Kan vandra på tundra

Permafrost tundra includes vast areas of northern Russia and Canada. Arctic tundra contains areas of stark landscape and is frozen for much of the year. The soil there is frozen from 25 to 90 cm 10 to 35 in down, making it impossible for trees to grow. Instead, bare and sometimes rocky land can only support certain kinds of Arctic vegetation , low-growing plants such as moss, heath Ericaceae varieties such as crowberry and black bearberry , and lichen. There are two main seasons, winter and summer, in the polar tundra areas. However, extreme cold temperatures on the tundra do not drop as low as those experienced in taiga areas further south for example, Russia's and Canada's lowest temperatures were recorded in locations south of the tree line. During the summer, temperatures rise somewhat, and the top layer of seasonally-frozen soil melts, leaving the ground very soggy. The tundra is covered in marshes, lakes, bogs, and streams during the warm months.

Generally daytime temperatures during the summer rise to about 12 °C 54 °F but can often drop to 3 °C 37 °F or even below freezing. Arctic tundras are sometimes the subject of habitat conservation programs. However, it is desert-like, with only about — mm 6—10 in of precipitation falling per year the summer is typically the season of maximum precipitation. Although precipitation is light, evaporation is also relatively minimal. During the summer, the permafrost thaws just enough to let plants grow and reproduce, but because the ground below this is frozen, the water cannot sink any lower, so the water forms the lakes and marshes found during the summer months. There is a natural pattern of accumulation of fuel and wildfire which varies depending on the nature of vegetation and terrain. Research in Alaska has shown fire-event return intervals FRIs that typically vary from to years, with dryer lowland areas burning more frequently than wetter highland areas.

The biodiversity of tundra is low: 1, species of vascular plants and only 48 species of land mammals can be found, although millions of birds migrate there each year for the marshes. There are few species with large populations. Notable plants in the Arctic tundra include blueberry Vaccinium uliginosum , crowberry Empetrum nigrum , reindeer lichen Cladonia rangiferina , lingonberry Vaccinium vitis-idaea , and Labrador tea Rhododendron groenlandicum. Due to the harsh climate of Arctic tundra, regions of this kind have seen little human activity, even though they are sometimes rich in natural resources such as petroleum , natural gas , and uranium. A severe threat to tundra is global warming , which causes permafrost to thaw. The thawing of the permafrost in a given area on human time scales decades or centuries could radically change which species can survive there. In locations where dead vegetation and peat have accumulated, there is a risk of wildfire, such as the 1, km 2 sq mi of tundra which burned in on the north slope of the Brooks Range in Alaska.

Carbon emissions from permafrost thaw contribute to the same warming which facilitates the thaw, making it a positive climate change feedback. The warming also intensifies Arctic water cycle , and the increased amounts of warmer rain are another factor which increases permafrost thaw depths. Microbial respiration is the primary process through which old permafrost carbon is re-activated and enters the atmosphere. The rate of microbial decomposition within organic soils, including thawed permafrost, depends on environmental controls, such as soil temperature, moisture availability, nutrient availability, and oxygen availability. A perspectives article discussing tipping points in the climate system activated around 2 °C 3. In , a study of the northern permafrost peatlands a smaller subset of the entire permafrost area, covering 3. It had further suggested that after more years, those peatlands would have absorbed more carbon than what they had emitted into the atmosphere.

The IPCC Sixth Assessment Report estimates that carbon dioxide and methane released from permafrost could amount to the equivalent of 14— billion tonnes of carbon dioxide per 1 °C 1. A assessment of the economic impact of climate tipping points estimated that permafrost carbon emissions would increase the social cost of carbon by about 8. Their figures for combined permafrost emissions by amounted to — billion tonnes of carbon dioxide equivalent under 1. They compared those figures to the extrapolated present-day emissions of Canada , the European Union and the United States or China , respectively. The — billion tonnes figure would also be equivalent to the today's remaining budget for staying within a 1.

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Natali of Woods Hole Research Centre , had also led the publication of a complementary estimate in a PNAS paper that year, which suggested that when the amplification of permafrost emissions by abrupt thaw and wildfires is combined with the foreseeable range of near-future anthropogenic emissions, avoiding the exceedance or "overshoot" of 1. Antarctic tundra occurs on Antarctica and on several Antarctic and subantarctic islands, including South Georgia and the South Sandwich Islands and the Kerguelen Islands. Most of Antarctica is too cold and dry to support vegetation, and most of the continent is covered by ice fields or cold deserts. However, some portions of the continent, particularly the Antarctic Peninsula , have areas of rocky soil that support plant life. The flora presently consists of around — species of lichens, mosses, 25 liverworts , and around terrestrial and aquatic algae species, which live on the areas of exposed rock and soil around the shore of the continent.

Antarctica's two flowering plant species, the Antarctic hair grass Deschampsia antarctica and Antarctic pearlwort Colobanthus quitensis , are found on the northern and western parts of the Antarctic Peninsula. Sea mammals and sea birds, including seals and penguins, inhabit areas near the shore, and some small mammals, like rabbits and cats, have been introduced by humans to some of the subantarctic islands. There is some ambiguity on whether Magellanic moorland , on the west coast of Patagonia , should be considered tundra or not. The flora and fauna of Antarctica and the Antarctic Islands south of 60° south latitude are protected by the Antarctic Treaty. Alpine tundra does not contain trees because the climate and soils at high altitude block tree growth. Alpine tundra is generally better drained than arctic soils.

Tundra - Wikipedia

Alpine tundra occurs in mountains worldwide. The flora of the alpine tundra is characterized by plants that grow close to the ground, including perennial grasses , sedges , forbs , cushion plants , mosses , and lichens. Tundra climates ordinarily fit the Köppen climate classification ET , signifying a local climate in which at least one month has an average temperature high enough to melt snow 0 °C 32 °F , but no month with an average temperature in excess of 10 °C 50 °F. Despite the potential diversity of climates in the ET category involving precipitation, extreme temperatures, and relative wet and dry seasons, this category is rarely subdivided. Rainfall and snowfall are generally slight due to the low vapor pressure of water in the chilly atmosphere, but as a rule potential evapotranspiration is extremely low, allowing soggy terrain of swamps and bogs even in places that get precipitation typical of deserts of lower and middle latitudes.

Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version. In other projects. Wikimedia Commons Wikivoyage. Biome where plant growth is hindered by frigid temperatures. For other uses, see Tundra disambiguation. See also: Arctic vegetation. This section is an excerpt from Permafrost carbon cycle § Carbon release from the permafrost. Greater summer precipitation increases the depth of permafrost layer subject to thaw, in different Arctic permafrost environments. Although temperatures will increase, this does not imply complete loss of permafrost and mobilization of the entire carbon pool. Much of the ground underlain by permafrost will remain frozen even if warming temperatures increase the thaw depth or increase thermokarsting and permafrost degradation. Carbon dioxide and methane in CO 2 equivalent emissions from subsea permafrost alone under the different Representative Concentration Pathway scenarios over time.

This would have a warming impact of 0. It also suggested that at between 3 °C 5. Main article: Alpine tundra. Main articles: Tundra climate and Alpine climate. World Wildlife Fund. Archived from the original on 4 June Kieli-ikkunat in Finnish. Archived from the original on 1 October Retrieved 19 January The World's Biomes. University of California, Berkeley. Retrieved 5 March Wild World. National Geographic Society. Archived from the original on 5 August Retrieved 2 November December Ecological Applications. ISSN Retrieved 16 February Retrieved 18 October Ecological Society of America. Blue Planet Biomes.

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National Geographic. Retrieved 3 April The New York Times. Retrieved 17 December Syndonia; Hollingsworth, Teresa N. Bibcode : Natur. PMID S2CID Archived from the original PDF on 14 November Retrieved 20 July Bibcode : Oecol. PMC Science of the Total Environment. Bibcode : ScTEn. Nature Communications. Bibcode : NatCo.. Soil Science Society of America Journal. Archived from the original on 17 July Retrieved 5 June Environmental Research Letters. Archived from the original on 19 May Retrieved 11 February Proceedings of the National Academy of Sciences. Bibcode : PNAS.. Bibcode : BGeo Hewitt, C. Xiao, G. Aðalgeirsdóttir, S. Drijfhout, T. Edwards, N. Golledge, M. Hemer, R. Kopp, G. Växtsäsongen på tundran varar vanligen 60 till 80 dagar, [ 1 ] och frostperioden varar nio till tio månader. Områden med kontinuerlig permafrost uppträder vanligen i områden med en högsta årsmedeltemperatur på -1°C till -4°C och diskontinuerlig permafrost där årsmedeltemperaturen är lägre än -7°C till -8°C.

Marken i tundraområden består oftast av en sula av kontinuerlig eller diskontinuerlig permafrost, i många fall är dock berggrunden helt i dagen. Ovanpå permafrosten ligger en dåligt utvecklad jordmån uppbyggd av torv , vilken är påverkad av frys- och smältperioder. Under sommaren smälter detta övre, så kallade aktiva lager , och bildar en vattenmättad sörja. Det aktiva lagret är vanligen omkring en meter djupt från 15 cm i torv till fem meter i oskyddad jord. Vissa tundraregioner är lika torra som polaröknar , men ofta är den relativa luftfuktigheten hög och evaporationen låg. Den vattenmättade torven i det aktiva lagret och den underliggande permafrosten både förhindrar en effektiv dränering och djup rotbildning. Jorden är sur till neutral och fattig på näringsämnen. Markkväve är en bristvara, och det finns bara några få ärtväxter med kvävefixerande bakterier. Höga växter som träd kan inte utvecklas under tundrans förhållanden och vegetationen består huvudsakligen av gräs , halvgräs , mossor , lavar och mindre buskar.

Snödjupet är den största enskilda faktorn för hur höga växterna blir, och norr om e breddgraden, där klimatet att betrakta som öken eller halvöken , blir mycket få växter högre än fem centimeter. Mellan 50 och 98 procent av biomassan är under markytan. Vissa perenna växter som växer i tundramiljön har på grund av den korta växtperioden utvecklats så att de bildar knopp ett år och blommar ut året därpå. Tundravegetationen kan delas upp i två klasser, fjällvegetation respektive tundravegetation. Fjällvegetation som inte bara återfinns i fjällen har en tunn och spridd växthorisont i jorden eller växer direkt på berggrunden.

Vad vaxer i tundran? –

Typiska växter för fjällvegetationen är fjällglim och olika medlemmar ur bräckesläktet. Tundravegetationen å andra sidan har en tydlig växthorisont med sammanhängande rotfilt och gör det lättare för många växter att etablera sig. Exempel på tundravegetation är dvärgbjörk , krypande videväxter och olika Vaccinium -arter. Faunan på den arktiska tundran inkluderar förutom de flitigt förekommande myggorna lämmel och andra mindre gnagare, kanin , myskoxe , ren , fjällräv , varg , vessla , isbjörn , fjälluggla och ripor. Flera sjöfåglar, som gäss och svanar , har sin häckning i tundran. I den alpina tundran återfinns, beroende på kontinent, bland annat snöget , tjockhornsfår och wapitihjort. Tundralandskap i Stora Sjöfallets högfjällsmarker. Huvudsaklig utbredning för arktisk tundra.