PROCEEDINGS: Index of Abstracts
RELATIVE NITROGEN MINERALIZATION AND NITRIFICATION
POTENTIALS IN RELATION TO SOIL CHEMISTRY IN OAK FOREST SOILS ALONG
A HISTORICAL DEPOSITION GRADIENT
1-Department of Plant Biology, 1735 Niel Ave.,
Ohio State University, Columbus, OH 43210-1293. 2-USDA Forest Service,
Northeastern Forest Experiment Station Delaware, OH 43015.
This study quantified soil nutrient status and N mineralization/nitrification
potentials in soils of oak-dominated, unmanaged forest stands in
seven USDA Forest Service experimental forests (EF) ranging along
a historical and current acidic deposition gradient from southern
Illinois to central West Virginia. Among these seven sites (that
spanned 8.5° of longitude) soil pH and Ca2+ decreased and soil
organic C and soluble Al3+ increased from west to east. In general,
initial soil solution NO3- and NH4+ was uncorrelated with longitude.
The Fernow EF (WV), the easternmost site, was the exception to this
trend. Soils from the Fernow had the highest concentrations of both
NO3- accumulation, and the greatest N mineralization potential.
Stepwise regressions of N mineralization rate, net NO3- 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 NO3-,
pH, and Ca:Al ratio and negatively correlated with soil solution
Al3+ concentrations. Differences in oak growth and mortality may
be related to the differences in soil chemical status and soil N
dynamics along these seven experimental forests.