Linking hyperspectral PRISMA data with Ecosystem Functional Properties at ICOS sites

The Ecosystem Functional Properties (EFPs) are quantities characterizing key ecosystem processes, such as Net Ecosystem Exchange or Gross Primary Productivity. EFPs can be derived by observations of gas and energy exchanges between the ecosystems and the atmosphere; and these flux data are regularly collected by the tower stations of the Integrated Carbon Observation System (ICOS) network. EFPs represent relevant forest information, linked to functional and structural traits, and influenced by climate change impacts; their monitoring is a priority to understand ecosystem dynamics and changes. Specifically, the light use efficiency (LUE) is the capacity of vegetation to convert the incoming light into fixed carbon; water use efficiency (WUE) is the ability to convert each unit of water loss (by evapotranspiration) in gross biomass production; bowen ratio (BW) is used to define the amount (as ratio) of energy used for warming in comparison with the one used for evapotranspiration; and the gross primary productivity (GPP) stands for the photosynthetic capacity of the ecosystem [1]. The Italian PRISMA (Hyperspectral Precursor of the Application Mission) is an innovative satellite mission, equipped with a powerful hyperspectral sensor capable of collecting 240 tiny bands, from the visible up to the shortwave infrared regions, at high spatial resolution (30 m), that is able to revolutionize the opportunities to monitor the Earth and its resources [2]. PRISMA data already proved to be useful in retrieving forest traits, such as leaf area index or chlorophyll content [3].In this preliminary research, data from selected ICOS stations located in different ecosystems in Europe, were used to compute ecosystem-level EFPs. These ecosystem functional data are then linked with different vegetation indices derived from the hyperspectral PRISMA satellite mission, with the aim of investigating the capability of PRISMA data to model inter- and intra- ecosystem differences in EFPs. This study helps to detect innovative data and tools useful to better understand and characterize ecosystem functional variability; it also contributes to clarify the potential and limits of PRISMA satellite as an innovative monitoring system for ecosystem level analyses.