Factors affecting the availability of plant nutrients on an Antarctic island

An examination of material from Signy Island, in the South Orkney group, shows that large amounts of plant nutrients are moving through the ecosystem of the island. Physical weathering is a dominant process and the rocks are an important source of potassium and calcium. The ocean provides a steady supply of sodium and magnesium distributed via the atmosphere whilst the fauna provide a large reservoir of phosphorus, nitrogen and cations. Atmospheric distribution of nitrogen from the fauna sites is important but phosphorus appears to depend more on direct droppings and drainage for distribution. The capacity of the bryophyte vegetation to retain ions was demonstrated by experiment. It is suggested that this pattern of nutrient supply applies to much of the Antarctic perimeter zone.