Oak - Mexican Pinyon Pine - Juniper Woodland
An open, evergreen woodland community. Grasses typically comprise most of the understory. In the Memorial, this association occurs mostly on the north- and south-facing slopes. Dominant species vary with site, slope, and exposure. For example, nearly pure stands of oak occur on the south face of Montezuma Peak, while Pinyon pine and juniper dominate the north-facing slope near the head of the drainage containing Joe's Canyon Trail. Typical plant species include alligator juniper, Arizona white oak (Quercus arizonica), Emory oak (Q. emoryi), manzanita (Arctostaphylos spp.), Mexican blue oak (Quercus oblongifolia), mountain mahogany (Cercocarpus montanus), beargrass (Nolina microcarpa), desert spoon (Dasylirion wheeleri), and side oats grama (Bouteloua curtipendula). 

The Grama Grass (Bouteloua spp.) - Mixed Grass-Mixed Shrub Grassland
Largely a Chihuahuan semi-desert grassland community dominated by perennial grasses and shrubs. This association encompasses over 1,000 acres (430 ha) in the eastern third of the Memorial. Characteristic plant species include fairy duster (Calliandra eriophylla), rabbit brush (Chrysothamnus nauseosus), hedgehog cactus (Echinocereus pectinatus), Palmer agave (Agave palmeri), Lehman lovegrass (Eragrostis lehmanniana), and blue grama (Bouteloua gracilis). Lehman lovegrass, a species introduced form South Africa, appears to be spreading naturally throughout much of southern Arizona to the detriment of more palatable native grasses. Arizona white oak, Emory oak and honey mesquite (Prosopis glandulosa) are scattered throughout the habitat. 

The Western Honey Mesquite - Mixed Short Tree Woodland
A type of Sonoran Desert riparian forest that typically occurs below 3,900 feet (1190 m). It is restricted to streams, springs, along ephemeral drainages, and areas that have a shallow water table. Trees do not usually form a closed canopy in this association. This association is a minor biotic community in the Memorial. It covers only 224 acres (91 ha) and occurs in the eastern third of the park along drainages of lower Montezuma Canyon. Typical species of this association include Arizona white oak, desert willow (Chilopsis linearis), Emory oak, honey mesquite, poison ivy (Rhus radicans), rabbit brush, sumac (Rhus virens), cane cholla (Opuntia spinosior), Lehman lovegrass, and side oats grama. Relatively dense stands of desert willow and occasional honey mesquites are scattered along drainages in the southeastern corner of the Memorial. 

The Arizona Sycamore (Platanus wrightii) - Arizona Walnut (Juglans major) - Oak Riparian Forest
A mixed-broadleaf forest community that often forms a well-developed gallery, but has a depauperate understory. This association occurs along major and secondary drainages in which water is perennial or seasonally intermittent, such as in middle or upper Montezuma Canyon. Consequently, this association comprises only about 100 acres (40 ha), a minor portion of the Memorial. Plant species typical of this association include Arizona white oak, Arizona rosewood (Vauquelinia californica), Arizona sycamore, catclaw acacia (Acacia greggii), manzanita, brickellia (Brickellia sp.), wild grape (Vitis arizonica), and needle grass (Stipa sp.). 

Effects of The Peak Fire
The Peak Fire of June 1988, originated in Mexico, but spread into the United States, and affected most of Coronado National Memorial. The Oak - Mexican Pinyon Pine - Juniper Woodland Association was most affected, as about 2,600 acres (1050 ha) of the 3,700 acres (1500 ha) that burned were in this habitat. Most of this biotic community was burned to a moderate degree, except for some severely burned areas in the western portion of the Memorial. The Oak - Mexican Pinyon Pine - Juniper Woodland Association was probably most affected by the fast-moving, intense fire in continuous grass fuels. However, many of the trees had resprouted either from the roots or from undamaged areas of the trunk by August 1989. The species composition of the woodland understory was significantly changed after the fire, probably due to the influx of nutrients and/or appropriate conditions for germination of numerous herbaceous species that were either rare or absent before the fire. 

The Grama Grass - Mixed Grass - Mixed Shrub Association was relatively unaffected by the fire because little fuel was present to sustain a high temperature fire. Consequently, the effect of the fire on this habitat was largely ephemeral as most of these species are fire adapted and quickly resprout from roots.