Soil chemistry may change over time due to disturbance, forest growth, or species changes. We measured soil exchangeable cation concentrations, total C and N and forest floor mass and chemistry in a southern Appalachian mixed-oak hardwood forest and a white pine plantation watershed in 1970, 1990, and 2005. Data showed significant decreases in Ca, Mg, and K, and total C and N concentrations in the two upper soil horizons of the mixed-oak hardwood watershed during the first 20 years. Resampling at 35 years showed that A horizon total C and N were unchanged while concentrations in B horizon soils continued to decline. Soils in the white pine plantation also decreased in nutrient concentrations after 20 years however, proportionally the decrease was not as great. Sampling after 35 years found that total soil N continued to decline in B horizon soils. Nutrient declines were attributed to leaching losses and sequestration in the vegetation. Evidence for changes in nutrient cycling patterns within these forests includes increased forest floor mass and slowed nutrient release rates during litter decomposition.
See more of Symposium---New Horizons from Long-Term Soil Experiments: Interdisciplinary Opportunities to Examine Soil Change
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See more of The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)