Scaling spectroscopic approaches – from leaf albedo to ecosystems mapping

Abstract

Field based spectroscopy for ecological and environmental monitoring has become an indispensable part of complete observational systems as defined in GEOSS (Global Earth Observation System of Systems). Spectral scaling approaches are currently ranging from molecular to ecosystem or even biome scales. We discuss the use of field spectroscopy in relation to supporting large-scale ecosystem and ecotone inventorying, in particular the retrieval of biochemical and structural attributes of vegetation. First, attention will be put on using an object-relational database for the structured compilation of field spectral measurements and corresponding metadata. Spectral libraries have been collected over a wide variety of natural and man-made targets and their sampling scheme is discussed. Second, recent advances in reflectance and radiance terminology for field spectrometers are discussed, propagating the use of spectral albedo. Advanced measurement instrumentation and facilities are presented that complement solar reflective measurements with the angular, thermal and plant fluorescence domains. Further, experiments measuring leaf albedo, transmittance and absorbtance are discussed using examples from a wide range of ecosystems and their ecotones. Finally, we discuss scaling approaches from field measurements to airborne and spaceborne mapping methods, demonstrating the wide use of field spectrometers for environmental applications. We conclude on the importance of using field spectrometers over the past one and a half decades at our institutions.