Siberian boreal forest regions act as carbon sinks but are also affected by climate change impacts such as wildfires. Wildfires release carbon into the atmosphere and change soil decomposition and respiration. The scientists wanted to examine soil emissions, temperature, moisture and properties during successions after wildfires, using taiga study sites in Central Siberia. They expected the soil CO₂ emissions rates would depend on the recovery time, around 30 years.

Their chosen sites had wildfires between 1898 and 2018 and four other sites which had wildfires in 1973, 1886, 2005 and 2018. The forest ecosystems contained evergreen conifers, dwarf shrubs, lichen and mosses. The soils have been classified as podzols (under ash). They measured the emissions between June and September 2019, using PVC rings, a gas analyser and survey chamber. They used probes and sensors to measure soil temperature and moisture. They processed the data in accordance with Russian soil analysis procedures for organic matter.

The region had 318mm of precipitation and the average air temperature was +12.9°C which was slightly higher than the overall mean for all periods in the study. The coolest soil temperatures were found in the 1898 wildfire recovery site which had returned to full lichen ground cover. There was not much difference between 5cm and 15cm depth, except for the site which was 14 years after wildfires. The highest amount of soil moisture was at the sites 23 and 121 years after wildfires.

The CO₂ soil emissions varied through the study season, with July being the highest. 14 years after wildfires were quite low but the highest soil CO₂ emissions were found in the site that had wildfires 121 years previously. Their data showed that higher soil temperatures over a longer period of time affected rates of CO₂ emissions, releasing greater emissions into the atmosphere. Soil changes may be affected by the overall severity of the wildfire itself. Overall soil temperature affected soil emission fluxes, usually longer than 14 years after a wildfire with more emissions produced by higher volumes of ground cover.

Makhnykina A, Panov A and Prokushkin A 2023 The Impact of Wildfires on Soil CO2 Emission in Middle Taiga Forests in Central Siberia Land 12 1544 Online: http://dx.doi.org/10.3390/land12081544