Effects of alternative harvesting managements on spatio-temporal variability of soil CO2, CH4, and N2O fluxes in boreal drained forested peatland

This study evaluates the impact of different forest management practices on soil greenhouse gas (GHG) fluxes in the Ränskälänkorpi boreal drained forested peatland, in Southern Finland. The study site is part of the HoliSoils project (Holistic management practices, modelling, and monitoring for European forest soils; https://holisoils.eu/). The study is designed for a comparative analysis of non-harvested control, traditional clear-cut harvesting, and harvesting by continuous cover forestry (57% of basal area removed), carried out in spring 2021. The aim is to quantify mean differences in soil CO₂, CH₄, and N₂O emissions and improve the annual budget estimates.

Measurements of soil CO₂, CH₄, and N₂O fluxes, soil temperature, moisture, water table depth, and air temperature were conducted post-harvest every two weeks during the growing season (May to November). Soil chemistry, understory vegetation, and microbial populations were also surveyed and evaluated for relations to observed spatial patterns of the GHG fluxes. Machine learning and Bayesian data assimilation techniques were employed (i) to identify relationships between GHG fluxes and environmental variables, and (ii) to model spatio-temporal dynamics.

Clear-cutting (CUT) resulted in an immediate and sustained rise in the water table, with mean levels significantly higher than the control (CTR) and selection harvesting (COV) sites. In all CUT, COV, and CTR sites differences in mean values of soil CO₂, CH₄, and N₂O fluxes were significant.

Our findings underscore the significance of spatio-temporal variability in GHG fluxes across different management practices, highlight the management role in variation of dynamic environmental controls on CO₂, CH₄, and N₂O fluxes, and reduce the knowledge gap on the effects of harvesting methods on GHG fluxes in boreal drained forested peatlands.