They are adapted to an exceptionally harsh continental climate, where practically no other species of tree is a rival; except for the Holm oak, which occupies some of the old, deforested juniper groves, and the European black pine ("Pinus nigra") which can accompany it with a certain frequency. The common juniper ("Juniperus communis" subsp. "hemisphaerica") is habitually a secondary species of these groves. At high altitudes, they come in contact with forests of Scots pine and with the Savin juniper; the latter sometimes forming part of the shrubby stratum.