The vegatation, surface water chemistry and peat chemistry of moderate-rich fens in central Alberta, Canada

Abstract

The non-forested fens of the Athabasca area in central Alberta, Canada are characterized by their surface water and peat chemistry. Correlations between vegetation and chemical gradients are examined. The primary vegetation gradient is from stands dominated byDrepanocladus vernicosus, Meesiatriquetra, Menyanthes trifoliata, andCarex chordorrhiza to those dominated byBrachythecium mildeanum, Drepanocladus aduncus, Carex aquatilis, andDrepanocladus polycarpus. This vegetation gradient reflects a chemical gradient of increasing pH, magnesium, sodium, sulphur, organic nitrogen, and phosphorus in the fen water and increasing magnesium, iron, and phosphorus in the fen peats. Potassium and sodium in the fen peats show a decreasing trend along the vegetation gradient. A second gradient from shrub-moss vegetation to sedge-moss vegetation is significantly correlated with microtopography and an increase in nitrate content in the spring (May) waters. The fen waters in this study are in the 5.3–7.1 pH range, with specific conductance of 18–240μS. The calcium contents of the waters averages 19.5–22.1 mg/l and that of magnesium averages 4.3–5.3 mg/l in spring and fall, respectively. The subsurface fen peats are characterized by mean calcium contents of 17,426 mg/kg and magnesium contents of 1,719 mg/kg. Organic nitrogen, nitrate, and ammonium content in the spring and fall waters average 1,967–2,395 μg/l, 3.1–9.8 μg/l, and 16.8–88.9 μg/l, respectively.