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

全球碳(C)循环是指大气、海洋和陆地之间碳的交换。与大气和海洋碳循环相比，人们对陆地碳循环的了解更少，这是造成年度全球碳预算估算误差最大的原因。这主要是由于对CO2施肥对植物生长的影响程度和植物生长对气候变化的敏感性缺乏认识。拟议的研究计划将整合碳循环模型和新兴的地面和卫星技术，这些技术直接测量光合作用，以提高对光合作用过程的理解，从而缩小陆地碳循环估算的不确定性。该计划提出了陆地生态系统全球变化生态卫星遥感的一系列简化方法，包括从站点级的算法开发和验证，到区域尺度的改进产品开发，以及全球尺度的全球变化影响研究。该研究计划的总体长期愿景是量化和归因于卫星探测到的陆地生态系统功能变化中人类影响和自然变异的作用。根据长期愿景，通过拟议的五年计划，将实现以下三个偶然但独立的目标。在现场水平上，地面太阳诱导叶绿素荧光（SIF）和光合色素池的高光谱测量将用于参数化土耳其点和博登森林研究站叶绿素光的使用行为。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进行光合作用和物候模拟。最后，通过卫星和气候数据档案、大气CO2浓度和C循环模型等模式数据整合方案，在全球范围内研究水分胁迫和CO2施肥对植物生长的影响。现场水平的研究将加强加拿大的二氧化碳通量塔网络，这是通过仪器进行长期环境监测所必需的，同时也提高了我们对光合作用过程的理解。除了有助于缩小陆地C循环估算的不确定性外，拟议的研究计划还将建立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性关注将极大地有利于地球科学界，因为了解这些快速变化的生态系统目前如何响应，对于预测未来的情况至关重要。高纬度光合作用和物候估算可以作为基准数据，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.