The north-polar tundra represents merely a low graduated table of 1 of Norway but it is non less of import. It has some characteristics in common with Alpine tundra and it is found above the tree lines. We may establish this ecosystem in utmost North of Norway with Southern Arctic zone of tundra but it is chiefly represented in Svalbard, an island of Norway which is dominated by glaciers at 60 % . Normally the scientist delimits the north-polar zone with the isotherm bound of 10A°celsius in July. There are different zones of this tundra, Southern Arctic zone of tundra, middle-zone and the high-zone, besides divided in subzone late established, A to E with A the coldest and E the warmest subzones ( Jonsdottir, 2005 ) . The cold clime composition this ecosystem is chiefly explain by its high latitude which receive low visible radiation, due to low angle of incidence, low wet and precipitation, and a high reflective power consequence of the snow. The north-polar tundra is peculiarly immature in occupied the land for merely 2000-10,000 old ages ( Bliss et al. 1973 ) .
In these north-polar parts Permafrost is a dirt feature in keeping dirt to 0A°celsius for at least two back-to-back old ages ( Juliussen et al. , 2010 ) . It is composed of an active bed ( 30-50 centimeter ) of mineral and organic dirts with a deepness of 200 centimeter in good drained littorals and crushed rocks that unfreeze during summer to heighten flora ‘s growing ( Brown, R.J. E. , 1972 ) and a monolithic ice bed ; both in low-Arctic and high-Arctic ( Bliss et al. 1973 ) . The temperature of this permafrost is really utile ; it has been identified as one of indexs of clime alteration by the Global Climate Observing System ( GCOS ) . An of import long-run monitoring has been launched by the international permafrost association ( IPA ) with the international Polar twelvemonth ( IPY ) in 2007-2009: research undertaking Permafrost Observatory Project: a part to the Thermal State of Permafrost ( TSP ) . The scientists have computed land temperature by boreholes and besides temperature monitoring in the air, snow cover, at the land surface and/or in the upper land. Nowadays, this huge monitoring continues. In Norway, the permafrost observatory undertaking: part to the thermic province of permafrost in Norway and Svalbard ( TPS NORWAY ) usage observatories in the two northmost counties of Troms and Finmark and in cardinal western Svalbard ( Juliussen et al. , 2010 ) . All these research has allowed to set up a map of permafrost happenings. The permafrost in Svalbard is uninterrupted while in the mainland it is occur merely in mountain countries.
Harmonizing the flora screen, the north-polar tundra is by and large composed of shrublands, moisture sedge and grasslands, herbfields, steppes. It is a simple and delicate ecosystem with low energy budget, in portion due to its tough clime and its dirt composing hapless in food.
In the mainland of Norway, the north-polar tundra zone is represented in low-level between northern boreal and in-between north-polar. Usually it is characterized by a Podzol dirt with an acid pH and a flora screen resembling to the low alpine zone. This dirt is composed of humified organic constituent stuffs associated with aluminium and FER. They occur most frequently in countries with flaxen stuffs cold and moist clime, in a wood or bush flora. In despite of strict clime it exist an of import vegetation which persist throughout the twelvemonth with about 100 species of vascular workss and many cryptographs. This tundra flora is composed merely of midget shrubs species such as willows, Alnus, Betula and Dwarf birch. As a consequence of frequent snow screen and the length of seasons reduced, merely the quickly developing workss can prevail. Lichens, mosses and hepatics are common every bit good as Juniperus, Empetrum, Vaccinium species. We may establish in this country several adapted mammals: caribous, mountain hares, lemmings, stoats, weasels and field mouses and many migratory sea birds.
As see antecedently in Norway the chiefly portion of north-polar tundra is in Svalbard, an archipelago at the north-western border of the Barents Sea. This part has somewhat different characteristics due to its island features. This archipelago has comparatively mild clime in its western portion because of the warm North Atlantic current making Spitzbergen, the largest island ; whereas its east cost is making by a cold Barents Sea Waterss. Consequently there is big heterogeneousness through islands from Arctic polar desert and northern Arctic tundra ( high-zone ) and in-between Arctic tundra. During the last ice age Svalbard was about wholly covered by ice. Therefore, dirts take long clip to develop, and in comparing to the “ mainland ” there is a low species diverseness on Svalbard, and tellurian nutrient webs are simple with strong links to marine nutrient webs but in the other manus it is composed of alone biological communities. For illustration, birds play an of import function in soils composing. Where the seashore home ground allow sea bird genteelness settlements with drops, their guano contribute to a good alimentary handiness and increases productiveness and dirt organic for works community ( Jonsdottir, 2005 ) . Furthermore a survey of Hodkinson and Coulson ( 2004 ) showed an of import degree of complexness of invertebrates ‘ community in nutrient webs. The craniates present on this archipelago are common to the Arctic ecosystem and adapted to its conditions, which allowed an of import nutrient sink for other species.
In this tellurian nutrient web, the Arctic Fox ( Alopex Lagopus ) , Glaucous chump, Arctic bonxie and Polar bear ( Ursus maritimus ) are the top marauder, embracing besides the Snow bunting, Ptarmigan, Geese coinage and the endemic Svalbard caribou ( Rangifer tarandus platyrhynchus ) . There are a low figure of birds species, the most are sea birds such as Svalbard stone ptarmigan ( Lagopus muta Hyperborean ) , Atlantic puffin ( Fratercula arctica ) , and Snow bunting ( Plectrophenax nivalix ) . Some species were introduced but remain in little population such as the mountain hare ( Lepus timidus ) , the north-polar hare ( L. arcticus ) and the musk ox ( Ovibos moschatus ) now extinct. Harmonizing to the works community, merely few countries have flora screen of low bushs: Salix, Dryas, Herbs, Graminoids, Mosses and Lichen are the most vegetational species.
In effect, some perturbation may impact this delicate equilibrium in this sort of ecosystem. In this country the human perturbation is comparatively low but due to its breakability even vehicle paths may impact it because of the slow re-colonization and growing rates of the land beings, workss and delicate dirt construction. However, the current major perturbation is the long-run clime alteration particularly for its peculiarly location and current H2O implicates. An enlargement of species with warmer conditions or invasive species may besides be harmful.
At higher graduated table, the planetary changing affects peculiarly the permafrost. Indeed, several surveies showed an increasing permafrost temperature ( Juliussen et al. , 2010 ) .
The scientists predict in the hereafter serious effects of planetary heating on permafrost. Lars Kullerud, manager UArtcic and Svein Tveitdal studies and warns about the effects of the permafrost thaw for the United Nations Environment Programme ( UNEP ) :
1 ) Permafrost countries will be reduced, in southern Norway it is non uninterrupted any longer as the Northern hemisphere and scientific theoretical accounts from IPCC predict a possible decrease of up to 16 per cent the following 50 old ages in these discontinuous permafrost. 2 ) Danger to autochthonal people and ecosystems 3 ) spreeding up the nursery consequence: the tundra has worked as a C sink ; C dioxide is released and it is largely released as methane, because the decomposition procedure is go oning in wet dirt with small or no supply of O. A Huge H2O measure will released taking land eroding. That ‘s why many surveies are conducted to supervise and foretell these alterations in Svalbard and other portion of the Arctic polar zone.
The alpine tundra as north-polar tundra occur above the tree line, either in high height in cragged parts or above 60A°N latitude in Northern Norway until about 70A°N where it go north-polar zone. Norway is covered by about 48 % ( 148000 km2 ) of mountains ( Abrahamsen et al. , 1977 ) and Alpine tundra covers big countries: 32 % of land country, including Hardangervidda, a celebrated tableland in Norway, which is the largest European tableland wholly located beyond the treeline with an alpine tundra.
Among these latitudes it is hard to separate Alpine or Arctic tundra. However, Alpine tundra benefits warmer clime and longer season. In antonym of north-polar tundra one characteristic is singular: the home grounds are more disconnected, so works and animate beings disperses less quickly. Consequently the species and familial diverseness are more of import in this country.
This tundra is besides divided in low-alpine, mild-alpine and high-alpine. The low-alpine occurs in low-altitudes nearby the treeline with diverse workss as the willow species, blueberry, common retem and Linnaea borealis, but hayfield and moorlands workss rule these countries ; whereas mid-alpine has smaller workss such as mosses and lichens, similar to low-arctic species but the land is most cover even if the snow screen last into mid-summer. Then, the high-alpine tundra looks like more that north-polar tundra with bare stone, snow and glaciers embracing merely few workss species ( norway infoe3, 2010 ) such as the glacier buttercup ( Ranunclus glacialis ) , the drooping breakstone ( Saxifraga cernua ) and the moss silene ( Silene acaulis ) . Therefore, Alpine tundra has several characteristics in common with north-polar tundra, therefore its fauna portion many similarities with low-arctic zoologies: caribou, mountain hare, lemming, stoat, weasel and field mouses are common species. The most of these species live besides under the tree line, merely ptarmigan ( Lagopus mutus ) bird ‘s coinage seems to populate merely supra and other birds species migrate in high latitude towards north-polar zone such as willow grouse ( L. Lagopus ) .
The high latitudes ecosystems as Alpine and Arctic tundra are in general more sensitive and vulnerable to environmental alterations. Loffler and Pape ( 2008 ) suggested that they seem to be the most sensitive to climatic alterations happening on a planetary graduated table.
The Alpine tundra happening in mountains is mostly use for graze of sheep and caribou ( wild and semi-domesticate ) since a long clip ago. Although presents their populations are controlled by runing direction, and sheep graze is chiefly restricted to southern Scandinavian ( Norse ) mountains, where sheep portion their home ground with the wild caribou at several sites, they remain a important perturbation ( e.g. in Hardangervidda-Nordfjella, Rondane-Dovrefjell and Setesdalen ) ( Austrheim & A ; Eriksson, 2001 ) . Indeed, they have a important consequence on the alpine tundra. This graze has several effects and may be every bit good as positive or negative for the species diverseness. Yet, overgrazing is in most instance harmful for the ecosystem dependant of regional form: dirt characteristics, abiotic factors ( c.f. pH ) , productiveness, and distribution of snow, temperature, species pool and grade of atomization. Austrheim & A ; Eriksson ( 2001 ) conclude that control of graze is a cardinal procedure for keeping biodiversity in the Norse mountains. The gnawer and their strong graze following their rhythm have besides an of import impact and these ecosystems ( Austrheim & A ; Erikson, 2001 ) . All these effects act at larger graduated table in the other portion of tundra ( alpine in Northern latitudes and north-polar tundra ) . A survey from Hofgaard ( 1997 ) provides more inside informations about these effects and high spots on the inter-relationships of these two factors with an consequence more pronounced of the lessened graze on flora responses than altering clime.
Furthermore, as see antecedently the clime alteration is besides an of import factor at high latitudes, particularly in act on snow screen and glaciers. Davis ( 1986 ) , Pauli et. Al. ( 1996 ) showed that species community equilibrium ( carnal and vegetational ) is impacting by the clime alteration with clip slowdowns, frequently with populations denseness additions at the acme which lead to jobs of infinite and competition. Although they describe besides an increasing of species diverseness, we may foretell with such effects in the hereafter, extinction of some sensitive species because of the heater clime. Furthermore, it is besides of import to take in history an increasing touristry. Svalbard archipelago attracts more touristry each twelvemonth, a batch of sail touristry and expedition disturbed the sensitive ecosystem trough many ways: wildlife perturbation, debasement of flora, pollutions despite protected country and Torahs ( WWF, 2004 ) .
Some effects of these alterations are already clearly singular: the shrub enlargement in tundra ecosystems is a good illustration. Indeed, as position antecedently we can establish this species in both ecosystems but at rather little graduated table or under different signifier ( normal or midget ) .
Yet several recent surveies showed net alterations, peculiarly Myers-Smith et.al. ( 2011 ) . They used repetition picture taking and long-run ecological monitoring and they found a important increasing of bush copiousness at the circumpolar Arctic, high latitude and alpine tundra because of a heater clime and alterations in snow screen. This may basically alter and change the construction of biotic constituents such as energy fluxes, dirt, C and foods rhythms, and ecological interactions between species.
That is why understanding the mechanisms that control diverseness are necessary for foretelling alterations from land usage and altering clime.