Physiognomy and Structure: No Data Available

Floristics: Within Salinas Pueblo Missions National Monument in central New Mexico, this Madrean woodland or savanna is characterized by an open canopy of mature Juniperus monosperma; saplings or seedlings are also common. Occasionally seedling or sapling Pinus edulis can be present, commonly under the canopy of Juniperus monosperma. The understory is characterized by scattered bunches of Muhlenbergia pauciflora with a scattering of forbs. Within White Sands Missile Range in south-central New Mexico, this woodland is dominated by abundant Juniperus monosperma, with a grassy understory dominated by Muhlenbergia pauciflora. Scattered mature Pinus edulis may also be present. The shrub layer can be well-represented by a wide variety of species (38 species), with Gutierrezia sarothrae, Rhus trilobata, and Yucca baccata being the most abundant and constant. Cercocarpus montanus may also be present but is not dominant. In addition to Muhlenbergia pauciflora, other grasses may be well-represented or abundant, including Bouteloua curtipendula, Hesperostipa comata, Muhlenbergia setifolia, Tridens muticus, and Achnatherum scribneri (= Stipa scribneri). A wide variety of forbs can occur, but forb species richness and abundance on a stand-by-stand basis are low; Lesquerella fendleri, Melampodium leucanthum, and Viguiera dentata are most constant (Muldavin et al. 2000b).

Dynamics:  Juniperus monosperma is extremely drought-tolerant. It is also non-sprouting and may be killed by fire (Wright et al. 1979). The effect of fire on a stand is largely dependent on the tree height and density, fine fuel load on the ground, weather conditions, and season (Dwyer and Pieper 1967, Wright et al. 1979). Trees are more vulnerable in open stands where fires frequently occur in the spring, the relative humidity is low, wind speeds are over 10-20 mph, and there is adequate fine fuels to carry fire (Wright et al. 1979, Fischer and Bradley 1987). Under other conditions, burns tend to be spotty with low tree mortality. Large trees are generally not killed unless fine fuels, such as tumbleweeds, have accumulated beneath the tree to provide ladder fuels for the fire to reach the crown. Closed-canopy stands rarely burn because they typically do not have enough understory or wind to carry a fire. Altered fire regimes, cutting trees for fencing, and improper grazing by livestock have significant impacts on the quality of sites. Grazing by livestock can modify the fire regime by removing the fine fuels that carry fire. Juniperus monosperma invasion into grasslands has occurred in places. Control efforts by chaining and prescribed burning have mixed results. More study is needed to understand and manage these woodlands ecologically.