Alpine Shallow Cirque Floors Arctic willow – pink mountainheath-alpine laurel /smallwing sedge -shortstalk sedge (Salix arctica-Phyllodoce empetriformis/Kalmia polifolia/Carex microptera-Carex podocarpa)

Description

Current reference state- climate change does not greatly affect the vegetation community.
The 43A Alpine Shallow Cirque Floors ecological site is dominated by Salix arctica, which is a willow species with high ecological amplitude in that it can grow in both well drained and very poorly drained soils. Arctic willow has a circumpolar distribution and grows in tundra in the arctic and alpine. It is low-growing, forming dense, matted structures with round, shiny green leaves that are pubescent with long, silky, silvery hairs. It is dioecious, with male and female catkins on separate plants, which varies its appearance. It is a long-lived plant, growing extremely slowly. The site has a high cover of carex and juncus species. The carex species include smallwing sedge (Carex microptera), which is a facultative upland species, and shortstalk sedge (Carex podocarpa) which is a facultative wetland species. Other carex species include black alpine sedge (Carex nigricans) which is a facultative wetland designated plant and curly sedge (Carex rupestris) which is a faculatative upland. Rushes at the site include common spikerush (Eleocharis palustris) which is a wetland obligate species, and Drummond’s rush (Juncus drummondii) which is a wetland facultative species. Other species that have an affinity to wetland sites include wild chives (Allium schoenoprasum) which is facultative wetland species, fringed grass of Parnassus (Parnassia fimbriata) which is wetland obligate species, elephanthead lousewort (Pedicularis groenlandica) which is an obligate, Tiling’s monkeyflower (Mimulus tilingii) an obligate wetland species, purple monkeyflower (Mimulus lewisii) a facultative wetland species, arrowleaf ragwort (Senecio triangularis) which is facultative wetland, and American alpine speedwell (Veronica wormskjoldii), which is facultative wetland species. Other species present infrequently but in moderate cover include Rocky Mountain groundsel (Packera streptanthifolia), which is a facultative upland and pink mountainheath (Phyllodoce empetriformis), which is a facultative upland species.

This salix arctica dominated community has been found in other areas including the Canadian Rockies (Achuff and Corns 1982), on the Beaverhead National Forest (Cooper, 1999), in Colorado Rockies (Willard, 1979) and New Mexico (Baker, 1983). Reid (1999) found that this community type occurs throughout the West, on gently to moderately sloping alpine sites, on northerly aspects where snow lingers into the growing season. Salix reticulata and Polygonum bistortoides are common associates. The stands on saturated soils had Caltha leptosepala and Pedicularis groenlandica. A similiar site was found on drier sites that had salix arctica but lacked wetland associated species. It had Geum rossii, Sibbaldia procumbens, Erigeron melanocephalus, Agrostis spp., and Juncus drummondiana. Jones and Fertig (1999) found similiar wet and dry versions of this type on the Shoshone National Forest on both dry, windblown areas and wet, protected sites and on benches and talus slopes. Cooper (1999) found this wetter version salix arctica type to be wetland/turf hybrids in that sites were in potentially water-receiving positions close to snowbeds and turf communities and ephemeral springs with spongy ground throughout.

Submodel

Description

Climate change does affect the vegetation community in State 1.0 community phase 1.1 to the degree that there is a significant change in species composition that transitions 1.1 to that found in the relative community phase 2.1. It is predicted that the community will continue to be dominated by arctic willow, but that hydrophytic species of community phase 1.1 will be dramatically reduced at the site due to an increase in temperature leading to change in snowmelt timing, duration and amount, as well as late summer drier conditions. Arctic willow is a dioecious species with male and female plants, in which sex-specific physiological adaptations may enable the genders to occupy different habitats in which resources are particularly limited. Male and female plants responded differently to increased temperatures. As well, habitat differences in dry versus moist sites responded differently to experimental warming. In drier sites, peak season net assimilation in female willows tended to respond positively to summer warming while in males it was depressed. The differences also occurred in the moist sites, but were not significant (Jones, 1999). Arctic willow has relatively broad ecological amplitude and may be stable with climate change. In fact, Steltzer (2008) found that arctic willow had high genetic variation, a result of frequent sexual reproduction and this phenotypic variation would enable it to adapt and potentially prosper with climate change. Forb species are thought to have the most pronounced and varied reaction to increased temperatures and its effect on reproduction (Henry, 1997). Therefore, the changes to this wet, poorly drained ecological site dominated by arctic willow may be to lower the diversity and cover of associated hydrophilic forb species. Further research would be needed to understand the reaction of this ecological site to climate change.

Submodel