Plant organic matter in palsa and khasyrei type mires: Direct observations in West Siberian Sub-Arctic

International audienceThis article presents the first results of long-term direct measurements of a few major components of carbon cycle in permafrost mire landforms in the sub-Arctic region of Western Siberia, Russia. It reveals the main features of geographical distribution of plant organic matter, including both the above-ground and below-ground fractions of live biomass, the biomass of dead roots (mortmass), and net primary production (NPP) in peat-accumulating flat palsa mires and in “khasyrei”—ecosystems of drained lakes in thermokarst depression on epigenetic permafrost. The study based on original methods of direct field measurements elaborated by authors for northern peatlands. In northern taiga, the NPP of palsa mires was found in the range of 300–580 g m$^{−2}$ yr$^{−1}$ and an average biomass of 1800 g m$^{−2}$ ; in khasyrei, it accounts for 1100 g m$^{−2}$ yr$^{−1}$ and 2000 g m$^{−2}$ of NPP and live biomass, respectively. In forest tundra, the live biomass of palsa mires was found in the range of 1000–1800 g m$^{−2}$ , and in khasyrei it was 2300 g m$^{−2}$ . The NPP of palsa mires were in the range of 400–560 g m$^{−2}$ yr$^{−1}$ , and in khasyrei it was 800 g m$^{−2}$ yr$^{−1}$ . Overall, we conclude that the south–north climatic gradient in Western Siberia is the main driver of plant organic matter accumulation. It was found different across mire ecosystems of the same types but located in different bioclimatic regions