Monitoring and assessment of desertification using remote sensing

The analysis of ecosystem change represents a key aspect to evaluate the impacts produced by desertification. Desertification is a process that affects soils with high instability and produces, in some cases, irreversible abrupt change responses. Therefore, assessing and modelling the spatio-temporal dynamics of desertification with remote sensing is a high research priority. It is important to assess how desertification affects the percentage of vegetation cover. But it is also very important to know how it affects the distribution of species and their functional status. However, there are still many challenges to be addressed in order to optimise the information obtained from degraded soils or drylands. One of the main limitations lies in the low signal-to-noise ratio of vegetation characterised by high soil reflectance and relatively sparse and heterogeneous vegetation. In this work, we identify some aspects that would improve the reliability of remote sensing analyses. Specifically, we recommend 1) intensifying the study of indicators by including not only changes in structure but also changes in vegetation condition or functionality and vegetation composition, 2) improving the estimation of structural and functional indicators using physical models and advanced computer models, 3) improving the multi-scale study of changes in diversity by adapting field sampling methods to the different image resolutions, 4) analysing the processes of change in structure, functionality and composition based on dynamic models that contemplate the processes of change and allow for a better understanding of the impact of desertification on ecosystem services.