Factors causing the limitation of growth of terrestrial algae in maritime Antarctica during late summer

The factors causing the cessation of growth and decline of microalgal communities on Antarctic fell-field soils during late summer were investigated. Physical and chemical amendments were applied within small enclosures and the size and taxonomic composition of the communities assessed. Most treatments had no effect on the microalgal communities or individual taxa. The addition of calcium nitrate to the soil either singly or as part of a complete growth medium promoted growth of all taxa studied on most sites. As the cation was naturally present in excess in the soil it is concluded that growth of the microalgal communities during late summer was nitrogen-limited.