Spatial changes in forest floor and foliar chemistry of spruce-fir forests across New England |
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Authors: | S G McNulty J D Aber R D Boone |
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Institution: | (1) Complex Systems Research Center, Science and Engineering Research Building, University of New Hampshire, Durham, NH, 03824, USA;(2) Present address: Coweeta Hydrologic Laboratory, 999 Coweeta Lab Rd, Otto, NC 28763, USA |
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Abstract: | In the U.S., high elevation spruce-fir forests receive greater amounts of nitrogen deposition relative to low elevation areas. At high elevations the cycling of nitrogen is naturally low due to slower decomposition and low biological N demand. The combination of these factors make spruce-fir ecosystems potentially responsive to changes in N inputs.Excess nitrogen deposition across the northeastern United States and Europe has provided an opportunity to observe ecosystem response to changing N inputs. Effects on foliar and forest floor chemistry were examined in a field study of 161 spruce-fir sites across a longitudinal (west-to-east) N deposition gradient. Both foliar elemental concentrations and forest floor elemental concentrations and rates of potential N mineralization were correlated with position along this gradient.Nitrogen deposition was positively correlated with potential forest floor nitrification and mineralization, negatively correlated with forest floor C:N and Mg concentrations and with spruce foliar lignin, lignin:N and Mg:N ratios. Foliar lignin:N and forest floor C:N were positively correlated and both were negatively correlated with nitrification and mineralization. Correlations found between forest floor and foliar N and Mg concentrations support the theory of nutrient imbalance as a potential cause of forest decline. |
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Keywords: | nitrogen cycling nitrogen deposition red spruce picea rubens lignin |
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