Production and value of natural ranges of the high Andean plateau of Pampa Galeras (Western Peru). After having carried out a preliminary study of the plant sociology of the High Andean plateau of Pampa Galeras the authors report on their work about the productivity and the comparative feeding values of the mapped vegetation formations. The setting up of a theoritical farming system for the regrowth underlines the factors which influence food availability for the vigogne namely : season, age of regrowth, ration between annual and perennial herbaceous species on the one hand and the total amount of forage on the other hand, as well as the energetic, proteinaceous and mineral values.