Signy Island as a Paradigm of Biological and Environmental Change in Antarctic Terrestrial Ecosystems

Abstract

Terrestrial ecosystems throughout much of Antarctica are exhibiting local changes in their environment which are, either directly or indirectly, influencing biological processes. Central to these changes is the present climatic warming being experienced, especially in the more northerly regions, which is causing substantial recession of glaciers and ice fields and creating new surfaces on which biota may become established. Other temporal changes occur as a function of the natural process of colonisation, growth and ecosystem development but which may be strongly influenced by minor variations in climate or other components of the environment. Examples of such environmental, and consequently of biological, changes are presented for one climatically and ecologically sensitive locality, Signy Island in the South Orkney Islands, to illustrate the diversity of changes which may affect the structure and dynamics of Antarctic ecosystems in general. These are discussed in terms of ecological change resulting from long-term climatic trends, short-term climatic (especially summer temperature) fluctuations, plant colonisation and growth, community development, and environmental perturbation. A plea is made for implementing long-term monitoring studies to determine the direction and rate of environmental and ecological changes, with particular regard to assessing the resiliance of ecosystems to and their recovery from these phenomena. The Antarctic environment offers probably the most significant baseline to which global atmospheric changes may be related. The predicted trend in global warming implies disturbing consequences for the future integrity of Antarctica’s, or indeed the world’s, environment and biota. However, it offers ideal opportunities to study the cause-and-effect relationship of ecological change and, from this, to develop a strong management policy for the active use and conservation of the Antarctic biome.