Soil N chemistry in oak forests along a nitrogen deposition gradient |
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Authors: | Lars Ola Nilsson Håkan Wallander Erland Bååth Ursula Falkengren-Grerup |
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Institution: | 1. Department of Ecology, Microbial Ecology, Lund University, Ecology Building, SE-223 62, Lund, Sweden 3. Danish Centre for Forest, Landscape and Planning, KVL, H?rsholm Kongevej 11, DK-2970, H?rsholm, Denmark 2. Department of Ecology, Plant Ecology and Systematics, Lund University, Ecology Buiding, SE-223 62, Lund, Sweden
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Abstract: | Anthropogenic N deposition may change soil conditions in forest ecosystems as demonstrated in many studies of coniferous forests,
whereas results from deciduous forests are relatively scarce. Therefore the influence of N deposition on several variables
was studied in situ in 45 oak-dominated deciduous forests along a N deposition gradient in southern Sweden, where the deposition ranged from
10 to 20 kg N ha−1 year−1. Locally estimated NO
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deposition, as measured with ion-exchange resins (IER) on the soil surface, and grass N concentration (%) were positively
correlated with earlier modelled regional N deposition. Furthermore, the δ15N values of grass and uppermost soil layers were negatively correlated with earlier modelled N deposition. The data on soil
NO
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, measured with IER in the soil, and grass N concentration suggest increased soil N availability as a result of N deposition.
The δ15N values of grass and uppermost soil layers indicate increased nitrification rates in high N deposition sites, but no large
downward movements of NO
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in these soils. Only a few sites had NO
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concentrations exceeding 1 mg N l−1 in soil solution at 50 cm depth, which showed that N deposition to these acid oak-dominated forests has not yet resulted
in extensive leaching of N. The δ15N enrichment factor was the variable best correlated with NO
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concentrations at 50 cm and is thus a variable that potentially may be used to predict leaching of NO
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from forest soils. |
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Keywords: | 15N Deciduous forest Deschampsia flexuosa Enrichment factor Nitrate leaching |
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