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This article in SSSAJ

  1. Vol. 56 No. 6, p. 1959-1966
    Received: Sept 29, 1991

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Differences in Soil and Leaf Litterfall Nitrogen Dynamics for Five Forest Plantations

  1. Stith T. Gower  and
  2. Yowhan Son
  1. Dep. of Forestry, University of Wisconsin, Madison, WI 53706
    Dep. of Plant, Soil and Environmental Studies, Univ. of Maine, Orono, ME 04469



Vegetation can influence N cycling in forest soils; however, it is difficult to isolate the positive feedback of vegetation on N cycling because other factors are often not held constant. The objective of this study was to measure and compare leaf litterfall N and in situ and laboratory N mineralization rates for 28-yr-old northern red oak (Quercus rubra L.), European larch (Larix decidua Miller), eastern white pine (Pinus strobus L.), red pine (P. resinosa Aiton), and Norway spruce [Picea abies (L.) Karst.] plantations on a similar soil in southwestern Wisconsin. Average seasonal soil NO-3 and NH+4 concentrations (mg kg −1) were 3.9 and 3.4 for red oak; 7.7 and 5.8 for European larch; 5.4 and 6.7 for white pine; 4.9 and 5.1 for red pine; and 5.2 and 6.2 for Norway spruce, respectively. Annual in situ net N mineralization in the top 20 cm of mineral soil differed significantly (P < 0.01) among species and ranged from 46 kg ha−1 yr−1 for Norway spruce to 117 kg ha−1 yr−1 for European larch. Annual in situ nitrification differed significantly (P < 0.001) among species and comprised from 42 (red oak) to 95% (European larch) of the total annual net N mineralized. Laboratory net N mineralization rates also differed significantly among the five species. Average annual leaf litterfall N content for a 2-yr period ranged from 26 kg ha−1 yr−1 for white pine to 40 kg ha−1 yr−1 for Norway spruce but was not correlated to annual net N mineralization. We suggest that leaf litterfall lignin/N may be an important positive feedback mechanism that influences N mineralization.

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