Estimating methane emissions using vegetation mapping in the taiga–tundra boundary of a north-eastern Siberian lowland

Abstract

Taiga–tundra boundary ecosystems are affected by climate change. Methane (CH₄) emissions in taiga–tundra boundary ecosystems have sparsely been evaluated from local to regional scales. We linked in situ CH₄ fluxes (2009–2016) with vegetation cover, and scaled these findings to estimate CH₄ emissions at a local scale (10 × 10 km) using high-resolution satellite images in an ecosystem on permafrost (Indigirka lowland, north-eastern Siberia). We defined nine vegetation classes, containing 71 species, of which 16 were dominant. Distribution patterns were affected by microtopographic height, thaw depth and soil moisture. The Indigirka lowland was covered by willow-dominated dense shrubland and cotton-sedge-dominated wetlands with sparse larch forests. In situ CH₄ emissions were high in wetlands. Lakes and rivers were CH₄ sources, while forest floors were mostly neutral in terms of CH₄ emission. Estimated local CH₄ emissions (37 mg m⁻² d⁻¹) were higher than those reported in similar studies. Our results indicate that: (i) sedge and emergent wetland ecosystems act as hot spots for CH₄ emissions, and (ii) sparse tree coverage does not regulate local CH₄ emissions and balance. Thus, larch growth and distribution, which are expected to change with climate, do not contribute to decreasing local CH₄ emissions.

Keywords:

• CH₄ flux
• high-resolution vegetation mapping
• remote sensing
• scaling
• chamber flux measurement

Acknowledgements

We would like to thank the Institute for Biological Problems of Cryolithozone, Siberian Branch of the Russian Academy of Sciences, the Allikhovsky Ulus Inspectorate of Nature Protection for fieldwork support, and Drs. A. Isaev, V. Zakharova, A. Egorova, E. Ignatova and A. Efimova for plant identification. The WorldView-2 data were commercially provided by Digital Globe (https://www.digitalglobe.com).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the GRENE Arctic Climate Change Research Project, Ministry of Education, Culture, Sports, Science and Technology, Japan. Additional funding was granted by Belmont Forum COPERA, C budget of ecosystems cities and villages on permafrost in the eastern Russian Arctic, and JSPS KAKENHI grants JP21403011 (A. Sugimoto), JP16J07265 (T. Morozumi). This work was also supported by Hokkaido University.