DISTRIBUTION OF BRYOPHYTES ON SUB-ANTARCTIC HEARD ISLAND

Heard Island is a small, isolated subantarctic island dominated by art ice covered volcano. Glaciers descend the volcano to the sea. Coastal ice free areas of tundra are present separated from each other by gla ciers. Each of these areas cart be considered as individual islands an d Heard Island art archipelago. The distribution of 49 bryophyte taxa across five major and four minor ice-free areas was examined. Fifty pe rcent of the bryophyte taxa exhibited widespread distribution, occurri ng on all ice-free islands examined Absence of some conspicuous specie s from particular areas appeared to reflect situations where limited h abitat variation has restricted the establishment of species. With pre sent global warming, glacial retreat on Heard Island is rapid. Consequ ently, areas suitable for colonization by plants are increasing and pr eviously separated ice free areas are now merging. This study provides baseline data against which future studies will be able to investigat e possible changes in bryophyte species diversity and distribution on Heard Island.