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首页> 美国政府科技报告 >Effects of Acid Precipitation on Soil Acidity and Base-Cation Status of Infertile Forest Soils in Eastern Tennessee
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Effects of Acid Precipitation on Soil Acidity and Base-Cation Status of Infertile Forest Soils in Eastern Tennessee

机译：酸沉降对田纳西州东部瘠薄森林土壤酸度及土壤碱化状况的影响

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In three deciduous forests with soils classified as sensitive to acid rain, soil chemistry and nutrient cycling were examined to evaluate effects of acid precipitation on soil acidity, leaching, and supplies of base cations. Results indicated that strong acidity in precipitation (pH 4.3 to 4.4 to 0.6 keg ha exp -1 year exp -1 ) is rapidly neutralized by canopies and forest floors, before rainwater percolates beyond surficial layers of forest soil. Annual natural acid production exceeded H exp + -ion inputs in acid precipitation by at least 2.8 times at a study site where estimates were made of HCO sub 3- leaching and ion accumulation in aboveground biomass. The pH of solutions throughout soil profiles averaged 5.4 to 6.0, indicating that forest soils serve as sinks of enormous capacity for H exp + -ions of external and internal origin. In the surface 50 to 80 cm of oil, exchangeable base cations that are immediately available for plant uptake are more than two orders of magnitude greater than annual atmospheric inputs of H exp + -ions. In addition, the quantities of base cations that will become available to forest vegetation over time are much greater than current exchangeable pools. Although these soils are infertile with low cation exchange capacity, the conservative nature of forest nutrient cycling and soil change indicate that acid precipitation is unlikely to acidify soils or to deplete base cation supplies such that forest productivity will be adversely affected. Results of these studies suggest that minor effects should be expected in many other soils currently judged to be sensitive to acid rain. 12 references, 4 figures, 3 tables. (ERA citation 08:052192)

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