Vegetation patterns in the North Black River peatland, northern Minnesota

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Abstract
Raised bogs and water tracks in the 193-km2 North Black River peatland in northern Minnesota were examined in relation to the vegetation, water chemistry, and surficial water movements as inferred from infrared aerial photographs, LANDSAT imagery, and orthophoto topographic maps. Two noda of bog vegetation were distinguished by the Braun–Blanquet system; both bog noda are associated with relatively dilute, acidic waters (pH range 3.9–4.1; Ca2+ concentration range 0.6–1.6 mg L−1; specific conductivity, Kcorr range 1.3–83 μS cm−1). Rich-fen vegetation in contrast is more variable within this peatland and generally occurs in water tracks with a correspondingly wide range of pH (range 5.0–6.2), Ca2+ concentration (range 3.6–30.4 mg L−1), and Kcorr (range 31 to 182 μS cm−1). Poor-fen vegetation was most distinguishable by the transitional nature of its vegetation and water chemistry with at least a few minerotrophic indicator species present in all cases and intermediate ranges in pH (3.7–5.2), Ca2+ concentration (0.6–5.5 mg L−1), and Kcorr (16–72 μS cm−1). Bog and fen patterns in this peatland are consistently related to topographic features along the upland crest of each peatland watershed, indicating that topography controls the path of minerotrophic runoff draining onto the peatland, and thus creating zones with either enriched minerotrophic flow (in which water tracks develop) or stagnation zones (where bogs develop) on the peatland downslope.