An extraordinary peat-forming community on the Falkland Islands

Abstract

Most of Beauchêne Island in the South Atlantic is covered by tussac, the tussock-forming grass Poa flabellata (Lam.) Rasp., which has produced a deep accumulation of exceptionally dense peat during ∼12,500 yr. The basal peat is lignitic, yet it is several hundred times too young to be a true lignite. During an ecological survey of the island in December 1980¹, one of us (R.I.L.S.) sampled an 11-m high peat face. The age against depth profile in the peat is consistent with a constant proportional rate of decay of 1.1–2.2×10⁻⁴ yr⁻¹ and a constant rate of addition of dry matter to the peat of 430–720 g m⁻² yr⁻¹. This rate of decay is within the range recorded for peats in corresponding latitudes in the Northern Hemisphere, but the rate of addition of dry matter is about 10 times as great. This is not easy to accommodate within current hypotheses about peat formation. An unusual combination of biological, physical and chemical circumstances may be the cause. As the island is difficult to visit and no more information can be obtained in the near future, we now report these results, incomplete though they are.