Moss and lichen tundra

Moss and lichen tundra is a naturally treeless habitat restricted to areas with permafrost and characterized by a relatively thick and dense cover of mosses. Mean annual temperatures range from -7 to -1 °C. More important for the growing period of vegetation, which only starts in early summer, are the mean July temperatures, ranging from 2-3 °C in the north to 4-6 °C in the middle-arctic zone. Average annual precipitation is between 200 and 800 mm.

In Northern Europe, the habitat type is typically found in the lowlands and along the coast on acidic to neutral Mesozoic and Paleozoic bedrock (Svalbard, Bjørnøya) with Tomentypnum nitens and Warnstorfia sarmentosa as dominating species, while Racomitrium lanuginosum dominates on neutral to alkaline younger volcanic rocks (Jan Mayen, Iceland). The relief varies considerably. More eastwards in northern Russia the habitat occurs mainly in a flat or slightly hilly landscape. Permafrost leads to micro-patterns with slightly different relief within the habitat.

Characteristic vascular plants in Moss and lichen tundra are the dwarf shrubs Dryas octopetala and Cassiope tetragona, and Salix herbacea and S. polaris (in respectively neutral to alkaline and acidic snowbed-like, moist-soils), the sedges Carex rupestris, C. nardina, C. misandra, and Luzula arctica (on neutral to alkaline soils), as well as Luzula confusa (on acidic soils) and Saxifraga oppositifolia. While the vascular flora of the arctic region is relatively species poor, high numbers of lichens, mosses and fungi may be found. The species composition varies with changes in bedrock (alkaline - acidic), soil type (rocky to mesic), snow-cover and exposition.

On Svalbard four main types of Moss tundra may be distinguished: (1) Wet Moss tundra on calcareous bedrock, dominated by Tomentypnum nitens. (2) Dry Moss Tundra on calcareous soils with dominance of Dicranum angustum, (3) acidic Moss tundra with Polytrichum strictum, and (4) Wet Moss tundra on acidic bedrock dominated by Sphagnum squarrosum. Typical lichens of this tundra habitat are Cetrariella delisei (dominant on stony sites), Cladonia mitis, Cetraria nivalis and Sphaerophorus globosus (on acidic substrates). On Iceland, in the subarctic region, species-poor Racomitrium lanuginosum dominated habitats occur on relatively old lava. Such habitats are locally called ‘moss heath’ but are included here in ‘Moss and lichen tundra’. Vascular plants in these moss fields are heathland species, like Carex bigelowii or Empetrum hermaphroditum. The arctic island Jan Mayen is largely dominated by moss beds of Racomitrium lanuginosum and R. canescens, while – less frequently – also R. fasciculare occurs in this habitat. Here, very few plants are able to germinate in this moss tundra, that is only more open in places where it has been eroded, like on steep slopes. The habitat is found on dry slopes, but also on more foggy slopes.

Transitions occur towards more sparsely vegetated polar deserts (habitat H5.1b) in dry areas, tundra mires (habitat D4.2 with Deschampsia alpina, Carex stans and Eriophorum scheuchzeri) in wet locations, snow beds (habitat E4.1 and F2.1) in hollows and depressions with long lasting snow cover (dominated by Poa alpina and Salix reticulata), sparsely-vegetated stony riverbeds in valleys (habitat C3.5d), communities with different Potentilla species on screes (habitat H2.1 and H2.2), and shrub tundra with heathland species (F1.1) on Iceland.

Moss and lichen tundra is a circumpolar habitat type within the arctic regions of Russia, Canada, Alaska and Greenland. In the EU28+, the middle and northern arctic zone is limited to the Svalbard archipelago and to the islands of Jan Mayen and Bjørnøya. On Svalbard it is limited to a relatively small percentage of the total area, as the largest part is covered by glaciers or polar desert (type H5.1b). Additionally the habitat covers parts of Iceland, in the subarctic region. In addition to permafrost, moss tundra on Svalbard depends on the natural fertilizers birds and Svalbard reindeer. The typical Moss tundra can be found under bird cliffs but it is common in all parts of the north-arctic tundra zone on Svalbard.

Indicators of quality:

In good conditions the habitat shows the following characteristics:

• Very low cover of (dwarf) shrubs,

• Diversity of microhabitats due to frost patterns (polygons) and cryoturbation

• High diversity in mosses and lichens

• Absence of human disturbance

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats