Effects of pre-treatment on the nitrogen isotope composition of Japanese black pine (Pinus thunbergii) tree-rings as affected by high N input

M. Larry Lopez Caceres, Chitoshi Mizota, Toshiro Yamanaka, Yoshihiro Nobori

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12 Citations (Scopus)


Temporal changes in the acquisition of nitrogen (N) are recorded in tree-rings together with unique N isotopic values. Some debate continues regarding the importance of wood pre-treatment in isotope analysis and, thus, this study focuses on the removal of labile components to determine the intrinsic nature of N in tree-rings. The total concentration and stable isotopic value of N in annual tree-rings were determined for two cores from Japanese black pine (Pinus thunbergii) from areas colonized by black cormorant (Phalacrocorax carbo). One core sample was also collected from a control site, without cormorants. Sharp increases in tree-ring δ 15N values associated with migration of the cormorant population indicate positive incorporation of N from soils, whereas a less pronounced trend was observed for ring samples for periods without or substantially less migration, and for those obtained from the control site. All labile N components were removed by repeated extraction with toluene/ethanol (1:1) solution. Radial translocation of labile N is limited in tree-rings from Japanese black pine, providing intrinsic records on N acquisition. The difference in N isotopic values (up to 7.0°) following pre-treatment was statistically significant for trees affected by the avian colony, whereas the pre-treatment of the control samples did not influence N values. The implication is that in agreement with previous studies pre-treatment is not necessary when trees are exposed to natural N concentrations in the soil but the removal of enriched δ 15N labile components is necessary when woody plants are exposed to unusually high inputs of N into soils. However, the temporal trend in tree-ring δ 15N series of the avian N affected trees did not change. Thus, if the priority is not the value but the trend then pre-treatment is not necessary.

Original languageEnglish
Pages (from-to)3298-3302
Number of pages5
JournalRapid Communications in Mass Spectrometry
Issue number21
Publication statusPublished - Nov 15 2011

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry


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