Name:
Saxifraga bronchialis Scree Slope Alpine Sparse Vegetation
Reference:
NatureServe Biotics 2019
Description:
This subalpine to alpine community has been found across the north-south extent of Glacier National Park, Montana, and also is found in Waterton Lakes National Park, Alberta. This small-patch scree community occurs predominantly on steep to very steep (36 to 70%) talus slopes of all aspects; however, less frequently it has been noted on fell-fields of level ridges, reflecting a highly variable degree of substrate stability. Unconsolidated, unvegetated and actively moving scree mantles the slope between the vertically elongated vegetation patches. Disturbance, mass wasting on the steep slopes and congeliturbation on level summits and ridgetops, is the primary driver of structural and floristic composition. This type has been noted between 1500 and 2380 m (4920-7810 feet), occurring on red and green argillites. Exposed rock is mostly greater than 75%, and the rest of the ground surface is composed of litter (about 10% average cover) and moss/lichen (averaging about 15% cover); mineral soil is present in slightly greater than trace amounts. Soil development is minimal; what little organic and inorganic matter that accumulates does so under the protective mat of <i>Saxifraga bronchialis</i>. The indicator species for this community, <i>Saxifraga bronchialis</i>, has a highly variable cover, from trace amounts in exceedingly rocky expressions to approaching 20%. It consistently has the greatest cover of any vascular species, establishing in dense mats that act to block the movement of scree, which lodges upslope against the stout cushions. <i>Dasiphora fruticosa ssp. floribunda</i> is regularly present as a trace subshrub. Some forbs are broadly distributed (in trace amounts) across the type, including <i>Sedum lanceolatum, Achillea millefolium, Cerastium arvense, Poa secunda</i>, and <i>Eriogonum ovalifolium</i>. Other herbs appear to be elevationally stratified; those of lower elevations being <i>Woodsia scopulina, Penstemon albertinus, Selaginella wallacei, Pseudoroegneria spicata</i>, and <i>Artemisia michauxiana</i>, whereas at higher elevations (mostly above 2000 m) are found <i>Potentilla diversifolia, Poa alpina, Solidago multiradiata, Festuca brachyphylla, Penstemon ellipticus</i>, and <i>Sibbaldia procumbens</i>. Lichens and mosses generally comprise less than 10% combined cover, with no species particularly indicative of this environment.
Accession Code:
urn:lsid:vegbank.org:commConcept:34555-{B1491855-0893-47FA-831E-86EAE843D34E}
Plot-observations of this Community Concept:
0
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