Peatland carbon stores and fluxes in the Snowy Mountains, New South Wales, Australia

Abstract

Peatlands in the Snowy Mountains cover nearly 8000 ha and preserve 49 million m3 of peat, of which 27.1 million m3 is stored in Sphagnum shrublands and restiad moorlands and 21.9 million m3 is stored in sedge fen. The total carbon store is estimated to be about 3.55 Tg. Peat accumulation over the past 60 years indicates that the historical carbon accumulation rate is only 4950 Mg yr-1 for the entire peat estate. This equates to net carbon storage rates of 0.8–1.6 Mg ha-1 yr-1 which is similar to the rates of 0.2 to 2.3 Mg ha-1 yr-1 found in other temperate peatlands. Peat sections covering the last 3000 to 4000 years, however, retain a millennial-scale net long-term storage of 0.09 to 0.21 Mg ha-1 yr-1 totalling 2340 Mg yr-1. The lower storage value of the older peats is partly due to continuing slow peat decay but may also represent accelerated decay due to disturbance by a 100-year phase of stock grazing and intentional burning in the mountains. Some peatlands are recovering strongly since grazing was stopped but they are still vulnerable to hydrological changes caused by trampling by large mammals. Rates of carbon sequestration will be sensitive to climate change, as the peatlands are already stressed by these former land management practices and many are at their climatic limits. The active management of peatland hydrology and surface stabilisation is essential to peatland recovery and the conservation of these significant carbon stores.