Distribution of bryophytes on subantarctic Heard Island

Heard Island is a small, isolated subantarctic island dominated by an ice covered volcano. Glaciers descend the volcano to the sea. Coastal ice free areas of tundra are present separated from each other by glaciers. Each of these areas can be considered as individual islands and Heard Island an archipelago. The distribution of 49 bryophyte taxa across five major and four minor ice-free areas was examined. Fifty percent of the bryophyte taxa exhibited widespread distribution, occurring on all ice-free islands examined. Absence of some conspicuous species from particular areas appeared to reflect situations where limited habitat variation has restricted the establishment of species. With present global warming, glacial retreat on Heard Island is rapid. Consequently, areas suitable for colonization by plants are increasing and previously separated ice free areas are now merging. This study provides baseline data against which future studies will be able to investigate possible changes in bryophyte species diversity and distribution on Heard Island.