Pedosphere 17(6): 747--757, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Sensitivity to acidification of forest soils in two watersheds with contrasting hydrological regimes in the oil sands region of Alberta |
Y. S. OK1,2 , S. X. CHANG1 and Y. S. FENG1 |
1 Department of Renewable Resources, University of Alberta, Edmonton, A B T6G 2E3 (Canada). Email: soilok@kangwon.ac.kr
2 Department of Biological Environment, Kangwon National University, Chuncheon 200-701 (Korea) |
| ABSTRACT |
| Input of large amounts of N and S compounds into forest ecosystems through atmospheric deposition is a significant risk for soil acidification in the oil sands region of Alberta. We evaluated the sensitivity of forest soils to acidification in two watersheds (Lake 287 and Lake 185) with contrasting hydrological regimes as a part of a larger project assessing the role of N and S cycling in soil acidification in forest ecosystems. Fifty six forest soil samples were collected from the two watersheds by horizon from 10 monitoring plots dominated by either jack pine (Pinus banksiana) or aspen (Populus tremuloides). Soils in the two watersheds were extremely to moderately acidic with pH (CaCl2) ranging from 2.83 to 4.91. Soil acid-base chemistry variables such as pH, base saturation, Al saturation, and acid-buffering capacity measured using the acetic acid equilibrium procedure indicated that soils in Lake 287 were more acidified than those in Lake 185. Acid-buffering capacity decreased in the order of forest floor > subsurface mineral soil > surface mineral soil. The most dramatic differences in percent Ca and Al saturations between the two watersheds were found in the surface mineral soil horizon. Percent Ca and Al saturation in the surface mineral soil in Lake 287 were 15% and 70%, respectively;the percent Ca saturation value fell within a critical range proposed in the literature that indicates soil acidification. Our results suggest that the soils in the two watersheds have low acid buffering capacity and would be sensitive to increased acidic deposition in the region. |
| Key Words: acid-buffering capacity, Al saturation, base saturation, pH, soil acidification |
| Citation: Ok, Y. S., Chang, S. X. and Feng, Y. S. 2007. Sensitivity to acidification of forest soils in two watersheds with contrasting hydrological regimes in the oil sands region of Alberta. Pedosphere. 17(6): 747-757. |
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