Arctic High Polar Deserts
Plant life in these zones is often so thin on the ground that the striking aspect of vast areas is the prominence of geomorphic features, with many of the colour patterns resulting from bedrock geology. The vegetation is characteristically devoid of the dwarf shrubs so typical of the tundra further south, and the few flowering plants that do occur usually form cushions or compact rosettes, while the few graminoids are small, compact and caespitose. There is little soil development and plant cover can be down to less the 2%. In the Canadian Arctic Archipelago some of the more dominant species include Cerastium alpinum, Draba corymbosa, Minuartia rubella, Saxifraga oppositifolia, and the endemic Draba subcapitata (Brassicaceae), Papaver radicatum (Papaveraceae) and Puccinellia angustata (Poaceae). Other endemic vascular plants found, for example, in the Russian High Arctic of the Zemlya Frantsa-Josife and Severnaya Zemlya archipelagoes include Androsace triflora (Primulaceae), Arctagrostis latifolia, Dupontia fisheri, Poa abbreviata, P. arctica and Puccinellia vahliana (Poaceae), Carex ursina (Cyperaceae), Cerastium regelii and Stellaria crassipes (Caryophyllaceae), Ranunculus sabini (Ranunculaceae), Braya purpurascens, Draba macrocarpa, D. pohlei and Parrya nudicaulis (Brassicaceae), and Potentilla pulchella (Rosaceae). One of the major biological entities that breakes the monotony of these otherwise barren landscapes is the plant communities supported by melting snow – the so-called snow flush communities. Vegetation cover is significantly higher in these areas and often dominated by the endemic Eriophorum triste (Cyperaceae). Other typical vascular plants include Alopecurus alpinus, Oxyria digyna, Phippsia algida, Saxifraga caespitosa, S. cernua and S. oppositifolia, while other endemic species associated with this habitat include Antennaria canesens (Asteraceae), Draba glacialis and D. oblongata (Brassicaceae). Often more important than the vascular plants throughout these polar deserts are bryophytes such as Cephaloziella arctica, Bryum arcticum, Seligera polaris, and lichens such as Cetraria islandica var. polaris, Ochrolechia frigida and Umbilicaria arctica. In fact, many of the species of these more ancient plant groups have bipolar distributions. On the other hand, in parts of the Canadian Arctic Archipelago crustose and foliose lichens are virtually absent, and this together with a very depauporate vascular plant flora is thought to be evidence that these areas were wiped clean by ice during the Little Ice Age between 130-430 years BP.
Arctic Tundra
The most characteristic plant formation of the arctic is tundra. In the southern zones it is typically composed of shrubby species, which are either evergreen with small thick leaves as in Arctostaphylos alpinus (alpine bearberry), Ledum palustre (Labrador tea), Loiseleuria procumbens (trailing azalea) and Phyllodoce caerulea (blue heath), or deciduous such as Betula nana (dwarf birch), Salix herbacea (dwarf willow), S. polaris and S. reticulata (net leaved willow). In these more heathy areas, endemic species such as Antennaria glabrate and A. hansii (Astereaceae), Oxytropis artobia and O. terrae-novae (Fabeaceae), and the near endemic moonwort Botrychium borealis (Ophioglossaceae) may be found, although some of these are confined to the more calcareous areas. In such areas, arctic herbaceous species like Dryas octopetala (mountain avens) may dominant relatively rich association of species such as Arnica alpina, Campanula uniflora, Draba nivalis, Oxytropis lapponica, and Potentilla nivea, while in more acidic areas, graminoids such as Alopecurus, Arctophila, Arctagrostis, Carex and the endemic genus Dupontia may predominate. In Alaska, the drier areas may include the endemic grass Arctagrostis latifolia (Poaceae) as one of the main species, but with increasing wetness the endemic Dupontia fisheri is becomes more prevalent. This latter can also tolerate complete immersion, but where there is more permanent standing water the endemic Arctophila fulva (Poaceae) may becomes the main grass species, together with species such as Hippurus vulgaris and Potentilla palustris. Other endemic species associated with grass tundra include Cardamine digitata (Brassicaceae) and Papaver keelei (Papavaceae).
Arctic Saltmarsh
Most saltmarshes at these latitudes only support 3-5 herbaceous species and unlike temperate and tropical saltmarsh there are no woody plants or species belonging to the Chenopodiaceae. The most common saltmarsh grass in Alaska is Puccinellia phryganodes, which usually occurs with scattered clumps of the endemic Carex ursine (Cyperaceae), together with Carex ramenski, C. subspathaceo, Cochlearia officinalis and Stellaria humifusa. Few other species are associated with these Arctic saltmarshes but several endemic species of the grass genus Puccinellia may be encountered including P. andersonii, P. groenlandica and P. tenella. The Arctic endemic Gentiana detonsa (Gentianaceae) is also associated with saline coastal areas.
Subarctic Alaskan Saltmarsh
In subarctic Alaska in the Cook Inlet five major saltmarsh zones have been identified:
1 Outer vegetated mudflats
2 Outer sedge marsh
3 Inner vegetated mudflats
4 Inner sedge marsh
5 Riverbank levee
Outer Vegetated Mudflats
On the seaward fringes this vegetation mainly comprises Puccinellia phryganodes and Triglochin maritimum, with the former spreading throughout the short summer to form lawnlike carpets. Other scattered plants include Puccinellia nutkaensis, Salicornia europaea agg and Suaeda depressa. In some places Puccinellia nutkaensis becomes the dominant grass.
Outer Sedge Marsh
This zone consists almost exclusively of Carex ramenskii and has a superficial resemblance to Spartina on temperate Atlantic coasts. The few other species include Potentilla egedii, Ranunculus cymbalaria and Stellaria humifusa.
Inner Vegetated Mudflats
This zone is more floristically diverse than the outer mudflats with a more even distribution of Triglochin maritimum. Other species include Glaux maritima, Plantago maritima, Poa eminens, Potentilla egedii and Puccinellia grandis.
Inner Sedge Marsh
Here the tall Carex lyngbyaei become the main species forming almost monospecific stands in places especially in the more water logged zones. In the drier zones mixtures including Chrysanthemum arcticum, Potentilla egedii and Triglochin maritimum occur, while in other places clumps of Carex pluriflora occur surrounded by pools of stagnant water. Other species include Carex lyngbyaei, Cicuta douglasii, Hippurus tetraphylla, Scirpus paludosus, Scirpus validus and Triglochin palustris.
Riverbank Levee
These slightly elevated zones support a mixture of species. The lower levels include mixtures of Festuca rubra, Lathyrus palustrus, Ligusticum scoticum, Potentilla egedii and Poa eminens, while high levels comprise Elymus arenarius and various large herbs such as Angelica lucida, Rumex arcticum and Saussurea nuda. Other species found on these levees include Achillea borealis, Conioselinum chinense, Dodecatheon pulchellum, Hierochloe odorata, Hordeum brachyantherum, Fritillaria kamchatkensis, Lupinus polyphyllus, Parnassia palustris and Trientalis europaea.
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