Alpine Shallow Meadow yellow avalanche-lily-Scouler’s St. Johnswort-alpine leafybract aster-Sitka valerian- heartleaf arnica/Hitchcock’s smooth woodrush

Description

The vegetation community that defines the reference phase of43A Alpine Shallow Meadow ecological site includes perennial snow-loving forbs and grasses, sedges, and rushes. This site is very diverse with early, mid, and late season blooming forbs. The defining species include yellow avalanche lily (Erythronium grandiflorum), Scouler’s St. Johnswort (Hypericum scouleri), alpine leafybract aster (Symphyotrichum foliaceum), Hitchcock’s smooth woodrush (Luzula glabrata var. hitchcockii), shortstalk sedge (Carex podocarpa). There is a constant presence of subalpine fir (Abies lasciocarpa), but it provides very low cover. Species at this site are not wetland obligates, rather some may have moderate affinity to wetlands while others to uplands. Bear and rodent digging will churn up the soil and have an increase in bare ground which will lead to phase 1.3. In the event of sustained human trampling, the reference phase vegetation community will have an increase in bare ground, some soil compaction and trace to low cover of weedy species, which indicate phase 1.2.

This community goes through a phenological sequence of blooming. The earliest species to bloom, directly after snowmelt, is lanceleaf springbeauty (Claytonia lanceolata). This is followed by yellow avalanche-lily and then Hitchcock’s smooth woodrush. Shortstalk and smallwing sedges bloom in May through August. Next to bloom in June and July are pacific anemone (Anemone multifida), broadleaf arnica (Arnica latifolia), and nineleaf biscuitroot. Flowering from June through August are other Arnica species, autumn dwarf gentian (Gentianella amarella), Hitchcock’s smooth woodrush, and western meadow-rue (Thalictrum occidentale). In July and August, numerous species bloom including Aster species, splitleaf Indian paintbrush (Castelleja rhexifolia), western showy aster (Eurybia conspicua), Scouler’s St. Johnswort (Hypericum scouleri subsp. scouleri), arrowleaf ragwort (Senecio triangularis), Sitka valerian (Valeriana sitchensis), American alpine speedwell (Veronica wormskjoldii), and mountain deathcamas (Zigadenus elegans). Near summer’s end, the rushes bloom in July through September, including Drummond’s rush (Juncus drummondii) and Mertens’ rush (Juncus mertensianus). By mid-August, the subalpine fleabane blooms. Lastly, alpine leafybract aster (Symphyotrichum foliaceum) and sticky purple geranium (Geranium viscosissimum) bloom in August through September.

This community is considered intermediate in its snow-holding capacity: it holds less snow than the ecological site 43A Nivation Hollow (dominated by turf forming sedges), which can sit directly next to glaciers and perennial snowfields at the highest elevations, and has a concave position that holds snow longer than surrounding areas. The alpine shallow meadow ecological site, in contrast, is found primarily on toeslope positions of colluvial slopes or in gently rolling, slightly wind-protected positions on undulating landforms. Snow accumulates on these landforms and the growing season is only 3.5 to 4 months long. There are few species that tolerate these site conditions. Thus, there is an affinity of species between the Nivation Hollows and the Alpine Shallow Meadow vegetation communities, in that similar sedge species occur in both ecological sites, though in far different proportions. The Nivation Hollow community is dominated by sedges.

The 43A Alpine Shallow Meadow ecological site is generally moist and, for the most part, does not burn frequently. The closest fire regime to this ecological site is that of the Northern Rocky Mountain Alpine and Subalpine Meadows and Grasslands community (Landfire, 2005), which has a fire interval of 350 years for replacement fire interval and 750 years for mixed fire interval, the average for all fires is 239 years (Agee, 1993). The National Park Service (NPS) regards the fire return interval for the Logan Pass area (this area is dominated by the alpine shallow meadow ecological site) to be approximately 200 years, maybe up to 300 or more (personal communication, McClellan, NPS Fire Effects, 2016). Hitchcock’s smooth woodrush is a co-dominant at this ecological site. It is a short, rhizomatous perennial rush specie that regenerates into extensive colonies. It also reproduces via seed, which is dispersed by the splash cup method using raindrops, wind, or the vibrations of passing animals. It is considered an indicator of cold environments, found mainly where deep snow lies late at high elevations. Following fire, it resprouts from surviving rhizomes after the fire consumes all aboveground parts. Hitchcock’s smooth woodrush has been shown to increase in biomass following fire. Another of the main species found on this site is yellow avalanche-lily, a perennial forb with a deep corm. After fire, it can resprout from the corm. Yellow avalanche-lily is pollinated by bumblebees and other species of bees, and needs 100 days of cold stratification before germination. A fire would destroy that year’s seeds, preventing new plant establishment during the first post-fire year.

The 43A Alpine Shallow Meadow ecological site sustains disturbance from wildlife, particularly grizzly bears digging for the yellow avalanche-lily corms. Following digging disturbance, the seral progression proceeds from mineral soil colonized by moss species, then Hitchcock’s smooth woodrush, which forms a dense stand. Eventually, this is invaded by other forb species. Other animals that disturb this ecological site by digging for food or burrowing include gophers, marmots, voles, and other rodents. Yellow avalanche lily also is important forage for ground squirrels, sheep, cattle, horses, elk, and mule deer (Ellison, 1954).

Hansen et al. in 1995 found that certain species included in this site were generally good or fair forage for sheep, cattle, and horses including alpine leafybract aster, heartleaf arnica, fireweed, sticky geranium, and arrowleaf ragwort. These species were generally low in energy and protein value in the fall and winter. These species were general good to fair food value for elk, mule and whitetail deer, and antelope. Alpine leafybract aster and arrowleaf ragwort were deemed good to fair food value for upland, waterfowl, small mammals, and small non-game birds, while fireweed and sticky geranium were fair to poor in those categories.

The 43A Alpine Shallow Meadow ecological site is impacted by human trampling from visitors. In a long-term study monitoring visitor impact on Logan Pass in Glacier National Park, Hartley (2000) found that it took up to 30 years to recover after trampling treatments to pre-treatment ratios of vegetation, litter, and bare ground. Vegetation took 19-25 years to recover after trampling 15 times per week, and 25-30 years when trampled 50 times per week. In studies on trampling by Landals and Scotter (1973, 1974), it was found that the community type Sitka valerian subalpine forb meadow responded to repetitive trampling by a dramatic drop in canopy cover of 75 percent within 100 passes. It was categorized as being somewhat susceptible to both light and heavy trampling. This meant that it took 26-100 passes to reduce cover to 50 percent of the original condition. The relative cover after 800 passes was 8-15 percent, which was categorized as neither susceptible nor resistant. Alpine leafybract aster (Symphyotrichum foliaceum) was considered neither resistant nor sensitive to trampling, whereas heartleaf arnica and showy aster were considered sensitive species.

A yellow mountainheath subalpine meadow also was found to respond dramatically to trampling with a similar decrease in canopy cover. It was categorized as being somewhat susceptible to light trampling. This meant that it took 26-100 passes to reduce cover to 50 percent of the original condition. It was categorized as very susceptible to heavy trampling, meaning that relative vegetation cover after 800 passes was 0-3 percent.

Climate change may have an effect on this community. Altered temperature and precipitation regimes as well as changes in the extent of glaciers and snowpack will have a more pronounced effect on plants in the alpine. Plants in this ecological site are adapted to living in the harsh alpine environment with a short growing season. Changes to snowpack will particularly effect plants that are the earliest flowering species. Erythronium grandiflorum is one the earliest flowering species and was shown to flower earlier by 4.14 days per decade over a 30 year period (Lambert, 2010). Snowmelt was shown to be arriving earlier, which caused earlier flowering. Numerous animals rely on Erythronium grandiflorum and the shift in earlier flowering may have cascading effects. Queen bumblebees, broad tailed hummingbirds, elk, deer and grizzly beer rely on it for green vegetation food directly after snowmelt in early spring.

Submodel

Description

Intense grazing and/or human trampling with weedy species dominance. This community has sustained a dramatic reduction in foliar cover, species production or even a change in species composition from the Reference Community (1.1) due to intense grazing or trampling and an introduction, establishment and dominance of weedy species.

Submodel