This article provides an analysis of a wetland site in southern Illinois from presettlement to the present. The study area is part of the Cache River‐Cypress Creek Wetland, which has international importance, as recognized by the Ramsar Convention on Wetlands. Land‐cover data for 1807, 1938, and 1993 were created and analyzed with a geographic information system (GIS). Land‐use change by topographic setting (uplands, transitional, and bottomlands) and soil productivity was quantified and studied. Interviews with local experts informed this analysis. Results illustrate the complexity of environmental change and its driving forces. First, notable forest and swamp acreage was converted to cropland between 1807 and 1938 and, to a lesser degree, from 1938 to 1993. Second, there were land‐use variations by topographic region. Between 1807 and 1938, the largest transformation occurred in the uplands, with substantial acreage converted from forest to cropland. Between 1938 and 1993, however, agriculture decreased in the upland areas as hilly areas reverted to forest cover. At the same time, agriculture expanded in the bottomlands as this land was drained for farming. Third, there are interesting patterns within these categories of land‐use change, as soil productivity is an indicator of what lands were taken out of cropland and converted back to grassland and forest.
Within U.S. soil taxonomy,soil temperature regimes (STRs) are recognized and incorporated in the classification and mapping of soils. Although knowledge of STR can inform crop selection, yield estimates, and nutrient management decisions, detailed and current maps of STRs derived from measured data are not available for most of the United States. Soil temperature measurements at the prescribed depth of 50 cm were summarized for 69 Soil Climate Analysis Network (SCAN) stations in the eastern United States. Mean annual soil temperature (MAST) was calculated for the 2005-2015 period from monthly averages calculated from daily soil temperature observations. A prediction equation for MAST was developed using mean annual air temperature (MAAT) from the PRISM (Parameter-elevation Regressions on Independent Slopes Model) group as a predictor: MAST = 2.49 + (0.91 × MAAT). The adjusted r 2 was .96 with a RMSE of 0.74 ˚C and mean absolute error of 0.59 ˚C based on 10-fold cross-validation. Orographic influence is incorporated in PRISM MAAT, yielding a simple model. The MAST surfaces were calculated by applying the prediction equation to MAAT grids for the 1895-2015 period. The yearly MAST surfaces allow estimation of STR over time and for various summary periods including the 1895-2015 record, 30-yr normal, and probabilities based on individual years for the 1895-2015 period. Based on this investigation, the mesic-thermic STR boundary occurs north of the presently recognized location, is dynamic, and is supported by existing native plant communities associated with thermic STR. INTRODUCTIONSoil temperature is a dynamic soil property that influences the physical, chemical, and biological processes in the soil (Soil Survey Staff, 2014). Solar radiation is the primary source of heat entering the soil (Shul'gin, 1965). Local site characteristics including land cover, slope aspect, slope gradient, and the
A study was initiated in soils of two southern Illinois loess‐derived landscapes to investigate the distribution of selected trace and major elements. The objective of the research was to link the distribution of elements in different landscape positions to important soil and landscape processes. Seventeen pedons (representing different geomorphic hillslope positions) at the Morgan Pond (MP) and Bean Ridge (BR) sites were sampled by horizon. Data were evaluated by grouping selected horizons (A, Bt) by site (MP and BR) as well as by geomorphic hillslope position. Results show that relative concentrations of total As, Cr, Cu, V, Ni, Pb, Se, and Zn between these two sites were impacted by differences in inherent particle size distribution of the parent material. These elements were also greater in Bt versus A horizons within each site, suggesting that select elements were redistributed by clay illuviation processes. Barium, Ca, Cd, Hg, and Pb were all significantly elevated in A relative to Bt horizons at the BR site and were strongly correlated with total C, suggesting biocycling and trace element bioaccumulation were important in landscape positions of this site. The MP site lacked this same concentration of elements in surface horizons, demonstrating the effect of accelerated erosion due to more intensive cropping history. When grouping data by landscape position, elemental distribution and Bt/A clay ratios showed that landscape stability was greatest in summit positions relative to other positions (summit > shoulder > backslope positions), confirming that relative amount of soil erosion was also related to landscape position among these sites.
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