Biogeography in the Sub-Arctic. Группа авторов

Biogeography in the Sub-Arctic - Группа авторов


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Biotas from the North Atlantic Islands

       Ole Bennike1 and Jens Böcher2

       1 Geological Survey of Denmark and Greenland, Copenhagen, Denmark

       2 Zoological Museum, Copenhagen, Denmark

      Large parts of the North Atlantic islands are mountainous, with the highest peak at 3693 m found in East Greenland. In addition to the Inland Ice, numerous local ice caps and other types of glaciers are found in Greenland and Iceland, whereas the Faroe Islands are unglaciated. Fjords and straits are common.

      The mean temperature for the warmest month shows a fall from 10 to 12 °C in the Faroe Islands, Iceland and southern‐most Greenland to 2 °C in the far north and the mean temperature for the coldest month shows a fall from 4 to –34 °C. The precipitation also falls towards the north, from ~4000 mm/year locally on the Faroe Islands and on ice caps in south‐western Iceland to below 200 mm/year in some areas of northern Greenland. The Faroe Islands, Iceland and south‐west Greenland are influenced by northward flowing relatively warm ocean currents, whereas North and East Greenland as well as northern Iceland are influenced by cold, southward flowing currents. The sea off northern Greenland is covered by ice all year round, whereas sea ice is not found in the Faroe Islands, which are characterized by a strongly maritime climate.

An illustration of a map depicting the North Atlantic region showing the location of place names used in the text.

      The North Atlantic Islands were repeatedly glaciated during the Quaternary glacial stages and only glimpses of the pre‐Holocene history are available. Nevertheless, the scattered occurrences of interglacial deposits give a fairly detailed picture of plant and animal life as well as climatic changes. Holocene deposits are much more widespread than pre‐Holocene deposits, and detailed studies of changes of climate, vegetation history as well as flora and fauna history have been conducted. Late glacial lake deposits have been found in northern Iceland and in southernmost Greenland.

Schematic illustration of stratigraphical overview of the Quaternary showing ages of interglacial deposits from the North Atlantic islands.

      In Iceland, plant fossils from interglacial deposits were first described in the 1930s (Áskelsson 1938; Líndal 1939) and a review of the palaeobotany of Pleistocene deposits in Iceland was recently provided by Grímsson (2011). The oldest interglacial plant‐bearing deposits are from the Early Quaternary, and the youngest interglacial deposits with plant and invertebrate remains probably date from the last interglacial period. Pollen analyses and macro‐fossil analyses of late glacial and Early Holocene deposits in Iceland were conducted by Rundgren (1995, 1998) and Rundgren and Ingólfsson (1999). Studies of the Early to Mid‐Holocene vegetation history of Iceland have been published by, for example, Caseldine (2001), Wastl et al. (2001), Hallsdóttir (1995), Hallsdóttir and Caseldine (2005) and Caseldine et al. (2006).

      In Greenland non‐marine interglacial biotas were not documented until 1979, when the Kap København Formation was discovered (Funder and Hjort 1980; Funder et al. 1984, 1985, 2001; Bennike 1990; Böcher 1995). The first description of Late Quaternary interglacial biotas in Greenland was published by Meldgaard and Bennike (1989). Later on, near‐shore marine deposits with washed‐out remains of plants and invertebrates were discovered in North‐West and East Greenland in the 1990s (Funder 1990; Bennike and Böcher 1992, 1994; Funder et al. 1994, 1998; Hedenäs 1994; Hedenäs and Bennike 2003; Böcher 2012). Remains of southern extra‐limital plants and beetles have been discovered at several sites. Southern extra‐limital species are species that only occur south of the fossil locality at present. Interglacial deposits in Greenland with non‐marine biotas are mainly dated to the Early Quaternary and to the last interglacial stage, the Eemian. Analyses of Holocene non‐marine floras and faunas were initiated by Iversen (1954) and followed up by Fredskild, Funder and Bennike (e.g. Fredskild 1973, 1983, 1985; Funder 1978, 1979; Bennike et al. 1999, 2008a,b; Bennike 2000a; Wagner et al. 2008; Bennike and Wagner 2012; Wagner and Bennike 2012). In addition to pollen, plant macro‐fossils and insect remains have been studied. Arthropod remains from Early to Mid‐Holocene deposits have been reported by, for example, Fredskild et al. (1975), Böcher and Fredskild (1993), Böcher and Bennike (1996), Bennike et al. (2000, 2004) and Böcher et al. (2012).

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