| In the Driftless Area of southwestern Wisconsin, weathering of sedimentary bedrock layers forms valleys with benched backslopes. Soil catenas, in this landscape, are controlled by the benched topography. This study characterizes and models soil catenas on complex hillslopes and examines changes due to aspect, past land use and deforestation and subsequent conversion to pasture. Three hillslopes, were sampled for soil and vegetation attributes. Linear regression, linear discriminant analysis, terrain analysis, fuzzy clustering and a fuzzy neural network were used to analyze and classify the data. Features common to the soil catenas are: perched water tables at the crest; absence of toeslopes; and compound backslopes, composed of a series of mini-slopes. Analysis revealed that a previously cultivated slope has greater values for pH, Mg, Na, and smaller soil organic matter content than the never cultivated slopes. Comparison of a north-facing never-deforested lower backslope with a north-facing lower backslope under pasture found: values for A-horizon thickness, pH, Ca, Mg, Na, CEC, soil structure and size and distribution of roots are greater for forest soils; while values for bulk density, penetrometer resistance, soil consistence are greater for pasture soils. The landsurface unit classification was consistent with geomorphic features, soil properties, and hydrologic processes observed during field sampling. In areas with differentially eroded sedimentary bedrock, distinctive soil catenas form, characterized by compound backslopes composed of a series of mini-slopes. Differences in aspect and past land use histories result in changes to the soil landscape. The major changes in soil properties, upon deforestation and conversion to pasture, are associated with compaction of the pasture surface by cattle. The fine-scale information obtained from the characterization studies was used to develop a model of the soil landscape. |
