Vegetation patterns in the North Black River peatland, northern Minnesota.

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, K_corr range 1.3-83 mu S 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 K_corr (range 31-182 mu S 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 k_corr (16-72 mu S 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 flows (in which water tracks develop) or stagnation zones (where bogs develop) on the peatland downslope.-from Author