Spectral properties and sources of variability of ecosystem components in a Mediterranean semiarid environment

Monitoring changes in soil and vegetation is crucial in fragile Mediterranean semiarid environments. To identify early perturbation warnings using radiometric techniques, the spectral variability of the ecosystem components must be understood and the ranges of their natural variability established. This paper aims to assess the potential of hyperspectral information for analysing spectral variability and to provide guidelines for using spectroscopy to monitor semiarid environments. Spectral field measurements of different soil (volcanic and calcareous), vegetation (esparto and dwarf palm) and natural mixtures (NPV and BSC) were acquired: spectral assessment focused on albedo, spectral shape and absorption bands. Results show high variability of soil background between and within soil typologies. The presence of biotic elements masks the distinctive characteristics between soil typologies, making combination of the VIS-NIR and SWIR regions necessary for correct discrimination and quantification of soil properties. Plant species are discriminated by taking advantage of their spectral properties based on the differences in absorption by chlorophyll, water and lignin. In summer, these differences are more significant, predictably due to their specific survival strategies. Radiometric techniques enable discrimination of ecosystem components, although the high variability of the landscape and subtle differences between components makes it necessary to use high-spectral resolution information. (C) 2010 Elsevier Ltd. All rights reserved.