Abstract
Responding to a new food market demand, the Southern Altiplano region of Bolivia has become the world's largest exporter of quinoa, a traditional food of Andean populations, now consumed in many countries in the North. This thesis investigates the changes induced by the transition from subsistence agriculture to family-based export agriculture, with a particular focus on the spatial mobility of the populations and its relation to the profound changes experienced by this region. Reconstruction through life narratives of the biographies of 170 people originating from 5 rural communities facilitated a reframing of the quinoa boom in the context of the residential, professional and circulatory histories of the populations. Through study of the links between mobility, agricultural dynamics, and local resource management, this study demonstrates i) the great reactivity of the families and communities facing the demands of new production systems, ii) the emergence of multiple forms of social agreements, iii) the plasticity of the livelihood territories revealed by various practices of mobility and pluriactivity based on a reticular socio-spatial organization connecting the city and the countryside. However, in this region of fragile environment and harsh climate conditions, the resurgence of interest in agricultural activities, precipitating the return of many migrants and the emergence of multiple actors, is accompanied by huge pressures on land resources, social tensions and a risk of environmental degradation, calling into question the crucial issue of the sustainable management of the region.