Joshua Tree National Park

On the border between the Mojave and Colorado Deserts, this area supports a rich and diverse flora and fauna. Plant communities range from low desert wash with desert willow, Chilopsis linearis, and palo verde, Cercidium floridum, to a pinyon-juniper forest, with single-leaved pinyon pine, Pinus monophylla, California juniper, Juniperus californica, and some scrub oak, Quercus turbinella.

The major communities are the Joshua tree woodland and the creosote bush scrub. The Joshua trees, Yucca brevifolia, form dense and extensive groves here. Other plants include the California juniper, scrub oak, bigberry manzanita, Arctostaphylos glauca, California buckwheat, Eriogonum fasciculatum, paper-bag bush, Salazaria mexicana, and thornbush, Lycium andersonii.

Among the plants forming the creosote bush scrub here are, in addition to the creosote bush, Larrea tridentata, mesquite, Prosopis glandulosa var. torreyana, goat-nut jojoba, Simmondsia chinensis, three Ephedra, Ephedra californica, Ephedra nevadensis and Ephedra viridis, and the Mojave yucca, Yucca schidigera.

Thare are several oases with California fan palms, Washingtonia filifera; the largest grova, with more than 100 palms, is in Lost Palms Canyon. At least seven rare plants are found in the Monument: Ayenia compacta, Cheilanthes parishii, Escobaria vivipara var. alversonii, Ditaxis californica, Leptodactylon jaegeri, Linanthus maculatus and Monardella robisonii.

A wide variety of animal life is present. The largest, mammal is the desert bighorn, Ovis canadensis; approximately 100 individuals inhabit the Monument but are infrequently seen. The more commonly sighted mammals include the antelope squirrel, Ammospermophilus leucurus, and kangaroo rat, Dipodomys spp. Over 230 species of birds have been observed in the area; many are migrants but a number are resident in or near the oases. Over 20 species of reptiles have been sighted, perhaps the most common being side-blotched lizard, Uta stansburiana, and the chuckwalla, Sauromalus obesus.

Several mountain ranges are included in the Monument, the Little San Bernardinos, Pinto, Eagle, Hexie, Cottonwood and Coxcomb. All but the latter two are considered a part of the Transverse Range Province. Rocks of several eras are present but the two dominant types are the Pinto gneiss, a dark rock composing the bulk of the mountains and dating to the Pre-Cambrian. Intruded into the gneiss are numerous outcrops of a light gray or pinkish quartz monzonite (adamellite) dating from the mid-Jurassic or Cretaceous era. Many of these outcrops have eroded into unusual forms. Much of the Pinto Basin is Quaternary alluvium or lake deposits and in the Pinto Mountains there are late Pleistocene or Recent basalt flows overlying some of the lake deposits.

Integrity: Though there are some abandoned mines as well as roads, camping areas, nature trails, buildings and other facilities, much of the area is virtually undisturbed.

Use: Research, educational, observational, light recreation.

Ref: Miller, A. H. and R. C. Stebbins, 1974. The Lives of Desert Animals in Joshua Tree National Monument. Univ. of Calif. Press, Berkeley, 452 pp.

August 1976