Vegetation dynamic patterns of arid rangelands : a multifractal approach

Abstract

Rangelands are complex ecosystems with non-linear dynamics in space and time, however, their temporal dynamics have only recently started to be studied and they are not fully understood. Rangelands comprise 30-40% of the Earth´s landmass and their degradation caused by increasing misuse remains a global concern, affecting 73 % of all rangelands. Remote sensing and satellite monitoring methods are commonly used to study ecology and agriculture. Among different satellite indices, the Normalized Difference Vegetation Index (NDVI) is the most widely used vegetation index by rangeland ecologists. The NDVI reveals a good correlation with the biomass of different vegetation types in arid and semi-arid areas. NDVI anomalies (NDVIa and ZNDVI) are other indexes proven useful for identifying drought and water stress on vegetation; therefore, it is suited to study arid and semi-arid ecosystems List of tables xviii NDVI trend are included. For each phase, bold values show the strongest correlations among the different time lags tested.