Sphagnum moss: an indicator of climate change in the sub-Antarctic

Abstract

Sphagnum moss has been used globally as an indicator of climate change. Since continuous meteorological recording started in the late 1940s, there has been a marked change in the climates of Southern Ocean islands. The distribution of Sphagnum on Macquarie Island appeared to be expanding through the 1980s. All patches of Sphagnum were mapped in the 1992/93 austral summer, with 112 Sphagnum moss patches (<3 m²) and 12 larger (≥3 m²) patches recorded. The vast majority of sites recorded were lowland coastal, with a few sites around plateau lakes. The area of moss beds ranges from 0.03 m² to 32.4 m². A total of 23 sites were pegged and tagged by 1996, but only 14 of these sites still had Sphagnum moss present by 2004. It is considered that the climatic conditions (higher than average temperatures and wind speeds and lower than average humidity and precipitation) that occurred between April 1999 and May 2000 would have resulted in a period of desiccation that accounts for the destruction of the smaller and/or shallower Sphagnum beds on the island. It is highly likely that both the spatial distribution and size of Sphagnum moss beds on Macquarie Island will continue to decline with predicted changes in sub-Antarctic climate.