Plants, algae and lichens communities of Hope Bay, Antarctic Peninsula: floristic inventory and seabirds' influence.

The study aimed to describe and map the different plant communities that occur in Hope Bay (HB), Antarctic Peninsula. Floristic description was based on mosses, lichens and terrestrial algae species, forming a mosaic of cryptogamic plant communities. A vegetation map was developed based on images taken by the QuickBird sensor. Field campaigns were performed visiting 15 points previously selected in the image. All communities were georeferenced, and floristic work was done. The green alga Prasiola crispa forms the most widespread plant community in HB, closely associated with ornithogenic soils. All other plant communities are more restricted. A mixed Prasiola crispa/Caloplaca spp./Acarospora macrocyclos (lichens) community is distributed around abandoned Pygoscelis adeliae nesting areas. The high availability of P and N, and the tolerance to acid pH benefit the distribution of these species closer to penguin rookeries, from where it gets rich leachates. The dynamics of seabird populations seem to be the main driver of plant communities' development in ice-free areas of HB. Deschampsia antarctica (the Antarctic grass) and Colobanthus quitensis (pearlwort), widely distributed in Maritime Antarctica, are absent in the Hope Bay, representing a semiarid transitional area between humid and polar desert climatic regions.