CO₂ Emission by Soils of the Ecotone Zone in the North of Western Siberia

Abstract

The study area in the North of Western Siberia is located at the southern limit of the distribution of surficial permafrost in the ecotone zone on the border of taiga and southern tundra. Area is characterized by the contrasting landscapes: pine forests with Albic Podzol; palsa with Histic Oxyaquic Turbic Cryosol and bog ecosystems with Fibric Histosol. The objectives of the study included evaluation the values of CO2 emission (SR) by soils of key landscapes in the growing seasons of 2019–2022, and evaluation the factors of spatial variability of this indicator and its interannual variability. The study included analysis of the RS database (static closed chamber method) and soil hydrothermal parameters for four years in August. In the absence of trends in changing climatic parameters over the past 10 years, a gradual increase in soil temperature in all landscapes and an increase in the depth of thawing in palsa were observed. These changes were not accompanied by significant changes in the SR value. It averaged from 485 to 540 mgCO2/(m2 h) in forest ecosystems, from 150 to 255 mgCO2/(m2 h) in the peat-bog complex with high coefficients of spatial variability. High values of SR in forest ecosystems are determined by a favorable hydrothermal regime, high reserves of root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported by supra-permafrost waters and released from the surface of bog soils. Soil temperature, regulated by seasonal thawing, was a significant predictor of the spatial variability of SR on the soils of the palsa-bog complex.