Remote sensing spectroscopy to discriminate plant functional types and physiological function

Terrestrial ecosystems influence the Earth's climate by regulating exchanges of matter and energy between the land and atmosphere [1]. On an annual basis, photosynthesis and respiration absorb and release approximately 20% of the total atmospheric carbon (C) pool [2]. In recent decades, a net imbalance between these processes, linked to strong C sinks in soils and living vegetation, has offset a substantial fraction of human CO2emissions [3]. The ability of ecosystems to continue sequestering C at such high rates is unclear [4, 5]. Addressing this topic is critical to future climate forecasting and will require new tools for characterizing ecosystems and improving models that simulate their response to change. A key challenge that limits our ability to monitor and model global terrestrial ecosystem functioning, defined as the chemical, biological and physical processes occurring within an ecosystem, is the lack of comprehensive information on the spatial and temporal variability of the critical traits as well as environmental parameters that drive physiological processes in terrestrial vegetation [6].