Common (Translated Scientific) Name: Subboreal Glaciere Talus Sparse Vegetation

Colloquial Name: Subboreal Glaciere Talus

Hierarchy Level:  Association

Type Concept: This boreal talus community is found in the upper midwestern United States and in adjacent Canada in northern Ontario. Stands contain quartzite or other metamorphic or igneous rock talus slope or ''felsenmeer'' communities that are characterized by all-summer upwellings of cool, moist air near or at their bases. Glaciere talus forms as the result of periglacial frost and ice-wedging. Quartzite, in particular, is a brittle rock that is susceptible to frost-wedging. The talus slopes themselves consist of lichen-covered boulders ranging from 0.25-1 m in diameter. Nearly all sites occur in areas that were glaciated during the Pleistocene. The vegetation is physiognomically complex, tending to be shrubby with scattered trees and patches of ferns, mosses, and lichens. At the Wisconsin sites, there may occur scattered soil pockets that support scattered pines (Pinus strobus and Pinus resinosa). These are often associated with mossy beds of Polypodium virginianum. At the base of the talus slope, cold air upwells during the summer among the jumbled boulders along a narrow (3-20 m wide) front. Here, among the talus blocks, shrublands typically occur, dominated by Acer spicatum, Ribes glandulosum, and Cornus rugosa, under which is a dense carpet of ferns (mostly Polypodium virginianum) and rare and disjunct mosses and lichens. Scattered trees of Betula papyrifera, Acer saccharum, Acer rubrum, and Abies balsamea may be present. Rare plants present may include species disjunct from slightly to much farther north, such as Viburnum edule, Ribes oxyacanthoides, Clematis occidentalis, Ledum groenlandicum, and Abies balsamea. In general, this community type has been incompletely surveyed and occurrences should be carefully inspected for rare bryophytes, lichens, and terrestrial snails.

In Ontario (Ouimet Canyon and Cavern Lake), slow-melting ice is present throughout the summer among the talus blocks and arctic disjunct plants, such as Arenaria humifusa, Pyrola grandiflora, Carex atratiformis, Arnica lonchophylla ssp. lonchophylla, Salix myrtillifolia, Saxifraga paniculata, and Polygonum viviparum, occur. The moss Aulacomnium acuminatum is dominant and may comprise 90% of the ground cover. Scattered ''layering'' of small trees of Picea mariana and Betula papyrifera may occur in the cold upwelling zone, and Ledum groenlandicum is locally frequent.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: A proposed name for this type is Polypodium virginianum - Acer spicatum - Ribes spp. - Lichen species - Moss species Herbaceous Vegetation (E. Judziewicz and E. Epstein pers. comm. 1999). This type is related in geomorphological characteristics and (to a lesser degree) in floristic composition to Algific Talus Slope, ~Impatiens pallida - Cystopteris bulbifera - Adoxa moschatellina Algific Talus Rock Vegetation (CEGL002387)$$, which, however, is found on dolostone and strictly in unglaciated territory. The type may occur in extreme northeastern Minnesota, as many rare plants occur on the diabase and gabbro cliffs and talus there. But, apparently at these sites, the plants occur on the slopes, ledges, and tops of the talus slopes (Coffin and Pfannmuller 1988), and no cold air upwellings are reported from the base of the slope.

Similar NVC Types: No Data Available

note: No Data Available