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