IMPACT OF CLIMATE CHANGE AND ANTHROPOGENIC ACTIVITIES IN THE DYNAMICS OF LAND COVER IN MEDITERRANEAN STEPPE OF WEST ALGERIA

摘要

The last thirty years, there is a real dynamic change of land cover with intensive degradation of the natural vegetation especially in arid zone. Indeed, the adverse effects of drought periods from the year 1970 combined with population growth and economic conditions experienced by the country in the 1980s have greatly upset the delicate balance of the natural environment. These adverse effects may result in partial or total disappearance of some natural ecosystems. The objective of this work is to study the distribution of plant formations that constitute the ecosystem typical of west Algeria and their dynamics in time and space, as well as to develop a method to monitor the degradation process and a system capable of effectively protecting areas classified for their plant and animal species. The Landsat satellite images were used to map the vegetation of the study area at a scale of 1:200,000. A comparison was then made between the map obtained from satellite images (Landsat 8) of 2014 and (Landsat 5) of 1987. The results show the following main trends in the distribution patterns of steppe species, a strong decrease of land occupied by steppe of Stipatenacissima and steppe of Artimesiaherba-alba, witch replaced by three taxarnThymelaeamicrophylla, Salsolavermiculata andrnPeganumharmala. Steppe of Artemisia herbaalba has been transformed by steppe of. taxa Thymelaeamicrophylla,rnSalsolavermiculata and Lygeumspartum. Woody species such as Quercus ilex and Juniperusphoenicea are characterized by a large regression.