Name:
Picea mariana / Kalmia angustifolia Dwarf-shrubland
Reference:
Eastern Ecology Working Group of...
Description:
This heathland occurs in subalpine regions of northern New England and adjacent Canada, or at lower elevations in boreal coastal regions. It is found on acidic rock outcrops, upper ridges, or summits; a common subalpine setting is between the open alpine ridges and the lower-elevation forest. Exposed bedrock is typical; soil development is restricted to crevices or sheltered areas, where shallow organic accumulation occurs over thin a mineral layer, with shallow peat accumulating in depressions. The organic horizon may be saturated by fog in spring and fall but dry in summer. Soils are shallow, stony, coarse gravels and sands over gravel, scree or bedrock. Elevations range from 1800-4700 feet inland to near sea level in coastal regions. Physiognomy of this community is variable, ranging from sparse woodland to shrubland to sparsely vegetated rock; many occurrences will have patches of all three. The tree canopy is sparse, averaging less than 20%, and individuals are stunted. Most trees in this community actually fall into the "tall shrub" physiognomic form. Tall shrubs may be scattered, or form patches in somewhat protected areas. The dwarf-shrub layer is very well-developed, and the dominant feature of the vegetation. Herbs are sparse. The bryoid layer is variable but is often extensive, with both bryophytes and lichens. The most typical trees are Picea mariana and Picea rubens; associates include Abies balsamea, Betula papyrifera var. cordifolia, Betula papyrifera var. papyrifera, and occasionally Acer rubrum. Characteristic tall shrubs are Nemopanthus mucronatus, Sorbus americana, Sorbus decora, and Viburnum nudum var. cassinoides. Kalmia angustifolia and Ledum groenlandicum are prominent dwarf heaths, in association with others such as Vaccinium angustifolium, Vaccinium myrtilloides, Vaccinium uliginosum, Vaccinium vitis-idaea, Gaylussacia baccata, Rhododendron canadense, Empetrum nigrum, and Empetrum eamesii ssp. atropurpureum. At the higher elevations (>4000 feet), Kalmia angustifolia drops out, and Picea mariana replaces Picea rubens. Herbs include Sibbaldiopsis tridentata, Maianthemum canadense, Deschampsia flexuosa, and Geocaulon lividum. The bryoid layer includes Pleurozium schreberi, Polytrichum commune, Leucobryum glaucum, and Cetraria, Cladina, and Cladonia lichens. This community is distinguished from other northeastern subalpine/alpine types by the prevalence of dwarf-shrubs (rather than tree species or bare rock) and the lack of true alpine plants (Diapensia lapponica, Carex bigelowii, etc.). It differs from more temperate dwarf-shrublands in the presence of some more northern or boreal species, such as Ledum groenlandicum and Empetrum spp,. and the absence of temperate bald species such as Quercus rubra and Betula populifolia.
Accession Code:
VB.CC.25724.PICEAMARIANAKAL
Plot-observations of this Community Concept:
0
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