| Concern over damage to wetlands caused by cultural practices prompted our efforts to develop methods that can be used to monitor the ecological condition of wetlands. This two-year pilot study focused on field and laboratory methods appropriate for measuring soil-based ecological variables that, conceivably, might threaten biological and hydrological functions of wetlands. Field methods included slope measurements and soil classification. Laboratory soil testing methods measured NO{dollar}sb3{dollar}-N by transnitration of salicylic acid, P by NaHCO{dollar}sb3{dollar} extraction, organic matter (OM) by loss on ignition, pH, soluble salt content by electrical conductivity, particle size analysis (PSA), and soil erosion by {dollar}sp{lcub}137{rcub}{dollar}Cs activity.; The overall study contained two separate components. First, during June of 1992, I sampled four wetlands at the Cottonwood Lake Research Area (CWLRA), near Woodworth, ND. Subsequently, after an evaluation of the methods used at the CWLRA, I continued similar sampling on 40 wetlands found in three geographic ecoregions, or strata, including portions of eastern North Dakota and western Minnesota, the drift prairie of central North Dakota and eastern South Dakota, and the Prairie and Missouri Coteaus of South Dakota and North Dakota, respectively.; The results at the CWLRA showed surface (0-15 cm) P levels were 2.5 to 5 times higher in cultivated wetland soils than in grassland soils. Subsoil organic matter and nitrate levels were higher in the wet meadow zone of the cultivated wetland than in the grassland wetlands. Cultivated wetland basins also had soil erosion rates at least 3 times higher than grassland soils, as measured by {dollar}sp{lcub}137{rcub}{dollar}Cs activities. Analysis of data from the drift prairie and coteau strata showed significant indicators of land use practices, including surface soil P (P {dollar}>{dollar} F = 0.001 in 1992, 0.006 in 1993), subsoil P (P {dollar}>{dollar} F = 0.003 in 1992, 0.021 in 1993), subsoil NO{dollar}sb3sp{lcub}-{rcub}{dollar} (P {dollar}>{dollar} F = 0.011 in 1992, 0.021 in 1993), and surface OM (P {dollar}>{dollar} F = 0.077 in 1992, 0.029 in 1993). Surface soil NO{dollar}sb3sp{lcub}-{rcub}{dollar} was significant between treatments (P {dollar}>{dollar} F = 0.025) in 1992, but not in 1993. |
