INFLUENCE OF SOIL PROPERTIES ON THE BIOGEOCHEMISTRY OF A BEAVER MEADOW HYDROSEQUENCE

Previous research about the biogeochemistry of beaver (Castor canadensis Kuhl) impoundments has generally overlooked the influence of soil type on solutes. In this study, soils derived from glacio-lacustrine and glacio-fluvial parent materials in northern Minnesota beaver meadows (i.e., former beaver ponds that have drained and revegetated) were studied to: (i) describe soil morphology, (ii) analyze soil and solute chemistry, and (iii) statistically evaluate the relative influence of hydrology and soil type on solute chemistry. With decreasing depth to groundwater, soils in both hydrosequences were increasingly reducing; redox potentials were consistently negative in the Borosaprist. Differences in soil morphology associated with increasing wetness included: (i) increasing thickness of O and A horizons, (ii) decreasing thickness of the Pt horizon (glacio-lacustrine hydrosequence), (iii) disappearance of E and Bk horizons (glacio-lacustrine hydrosequence), and (iv) decreasing depth to redoximorphic features. In the glacio-lacustrine hydrosequence, depth to subsurface concentrations of oxalate-extractable Fe (greater than or equal to 800 g m(-3)) decreased with increasing wetness. Two-way ANOVA indicated that differences in water chemistry among soils were due to moisture, parent material, and their interaction. Increasing moisture was associated with increased concentrations of Fe2+, Ca2+, and Mg2+ and decreased concentrations of SO4-S. Glacio-lacustrine soils contained higher concentrations of base cations (K+, Ca2+, and Mg2+) than did glacio-fluvial sails, and so did their soil water. There were pronounced seasonal variations in cation concentrations and significant interannual differences for NH4-N, total N, and K+. Nitrate concentrations were consistently low and did not differ significantly among any of the groupings.