Name:
Dryas octopetala - Carex elynoides - Silene acaulis Alpine Tundra Macrogroup
Reference:
NatureServe Biotics 2019
Description:
This macrogroup occurs at and above upper timberline throughout the Rocky Mountains cordillera from New Mexico and the Sierra Nevada north into southwestern Alberta and southeastern and south-central British Columbia. Vegetation physiognomy ranges from sparse cushion plants to dense turf or dwarf-shrublands. Most fell-field plants are cushioned or matted, frequently succulent, flat to the ground in rosettes, and often densely haired and thickly cutinized. Plant cover is 15-50%, while exposed rocks with crustose lichens make up the rest. Fell-fields are usually found within or adjacent to alpine dry turf. Common species include <i>Arenaria capillaris, Geum rossii, Kobresia myosuroides, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Phlox pulvinata, Silene acaulis, Trifolium dasyphyllum</i>, and <i>Trifolium parryi</i>. The moderately dense to dense cover of low-growing, perennial graminoids and forbs include <i>Artemisia arctica, Carex elynoides, Carex siccata, Carex scirpoidea, Carex nardina, Carex rupestris, Festuca brachyphylla, Festuca idahoensis, Geum rossii, Juncus drummondii, Kobresia myosuroides, Phlox pulvinata</i>, and <i>Trifolium dasyphyllum</i>. Dwarf-shrublands are characterized by a semi-continuous layer of ericaceous dwarf-shrubs or dwarf willows less than 0.5 m in height. Dense tufts of graminoids and scattered forbs occur. <i>Dryas octopetala</i>- and <i>Dryas integrifolia</i>-dominated communities occur on more windswept and drier sites than the heath communities. Within the heath-willow communities <i>Cassiope mertensiana, Salix arctica, Salix reticulata, Salix vestita</i>, or <i>Phyllodoce empetriformis</i> can be dominant shrubs. <i>Ledum glandulosum, Kalmia microphylla, Phyllodoce glanduliflora</i>, and <i>Vaccinium</i> spp. may also be shrub associates. Snowbed communities are characterized by <i>Sibbaldia procumbens</i> and <i>Carex subnigricans</i>. Species composition overlaps across the range of this macrogroup, although there is some significant regional and local variation. The drier alpine vegetation of the Great Basin ranges and Sierra Nevada may include lower elevation semi-desert species such as <i>Carex filifolia, Poa fendleriana, Poa secunda</i>, and <i>Artemisia frigida</i>. Environments are varied due to climatic and site variation. Wind and its effect on snow movement has a strong local effect, producing wind-scoured fell-fields, dry turf, snow accumulation heath communities, and short growing season snowbed sites. Fell-fields are typically free of snow during the winter as they are found on ridgetops, upper slopes and exposed saddles, whereas dry turf is found on gentle to moderate slopes, flat ridges, valleys, and basins where the soil has become relatively stabilized and the water supply is more-or-less constant. Dwarf-shrubland sites tend to be in level or concave areas with late-lying snow and subirrigation from surrounding slopes.
Accession Code:
urn:lsid:vegbank.org:commConcept:40505-{5A3987DA-4F2D-4139-BF1C-0D5321D2777D}
Plot-observations of this Community Concept:
0
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