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

Abstract

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 transport routes of ice‐rafted debris and dendrochronologically dated driftwood is used to investigate chance dispersal of diaspores. In addition, the extremely 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 chance dispersal of diaspores from Siberia and North‐west Russia to parts of the North Atlantic region, in the Late Weichselian or early Holocene. It is proposed that the extremely disjunct distribution of some vascular plants in northern Scandinavia and East Greenland (e.g. Draba sibirica, Oxytropis deflexa ssp. norvegica, Potentilla stipularis and Trisetum subalpestre) are examples of this type of long‐distance dispersal. Main conclusions The concentration of extremely disjunct distributed vascular plant species in parts of northern Norway and East Greenland is suggested 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.

The role of large wood in retaining fine sediment, organic matter and plant propagules in a small, single-thread forest river

“…The process of hydrochory (i.e., dispersal of diaspores by water: van der Pijl, 1982;Andersson et al, 2000) has been investigated by many researchers in relation to the colonisation of riparian zones and related influences on riparian vegetation communities (e.g., Nilsson and Grelsson, 1990;Nilsson et al, 1991;Andersson et al, 2000;Jansson et al, 2000;Gurnell et al, 2006). As well as floating freely in rivers, plant propagules can be transported within the water column in the same manner as sediment particles-and by attaching to floating objects such as small pieces of wood, logs, twigs, and leaves-and can then be stranded in large wood accumulations (Johansen and Hytteborn, 2001) and other obstructions within the channel.…”

Spatio-temporal distribution of floating objects in the German Bight (North Sea)

“…Thus, floating wood in the German Bight appears to come from local (the Elbe, Weser and Ems rivers) and distant sources (British Channel or Rhine river). In order to identify source regions, future studies might apply dendrochronological techniques (Johansen and Hytteborn, 2001), histology (Pailleret et al, 2007), or molecular approaches (Hurr et al, 1999).…”

“…seaweed and wood) and anthropogenic debris (e.g. plastics items) have been suggested as dispersal vectors for a wide range of species from marine and terrestrial environments (Ingólfsson, 1995;Barnes and Milner, 2005;Johansen and Hytteborn, 2001;Waters, 2008); recent molecular studies have added support to this view (Muhlin et al, 2008;Nikula et al, 2010). Anthropogenic floating objects (mainly plastic debris) may facilitate long-distance dispersal of invasive species, and furthermore impact marine wildlife (e.g.…”

Hybridisation, Introgression and Phylogeography of Icelandic Birch

“…The alternative route of Holocene dispersal, which is especially important for species lacking a wind-dispersal mechanism, is by ice-rafting and wood-drifting with the transpolar current from Siberia to northern Scandinavia, Iceland and eastern Greenland (Johansen & Hytteborn 2001). The arctic flora appears to be highly mobile (Alsos et al 2007), as some dispersal vectors may be particularly efficient in the Arctic as a result of the open landscape, strong winds and extensive snow and ice cover.…”