A cooperative USA/Peru contribution to Project 6 of UNESCO MAB programme. The English language version is already published (Occasional Paper 27, 1978). The high-altitude ecosystem of S Peru is an ecosystem in which the human population is a dominant but interactive component. The geology, climate, soils, and natural and domesticated biota are considered. Initial description is of the central Andes and of the complex gradients of climate and vegetation. This provides a context for more detailed treatment of the area surrounding Nunoa (Nelgar Province, Puno) as an altiplano example. The examination of the human modification of this environment concludes that the subsistence system appears to be effective in reducing environmental dislocation, and in increasing human access to material and energy flows of the biotic community.-D.A.Preston