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Biogeography in the Sub-Arctic


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remains of non‐marine plants and animals, with many different groups represented. Vascular plants include a mixture of boreal and arctic species (Figure 6). Taxa such as Larix groenlandii, Picea mariana, Thuja occidentalis and Taxus sp., Betula sect. Albae, Myrica arctogale, Cornus stolonifera, Viburnum cf. edule and Scirpus microcarpus belong to the first group, whereas D. octopetala, O. digyna and Papaver sect. Scapiflora belong to the second. All remains of wood come from small trees or shrubs, and the largest log that was found had a diameter of 18 cm. Growth rings are narrow to extremely narrow, which may indicate that the mean temperature for the warmest month of the year was ~10–11 °C. Thuja and Taxus cannot tolerate very cold winters, and the mean temperature for the coldest month was probably not below −17 °C. Thus, it appears that the area was dominated by forest tundra, which grew in an oceanic type of sub‐arctic climate.

Photos depict (a) a log of Larix sitting in sandy deposits of the Kap København Formation in North Greenland. The light part has been bleached by the sun. Note the contrasting modern treeless landscape. (b) Organic-rich layers of the Kap København Formation. (c) Excavation of last interglacial deposits on Jameson Land, central East Greenland. (d) Sandy interglacial deposits on Jameson Land with organic-rich sediments in the bottom of a trough. (e) Archaeological excavation of a Mid-Holocene midden in central West Greenland.

Schematic illustrations of plant remains from the Kap Kobenhavn Formation in North Greenland. (a-b) Leaves of Dryas octopetala. Leaf that comes from a plant that grew on a protected site (a) and a narrow leaf with recurved leaf margin, which comes from a plant that grew on a wind-exposed site (b). (c, d) Leaves of Betula nana. (e) Fruit stone of Cornus stolonifera. (f) Cone of Larix groenlandii. (g) Twig of Thuja occidentalis with three small cones. (h) Twig of Thuja occidentalis with scaly leaves. Thick scale bars: 10 mm, thin bars: 5 mm.

      Source: From Bennike (1990).

      The insect fauna of the Kap København Formation allows a detailed palaeoecological reconstruction of a highly diverse environment. Freshwater, freshwater shores, humid terrestrial biotopes, forests and alpine biotopes each contributes about equal numbers of species, with somewhat fewer taxa from dry environments, including steppe and saline ponds (Böcher 1995).

Photos depict scanning electron microscope photographs of beetle and ant remains from the Kap København Formation in North Greenland. (a) Head of Cicindela cf. hybrida. (b-d) Elytra of Aegialia terminalis, Scolytus piceae and Kalissus nitidus. (e) Head of Formica sp. (f) Elytron of Litodactylus leucogaster. Scale bars: 0.5 mm.

      Source: From Böcher (1995).

An illustration of a map depicting the northern parts of the Earth, showing present geographical ranges of Picea mariana (a), Thuja occidentalis (b) and Cornus stolonifera (c). Remains of these species have been found in the Kap København Formation.

      Source: From Bennike (1990).

Photos depict scanning electron microscope photographs of fruits from extinct plants from the Kap København Formation in North Greenland. (a) Myrica arctogale. (b) Aracites globosa.