Portuguese oak groves of the Sierra del Madero Nature · Pozalmuro, Frentes, Soria The municipal district contributes 1,279 hectares to the Natura 2000 site known as the Portuguese oak and holm oak woods of the Sierra del Madero, the mountain barrier that closes the municipality on the east against the plain of the Rituerto. Photo: Miguel Ángel García. (CC BY 2.0) What to see and do in Pozalmuro