Hydroclimatic influences on peatland CO2 exchange following upland forest harvesting on the Boreal Plains

A comparative study of forest clear-cut logging effects on daily growing season (May to October) net ecosystem CO2 exchange (NEE) of adjacent peatlands was conducted in two neighbouring forest upland-peatland complexes over 4 years (2005 to 2008) on the Boreal Plains (BP) of Alberta, Canada. Higher vapour pressure deficit at the harvested-upland (H-U) peatland, reflecting increased turbulent mixing after adjacent upland forest removal (2007 and 2008), resulted in increased peatland evapotranspiration rates that contributed to a seasonal decline in soil moisture (volumetric moisture content) influencing NEE. Overall, a significant change in mid-season NEE occurred at the H-U peatland 1 year post-harvesting, greater than NEE changes at the neighbouring intact-upland peatland. However, 2 years post-harvesting, mid-season NEE returned to within range of pre-harvesting variability (-0.54 to 1.34 g CO2-Cm-2 day(-1)). Results of this study demonstrate that BP peatland NEE is largely regulated by site-specific water availability, which, in turn, may be influenced in the short term by shifting microclimate and soil moisture patterns because of clear-cut logging. As such, predicting long-term carbon storage function of BP peatlands will require careful consideration of changing hydroclimatic conditions because of rapid expansion of BP deforestation, given that these ecosystems already exist in a state of hydrologic risk in this moisture deficit eco-region. Copyright (C) 2016 John Wiley & Sons, Ltd.