Sphagnum decay patterns and bog microtopography in south-eastern Finland

This study addresses differences in Sphagnum decay in the context of variations in physico-chemical peat properties linked to bog microtopography. The decay rates of six Sphagnum species were studied using litter bag techniques at Haukkasuo, a concentric raised bog in south-eastern Finland. The Sphagnum species were buried in their native microhabitats in oxic, intermittently anoxic and anoxic peat layers for one or two years. The hummock species generally decayed at slower rates than species growing in hollows and transitional zones of hollows (lawns). The average mean loss in mass of all Sphagnum species was 17.7 % after the first year and 18.6 % after two years. The mass loss correlated most positively with oxygen, carbon/nitrogen quotient and sodium, and most negatively with nitrogen, carbon, iron and depth in the native microhabitat. Knowledge about the litter quality of Sphagnum species is important for improving our understanding of ecosystem functions in northern peatlands, and particularly in relation to the development of microtopography