Cleveland National Forest is a study in contrasts. Forest vegetation includes chaparral. Meadows and stream banks host magnificent oaks. Higher elevation provide Jeffrey and Coulter pine forest.

The first section of what is now Cleveland National Forest was the 50,000-acre Trabuco Ca'on Forest Reserve in the Santa Ana Mountains, created by President Harrison in February 1893. In February 1897, President Cleveland created the San Jacinto Forest Reserve from 700,000 acres, including the desert lands southeast of Palomar Mountain. Then in 1899, the area of the Trabuco Reserve was more than doubled in response to a petition by area residents.

President Roosevelt made additional additions to both the original Trabuco reserve and the San Jacinto Forest, including Palomar and Laguna Mountains, and south to the US-Mexico border. In 1908, he combined the two reserves to form Cleveland National Forest. Considerable land has been removed from the Forest over the years, via transfer of the San Jacinto unit to the San Bernardino National Forest, and return of non-forest lands to the public.

This forest, the southern-most protected forest land in California, spreads into three counties - San Diego, Orange, and Riverside - and primarily consists of conifer woodlands and chaparral. It is home to more than 78 sensitive, threatened or endangered plants and animals. Wilderness areas within the Forest include the Aqua Tibia, Hauser, Pine Creek, and the San Mateo Canyon. Wildlife includes the golden eagle, hawks, owls, deer, mountain lions, coyotes, gray foxes, and reptiles.