Differences in Belowground Heterogeneity Within a Restoration of a Dewatered Reservoir in Southwestern Wisconsin


Address correspondence to N. J. Balster, email njbalster@wisc.edu


Integrating belowground properties into ecological restoration is critical for understanding aboveground response. We investigated a recently dewatered basin in southwestern Wisconsin to test hypotheses related to the magnitude, heterogeneity, and spatial dependence of physicochemical properties between sediments and buried soils. A spatial grid was established in a 2.4-ha basin to sample 7 physical and 13 chemical properties. Sediment depth (Sd) averaged 43 cm (std dev = 15) across the study area. The mean bulk density (BD) of the buried soils (1.41 g/cm3) was significantly greater than the sediments (0.97 g/cm3), which corresponded with a significantly higher soil moisture content (SMC) and hydraulic conductivity (Ks) of the sediments. Relative to one another, buried soils had significantly higher concentrations of Bray P, Cu, and Mn, whereas sediments had higher concentrations of Bray K, K, total phosphorus, Na, S, Al, and Ca and thus had a higher pH; Fe and B concentrations were similar between the sediments and the buried soil. Sediments were consistently less spatially heterogeneous than the buried soils. Using geostatistics, sediment BD and SMC displayed both small-scale spatial structures and large-scale trends, whereas Sd and the buried soil SMC displayed only small-scale variability. Distance from the former dam was positively related to nine physicochemical properties and negatively related to only S, SMC, and the percentage of clay; no trends were found in the buried soils. These results demonstrate that damming, inundation, and dewatering due to dam removal yielded a spatially distinct and homogenized substrate relative to the soils that were buried.