Soil moisture as determinant of the seasonal soil co2 emission: evidence from central siberia

Abstract

Background The soils of the boreal zone contain significant reserves of carbon, therefore, their response to current climate changes will significantly affect the sustainability of forest ecosystems and the future concentration of CO 2 in the atmosphere. When modeling soil emission, it is necessary to focus on the main soil environment factors. In this paper, a simple exponential model of the soil CO 2 emissions growth was modified by introducing an additional parameter - the threshold soil moisture in different types of ecosystems based on the direct measurements. Results The developed model adequately reflects the dynamic changes in soil emission for different types of ecosystems. This result was achieved by including moisture as a second environmental factor besides temperature, describing changes in soil CO 2 emissions during the summer period. The error of direct measurements for all measuring seasons was about 20% of the values of direct measurements of the CO 2 flux. Note that such a high error was observed once per season in early and mid-June, reaching 60-80% on some days. Our models demonstrate in the season with the highest amount of precipitation the smallest differences in modeled fluxes about 15-20%, which indirectly indicates that the emission flux is not inhibited by insufficient moisture in this season. Conclusions The final model application depends on the characteristics of the microclimatic conditions of a particular ecosystem, namely, a factor that has a limiting effect on the biological processes. When studying the functional role of boreal forest ecosystems the moisture conditions consideration is crucial to explain the atmospheric CO 2 emission processes.