Adel Sephr - Assistant Professor at Ferdowsi University of Mashhad (FUM), Mashhad, Iran

A new view to desertification phenomenon based on thermodynamics laws for open systems has been followed in this article. Desertification is defined as irreversible land degradation that is caused by human activity and climate fluctuations leads to deterioration of human well-being. Some ecosystems may occasionally change quite abruptly to a contrasting state. Shift may occur in ecosystems with alternative stable states in which the conditions change gradually toward a critical point, called a bifurcation, where the ecosystem becomes unstable and shifts to the alternative state. In any systems that are close to a critical transition, recovery upon small perturbations becomes slow, a phenomenon known as critical slowing down. In this article the desertification has been analyzed under this fact and considered a result of non-equilibrium point in ecosystem near to critical transition. To investigate equilibrium oscillation, the land use alteration of Khorasan Razavi (KR) was monitored between years 2000-2012 by imagery data using NDVI changes. The descending trend of vegetation cover density was considered as tipping point in ecosystems near to critical transition and prone to desertification. Results indicated that vegetation cover decreasing shows a descending effect on ecosystem resilience to keep equilibrium. Also following these consequences was determined that in ecosystem with low resilience, a desert landscape is emerging. So increasing resilience can be an action to combat desertification. The equilibrium thinking used in this research can be helpful for development of sustainable ecosystems and combating desertification.

Critical Slowing Down, Resilience, Desertification, Bifurcation, Equilibrium