Mass and energy exchange between land surfaces and the atmosphere in central Canadian ecosystems

应对气候变化的潜在对策包括改变景观管理，以减少排放或增加温室气体的汇。这项研究的目的是通过在实地尺度上利用微气象技术测量温室气体净通量，来评估其中一些管理选择的效果。该计划包括加拿大中部的森林和农业景观(重点是马尼托巴省和萨斯喀彻温省)，特别关注植被的变化和干扰，如火灾。这些活动包括在比较不同的管理措施时，严格评估使用涡旋协方差通量塔测量净通量的统计和空间代表性。这对全球测量界来说很重要，可以证明缺乏复制的合理性，并使人们相信我们有能力为景观管理选择的政策决策提供信息。另一项活动是测量北方森林的碳动态，特别是与火灾有关的碳动态。这项工作建立在从马尼托巴省北部和萨斯喀彻温省中部的通量塔收集的数据集的基础上，以回答与成熟森林在净碳交换中的作用以及火灾对碳循环的影响有关的全球假说。特别是，数据集将提供森林从燃烧排放中恢复所需的时间长度，但如果要使用这些数据来验证数学模型，则必须评估不确定性。第三项活动是衡量农地管理做法对温室气体交换的影响。这涉及到改变种植做法，将土地从多年生作物转变为一年生作物，或从一年生作物转变为多年生作物。二氧化碳和一氧化二氮的交换都需要考虑，并将在几个地点进行测量。该计划侧重于对学生进行高质量的培训，使他们学习与实用的全球和局部问题相关的测量和分析技术，以提高我们对景观在温室气体和能源交换中的作用的理解。

Potential responses to climate change include alteration of landscape management to either decrease emissions or increase sinks of greenhouse gases. This research aims to evaluate the effects of some of these management options through measurement of the net flux of greenhouse gases using micrometeorological techniques at the field scale. The program includes both forested and agricultural landscapes of central Canada (focusing on Manitoba and Saskatchewan), with special attention to vegetation changes and disturbances, such as fire. The activities include a rigorous evaluation of the statistical and spatial representativeness of using eddy covariance flux towers to measure net fluxes when comparing different management treatments. This is important to the global measurement community to justify lack of replication and to gain confidence in our ability to inform policy decisions on landscape management choices. Another activity is the measurement of carbon dynamics of boreal forests, especially related to fire. This work builds on data sets that have been collected from flux towers in northern Manitoba and central Saskatchewan to answer global hypotheses related to the role of mature forests in net carbon exchange, and the effects of fire on the carbon cycle. In particular, the data sets will provide the length of time required for forests to recover from combustion emissions but uncertainty must be evaluated if these data are to be used to validate mathematical models. A third activity is the measurement of the effect of agricultural land management practices on greenhouse gas exchange. This involves changes to cropping practices where land is converted from perennial to annual crops, or from annual to perennial crops. The exchange of carbon dioxide and nitrous oxide both need to be considered, and will be measured at several locations. The program focuses on high-quality training of students so that they learn measurement and analysis techniques related to practical global and local questions to improve our understanding of the role of the landscape on greenhouse gas and energy exchange.