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Abstract
This study quantified soil nutrient status and N mineralization/nitrification potentials in soils of oakdominated, unmanaged forest stands in seven experimental forests ranging along a historical and current acidic deposition gradient from southern Illinois to central West Virginia, U.S.A. Among these seven sites (that spanned 8.5º of longitude) soil pH and Ca
2+ decreased and soil organic C and extractable Al
3+ increased from west to east. In general, initial soil solution NO
3- total N mineralization potential and net NO
3-accumulation over 30 days of incubation (as measured by aerobic laboratory incubations) also decreased from west to east, whereas initial soil solution NH
4+ was uncorrelated with longitude. The Fernow Experimental Forest (W.Va.), the eastern-most site, was the exception to this trend. Soils from the Fernow had the highest concentrations of both NO
3- and NH
4+ in the soil solution, and the greatest N mineralization potential. Stepwise regressions of N mineralization rate, net NO
3- accumulation, and proportional nitrification on initial soil properties produced models with overall r² of 0.705, 0.772, and 0.708, respectively. Rates of N turnover were positively correlated with initial NO
3- pH, and Ca:Al ratio and negatively correlated with extractable Al
3+ concentrations. Differences in oak growth and mortality may be related to the differences in soil chemical status and soil N dynamics among these seven experimental forests.
Parent Publication
Citation
Boerner, Ralph E. J.; Sutherland, Elaine Kennedy. 1995. Nitrogen dynamics in oak forest soils along a historical deposition gradient. In: Gottschalk, Kurt W.; Fosbroke, Sandra L. C., ed. Proceedings, 10th Central Hardwood Forest Conference; 1995 March 5-8; Morgantown, WV.: Gen. Tech. Rep. NE-197. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 523-533
