Remote sensing of solar induced fluorescence and the Photochemical Reflectance Index (PRI) for carbon uptake in two contrasting forest ecosystem types

大气中二氧化碳浓度的增加及其对全球变暖的贡献是最紧迫的环境问题之一。大气二氧化碳的增加主要归因于化石燃料的燃烧和热带森林的砍伐。在估计的二氧化碳排放量中，大气二氧化碳的增加约占45%，但其余的大部分下落不明，据信是陆地生物圈和海洋占据了剩余的部分。许多科学研究表明，植被是吸收过量二氧化碳的主要原因，但这些估计值并不确定，而且对驱动它们的过程的理解也是不确定的。这项工作的目的是利用遥感具体改进对光合作用和逆境(例如缺水和高温)过程的估计。利用包括快速响应气体(CO2)分析仪在内的先进系统，可以直接测量大气和生物圈之间的光合作用二氧化碳交换。这样的系统已经安装在全球200多个地点的网络中，并积极收集不同植被类型的二氧化碳通量数据。虽然这些测量是强大的，因为它们提供了关于大片植被光合作用的连续数据，但它们只代表了空间中的一个点，我们希望利用其他方法，即遥感，也可以提供这种信息，但测量范围要大得多。简而言之，具有全球影响的全球问题需要全球测量，而这只能通过遥感来实现。在我们的团队中，我们已经成功地开发了从遥感(从飞机上)检测光合作用反应变化的方法，但只测试了这是选定的几个生态系统类型。因此，这为研究利用遥感测量光合作用提供了一个独特而令人兴奋的机会，使我们能够迈向“从太空测量生物”的现实，这将是光合作用研究的关键突破，并促进我们对植被在陆地碳循环中的作用的理解。这个领域特别令人兴奋，因为它涉及基本的科学和政治问题。政府间气候变化专门委员会发布了其最终综合报告，其中不仅强调了支持气候变暖的明确证据，而且还强调了这将对陆地生态系统产生的影响。因此，该提案具有非常重要的意义，因为它涉及植物吸收碳的问题，以及气候变化带来的压力将如何影响这一问题。

The increase in concentration of carbon dioxide (CO2) in the atmosphere and its contribution to global warming is one of the most urgent of environmental issues. The rise in atmospheric CO2 has been principally ascribed to the burning of fossil fuels and tropical deforestation. Around 45% of the estimated emissions of CO2 are accounted for by the increase in atmospheric CO2, but the remainder is largely unaccounted for and it is believed that the terrestrial biosphere and the oceans are taking up the remainder. A number of scientific studies suggest that it is the vegetation that is primarily responsible for taking up this excess CO2, yet these estimates are uncertain, as well as an understanding of the processes that drive them. The aim of this work is to specifically improve estimates of the processes of photosynthesis, and stress (such as lack of water, and heat, for example) using remote sensing. The direct measurement of the photosynthetic CO2 exchange between the atmosphere and biosphere can be carried out by using advanced systems that include fast responding gas (CO2) analysers. Such systems are already installed globally in a network of over 200 sites and actively collect CO2 flux data over contrasting vegetation types. Whilst these measurements are powerful in that they provide continuous data on photosynthesis of large areas of vegetation, they only represent one point in space and we wish to utilise other methods, namely remote sensing, that can also provide this information yet measure over a much larger geographical area. In a nutshell, global issues with global impact, requires global measurement and this can only be achieved using remote sensing. Within our group we have successfully developed methods to detect changes in the photosynthetic reactions from remote sensing (from aircraft) but have only tested this is a select few ecosystem types. This therefore presents a unique and exciting opportunity to investigate the use of remote sensing for measuring photosynthesis such that we can move towards the reality of 'measuring biology from space', which would be a key breakthrough in photosynthesis research and advance our understanding of the role of vegetation in the terrestrial carbon cycle. This field is particularly exciting because it addresses fundamental scientific and political issues. The Intergovernmental Panel on Climte Change released its final synthesis report which highlighed not only the unequivocal evidence in support of climate warming, but also the impact this will have on terrestrial ecosystems. The proposal is therefore of high importance since it addresses the issue of carbon uptake by vegetation and how it will be affected by the stresses imposed by a changing climate.