The Biogeochemistry of Soil at Depth Within the Wetland Landscape of the Prairie Pothole Region

Abstract

The impact of agricultural practices on wetland ecosystems in the Prairie Pothole Region (PPR) has long been recognized but little is understood about impacts on the biogeochemistry of the wetlands at depth. Understanding the relationship of multi-elements within the wetland and surrounding landscape can aid in wetland restoration and provide guidance for wetland management. The objectives of this study were to: 1) identify biogeochemical characteristics of PPR wetlands; 2) identifying differences or similarities in biogeochemical characteristics of the landscape; 3) assess the vertical variation in chemical composition at depth in wetland, wetland and fringe, footslope and backslope soils; and 4) interpret the soil chemistry of undisturbed sites (good quality; prairie vegetation) and disturbed sites (poor quality; cultivated) relative to differences in landscape position locations. A field study was conducted on six disturbed (DW) and 6 undisturbed (UW) wetlands with evaluation of fringe (F), footslope (FS), or backslope (BS) positions. Using redundancy analysis (RDA) with selected environmental variables models of element concentrations at depth in each position were generated. The RDA ordination plots of element concentrations to depth of 1m was constrained by variables sand, silt, clay, depth, bulk density, site, organic matter, electrical conductivity, and pH. Pearson correlation coefficients between soil properties and the five most prominent soil elements differed between landscape positions. Anthropogenic activity likely influenced the subsurface hydrology but differed in physical and chemical properties. These differences appear to be related to the vegetation, levels of soil disturbance of surrounding landscapes and unique chemical and physical characteristics of parent material.