The present work was focused as an ecological and tree mensuration Quercus pyrenaica stands study in Galicia. With that objective, a parametric characterization of the species actual located biotypes was made measuring 40 plots and 33 ecological parameters and another 14 tree mensuration and sylvicultural ones. This data has allowed to determine physiographic, climatic and edaphic habitat, central and marginal, of Quercus pyrenaica in Galicia. The results shows that this forests are more dry and less productive than Quercus robur and Q. petraea stands, what means abandonment of the traditional uses like firewood and a great fire risk with its sequential degradation. This situation involves a lot difficult to find good stands of Quercus pyrenaica. As summary it could be said that this forests present an altitudinal variation higher to 1000 m, what means an average temperature difference near to 6 C, and the annual precipitation average is 1067.5 mm, being the summer average 115.2 mm, with somewhere summer drought.
