Keywords:
Vegetation distribution, controlled by topography, may affect scaling
methane flux in taiga-tundra boundary, Indigirka lowland, northeastern
Siberia
*Tomoki Morozumi1, Ryo Shingubara1,2, Shunsuke Tei2, Shinya Takano1, RONG FAN1, Ruslan
Shakhmatov1, Hideki Kobayashi3, Rikie Suzuki3, Trofim C. Maximov4,5, Atsuko Sugimoto2
1. Graduate School of Environmental Science, Hokkaido University, 2. Arctic Research Center, Hokkaido University, 3.
Japan Agency for Marine-Earth Science and Technology, 4. Institute for Biological Problems of Cryolithozone, SB RAS,
Russia, 5. North Eastern Federal University, Russia 
Assessing methane emissions in high latitude regions has been conducted, although those challenges are
scarce because of the limitation of monitoring observations in remote area and the spatial heterogeneity
of land surface conditions on permafrost landscapes (e.g. polygon mires). Vegetation cover is the essential
information for scaling methane flux, which requires wetland extent where biogenic methane is mainly
released. We focused on Taiga-Tundra boundary ecosystem, covered with dwarf shrub tundra, sparse
larch forest and polygonal wetlands which grow on permafrost landscape, and are thought to be affected
by climate change. 
The study investigated that regional methane emission with in-situ flux observations (2009-2016) and
satellite remote sensing of vegetation, using spectral unmixing method to obtain fractions of small
vegetation patches with ALOS AVNIR2 (JAXA) satellite image (70 ×70 km) in Indigirka lowland eastern
Siberia (70oN, 148oE) in July summer. Additionally, digital surface model (AW3D30, JAXA) and series of
historical surface reflectance images (Landsat5 and Landsat8, USGS/NASA) were analyzed to understand
the spatial distribution and temporal dynamics of each vegetation with topographical gradient on regional
scale. Landsat derived normalized vegetation index (NDVI) trends in several recent years indicated that
vegetation growth was probably topographically differed at approx. < 18 m and mainly expected on tall
erect willows (Salix boganidensis and others). There was no methane emission observed in willow class,
therefore, lower topographic land cover might be partly altered by less methane emitting willow cover and
might affect local net methane emission. Vegetation data supported by topographic analysis allows us to
describe regional impact of observed CH4 emission, and expected to contribute research for vegetation
dynamics and CH4 emission in circumarctic terrestrial ecosystem. 
Vegetation, methane flux, NDVI 
ACG38-02Japan Geoscience Union Meeting 2018
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