Vegetation dynamics of Algerian’s steppe ecosystem. A case of the region of Tiaret

Abstract

The Algerian steppe pastures cover an area of 20 million hectares. Their geographical location gives them a buffer zone between the north with a sub-humid climate and the great arid Sahara in the south. The steppe ecosystem is now facing a serious problem of degradation – desertification. The characterisation of steppe vegetation and its use as a biological indicator makes it possible to define the evolution of the steppe ecosystem and to identify the changes that have occurred. An approach based on the combination of various studied parameters by the establishment of a geographical system is adopted. A series of Landsat satellite images, covering the period 1987–2016, with seven images was used to produce land use maps. Data from salinity index SI and moisture index NDWI as well as climatic data were acquired from the Google earth engine platform. The results obtained demonstrate a variability of the spatio-temporal distribution of the steppe vegetation of the study area with a tendency to degradation. The canonical correspondence analysis reveals associations between the steppe vegetation cover and the precipitation and salinity parameters, demonstrating a strong sensitivity of steppe vegetation to external hazards.