Carbon dioxide and methane exchange of a patterned subarctic fen during two contrasting growing seasons

Abstract. The patterned microtopography of subarctic mires generates a variety environmental conditions, and carbon dioxide (CO2) methane (CH4) dynamics vary spatially among different plant community types (PCTs). We studied the CO2 CH4 exchange between fen atmosphere at Kaamanen in northern Finland based on flux chamber eddy covariance measurements 2017–2018. observed strong spatial variation four main PCTs studied, which were largely controlled by water table level differences vegetation composition. ecosystem respiration (ER) gross primary productivity (GPP) increased gradually from wettest PCT to drier ones, both ER GPP larger for all during warmer growing season 2018. estimated that 2017 balances ranged ?20 g C m?2 (Trichophorum tussock PCT) 64 (string margin PCT), while 2018 small sources (10–22 m?2). emissions (< 1 m?2) driest PCT, other three had significantly (mean 7.9, range 5.6–10.1 two seasons. Compared annual balance (?8.5 ± 4.0 2017, (?5.6 3.7 was affected an earlier onset photosynthesis spring, sink, drought event summer, decreased sink. also drought. 7.3 0.2 6.2 0.1 Thus, close zero years. adapted conditions provided ecosystem-level resilience loss due drawdown.