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Nitrogen Uptake and Release in a Forested Watershed, Lake Tahoe Basin, California
Robert N. Coats, Robert L. Leonard and Charles R. Goldman
Vol. 57, No. 5 (Late Summer, 1976), pp. 995-1004
Stable URL: http://www.jstor.org/stable/1941064
Page Count: 10
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Inorganic nitrogen supply is an important factor limiting primary productivity in Lake Tahoe, Californai-Nevada. To estimate the influence of a watershed ecosystem on nitrogen input to the lake, samples of precipitation, soil water and stream water were collected and analyzed for NO_3-N, NH_4-N and, with less intensity, dissolved organic nitrogen. Factors controlling nitrification in selected plots were studied using a soil perfusion technique. Inorganic nitrogen input by precipitation to the watershed is 1-2 kg@? ha^(-1)@?yr^(-1). Output of inorganic nitrogen from the watershed to the lake is 10 to 33% of the precipitation input. Inorganic nitrogen is removed from snowmelt water almost completely by well-developed conifer stands, but less efficiently by poorly developed or disturbed stands. Alder stands release NO_3-N to soil water especially in fall and early winter. Nitrification does occur in some coniferous forest soils in the watershed and is closely associated with NO_3-N release. The occurrence of significant nitrification in the watershed is related more to the C:N ratio and stand basal area than to either pH or release of toxic substances by decaying litter.
Ecology © 1976 Wiley