Name:
Boreal Glaciere Talus Sparse Vegetation
Reference:
Midwestern Ecology Working Group...
Description:
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 (= Arnica chionopappa), 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.
Accession Code:
VB.CC.25492.BOREALGLACIERET
Plot-observations of this Community Concept:
0
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