The concept of "entre-tenir" the mountains is at the heart of this thesis. This research attemps to show how farmers have reacted and adapted their ways of working, thinking and organizing the pastoral territory facing the crisis affecting both the social and landscape aspects of the Pyrenees, particulary since the 1970s. Three valleys form the framework for a comparative analysis: the valley of Oueil-Larboust (31), the valley of Campan (65) and the upper valley of the Gave de Pau (65). The modalities of "entre-tenir" the mountains are discussed from three different perspectives: (1) a spatial perspective on a regional scale and that of the valley, (2) a temporal perspective between the maintened and the abandonned, and (3) a social perspective of modes of collective organization.The developed ethnogeographical approach is based on a combination of in situ spatial analysis of landscapes, a diachronic analysis of landscape changes from photo comparisons and a social survey among farmers to gather viewpoints of their practices and their perceptions.The main results show that the nuances in the landscape maintenance are particulary related to changes in practices and/or the existence of individual or group prjects, in which the landscapre concern of "entre-tenir" is present in the background, sometimes implicitly, but often more and more explicitly. This finding sheds light on innovative practices of mountain agriculture and the role of the landscape. It throws light on the ability of social groups to take responsability over the management of their territory and opens perspectives for the thinking about of the future of mountain landscapes.
