15Seabirds are amongst the most important vectors transferring biogenic compounds from the 16 sea onto land in the polar regions and, consequently, influencing the properties of soil and 17 vegetation. We studied the influence of bird colonies (Adélie and gentoo penguins, giant 18 petrels), on soil properties and plant communities on King George Island, Maritime Antarctic. 19We designated seven transects, each starting from the colony edge and running to a natural 20 boundary feature, which were divided into contiguous sample plots where we identified

Prolonged chasing of an adult reindeer (Rangifer tarandus) by a polar bear (Ursus maritimus) was observed both on land and in the sea, in Magdalenefjorden, northwest Spitsbergen. Polar bears were also observed catching black guillemot (Cepphus grylle) in the sea in northwest Spitsbergen and feeding on chicks in the arctic tern (Sterna paradisea) colony in Hornsund, southwest Spitsbergen. While feeding on seabird species is unsurprising, the prolonged chasing of adult reindeer is unusual for polar bear hunting behaviour. The few documented cases of polar bear hunting reindeer consist of either surprising and killing resting/sleeping prey or stalking and a short rapid chase of the reindeer. Our observations describe new feeding habits of polar bears that may be in response to decreasing seal availability due to shrinking sea-ice cover in the Arctic.

Solar radiation reflectance was analysed to characterize Arctic ornithogenic tun− dra developing in the vicinity of large breeding colony of Brunnich's guillemots Uria lomvia and kittiwakes Rissa tridactyla at the foot of Gnålberget cliff (Hornsund, SW Spitsbergen). Radiometric method was found to be a useful tool for studying structure and functioning of plant formations. We measured reflectance of four wavelengths: 554 nm (YG), 655 nm (RED), 870 nm (NIR) and 1650 nm (SWIR) at 10 plots situated along the transect running from the colony to the sea. Moreover, data of plant community character, species quantitative composition as well as total biomass were collected to relate these pa− rameters with the spectral values. The results showed that radiometric data characterized vegetation well enough to recognize the same plant communities on the basis of spectral reflectance as distinguished with traditional phytosociological methods.

In the resource-limited Arctic environment, vegetation developing near seabird colonies is exceptionally luxuriant. Nevertheless, there are very few detailed quantitative studies of any specific plant species responses to ornithogenic manuring. Therefore, we studied variability of polar scurvygrass Cochlearia groenlandica individual biomass and leaf width along a seabird influenced gradient determining environmental conditions for vegetation in south-west Spitsbergen. We found seabird colony effect being a paramount factor responsible for augmented growth of C. groenlandica. The species predominated close to the colony and reached the highest mean values of individual biomass (1.4 g) and leaf width (26.6 mm) 10 m below the colony. Its abundance and size declined towards the coast. Both C. groenlandica individual traits significantly decreased with distance from the colony, soil water and organic matter content and increased with guano deposition, soil d 15 N, conductivity, acidity and nitrate, phosphate and potassium ion content. Our study supports the hypothesis that seabirds have fundamental importance for vegetation growth in poor Arctic environment. Highly plastic species such as C. groenlandica may be a useful instrument in detecting habitat condition changes, for instance resulting from climate change.

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