Fire and Logging Decrease Soil CO2 Efflux in Siberian Central Taiga Forests

Extensive wildfires and logging have affected the Russian boreal forests in recent decades. Scots pine (Pinus sylvestris L.) forests are widespread in Russia and are one of the most disturbed tree species in Siberia. However, the effects of disturbance on soil CO2 efflux in the vast Siberian forests are still poorly understood. We used the LI 8100A infrared gas analyzer to study changes in soil CO2 efflux into the atmosphere in mature Scots pine forests in the Siberian central taiga five&ndash:six years following fires and logging. Measurements of soil CO2 efflux rates were performed on sites where automatic weather stations have been continuously operational since 2022, which gives us temporal patterns of meteorological fluctuations across forests with different disturbance histories. We found significant differences in soil efflux rates depending on the site and disturbance characteristics. In the undisturbed dry lichen-dominated forest, CO2 efflux was 4.8 &plusmn: 2.1 &micro:mol m&minus:2 s&minus:1, while in the wet moss-dominated forest it was 2.3 &plusmn: 1.3 &micro:mol m&minus:2 s&minus:1, with soil efflux in Sphagnum sp. being twofold of that in feather moss. Both fire and logging significantly reduced CO2 efflux, with a smaller reduction in soil CO2 efflux observed in the moss-dominated plots (5%&ndash:40%) compared to the lichen-dominated plots (36%&ndash:55%). The soil efflux rate increased exponentially with increasing topsoil temperatures in lichen-dominated Scots pine sites, with disturbed plots showing less dependence compared to undisturbed forest. In the wet moss-dominated Scots pine forest, we found no significant dependence of soil efflux on temperature for all disturbance types. We also found a positive moderate relationship between soil efflux and forest floor depth in both lichen- and moss-dominated Scots pine forests across all the plots studied. Our findings advance the understanding of the effects of fire and logging on the carbon cycle and highlight the importance of accounting for disturbance factors in Earth system models due to changing climate and anthropogenic patterns.