Barreiro Oak Woods occupy part of the west slope of the valley of the Laboreiro River, on the right bank of the river. It is a well-preserved oak wood, although fragmented by the villages and water meadows as well as by areas scrub, which form open areas essential for the survival of many species. Given the altitude at which it is located (750 and 950 meters), this woodland is dominated by the Pyrenean Oak, which in association with other species, form an important biological community.

The biodiversity in the Barreiro woo is indeed significant, being particularly noticeable in the spring, when the mountain broom is in flower, as well as white broom and white heather (in the shrub-cover) or the wood anenomie, wild narcissus, dogtooth violet, forget me not and the common violet (at the plant level). Among animals, birds of prey are often to be seen, such as the buzzard, which nests in wooded areas and taking advantage of the water meadows and other more open areas as hunting grounds. Among the wooded areas and the water meadows small species of passerines are common, mostly resident species, such as the Iberian chiffchaff, bull finch, chaffinch, robin, among many others. This oak woodland also provides a refuge for the Iberian Wolf, fox and the roe deer.

Due to its importance in nature conservation and biodiversity, this type of oakwood falls within the protected habitat "Portuguese-Galician Quercus Robur and Quercus pyrenaica woodlands".