RESOLVE · Remote sensing of photosynthetic traits for high latitude plant productivity modelling

Remote sensing of photosynthetic traits for high latitude plant productivity modelling

- Background to the research problem The arctic is experiencing unprecedented climate change, with land surface temperatures in northern regions increasing at double the global average rate. However, the impacts of these climate-induced changes on vegetation productivity and species distribution, and the impacts that any changes may have on the terrestrial carbon sink is highly uncertain. Attempts to accurately model vegetation productivity are crucial to understanding the extent and implications of a changing climate. Such predictions are complicated in high latitude regions, because there is no comparable analogue in current climates or in recent geological records. This uncertainty is exacerbated by the sparsity of field observations, due primarily to a lack of accessibility and a lack of long term monitoring sites. The use of remote sensing satellite data offers an opportunity, both to investigate trends over large spatial extents and track to historical changes through an available archive of legacy satellite data. A remote sensing-based approach is crucial for detecting changes in vegetation productivity and understanding the implications for atmospheric CO2 levels within the complex northern ecosystems. - Why is this work important? Plants take up a large proportion of CO2 from the atmosphere through photosynthesis. Any climate-induced changes in photosynthesis could either modulate or amplify increasing atmospheric CO2 concentrations. It is therefore imperative that the exchange of CO2 between plants and the atmosphere is accurately quantified. Recent developments in remote sensing methods and satellite technologies have opened up exciting new opportunities to improve modelled plant photosynthesis over large areas. These include an increase in the number of optical narrowband satellite sensors that measure reflected radiance in red-edge wavelengths (~705-740 nm), which have improved our ability to spatially map leaf chlorophyll content; a key component of plants’ photosynthetic machinery, over regional to global scales. A second key advance, is the use of several satellite sensors that were originally designed for atmospheric research in measuring the extremely small fluorescence signal emitted by plants. Advances in both solar induced fluorescence and leaf chlorophyll satellite retrieval methods may allow a more refined approach for targeting more precisely how vegetation function is changing across arctic plant communities, and improve estimates of the terrestrial carbon budget, under current and future climate scenarios. However, in order to understand these measurements at the satellite scale, we must first link remote sensing measurements to plant variables and processes using ground experiments, at the leaf level. The overall objectives were to: 1) investigate how arctic-boreal vegetation physiology has changed over decadal time-frames at the biome scale; 2) determine the the main environmental drivers that are affecting vegetation productivity across the Arctic and subarctic regions?

Data: CORDIS, © European Union