Castile and León has many protected natural sites. Actively collaborates with the European Union program Natura 2000. There are also some special protection area for birds or SPA. The solitary evergreen oaks and junipers (Juniperus sect. Sabina) that now draw the Castilian-Leonese plain are remnants of the forests that covered these same lands long ago. The agricultural holdings, due to the need of land for the cultivation of cereal and pastures for the immense herds of the Castilian Plateau, supposed the deforestation of these lands during the Middle Ages. The last Castilian and Leonese forests of junipers are found in the Provinces of León, Soria and Burgos. They are not very leafy forests that can form mixed communities with evergreen oaks, Portuguese oaks or pines.

The Castilian-Leonese slope of the Cantabrian Mountains and the northern foothills of the Sistema Ibérico have a rich vegetation. The most humid and fresh slopes are populated by large beeches, whose extension areas can reach 1,500 m altitude. In turn, the European beech forms mixed forests with the yew, the sorbus, the whitebeam, the European holly and the birch. On the sunny slopes the sessile oak, the European oak, the ash, the lime tree, the sweet chestnut, the birch and the scots pine (a typical species from the north of the Province of León).