. The Canadian field-naturalist. 196 The Canadian Field-Naturalist Vol. 97 Results The Grand Marais fen consists of a wet marginal lagg, an inner swamp forest, and a central patterned area with strings and flarks. The marginal lagg is dominated by Thuja occidentalis (White Cedar) and Alnus rugosa (Speckled Alder) whereas toward the interior Picea mariana (Black Spruce) is dominant. The spruce trees become progressively restricted to sinuous peat ridges toward the center as the swamp forest gives way to patterned fen. The central strings and flarks are clearly distinguished by their character-
. The Canadian field-naturalist. 196 The Canadian Field-Naturalist Vol. 97 Results The Grand Marais fen consists of a wet marginal lagg, an inner swamp forest, and a central patterned area with strings and flarks. The marginal lagg is dominated by Thuja occidentalis (White Cedar) and Alnus rugosa (Speckled Alder) whereas toward the interior Picea mariana (Black Spruce) is dominant. The spruce trees become progressively restricted to sinuous peat ridges toward the center as the swamp forest gives way to patterned fen. The central strings and flarks are clearly distinguished by their character- istic species assemblages and landform patterns (Fig- ure 2; Table I and 2). The flarks are progressively better developed toward the center of the fen as first Carex limosa (Sedge) and then Rhynchospora alba (Beak-rush) attain dominance. The central flarks are characterized by relatively flat, wet carpets of Sphagnum majus, with Carex limosa, Rhynchospora alba, Menyanthes trifoliata (Buckbean), Scheuchzeriapalustris, Utricu- p-^tf- laria cornuta (Bladderwort), and Drosera intermedia (Sundew). In places, pools of standing water occur with mud bottoms and a sparse cover oi Menyanthes trifoliata and Utricularia intermedia (Bladderwort). The string vegetation also varies continuously from the margins to the interior of the patterned area. Along the margins, strings are dominated by Carex rostrata (Sedge) and Carex lasiocarpa (Sedge), which also grow profusely in the hollows. Only Picea mari- ana is restricted to the string-like ridges in this area. Toward the center, however, the strings are more sharply defined by well-developed hummocks of Sphagnum magellanicum, S. fuscum, and S. rubel- lum, with Aulocomnium palustre and Polytricum juniperinum var. affine. An apron of Sphagnum angustifolium commonly spreads out from the lower margins of these strings and merges with the adjacent flark. The strings contain stunted trees of Picea mari- ana, with an understory of Carexpauciflora (S
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