climate regulation is identified as one of their most important benefits to society. Wetland ecosystems play an important role in the global carbon (C) cycle; they provide the ideal environment for C sequestration and long-term storage of atmospheric carbon dioxide (CO2), yet they are also the largest single source of atmospheric methane (CH4), a much more potent greenhouse gas (GHG) than CO2 in the short term. Climate change has the potential to increase GHG emissions from wetlands, however, the consequences of rising temperatures on wetland GHG dynamics and C cycling remains uncertain. Furthermore, preventing further wetland loss and restoring wetland ecosystems has been identified as important in limiting future emissions to help meet climate goals. While wetlands have the potential to both amplify and attenuate global warming, wetland responses to climate and land-use change are still poorly understood. This research program aims to address this knowledge gap by providing an improved mechanistic understanding of the response of wetland C and GHG dynamics to climate variability and management. Over the next five years, we will investigate land-atmosphere interactions across three distinct natural and managed wetland ecosystems to quantify and compare annual GHG and C budgets, identify key controls on trace gas fluxes, and improve predictions of wetland C fluxes. The four short-term objectives of this research program are addressed through linked research activities that combine field-based measurements, remote sensing, and modeling to provide novel insights into the controls and timing of wetland C and GHG fluxes across a range of spatial and temporal scales. The core of this research program will be new and ongoing eddy covariance measurements of ecosystem-scale CO2, CH4, water and energy fluxes at the three wetland sites. These sites include a natural and restored bog in the Burns Bog Ecological Conservancy Area, BC, and a tidal marsh in the Boundary Bay Wildlife Management Area, BC. By conducting year-round measurements of trace gas fluxes across the sites, we will quantify annual C and GHG budgets across these wetland ecosystems to assess and compare their net warming or cooling effect on climate. We will also investigate the dominant controls on wetland GHG exchange across hourly to interannual time scales, explore how drivers vary across wetland types and between natural and restored sites, and characterize within-site spatial variability in trace gas fluxes. We will also link remote-sensing indices to flux tower measurements to model and upscale C fluxes in restored and natural wetlands. This research is critical to better predicting current and future contributions of wetlands to climate change, which is highly relevant for policies aiming to limit the level of global temperature rise.