Greenhouse gas fluxes from boreal forest soils during the snow-free period in Quebec, Canada

• Published in: Canadian Journal of Forest Research
• Main Authors: Ullah, Sami, Frasier, Rebeccah, Pelletier, Luc, Moore, Tim R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2009
• Subjects: Canada; Eastmain
• Online Access: http://dx.doi.org/10.1139/x08-209; http://www.nrcresearchpress.com/doi/full-xml/10.1139/X08-209; http://www.nrcresearchpress.com/doi/pdf/10.1139/X08-209

This paper presents soil fluxes of methane (CH 4 ), nitrous oxide (N 2 O), and carbon dioxide (CO 2 ) from 12 sites located in four major forest types, black spruce ( Picea mariana (Mill.) BSP), jack pine ( Pinus banksiana Lamb.), aspen ( Populus spp.), and alder ( Alnus spp.) stands, in the Eastmain and Chibougamau regions of Quebec. Fluxes were determined with closed chambers during the snow-free period from May to October 2007. Well-drained black spruce, jack pine, and aspen forest soils were net sinks of atmospheric CH 4 (–0.33 ± 0.11 mg·m –2 ·day –1 ), while alder-dominated wetland soils were sources of CH 4 (0.45 ± 0.12 mg·m –2 ·day –1 ). The cut-over alder wetland soil produced 131 times more CH 4 than the undisturbed wetland soil. Soil moisture and temperature mainly regulated CH 4 fluxes. N 2 O fluxes from these forest soils were highly variable and smaller (1.6 ± 0.33 µg N·m –2 ·h –1 ) than those from deciduous forest soils. N 2 O emission from the cut-over black spruce forest soil was 2.7 times greater than that from the mature black spruce forest soil. Large C/N ratios (27 to 78) and slow soil N mineralization and nitrification rates in these forest soils may have led to small N 2 O fluxes. CO 2 emissions from these forest soils, ranging from 0.20 to 2.7 g·m –2 ·day –1 , were mainly controlled by soil temperature.