Name:
Alnus incana ssp. rugosa - Ilex mucronata / Sphagnum spp. Acidic Peatland
Reference:
NatureServe Biotics 2019
Description:
This alder-dominated community is associated with peatlands across northern New England and adjacent Canada. It is most often found at the landward edge of acidic peat mats (i.e., the lagg), where it receives slightly more enriched waters than those of the adjacent oligotrophic or ombrotrophic peatland. Nitrogen levels are higher than in other peatland communities, presumably as a result of nitrogen fixing by the alders. Occasionally, it occurs in a montane setting (>730 m [2400 feet]) on thin organic soils over coarse cryic soils. Tall shrubs are the dominant physiognomy, with at least 50% cover; trees may be present but are sparse. Herb cover varies from sparse to extensive depending on the shrub cover. The bryophyte layer is well-developed, usually with at least 50% cover. <i>Alnus incana ssp. rugosa</i> is the dominant or characteristic tall shrub; <i>Ilex verticillata</i> or <i>Ilex mucronata</i> are often present and sometimes abundant. Other shrubs include <i>Alnus viridis, Viburnum nudum var. cassinoides, Vaccinium corymbosum</i>, or <i>Spiraea tomentosa</i>. A tree canopy is lacking, but there may be scattered trees of <i>Acer rubrum, Picea mariana, Thuja occidentalis</i>, or <i>Abies balsamea</i>. Dwarf-shrub cover is variable, with <i>Rhododendron canadense</i> and <i>Chamaedaphne calyculata</i> the most typical, and <i>Kalmia angustifolia, Gaylussacia baccata</i>, and <i>Ledum groenlandicum</i> often also present. (<i>Ilex mucronata, Picea mariana, Thuja occidentalis, Abies balsamea</i>, and <i>Ledum groenlandicum</i> drop out at the southern extent of the range.) The most characteristic herbs are <i>Carex trisperma, Calla palustris</i>, and <i>Osmunda cinnamomea</i>; other species include <i>Triadenum virginicum, Carex intumescens, Carex magellanica ssp. irrigua, Doellingeria umbellata, Iris versicolor, Gaultheria hispidula, Lysimachia terrestris, Maianthemum trifolium, Onoclea sensibilis, Sarracenia purpurea, Thalictrum pubescens</i>, and <i>Trientalis borealis</i>. The bryoid layer consists of <i>Sphagnum</i> spp., including <i>Sphagnum recurvum, Sphagnum palustre, Sphagnum fallax</i>, and <i>Sphagnum magellanicum</i>. The combination of <i>Alnus incana</i> dominance with <i>Ilex mucronata</i> and understory plants characteristic of peatlands is diagnostic.
Accession Code:
urn:lsid:vegbank.org:commConcept:34806-{E3B8AF6E-D2A9-4287-A29E-12FD36E27A2F}
Plot-observations of this Community Concept:
12
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