Mojave Desert Chaparral

This ecological system is composed of evergreen shrublands or dwarf-woodlands on sideslopes transitioning from low-elevation desert landscapes up into woodlands of the western Mojave and Sonoran deserts. It extends from northeast Kern County, California, into Baja Norte, Mexico. Associated species include Quercus john-tuckeri, Quercus cornelius-mulleri, Quercus berberidifolia, Arctostaphylos patula, Arctostaphylos pungens, Arctostaphylos glauca, Rhus ovata, Cercocarpus montanus var. glaber, Ceanothus greggii, Garrya flavescens, Juniperus californica, and Nolina parryi. Sometimes Juniperus californica forms an open, shrubby tree layer over the evergreen oaks and other shrubs.

This ecological system is composed of evergreen shrublands or dwarf-woodlands. Associated species include Quercus john-tuckeri, Quercus cornelius-mulleri, Quercus berberidifolia, Arctostaphylos patula, Arctostaphylos pungens, Arctostaphylos glauca, Rhus ovata, Cercocarpus montanus var. glaber (= Cercocarpus betuloides), Ceanothus greggii, Garrya flavescens, Juniperus californica, and Nolina parryi. Sometimes Juniperus californica forms an open, shrubby tree layer over the evergreen oaks and other shrubs. The floristic description is based on several references including Cable (1975a), Carmichael et al. (1978), Brown (1982a), Cope (1992b), Howard (1993), Reid et al. (1999), Comer et al. (2003), League (2005), Gucker (2006e), Hauser (2007), Sawyer et al. (2009), and NatureServe Explorer (2011).

This ecological system occurs on sideslopes transitioning from low-elevation desert landscapes up into woodlands of the western Mojave and Sonoran deserts. It extends from northeastern Kern County, California, into Baja Norte, Mexico. This system includes chaparral on sideslopes transitioning from low-elevation desert landscapes up into pinyon-juniper and ponderosa pine woodlands of the western Great Basin between 1220 and 2135 m (4000-7000 feet) elevation. Adjacent upland systems include Madrean Encinal (CES305.795), Madrean Pinyon-Juniper Woodland (CES305.797) or Great Basin Pinyon-Juniper Woodland (CES304.773) above and at lower elevations, Sonoran Mid-Elevation Desert Scrub (CES302.035) and Mojave Mid-Elevation Mixed Desert Scrub (CES302.742). The environmental description is based on several references, including Cable (1975a), Carmichael et al. (1978), Brown (1982a), Cope (1992b), Howard (1993), Reid et al. (1999), Comer et al. (2003), League (2005), Gucker (2006e), Hauser (2007), Sawyer et al. (2009), and NatureServe Explorer (2011).

Most chaparral species are fire-adapted, resprouting vigorously after burning or producing fire-resistant seeds. Stands occurring within montane woodlands are seral and a result of recent fires. Disturbance dynamics in this system are variable because of variation in composition of dominant species; however, most dominant shrubs are evergreen species that are adapted to medium frequency, medium to large-sized and medium- to high-intensity fire, in late summer or fall. Some species, such as Arctostaphylos patula, Cercocarpus montanus, Garrya flavescens, Quercus cornelius-mulleri, Quercus berberidifolia, Quercus john-tuckeri, and Rhus ovata, are generally top-killed in burns, but then vigorously resprout from root crown or buried lignotubers (Gucker 2006e, Hauser 2007, Sawyer et al. 2009). Most also have seeds stored in soil and duff that need fire scarification to germinate. Other chaparral shrub, such as Arctostaphylos glauca, Arctostaphylos pungens, Ceanothus greggii, and Juniperus californica, are killed or sprout only weakly after fire and regenerate from fire-scarified seeds in the seedbank (Cope 1992b, Howard 1993, Zouhar 2000, League 2005, Sawyer et al. 2009). Some deciduous species such as Cercocarpus montanus are also adapted to fire, vigorously resprout after burning and have fire-scarified seeds (Gucker 2006e). Fire-return interval (FRI) for this systems is medium (10-100 years) on most of the dominant species (Howard 1993, Zouhar 2000, League 2005, Gucker 2006e, Sawyer et al. 2009). Fire-return intervals for Juniperus californica-dominated stands are between 100 and 200 years (Sawyer et al. 2009).

The foliage of most of these chaparral shrubs is utilized as browse at least to some degree (new growth) by big game species with Ceanothus greggii, Cercocarpus montanus, and Garrya wrightii being especially important (Howard 1993, Zouhar 2000, Gucker 2006e). Small mammals and birds use the acorns and fruits of many of the dominant chaparral species (Cable 1975a, Howard 1993, Zouhar 2000, League 2005, Gucker 2006e).

Chaparral shrubs are generally considered to be poor forage for cattle (USFS 1937), but good for domestic goats (Cable 1957, 1975a); however, the more open shrub stands may have a moderate to dense grass layer. Much of this chaparral system has been impacted by livestock use because of high accessibility and relatively gentle terrain, especially in lower-elevation stands (Brown 1982a).

Human development has impacted many locations throughout the ecoregion. High- and low-density urban and industrial developments also have large impacts. For example, residential development has significantly impacted locations within commuting distance to urban areas. Impacts may be direct as vegetation is removed for building sites or more indirectly through natural fire regime alteration, and/or the introduction of invasive species. Mining operations can drastically impact natural vegetation. Road building and power transmission lines continue to fragment vegetation and provide vectors for invasive species.

This system occurs in the western Mojave and Sonoran deserts, from northeast Kern County, California, into Baja Norte, Mexico.