Name:
Pinus flexilis Woodland Alliance
Reference:
Western Ecology Working Group of...
Description:
Woodlands included in this alliance occur intermittently from timberline to lower montane and foothill zones throughout much of the Rocky Mountains, on escarpments and other geographic breaks in the northwestern Great Plains, and in mountains in the Great Basin and southern California. Elevations range from 850-3500 m. Sites are typically xeric on exposed, wind-swept rocky slopes and ridges from subalpine to foothills and prairie breaks. Some stands are on eroded substrates and resemble 'badlands' while others may occur on lava flows. These open woodlands occur on all aspects, but are most common on dry south- and west-facing slopes. Soils are typically shallow, skeletal and coarse-textured, such as gravelly, sandy loams or loams, but may include alkaline clays. Exposed bedrock is common and many stands have over 50% bare soil. The vegetation is characterized by an open canopy typically 3-10 m tall, but individuals may reach 15 m. Stands are solely dominated or codominated by the evergreen needle-leaved tree Pinus flexilis. Other trees species that may be present to codominant vary by geography and elevation zones throughout the woodland's range and include Pinus albicaulis, Picea engelmannii, or Pseudotsuga menziesii in the subalpine; Pinus contorta, Pinus ponderosa, or Pseudotsuga menziesii in the montane zone; and Juniperus osteosperma or Juniperus scopulorum in the lower montane transition zone from woodlands to grasslands or shrublands. In California, other associates may include Abies concolor, Pinus albicaulis, Pinus balfouriana, Pinus contorta, Pinus jeffreyi, and Pinus longaeva. The understory vegetation is typically sparse because sites are dry and have a large cover of rock. A sparse shrub layer may be present that includes tall shrubs such as Artemisia tridentata, Cercocarpus ledifolius, Jamesia americana, Rhus trilobata, Shepherdia canadensis, and Symphoricarpos oreophilus. Arctostaphylos uva-ursi, Artemisia arbuscula, Artemisia nova, Juniperus communis, Mahonia repens, Purshia tridentata, and Yucca glauca are the most frequent low shrubs. The herbaceous layer often dominates the understory and is composed primarily of graminoids such as Bouteloua gracilis, Calamagrostis purpurascens, Carex rossii, Festuca idahoensis, Festuca campestris, Leucopoa kingii (= Festuca kingii), Koeleria macrantha, Achnatherum hymenoides (= Oryzopsis hymenoides), and Pseudoroegneria spicata. Scattered forbs may include species of Achillea, Antennaria, Arenaria, Arnica, Astragalus, Erigeron, Eriogonum, Hymenopappus, Hymenoxys, Liatris, Sedum, Solidago, and Thermopsis.
Accession Code:
VB.CC.17987.PINUSFLEXILISWO
Plot-observations of this Community Concept:
0
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