The decline in steppe vegetation in Algeria was first reported in the mid-20th century, and for many years was attributed to recurrent droughts. Hypotheses suggesting that this decline was a consequence of human activities emerged in the 1970s – a time of major socioeconomic trends in the region. Changes such as strong population growth, sedentarisation, herd size increases and use of pasture land for crops, all had considerable impact on rangeland vegetation. The aim of the present work was to identify heterogeneity in the pasture vegetation of a given 'territory' (in the sense of a 'terroir'), or biophysical environment (including meteorological), taking into account rangeland distribution, land use changes and herd management in the Aflou region of Algeria. Characterisation and mapping of the vegetation and its environment in the study area led to the hypothesis that, apart from some very slight soil differences, heterogeneity in rangeland vegetation appeared mainly related to human impacts. Bertin's Semiology of Graphics was used to analyse the results, and indicated a major decline in vegetation productivity and biodiversity in the steppe rangelands of the study zone. Beyond this general trend in the municipal territory studied, areas were found with contrasting flora communities, with some showing relatively stable plant communities, while other areas had some plant communities that had undergone regressive succession. Grazing conditions and the proximity of ploughed land were responsible for these different vegetation situations.