The effect of altered moisture availability on greenhouse gas emissions in sub-alpine peatlands in southern Australia

Peatlands store amongst the highest proportion of soil carbon in terrestrial ecosystems, but there is significant concern surrounding the effect climate change, and in particular, altered soil moisture regimes have on carbon cycling in these ecosystems. While greenhouse gas dynamics of boreal and high-elevation peatlands are well-studied in the northern hemisphere, less is known about peatlands in an Australian context. Soils were sampled from Lake Mountain, a sub-alpine peatland in south-eastern Australia at along a transect at four sites; sphagnum, wet peat, mid slope and woodland sites. The soils were incubated for 31 days to determine the effect of altered moisture content on CO2, CH4 and N2O fluxes under controlled conditions. Three moisture scenarios were assessed, a wet, dry and a 14-day wet-dry cycle examined over four sites, with three replicate cores per site. The Lake Mountain peatlands were estimated to store 114.52 Mg ha-1 in the top 20 cm, which is lower than other estimates of high elevation peatlands in south-eastern Australia. There was no effect of treatment on greenhouse gas fluxes, but higher carbon to nitrogen ratio was found to increase CO2 and CH4 fluxes. Some N2O sequestration was also identified. The results suggest that over the short term where soils do not dry out completely, site characteristics have a larger influence on GHG emissions compared to altered moisture availability.