Abstract. Vegetation and hydrology are important controlling factors in
peatland methane dynamics. This study aimed at investigating the role of
vegetation components, sedges, dwarf shrubs, and Sphagnum mosses, in methane fluxes
of a boreal fen under natural and experimental water level drawdown
conditions. We measured the fluxes during growing seasons 2001–2004 using the
static chamber technique in a field experiment where the role of the
ecosystem components was assessed via plant removal treatments. The first
year was a calibration year after which the water level drawdown and
vegetation removal treatments were applied. Under natural water level
conditions, plant-mediated fluxes comprised 68 %–78 % of the mean growing
season flux (1.73±0.17 g CH4 m−2 month−1 from June to
September), of which Sphagnum mosses and sedges accounted for one-fourth and three-fourths,
respectively. The presence of dwarf shrubs, on the other hand, had a
slightly attenuating effect on the fluxes. In water level drawdown
conditions, the mean flux was close to zero (0.03±0.03 g CH4 m−2 month−1) and the presence and absence of the plant groups had a
negligible effect. In conclusion, water level acted as a switch; only in
natural water level conditions did vegetation regulate the net fluxes. The
results are relevant for assessing the response of fen peatland fluxes to
changing climatic conditions, as water level drawdown and the consequent
vegetation succession are the major projected impacts of climate change on
northern peatlands.
Interacting effects of vegetation components and water table on methane dynamics in a boreal fen
