The rate of peat accumulation in Antarctic moss banks
(1) Three Antarctic moss banks were studied in detail: two dominated by Polytrichum alpestre Hoppe and one by Chorisodontium aciphyllum (Hook. f. et Wils.) Broth. (2) The rate of upward growth of the moss banks, 0.9-1.3 mm yr-1, is approximately half the annual shoot growth. (3) The amount of decomposition which has occurred at different depths of the peat in these banks was calculated from measurements of bulk density and compression. The decomposition rate appears to be $< 1% mathrm{yr}^{-1}$. Peat 20-30 cm below the surface is permanently frozen, and about half the original material has decomposed by the time it becomes incorporated into this permafrost. Evidence is presented that a slow decomposition rate is an intrinsic characteristic of Polytrichum alpestre. (4) The rate of peat accumulation, 89-158 g m-2 yr-1, is about half the rate of production, 162-350 g m-2 yr-1. The former is similar to accumulation rates of peat elsewhere in the world.