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Simulated Effects of Sulfur Deposition on Nutrient Cycling in Class I Wilderness Areas
Author(s) -
Elliott Katherine J.,
Vose James M.,
Knoepp Jennifer D.,
Johnson Dale W.,
Swank Wayne T.,
Jackson William
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0358
Subject(s) - deposition (geology) , nutrient , cycling , soil water , environmental chemistry , sulfate , forest floor , environmental science , acid rain , soil acidification , sulfur , soil ph , nutrient cycle , chemistry , vegetation (pathology) , hydrology (agriculture) , soil science , geology , sediment , geography , geomorphology , forestry , geotechnical engineering , organic chemistry , medicine , pathology
We predicted the effects of sulfate (SO 4 ) deposition on wilderness areas designated as Class I air quality areas in western North Carolina using a nutrient cycling model (NuCM). We used three S deposition simulations: current, 50% decrease, and 100% increase. We measured vegetation, forest floor, and root biomass and collected soil, soil solution, and stream water samples for chemical analyses. We used the closest climate stations and atmospheric deposition stations to parameterize NuCM. The areas were: Joyce Kilmer (JK), Shining Rock (SR), and Linville Gorge (LG). They differ in soil acidity and nutrients, and soil solution and stream chemistry. Shining Rock and LG have lower soil solution base cation and higher acidic ion concentrations than JK. For SR and LG, the soil solution Ca/Al molar ratios are currently 0.3 in the rooting zone (A horizon), indicating Al toxicity. At SR, the simulated Ca/Al ratio increased to slightly above 1.5 after the 30‐yr simulation regardless of S deposition reduction. At LG, Ca/Al ratios ranged from 1.6 to 2.4 toward the end of the simulation period, the 100% increase scenario had the lower value. Low Ca/Al ratios suggest that forests at SR and LG are significantly stressed under current conditions. Our results also suggest that SO 4 retention is low, perhaps contributing to their high degree of acidification. Their soils are acidic, low in weatherable minerals, and even with large reductions in SO 4 and associated acid deposition, it may take decades before these systems recover from depletion of exchangeable Ca, Mg, and K.