Name:
Pinus edulis - Juniperus osteosperma Grassy Open Woodland Alliance
Reference:
NatureServe Biotics 2019
Description:
This woodland alliance is characterized by diagnostic tree species <i>Pinus edulis</i> that forms a very open to moderately dense tree layer often with <i>Juniperus osteosperma</i> or, less frequently, <i>Juniperus monosperma</i> within the range of <i>Juniperus osteosperma</i> in northern Arizona. <i>Juniperus osteosperma</i> may also dominate stands as long as there is significant presence of <i>Pinus edulis</i> (not accidental) to characterize the stand as a pinyon-juniper stand and not the more xeric, typically lower elevation <i>Juniperus osteosperma</i> woodland and savanna. At higher elevations and relatively mesic sites, such as along drainages, <i>Juniperus scopulorum</i> may be present and sometimes dominant. Other conifers are absent or accidental with very low cover. The understory is characterized by an open to dense herbaceous layer. Scattered shrubs may be present but do not form a layer and do not exceed cover of the herbaceous layer. Perennial grasses typically dominate the herbaceous layer, although diverse forbs species are often present, but with low cover. Characteristic species include <i>Achnatherum hymenoides, Bouteloua gracilis, Elymus elymoides, Hesperostipa comata, Hesperostipa neomexicana, Leymus salinus, Muhlenbergia pungens, Poa fendleriana, Poa secunda, Pleuraphis jamesii</i>, and <i>Pseudoroegneria spicata</i>. The non-native, invasive annual grass <i>Bromus tectorum</i> becomes abundant in disturbed stands and may dominate the understory of highly disturbed stands. Some stands included in this alliance have been seeded with non-native perennial grasses such as <i>Psathyrostachys juncea</i> or <i>Agropyron cristatum</i> to control soil erosion or increase forage production and now have a semi-natural understory. This alliance occurs on warm, dry sites on mountain slopes, foothills, and plateaus in the Colorado Plateau extending east into the west slope of the southern Rocky Mountains. The climate of the region is semi-arid with drought not uncommon. Stands typically occur on nearly level to moderately steep, rocky slopes on hillsides and mesatops. Aspect does not seem important except in elevational extremes for a given latitude where low-elevation stands are restricted to the more mesic north slopes; canyons and high-elevation stands occur on south aspects. Sites are typically dry with shallow, rocky, calcareous and alkaline soils. Other sites include eroded "badlands," lava flows, scree slopes, and deep sands.
Accession Code:
urn:lsid:vegbank.org:commConcept:38792-{E22E9AD6-709F-4665-9A0B-2B12E00F4663}
Plot-observations of this Community Concept:
0
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