Today, spreading deserts are threatening a vast part of the world's fertile soil. The regions surrounding the spreading deserts poses a vital importance, for in these intermediate regions, the actual process of desertification takes place. Research effort is focusing in the study of large scale vegetation patterns in semi arid climatic zones, with a special emphasize on the way the patterns, created by the complex plant-plant and plant-soil interactions, reveals possible degradation processes. The transition from populated to the desert state, can be approached through the basic concepts of non-equilibrium statistical mechanics. Patch size distributions as well as spatial correlations can be measured in field, and explained through simple stochastic models that take into account only the basic facilitation, competition and environmental stochasticity. Model's time evolution also supplies us with valuable information pertaining the underling processes that governs it's dynamics. This raises the possibility of studying natural vegetation populations by successively taking areal snapshots and analyzing the time evolution.