Poa annua is the only flowering plant species that has established a breeding population in the maritime Antarctic, through repeated anthropogenic introduction. The first appearance of this species in the Antarctic was observed in 1953. Annual bluegrass inhabits mainly anthropogenic sites, but recently has entered tundra communities. The functioning of P. annua in the Antarctic could not have been possible without adaptations that enable the plants to persist in the specific climatic conditions typical for this zone. Poa annua is highly adaptable to environmental stress and unstable habitats: huge phenotypic and genotypic variability, small size, plastic life cycle (life-history types ranging from annual to perennial forms). The spreading of P. annua in the Antarctic Peninsula region is a classic example of the expansion process following anthropogenic introduction of an invasive species, and illustrates the dangers to Antarctic terrestrial ecosystems that are associated with increasing human traffic.

Poa annua, an alien species reported from the Antarctic continent and many Antarctic and sub-Antarctic islands, was accidentally introduced in the vicinity of the Polish Antarctic Station H. Arctowski. Recently the species has been found entering native plant communities. In almost 30 years it dispersed over 250 m from the site it was first observed and can therefore be considered invasive. We report the first steps to eradicate the species following the initial research to quantify the biology, ecology and genetics of the species. After detailed mapping of all 1439 tussocks located in the Arctowski Station area we removed 314 tussocks closest to a moss carpet formation (native plant community of high conservation value). All of the 49 tussocks growing in the Ecology Glacier forefield were removed. It is the biggest alien plant eradication act conducted so far in Antarctica. We plan to continue the eradication process and monitor the eradicated sites. This will provide valuable information on impacts and issues related to removal of alien species in the maritime Antarctic and will help in informing future decisions on management of other plant invasions in the region. Given the increasing human traffic to the Antarctic and the associated risks of invasion our results will be important not only for Arctowski but also for the whole Antarctic region.

Abstractbank, but also directly in the previous year's inflorescences.

Poa annua L. (annual bluegrass) is the only non-native flowering plant species that has successfully established a breeding population in the maritime Antarctic and has been shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic population of this species is the formation of distinct dense clumps-tussocks. In the temperate zone the species is only loosely tufted. We focused on the characteristics of seed deposition associated with the tussocks and some aspects of the spatial heterogeneity of the soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is highly associated with the presence of tussocks. Seeds are deposited underneath the tussock rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive the Antarctic winter and readily germinate under optimal conditions.

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