The effects of elevated ultraviolet-B (UVB)
radiation on methane dynamics was studied in a
natural fen in Northern Finland for three growing
seasons (2003–2005). This is the first in situ study on
the effects of elevated UV-B radiation on methane
dynamics in a natural fen. The experimental setup
consisted of 30 study plots (120 9 120 cm) that were
randomly divided into three treatments: ambient
control, UV-A control and elevated UV-B. The UVB
enhancements were 63, 37 and 21% above ambient
during the growing seasons 2003, 2004 and 2005,
respectively. Elevated UV-B did not affect net methane
emission. Stable isotope composition of methane
indicated that methane was produced by the acetate
fermentation. Under elevated UV-B there was a slight
increase in the concentrations of acetate and propionate
but decrease in the oxalate concentration suggesting
UV-B-induced changes in the belowground processes.
The results emphasize the need for long-term field
studies under moderately enhanced exposures to estimate
whether the function and feedbacks of mire
ecosystems change under increased UV-B radiation.