Remote sensing based assessment of biophysical indicators for land degradation and desertification

Abstract

Desert ecosystems spanning moisture conditions from dry grasslands to barren hyper-arid landscapes are the largest terrestrial biome with more than 40% of the terrestrial landmass. Remote sensing data provide an efficient costeffective means to assess biophysical indicators of land degradation and desertification, providing that essential ecosystem properties can be monitored. We review the spectral characteristics of plants and soils that are detectable using optical sensors and methods to identify and quantify properties that have potential for monitoring arid ecosystem processes. Vegetation indexes have little sensitivity at low leaf area, particularly when the soil background is highly variable, as is characteristic of many arid systems. Additionally, accumulated dry plant material on the soil surface challenges measurement. Although the absorption characteristics of the major biochemical constituents of plants and soils are generally understood, the methods to retrieve this information from reflectance data and to understand the significance of how the structural organization alters the absorption features remains an area of active research. The overlapping absorption features of plants and soils preclude direct assessment of many biogeochemicals of interest. New biophysical methods that take the full spectral shape into account, including the effect of one compound on the spectral absorption of another, are needed to reduce uncertainty in their estimates. As a result, despite significant progress in developing fundamental understanding of ecosystem processes and optical properties, more research is needed before fully predictable quantitative methods are available.

Evaluating exposure to land degradation in association with repetitive armed conflicts in North Lebanon using multi-temporal satellite data

“…However, extrapolating and upscaling findings from local scale field studies to relatively large areas remain ambiguous. Other studies have shown that ecological and biophysical factors influencing land degradation processes can be monitored and assessed through the analysis of remote sensing images, particularly those acquired from onboard satellite instruments (Haboudane et al 2002;Thiam 2003;Wessels et al 2004;Ustin et al 2005).…”