Montane alder - heath shrub thicket (S1)
Montane alder - heath shrub thickets are dominated by tall shrubs and are restricted to flat ridges and slopes near the transition to heath - krummholz communities and in certain high-elevation valleys in the White Mountains. Scattered trees are usually present. It may be expected in other parts of northern New Hampshire, though the similar alder wooded fen (which features fewer tall heath shrubs) is more common.
Soils are characterized by shallow organics over hydric, cryic, silty gravels. Organic soil depths are generally shallower than those in the related montane sloping fen community. Near-surface water pH is 5.0. Hummock and hollow topography is moderately developed.
This community differs from more lowland shrub thickets by the absence of more southern or coastal species such as highbush blueberry (Vaccinium corymbosum), black huckleberry (Gaylussacia baccata), and Virginia chain-fern (Woodwardia virginica). It differs from alder wooded fens by having more abundant heaths and other northern shrubs.
Characteristic Vegetation: Speckled alder (Alnus incana), rhodora (Rhododendron canadense), mountain holly (Nemopanthus mucronatus), witherod (Viburnum nudum), Labrador tea (Ledum groenlandicum), and blueberries (Vaccinium spp.) are common beneath a scattered overstory of black spruce (Picea mariana) or larch (Larix laricina). Scattered herbaceous plants, usually found in small openings in the community, may include tawny cotton-grass (Eriophorum virginicum), round-leaved sundew (Drosera rotundifolia), three-seeded sedge (Carex trisperma), Pickering's bluejoint (Calamagrostis pickeringii), tall meadow-rue (Thalictrum pubescens), flat-topped white aster (Doellingeria umbellata), white turtlehead (Chelone glabra), inflated sedge (Carex intumescens), and northeastern mannagrass (Glyceria melicaria). Peat mosses are abundant, and hummock and hollow microtopography is moderately developed.
Good examples of this community can be seen in the watershed of the upper East Branch of the Pemigewasset River near Shoal and Ethan Ponds in the White Mountains, at elevations above 2,400 ft.
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