Gambel oak is the only winter-deciduous oak in our region. Pine forest is more widespread in Chihuahua and Durango than in Sonora. Ponderosa pine replaces Arizona pine at the higher elevations in Chihuahua and on the northernmost sky islands. These closely-related pines can be found intermixed in the Santa Catalina Mountains in southern Arizona. Mountains ranges to the south have only Arizona pine, while the ranges to the north have only ponderosa pine.
Winters are cold and summers cool and moist.
It is most extensive in the northern sky islands and at the highest elevations in Chihuahua. Southward in Sonora, mixed conifer forest occurs in extremely limited areas on northfacing slopes and riparian canyons on north slopes. Because there are more extensive areas of higher elevation in Chihuahua the mixed conifer forest is more common there. These trees are commercially valuable for lumber.