Spatial variations in larch needle and soil δ<sup>15</sup>N at a forest–grassland boundary in northern Mongolia Lei Fujiyoshi Atsuko Sugimoto Akemi Tsukuura Asami Kitayama M. Larry Lopez Caceres Byambasuren Mijidsuren Ariunaa Saraadanbazar Maki Tsujimura 10.6084/m9.figshare.3490406.v1 https://tandf.figshare.com/articles/dataset/Spatial_variations_in_larch_needle_and_soil_sup_15_sup_N_at_a_forest_grassland_boundary_in_northern_Mongolia/3490406 <p>The spatial patterns of plant and soil δ<sup>15</sup>N and associated processes in the N cycle were investigated at a forest–grassland boundary in northern Mongolia. Needles of <i>Larix sibirica</i> Ledeb. and soils collected from two study areas were analysed to calculate the differences in δ<sup>15</sup>N between needle and soil (Δδ<sup>15</sup>N). Δδ<sup>15</sup>N 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 with <sup>15</sup>N-depleted N uptake by larch and <sup>15</sup>N-enriched N immobilization by microorganisms was proposed to cause large Δδ<sup>15</sup>N, whereas in the grassland boundary, small Δδ<sup>15</sup>N 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 Δδ<sup>15</sup>N.</p> 2016-07-18 11:50:13 Carbon-13 forest grassland isotope ecology nitrogen cycle nitrogen-15 tree