The search for expert-independent criteria has led to the idea to use
the dynamics of productivity of vegetation as an indicator of land degradation.
For instance NDVI (normalized difference vegetation index) has
been used for estimating the long term bio-productivity trends using
remote sensing data and after correction for climatic variations as an
indicator for land degradation (Bai et al., 2008). In a further development,
the previous approach was combined with global datasets on
natural resource andmodels for estimating the global status and trends
of land degradation processes (Nachtergaele et al., 2011). The analysis
of NDVI also encouraged Le et al. (2014) to make a global estimation
of land productivity for the assessment of the economic effect of land
degradation.