title: Spatial variations in larch needle and soil δ15N at a forest-grassland boundary in northern Mongolia.
abstract: The spatial patterns of plant and soil δ15N and associated processes in the N cycle were investigated at a forest-grassland boundary in northern Mongolia. Needles of Larix sibirica Ledeb. and soils collected from two study areas were analysed to calculate the differences in δ15N between needle and soil (Δδ15N). Δδ15N showed a clear variation, ranging from -8 ‰ in the forest to -2 ‰ in the grassland boundary, and corresponded to the accumulation of organic layer. In the forest, the separation of available N produced in the soil with15N-depleted N uptake by larch and15N-enriched N immobilization by microorganisms was proposed to cause large Δδ15N, whereas in the grassland boundary, small Δδ15N was explained by the transport of the most available N into larch. The divergence of available N between larch and microorganisms in the soil, and the accumulation of diverged N in the organic layer control the variation in Δδ15N.
authors.affiliation: a Graduate School of Environmental Science , Hokkaido University , Sapporo , Japan.
authors.forename: Lei
authors.initials: L
authors.lastname: Fujiyoshi
authors.affiliation: a Graduate School of Environmental Science , Hokkaido University , Sapporo , Japan.|b Faculty of Environmental Earth Science , Hokkaido University , Sapporo , Japan.|c Arctic Research Center , Hokkaido University , Sapporo , Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sugimoto
authors.affiliation: a Graduate School of Environmental Science , Hokkaido University , Sapporo , Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Tsukuura
authors.affiliation: a Graduate School of Environmental Science , Hokkaido University , Sapporo , Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Kitayama
authors.affiliation: d Faculty of Agriculture , Yamagata University , Tsuruoka , Japan.
authors.forename: M Larry
authors.initials: ML
authors.lastname: Lopez Caceres
authors.affiliation: e Plant Protection Research Institute, Mongolian University of Life Sciences , Ulaanbaatar , Mongolia.
authors.forename: Byambasuren
authors.initials: B
authors.lastname: Mijidsuren
authors.affiliation: e Plant Protection Research Institute, Mongolian University of Life Sciences , Ulaanbaatar , Mongolia.
authors.forename: Ariunaa
authors.initials: A
authors.lastname: Saraadanbazar
authors.affiliation: f Faculty of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Tsujimura
mesh_terms: D004784:Environmental Monitoring; D065928:Forests; D065948:Grassland; D028221:Larix / Q000737:chemistry*; D008986:Mongolia; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*
chemical_list: D009587:Nitrogen Isotopes; D012987:Soil; D009584:Nitrogen
keywords: Carbon-13; forest; grassland; isotope ecology; nitrogen cycle; nitrogen-15; tree