[4] The Sierra Juárez and San Pedro Mártir pine–oak forests are near the southern limit of the distribution of the California fan palm (Washingtonia filifera).

Endemic and near-endemic species include Amorpha apiculata (Fabaceae), Castilleja ophiocephala (Scrophulariaceae), Dudleya pauciflora (Crassulaceae), Ambrosia flexuosa, Stenotus pulvinatus, Cirsium trachylomum, Stephanomeria monocephala, and Artemisia martirensis (Asteraceae), and Echinocereus pacificus subsp.

[6] Native mammals include the puma (Puma concolor), desert bighorn sheep (Ovis canadensis nelsoni), mule deer (Odocoileus hemionus fuliginatus), bobcat (Lynx rufus), coyote (Canis latrans), fringed myotis (Myotis thysanodes), California chipmunk (Tamias obscurus), ornate shrew (Sorex ornatus),[3] and western gray squirrel (Sciurus griseus anthonyi).

[8] Native birds include the bald eagle (Haliaeetus leucocephalus), California condor (Gymnogyps californianus), pinyon jay (Gymnohinus cyanocephalus), and white-breasted nuthatch (Sitta carolinensis).

Laguna Hanson in Constitución de 1857 National Park is designated a Ramsar site (wetland of international importance).