Satellite remote sensing of global change ecology from the leaf to the globe

全球碳(C)循环是大气、海洋和陆地之间的碳交换。陆地碳循环比大气和海洋碳循环了解得少，对全球年度碳预算估计的误差最大。这在很大程度上归因于对二氧化碳施肥对植物生长影响的大小以及植物生长对气候变化的敏感性缺乏了解。拟议的研究计划将整合碳循环模型和直接测量光合作用的新兴地面和卫星技术，以提高对光合作用过程的理解，以缩小陆地碳循环估计的不确定性。该方案提出了一系列简化的方法，用于卫星遥感陆地生态系统的全球变化生态，范围从现场一级的算法开发和验证，到区域规模的改进产品开发，以及全球规模的全球变化影响研究。该研究计划的总体长期愿景是量化人类影响和自然变异对卫星探测到的陆地生态系统功能变化的作用，并将其归因于此。根据长期愿景，以下三个临时但独立的目标将通过拟议的五年方案实现。在站点一级，将使用地面太阳诱导的叶绿素荧光(SIF)和光合色素池的高光谱测量来对土耳其点和波登森林研究站的叶绿素光利用行为进行参数化。在区域尺度上，将利用基于卫星的高光谱和SIF观测对高纬度生态系统的光合作用和物候进行建模。最后，将通过涉及卫星和气候数据档案、大气CO2浓度和C循环模型的模型数据集成方案，进行全球范围内水分胁迫和CO2施肥对植物生长影响的研究。现场层面的研究将加强加拿大的二氧化碳通量塔网络，这些网络是通过仪器进行长期环境监测所需的，同时提高了我们对光合作用过程的理解。除了对缩小陆地碳循环估计不确定性的贡献外，拟议的研究计划还将建设加拿大在全球变化和陆地生态系统卫星遥感方面的科学能力，以支持国家气候变化影响评估和政策制定。对高纬度生态系统的区域关注将使地球科学界大大受益，因为了解这些快速变化的生态系统目前如何反应对于预测未来的情况至关重要。高纬度光合作用和物候估计可用作基准数据，以量化植被生产力和对气候变化、昆虫、野火和资源开采的健康反应，所有这些都是对加拿大森林的新威胁。

The global carbon (C) cycle is the exchange of C among the atmosphere, oceans, and land. The land C cycle is less understood than the atmosphere and ocean C cycles, contributing the largest error to the annual global C budget estimates. This is attributed largely to the lack of understanding of the magnitude of CO2 fertilization effect on plant growth and the changing sensitivity of plant growth to climate change. The proposed research program will integrate C cycle models and emerging ground and satellite technologies that directly measure photosynthesis for improved understanding of photosynthetic processes to narrow the land C cycle estimation uncertainty. The program proposes a pipeline of streamlined approaches for satellite remote sensing of global change ecology of terrestrial ecosystems that range from algorithm development and validation at the site level to improved product development at a regional scale, and global change impact study at a global scale. The overarching long-term vision of the research program is to quantify and attribute the roles of human influence and natural variability on satellite-detected changes in terrestrial ecosystem functioning. In light of the long-term vision, the following three contingent yet independent objectives will be achieved through the proposed 5-year program. At site level, ground-based sun-induced chlorophyll fluorescence (SIF) and hyperspectral measures of photosynthetic pigment pools will be used to parameterize chlorophyll light use behaviour at Turkey Point and Borden Forest Research Stations. At the regional scale, photosynthesis and phenology will be modelled for high latitude ecosystems using satellite-based hyperspectral and SIF observations. Finally, a global scale study of moisture stress and CO2 fertilization effects on plant growth will be conducted through model-data integration scheme that involves satellite and climate data archives, atmospheric CO2 concentration and C cycle models. The site level study will strengthen Canada's CO2 flux tower networks that are required for long-term environmental monitoring through instrumentation while improving our understanding of photosynthesis processes. In addition to its contribution towards narrowing the land C cycle estimation uncertainty, the proposed research program will build Canada's scientific capability in satellite remote sensing of global change and terrestrial ecosystems to support national climate change impact assessment and policy formulation. The regional focus on high latitude ecosystems will significantly benefit Earth science communities since knowing how these rapidly changing ecosystems are currently responding is paramount to predict what is yet to come. The high-latitude photosynthesis and phenology estimates can be used as benchmark data to quantify vegetation productivity and health responses to climate change, insects, wildfires and resource mining, all of which are emerging threats to Canada's forests.