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- Title
Identification of coniferous forests with incipient nitrogen saturation through analysis of arginine and nitrogen-15 abundance of trees
- Authors
Hogberg, Peter; Edfast, Ann-Britt; Nordin, Annika; Nasholm, Torgny
- Abstract
Stands of Norway spruce [Picea abies (L.) Karst.] differing in throughfall N deposition and NO{sub}3{end}{sup}-{end} leaching were investigated to determine if arginine concentrations and delta{sup}15{end}Nabundances of needles could be used to predict NO{sub}3{end}{sup}-{end} leaching from stands. Twenty-three stands, all located in southern Sweden, were sampled and five of these had average NO{sub}3{end}{sup}-{end} concentrations greater than 0.1 mg NO{sub}3{end}{sup}-{end}-N L{sup}-1{end} in soil water at a 50-cm depth. Arginine concentrations and delta{sup}15{end}N abundances of needles were significantly higher for sites that exhibited NO{sub}3{end}{sup}-{end} leaching. The delta{sup}15{end}N enrichment (Epsilon), i.e., difference between foliage and soil organic matter in delta{sup}15{end}N , showed less variation than delta{sup}15{end} N of needles alone in regressions against NO{sub}3{end}{sup}-{end} leaching and was, thus, a better predictorof leaching. All sites that exhibited N leaching had arginine concentrations greater than 5 mu mol g dw{sup}-1{end} and Epsilon greater than - 0.5 ( percento) and thus, there was a strong correlation between arginine and Epsilon values. To test if arginine accumulation, as such, can affect the delta{sup}15{end}N of needles, arginine and delta{sup}15{end}N were determined for Scots pine (Pinus sylvestris L.) trees given different amounts of N fertilizer. Although fertilization caused a dramatic increase in arginine concentrations of needles, no immediate change in delta{sup}15{end}N was observed. A hypothesis is proposed to explain the causal linkage between elevated arginine and delta{sup}15{end}N of needles and leaching of N. Thus, arginine accumulation in trees corresponds to decreased uptake rates of NH{sub}4{end}{sup}+{end} leaving NH{sub}4{end}{sup}+{end} ions available for nitrification. During nitrification, discrimination against the heavier {sup}15{end}N takes place resulting in a depleted NO{sub}3{end}{sup}-{en
- Subjects
ATMOSPHERIC deposition; FORESTS &; forestry
- Publication
Journal of Environmental Quality, 1997, Vol 26, Issue 1, p302
- ISSN
0047-2425
- Publication type
Article