Interannual variability of net ecosystem CO2 exchange at a subarctic fen

Landscape‐scale net ecosystem CO 2 exchange (NEE) and the energy balance of a subarctic fen were studied during five growing seasons near Churchill, Manitoba. Interannual variability in NEE was large and ranged from a net sink of −235 g CO 2 m −2 in 1996 to a net source of +76 g CO 2 m −2 in 1994. Annual estimates of CO 2 exchange indicate that during the present period the fen is losing carbon nearly 3 times faster than its long‐term …