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Nitrogen saturation and soil N availability in a high-elevation spruce and fir forest

Journal Article · · Water, Air, and Soil Pollution
A field study was conducted during the summer of 1995 to gain abetter understanding of the causes of nitrate (NO{sub 3}-N) leaching and ongoing changes in soil nitrogen (N) availability in high-elevation (1524-2000 m) spruce (Picea rubens) and fir (Abies fraseri) forests of the Great Smoky Mountains National Park, Tennessee and North Carolina, U.S.A. Indicators of soil N availability (total soil N concentrations, extractable NH{sub 4}-N, extractable NO{sub 3}-N, and C/N ratios) were measured in Oa and A horizons at 33 study plots. Dynamic measures included potential net soil N mineralization determined in 12-week aerobic laboratory incubations at 22 C. Potential net nitrification in the A horizon was correlated (r = + 0.83, P < 0.001) with total soil n concentrations. mostmeasures of soil n availability did not exhibit significanttrends with elevation, but there were topographic differences. Potential net soil N mineralization and net nitrification in the A horizon were higher in coves than on ridges. Relative amounts of particulate and organomineral soil organic matter influenced potential net N mineralization and nitrification in the A horizon. Calculations indicate that soil N availability and NO{sub 3}-N leaching in high-elevation spruce and fir forests of the Great Smoky Mountains National Park will increase in response to regional warming.
Research Organization:
Oak Ridge National Laboratory (ORNL)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
989642
Journal Information:
Water, Air, and Soil Pollution, Journal Name: Water, Air, and Soil Pollution Journal Issue: 3-4 Vol. 120; ISSN 0049-6979; ISSN 1573-2932
Country of Publication:
United States
Language:
English