Tuesday, November 14, 2006

Soil Characteristics in the Hydrogeomorphic Wetland Classification and Functional Assessment of Mid-Atlantic Piedmont Slope Wetlands Study Reference Sites.

Brian Dierberger, Soil & Water Cons. District, BLDAgronomics, 8924 Linda Ray Ln., Gregory, MI 48137, Bruce Vasilas, Univ of Delaware, 149 Townsend Hall, 531 S. College Ave, Newark, DE 19717-1303, and M.A. Wilson, USDA-NRCS, 100 Centennial Mall N., Rm. 152; MS 41, Lincoln, NE 68522.

The hydrogeomorphic (HGM) classification and wetland functional assessment study included a five-year data collection process on characteristics of piedmont slope wetland reference sites. These data are being used to create and calibrate a wetland classification and functional assessment model for Mid-Atlantic piedmont slope wetlands. Soils at most reference sites were sampled for full characterization, with lab analysis by the Natural Resources Conservation Service’s National Soil Survey Laboratory. Soil parameters addressed include texture, pH, CEC, total C, and total N. Water tables near the point of groundwater discharge were measured twice daily using automated recording wells. Three types of hydroperiods were observed at the reference sites: permanently inundated, permanently saturated, or seasonally inundated or saturated. Morphological characteristics of the soils varied with hydroperiod. Most permanently inundated sites showed very poorly drained morphology, having thick dark accumulations of organic matter at the surface. Permanently saturated soil morphology ranged from poorly drained, with a depleted matrix within 25 cm of the surface, to moderately well drained, with redoximorphic depletions starting between 50 and 100 cm from the surface. The seasonally inundated or saturated soil morphology were typically poorly drained to somewhat poorly drained, with redoximorphic depletions starting between 25 and 50 cm of the surface. There was no correlation between Field Indicators of Hydric Soils in the United States and hydroperiod. At least one soil in each hydroperiod did not meet a Field Indicator of Hydric Soils in the United States. There was also no relationship between soil taxonomic classification and hydroperiod.