A contribution to the discussion of biota dispersal with drift ice and driftwood in the North Atlantic

Aim The present work aims to review the early proposed hypothesis of biota dispersal by driftwood and drift ice. Location The North Atlantic region. Methods New knowledge gained about drift ice patterns and sources and trans port routes of ice-rafted debris and dendrochronologically dated driftwood is used to investigate chance dispersal of diaspores. In addition, the extr emely disjunct distribution patterns of some vascular plants in Scandinavia and East Greenland are examined in the light of this new data. Results Both drift ice and driftwood are thought to be important in the cha nce dispersal of diaspores from Siberia and North-west Russia to parts of t he North Atlantic region, in the Late Weichselian or early Holocene. It is proposed that the extremely disjunct distribution of some vascular plants i n northern Scandinavia and East Greenland (e.g. Draba sibirica, Oxytropis d eflexa ssp. norvegica, Potentilla stipularis and Trisetum subalpestre) are examples of this type of long-distance dispersal. Main conclusions The concentration of extremely disjunct distributed vascul ar plant species in parts of northern Norway and East Greenland is suggeste d to relate to the Late Weichselian ice free conditions and the topography and exposure of the coastline in these areas, allowing accumulation of ice- rafted debris and driftwood. A systematic survey of debris samples obtained from drift ice and driftwood trees is needed to evaluate the significance of these vectors for dispersal of biota to the North Atlantic region.