Name:
Populus tremuloides / Festuca thurberi Forest
Reference:
Western Ecology Working Group of...
Description:
This high-elevation forest association is present in southern and western Colorado and occurs on both sides of the Continental Divide in the Colorado Rocky Mountains. It is also known to occur within the Valles Caldera National Preserve and Bandelier National Monument in north-central New Mexico, as well as on the Aquarius and Fish Lake plateaus in Utah. In Colorado, this association is found on gentle to moderately steep slopes (ranging from 6-30%) with variable slope aspects on soils which are moderately deep, loamy alluvium and colluviums derived from a wide variety of parent material. In New Mexico, it occurs on cold, mid to upper slopes and ridges on northerly aspects and on lower slopes to ridges on southerly aspects. In Utah, this association occurs on relatively gentle slopes on soils derived from either volcanic or granitic parent material. Elevations range from 2400 to 3110 m (8600-10,200 feet). The ground surface is characterized by scattered bunchgrasses and sedges intermixed with litter and some exposed soil. The vegetation within this type is characterized by an open-canopy forest overstory dominated by <i>Populus tremuloides</i> with the herbaceous understory dominated by <i>Festuca thurberi</i>.<br /><br />In north-central Colorado, this association is recognized by the overstory dominance and reproductive success of <i>Populus tremuloides</i> and the dominance of the undergrowth by <i>Festuca thurberi</i> (10-65% cover). Shrubs, weakly represented, include <i>Amelanchier alnifolia, Artemisia tridentata, Rosa woodsii</i>, and <i>Symphoricarpos oreophilus</i>. Other important graminoids are <i>Elymus trachycaulus (= Agropyron trachycaulum), Bromus anomalus, Carex geyeri, Poa nemoralis ssp. interior (= Poa interior)</i>, and <i>Achnatherum nelsonii ssp. dorei (= Stipa columbiana)</i>. Important forbs often include <i>Achillea millefolium, Carex siccata (= Carex foenea), Campanula rotundifolia, Chamerion angustifolium, Erigeron speciosus, Lathyrus lanszwertii var. leucanthus (= Lathyrus leucanthus), Fragaria virginiana, Potentilla gracilis, Pseudocymopterus montanus</i>, and <i>Vicia americana</i>. In south-central Colorado, overstories consist entirely of <i>Populus tremuloides</i>, with various species present in the understory (most frequently encountered conifer is <i>Picea engelmannii</i>). The most constant herbaceous plant species include <i>Festuca thurberi, Carex siccata, Achillea millefolium, Campanula rotundifolia, Chamerion angustifolium, Fragaria virginiana, Potentilla gracilis</i>, and <i>Pseudocymopterus montanus</i>.<br /><br />In north-central New Mexico, the understory is characteristically grassy (approaches 70% cover) and, other than scattered young <i>Populus tremuloides</i>, shrubs are absent. Other grasses and sedges may be abundant, including <i>Bromus ciliatus, Koeleria macrantha, Carex siccata</i>, and the introduced perennial grass <i>Poa pratensis</i>. Forbs are well-represented by a mix of forest and montane grassland species (e.g., forest species include <i>Galium aparine, Viola canadensis, Geranium richardsonii, Thalictrum fendleri</i>, and <i>Fragaria virginiana ssp. glauca</i>; meadow species include <i>Taraxacum officinale, Lathyrus lanszwertii var. leucanthus, Achillea millefolium, Campanula rotundifolia, Androsace septentrionalis</i>, and <i>Iris missouriensis</i>). The fern <i>Pteridium aquilinum var. pubescens</i> is also often well-represented. This aspen association may represent an invasion of a montane meadow grassland by trees.<br /><br />In Utah, shrubs, particularly <i>Symphoricarpos oreophilus</i>, are sometimes present but never abundant. The grasses most commonly associated with <i>Festuca thurberi</i> in the undergrowth are <i>Achnatherum occidentale (= Stipa occidentalis)</i> and <i>Elymus trachycaulus</i>. Occasionally, <i>Bromus carinatus</i> or <i>Poa pratensis</i> may be abundant. Forbs are seldom abundant and few have high constancy. The most common forbs are <i>Achillea millefolium</i> and <i>Taraxacum officinale</i>.
Accession Code:
VB.CC.33016.CEGL000585
Plot-observations of this Community Concept:
0
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