Name:
Carex scirpoidea - Zigadenus elegans Herbaceous Vegetation
Reference:
Western Ecology Working Group of...
Description:
This is a small-patch herbaceous community found in Glacier National Park, Montana. It is associated with seep conditions providing a mesic to hygric moisture regime. Possibly the strongest determinant of this community is a strongly bimodal moisture regime; saturated and even having overland flow in spring and early summer and by mid to late summer subsurface flow ceases and soils dry rapidly due to warm site exposures. Within-type vegetation differences are explained by differences in water regime (considerable variation in when sites become dry, if ever) and amount of exposed rock. Plant cover is high (90+%) where continuous soils have developed but can be as low as 10% where rock cover exceeds 90%. The documented elevation range is from 1640 to 2190 m (5380-7185 feet). It is found primarily on west- to southwest-facing, moderate to steep slopes, mostly having greater than 45% inclination. This community often occurs in terrain with irregular relief owing to rock outcrops, stabilized fell-fields or talus with appreciable soil, or as a broad zone paralleling rivulets and the most incipient of first-order streams. Microsites of relatively flat outcrops of layered sedimentary rock accumulates organic humus with a high water-retention capacity providing in the aggregate an extensive substrate for this community.<br><br>The vascular plant cover is highly variable (8% to 98%) in this type, and more or less inversely proportional to rock exposure in the drier expressions of the type and on moister sites in inverse proportion to the bryophyte/lichen cover. Dwarf-shrubs are scattered, comprising not much more than 5% cover; the most constant being <i>Dasiphora fruticosa ssp. floribunda</i> and <i>Arctostaphylos uva-ursi</i>. On the more lush sites, <i>Carex scirpoidea</i>, the dominant, highly constant and diagnostic sedge, can approach a sward-like aspect, but on the rockier sites its cover may scarcely exceed a few percent. Other graminoids of high constancy but generally of low cover include <i>Danthonia intermedia, Festuca idahoensis, Festuca campestris (= Festuca scabrella)</i>, and <i>Poa alpina</i>. Alternatively, <i>Carex podocarpa, Carex spectabilis</i>, and <i>Deschampsia caespitosa</i> are present in the moister sites. Though generally typifying moist to hygric sites, this type can range to relatively wet environments as indicated by the presence of <i>Allium schoenoprasum, Triantha glutinosa (= Tofieldia glutinosa), Packera streptanthifolia (= Senecio cymbalarioides), Dodecatheon pulchellum, Parnassia fimbriata, Symphyotrichum foliaceum (= Aster foliaceus)</i>, and <i>Suksdorfia ranunculifolia</i>. A number of other mesic, high constancy forbs occur with low cover, including <i>Zigadenus elegans</i>. Forb cover tends to occur in patches and overall it seldom exceeds 30% cover, with individual species very seldom having more than 10% cover.
Accession Code:
VB.CC.32187.CEGL005866
Plot-observations of this Community Concept:
0
|
