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.