| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4436592 | Applied Geochemistry | 2010 | 4 Pages |
Natural abundances of 15N/14N ratios (commonly designated by δ15N notation) of annual rings from Pinus thunbergii trees were determined after transplantation from a nursery to breeding colonies of Black-tailed Gull (Larus crassirostris) in Miyagi and Aomori and a control site in Yamagata, in northeastern Japan. Tree-rings were collected in July/August/September, 2009. Transplanting was conducted in the year 2000 in the Miyagi site, whereas there is no information about transplanting data in the Aomori and Yamagata sites. Soils associated with piscivorous (fish eating) avian colonies receive large seasonal input of organic N in the form of feces. The organic N is microbiologically transformed into inorganic N in soils, from which P. thunbergii derives its N. The resulting NH4- and NO3-N are characterized by distinctly heavy δ15N ratios, due to coupled processes of mineralization, volatilization, nitrification and denitrification of feces. In general, total N concentration along with δ15N values stored in the annual rings of P. thunbergii increased steadily after transplanting from the nursery to locations under continued avian N input. Tree-ring N content and isotopic ratios provided a reliable record of past annual available soil N caused by changes in the Black-tailed Gull population, and thus can serve as an environmental tool to estimate past avian population dynamics.
Research highlights► N concentration and isotope ratio on tree-rings can be an important tool to infer past N soil conditions where trees grow. ► Changes in avian population on established or new breeding grounds caused by natural or anthropogenic mechanism could be inferred from the analysis shown in this paper. ► The property of trees to retain N concentration and N isotope characteristics is found in Pinus thunbergii. The use of other trees for similar analysis have to be determined because other species (Pinus densiflora, for example) do not have this property.
