[B-BG01] Elemental cycling in terrestrial and coastal ecosystems- Carbon and Nitrogen perspectives

[BBG01-05] Spatial and vertical variations of carbon and nitrogen isotopes of larch forest and NDVI in Eastern Siberia

*Aleksandr Nogovitcyn¹、Atsuko Sugimoto²、Ruslan Shakhmatov¹、Tomoki Morozumi¹、Shunsuke Tei²、Yumiko Miyamoto²、Trofim Maximov^3,4 (1.Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan、2.Arctic Research Center, Hokkaido University, Sapporo, Hokkaido, Japan、3.Institute for Biological Problems of Cryolithozone, Siberian Blanch of Russian Academy of Sciences, Yakutsk, Yakutia, Russia、4.International Center for Biogeoscience Educational and Scientific Trainings (BEST), North-Eastern Federal University, Yakutsk, Yakutia, Russia)

キーワード：taiga (boreal) forest, NDVI, carbon isotope, nitrogen isotope

Under a global climate change, taiga forest ecosystem is expected to change. Tree ring data obtained at northeast Siberian Taiga indicated tree growth decrease during warm climate (Tei et al., 2014), consequently primary production may decrease in the future. As tools for monitoring ecosystem changes, stable isotope of carbon δ¹³C and nitrogen δ¹⁵N are widely applied in ecological research. The δ¹³C is a common proxy for water use efficiency in plants, and the δ¹⁵N is for nitrogen availability that is important because boreal forest on permafrost is usually poor in the nitrogen (Popova et al., 2013).

Observations were conducted at Spasskaya Pad forest station (62°25’ N, 129°62’ E) near Yakutsk, Russia. The forest is usually dry, but after the extreme wet event in 2007, wet sites were distributed in the forest. Transect (60m x 510m) with 30m x 30m plots, in total 33, was set including dry sites and wet sites, to obtain needle samples from 104 trees at the height of 5-6 m were obtained in order to investigate spatial variations in δ¹³C, δ¹⁵N, and N contents. These spatial variations were compared with satellite-derived Normalized difference vegetation index (NDVI) using Landsat images with the resolution of 30 m. Lower NDVI and lower foliar N content were observed at wet sites than those at dry sites. A high δ¹³C and high δ¹⁵N were also observed at a wet site. After extreme wet event happened, ecosystem (and N availability) changes and NDVI also changes. We also obtained the needles from two trees at different heights in a jungle gym to investigate the vertical variations in δ¹³C and δ¹⁵N. There were large differences in δ¹³C, δ¹⁵N and N contents vertically.


Tei, S., A. Sugimoto, H. Yonenobu, T. Ohta, T. C. Maximov. Growth and physiological responses of larch trees to climate changes deduced from tree-ring widths and δ¹³C at two forest sites in eastern Siberia. Polar Science, 8, 183-195, doi:10.1016/j.polar.2013.12.002, 2014

Popova A.S., N. Tokuchi, N. Ohte, M.U. Ueda, K. Osaka, T.Ch. Maximov and A. Sugimoto. Nitrogen availability in the taiga forest ecosystem of northeastern Siberia. Soil Science and Plant Nutrition, 59, 427-441, doi:10.1080/00380768.2013.772495, 2013