Seasonal dynamics of methane emissions from a subarctic fen in the Hudson Bay Lowlands

[摘要] Ecosystem-scale methane (CH₄) flux (F_CH4) over asubarctic fen at Churchill, Manitoba, Canada was measured to understand themagnitude of emissions during spring and fall shoulder seasons, and thegrowing season in relation to physical and biological conditions.F_CH4 was measured using eddy covariance with a closed-pathanalyser in four years (2008–2011). Cumulative measured annualF_CH4 (shoulder plus growing seasons) ranged from 3.0 to9.6 g CH₄ m⁻² yr⁻¹ among the four study years, with a meanof 6.5 to 7.1 g CH₄ m⁻² yr⁻¹ depending upon gap-fillingmethod. Soil temperatures to depths of 50 cm and air temperature were highlycorrelated with F_CH4, with near-surface soil temperature at5 cm most correlated across spring, fall, and the shoulder and growing seasons. The responseof F_CH4 to soil temperature at the 5 cm depth and airtemperature was more than double in spring to that of fall. Emission episodeswere generally not observed during spring thaw. Growing season emissions alsodepended upon soil and air temperatures but the water table also exertedinfluence, with F_CH4 highest when water was 2–13 cmbelow and lowest when it was at or above the mean peat surface.

[学科分类] 地球化学与岩石