The Moroccan forest ecosystems are changing rapidly due to the ecological, social and economic constraints that result in different forms of degradation. Annually, WWF has estimated that more than 31000 hectares are subtracted from the forest estate because of clearing, harvesting fuel wood, cutting green wood, overgrazing, prolonged drought, urbanization, forest fires and woodland decline. The primary objective of this study is to high light the degradation and forest dynamics in the Achach forest which is located in the Moroccan central plateau. This forest area occupies 15995. 97 ha and is composed mainly of Tétraclinis, holm oak, cork oak and other secondary species. Bioclimatic analysis has allowed locating the area of study in bioclimatic semi-arid area with temperate variant. Remote sensing and GIS helped to establish land maps. The evolution map of Achach forest obtained from a diachronic analysis of Landsat 5 satellite images captured in July 1987 and August 2011 revealed a regression of 64.58% of pure holm oak area and 27.14% of pure Tétraclinis area compared to their initial areas of 1987. Permanent vegetation is under significant anthropozoogenic pressure.