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[[File:Rotjan - Enderbury Day 1 - 2nd half (62).JPG|thumb|This [[coral reef]] in the [[Phoenix Islands Protected Area]] provides rich habitatshabitat for numerous marine lifespecies.]]
[[File:Antarctic (js) 18.jpg|thumb |Few creatures make the [[ice shelf|ice shelves]] of [[Antarctica]] their habitat, but water beneath the ice can provide rich habitatshabitat for multiple species.<ref>{{cite journal|last=Wohlschlag|first=Donald E.|year=1968|title=Fishes beneath Antarctic ice|url=https://media.australian.museum/media/dd/Uploads/Documents/35612/ams370_vXVI_2_lowres.8077ffe.pdf|journal=Australian Natural History|publisher=Australian Museum|publication-date=1968|volume=16|page=45-48|access-date=19 July 2021|quote=Beneath the sea ice and the terminal portions of the Ross Ice Shelf and Koettlitz Glacier tongue is an aquatic habitat that has a nearly uniform freezing temperature of –1.9° C (28.6° F) and a remarkable assemblage of animals.|archive-date=12 April 2021|archive-url=https://web.archive.org/web/20210412130032/https://media.australian.museum/media/dd/Uploads/Documents/35612/ams370_vXVI_2_lowres.8077ffe.pdf|url-status=live}}</ref>]]
[[File:Ibex in the French Vanoise National Park.JPG|thumb| [[Ibex]] in an alpine habitat]]
 
In [[ecology]], the term '''habitat''' summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular [[species]]. A species habitat can be seen as the physical manifestation of its [[ecological niche]]. Thus "habitat" is a species-specific term, fundamentally different from concepts such as [[Biophysical environment|environment]] or [[vegetation]] assemblages, for which the term "habitat-type" is more appropriate<ref>Krausman, P.R. & Morrison, M.L. (2016) Another plea for standard terminology. Journal of Wildlife Management, 80, 1143–1144. https://wildlife.onlinelibrary.wiley.com/doi/full/10.1002/jwmg.21121</ref>.
 
The physical factors may include (for example): [[soil]], [[moisture]], range of [[temperature]], and [[light]] intensity. [[Biotic index|Biotic]] factors will include the availability of [[food]] and the presence or absence of [[Predation|predators]]. Every organismspecies has certainparticular habitat needsrequirements, forwith thehabitat conditionsgeneralist inspecies whichable it willto thrive, butin somea arewide tolerantarray of wideenvironmental variationsconditions while othershabitat arespecialist species requiring a very specificlimited inset theirof requirements.factors Ato speciessurvive. The habitat of a species is not necessarily found in a geographical area, it can be the interior of a stem, a rotten log, a rock or a clump of [[moss]]; a [[Parasitism|parasitic organism]] has as its habitat the body of its [[Host (biology)|host]], part of the host's body (such as the digestive tract), or a [[Cell (biology)|single cell]] within the host's body.<ref>For example:
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HabitatsHabitat types are environmental categorizations of different environments based on the characteristics of a given geographical area, particularly vegetation and climate<ref>Krausman, P.R. & Morrison, M.L. (2016) Another plea for standard terminology. Journal of Wildlife Management, 80, 1143–1144. https://wildlife.onlinelibrary.wiley.com/doi/full/10.1002/jwmg.21121</ref>. Thus habitat types do not refer to a single species but to multiple species living in the same area. For example, terrestrial habitat types [[forest]], [[steppe]], [[grassland]], semi-arid or [[desert]]. [[Fresh-water]] habitat types include [[marsh]]es, [[stream]]s, [[river]]s, [[lake]]s, and [[pond]]s; marine habitat types include salt marshes, the coast, the [[intertidal zone]], [[Estuary|estuaries]], [[reef]]s, bays, the open sea, the sea bed, deep water and [[Hydrothermal vent|submarine vents]]. Habitat types may change over time. Causes of change may include a violent event (such as the eruption of a [[volcano]], an [[earthquake]], a [[tsunami]], a [[wildfire]] or a change in oceanic currents); or change may occur more gradually over millennia with alterations in the [[climate]], as [[ice sheet]]s and [[glacier]]s advance and retreat, and as different weather patterns bring changes of [[precipitation]] and [[Solar irradiance|solar radiation]]. Other changes come as a direct result of human activities, such as [[deforestation]], the [[plowing]] of ancient grasslands, the diversion and damming of rivers, the draining of marshland and the dredging of the seabed. The [[Introduced species|introduction of alien species]] can have a devastating effect on native wildlife - through increased [[predation]], through competition for resources or through the introduction of pests and diseases to which the indigenous species have no immunity.▼
Geographic habitat types include [[Polar regions of Earth|polar]], [[Temperate climate|temperate]], [[Subtropics|subtropical]] and [[Tropics|tropical]] regions. The terrestrial [[vegetation type]] may be [[forest]], [[steppe]], [[grassland]], semi-arid or [[desert]]. [[Fresh-water]] habitats include [[marsh]]es, [[stream]]s, [[river]]s, [[lake]]s, and [[pond]]s; marine habitats include salt marshes, the coast, the [[intertidal zone]], [[Estuary|estuaries]], [[reef]]s, bays, the open sea, the sea bed, deep water and [[Hydrothermal vent|submarine vents]].
 
▲Habitats may change over time. Causes of change may include a violent event (such as the eruption of a [[volcano]], an [[earthquake]], a [[tsunami]], a [[wildfire]] or a change in oceanic currents); or change may occur more gradually over millennia with alterations in the [[climate]], as [[ice sheet]]s and [[glacier]]s advance and retreat, and as different weather patterns bring changes of [[precipitation]] and [[Solar irradiance|solar radiation]]. Other changes come as a direct result of human activities, such as [[deforestation]], the [[plowing]] of ancient grasslands, the diversion and damming of rivers, the draining of marshland and the dredging of the seabed. The [[Introduced species|introduction of alien species]] can have a devastating effect on native wildlife - through increased [[predation]], through competition for resources or through the introduction of pests and diseases to which the indigenous species have no immunity.
 
==Definition and etymology==
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Some plants and animals have habitat requirements which are met in a wide range of locations. The small white butterfly ''[[Pieris rapae]]'' for example is found on all the continents of the world apart from Antarctica. Its larvae feed on a wide range of ''[[Brassica]]s'' and various other plant species, and it thrives in any open location with diverse plant associations.<ref name="Richards" /> The large blue butterfly ''[[Phengaris arion]]'' is much more specific in its requirements; it is found only in chalk grassland areas, its larvae feed on ''[[Thymus (plant)|Thymus]]'' species and because of complex lifecycle requirements it inhabits only areas in which ''[[Myrmica]]'' ants live.<ref name="Spitzer" />
 
Disturbance is important in the creation of biodiverse habitatshabitat types. In the absence of disturbance, a climax vegetation cover develops that prevents the establishment of other species. [[Wildflower]] meadows are sometimes created by conservationists but most of the flowering plants used are either [[Annual plant|annuals]] or [[Biennial plant|biennials]] and disappear after a few years in the absence of patches of bare ground on which their seedlings can grow.<ref name="Sutherland" /> Lightning strikes and toppled trees in tropical forests allow species richness to be maintained as [[Pioneer species|pioneering species]] move in to fill the gaps created.<ref name="Huggett" /> Similarly coastal habitatshabitat types can become dominated by kelp until the seabed is disturbed by a storm and the algae swept away, or shifting sediment exposes new areas for [[Colonisation (biology)|colonisation.]] Another cause of disturbance is when an area may be overwhelmed by an [[Invasive species|invasive introduced species]] which is not kept under control by natural enemies in its new habitat.<ref name="0X7iN">{{cite web |url=https://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species.aspx |title=Invasive species |publisher=National Wildlife Federation |access-date=24 May 2016 |archive-date=31 May 2016 |archive-url=https://web.archive.org/web/20160531214213/http://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species.aspx |url-status=live}}</ref>
 
==Types==
[[File:Epiphytes (Dominica).jpg|thumb|left|Rich rainforest habitat in [[Dominica]]]]
Terrestrial habitat- types include forests, grasslands, wetlands and deserts. Within these broad [[biome]]s are more specific habitatshabitat types with varying climate types, temperature regimes, soils, altitudes and vegetation types. Many of these habitatshabitat types grade into each other and each one has its own typical communities of plants and animals. A habitat-type may suit a particular species well, but its presence or absence at any particular location depends to some extent on chance, on its dispersal abilities and its efficiency as a colonizer.<ref name="Breed" />
 
[[File:Danau Sentarum 2006.jpg|thumb|left|Wetland habitatshabitat types in Borneo]]
Freshwater habitatshabitat types include rivers, streams, lakes, ponds, marshes and bogs.<ref name="BBCNature" /> Although some organisms are found across most of these habitatshabitat types, the majority have more specific requirements. The water velocity, its temperature and oxygen saturation are important factors, but in river systems, there are fast and slow sections, pools, [[bayou]]s and [[Backwater (river)|backwaters]] which provide a range of habitatshabitat types. Similarly, [[aquatic plant]]s can be floating, semi-submerged, submerged or grow in permanently or temporarily saturated soils besides bodies of water. Marginal plants provide important habitat for both invertebrates and vertebrates, and submerged plants provide oxygenation of the water, absorb nutrients and play a part in the reduction of pollution.<ref name="Cook" />
 
[[Marine habitat]]s include brackish water, estuaries, bays, the open sea, the intertidal zone, the sea bed, reefs and deep / shallow water zones.<ref name="BBCNature" /> Further variations include [[Tide pool|rock pools]], [[Shoal|sand banks]], [[mudflat]]s, [[Brackish water|brackish]] lagoons, sandy and pebbly beaches, and [[seagrass]] beds, all supporting their own flora and fauna. The [[benthic zone]] or seabed provides a home for both static organisms, anchored to the [[Substrate (biology)|substrate]], and for a large range of organisms crawling on or burrowing into the surface. Some creatures float among the waves on the surface of the water, or raft on floating debris, others swim at a range of depths, including organisms in the [[demersal zone]] close to the seabed, and myriads of organisms drift with the currents and form the [[plankton]].<ref name="Roff" />
 
[[File:Marsa Alam R18.jpg|thumb|left|Desert scene in Egypt]]
A [[desert]] is not the kind of habitat that favours the presence of amphibians, with their requirement for water to keep their skins moist and for the development of their young. Nevertheless, some frogs live in deserts, creating moist habitatshabitat types underground and hibernating while conditions are adverse. [[Couch's spadefoot toad]] (''Scaphiopus couchii'') emerges from its burrow when a downpour occurs and lays its eggs in the transient pools that form; the tadpoles develop with great rapidity, sometimes in as little as nine days, undergo [[metamorphosis]], and feed voraciously before digging a burrow of their own.<ref name="96sA2">{{cite web |url=http://www.desertmuseum.org/books/nhsd_spadefoot.php |title=Couch's spadefoot (''Scaphiopus couchi'') |publisher=Arizona–Sonora Desert Museum |access-date=16 May 2016 |archive-date=30 May 2016 |archive-url=https://web.archive.org/web/20160530230901/http://www.desertmuseum.org/books/nhsd_spadefoot.php |url-status=dead}}</ref>
 
Other organisms cope with the drying up of their aqueous habitat in other ways. [[Vernal pool]]s are ephemeral ponds that form in the rainy season and dry up afterwards. They have their specially-adapted characteristic flora, mainly consisting of annuals, the seeds of which survive the drought, but also some uniquely adapted perennials.<ref name="78fxw">{{cite book |title=Ecology, Conservation, and Management of Vernal Pool Ecosystems |author=Witham, Carol W. |year=1998 |publisher=California Native Plant Society |isbn=978-0-943460-37-6 |page=1}}</ref> Animals adapted to these extreme habitatshabitat types also exist; [[Anostraca|fairy shrimps]] can lay "winter eggs" which are resistant to [[desiccation]], sometimes being blown about with the dust, ending up in new depressions in the ground. These can survive in a dormant state for as long as fifteen years.<ref name="KNkKt">{{cite web|url=http://www.vernalpool.org/inf_fs.htm |title=Fairy shrimp |author=Green, Scott |publisher=The Vernal Pool Association |access-date=17 May 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160423074123/http://www.vernalpool.org/inf_fs.htm |archive-date=23 April 2016}}</ref> Some [[killifish]] behave in a similar way; their eggs hatch and the juvenile fish grow with great rapidity when the conditions are right, but the whole population of fish may end up as eggs in [[diapause]] in the dried up mud that was once a pond.<ref name="KcmBa">{{cite news |title=The most extreme fish on Earth |author=Walker, Matt |url=https://www.bbc.co.uk/earth/story/20150519-the-most-extreme-fish-on-earth |newspaper=BBC Earth |date=21 May 2015 |access-date=17 May 2016 |archive-date=26 August 2016 |archive-url=https://web.archive.org/web/20160826050456/http://www.bbc.co.uk/earth/story/20150519-the-most-extreme-fish-on-earth |url-status=live}}</ref>
 
Many animals and plants have taken up residence in urban environments. They tend to be adaptable generalists and use the town's features to make their homes. [[Rat]]s and [[Mouse|mice]] have followed man around the globe, [[pigeon]]s, [[Peregrine falcon|peregrines]], [[Old World sparrow|sparrow]]s, [[swallow]]s and [[house martin]]s use the buildings for nesting, [[bat]]s use roof space for roosting, [[fox]]es visit the garbage bins and [[squirrel]]s, [[coyote]]s, [[raccoon]]s and [[skunk]]s roam the streets. About 2,000 coyotes are thought to live in and around [[Chicago]].<ref name="Read" /> A survey of dwelling houses in northern European cities in the twentieth century found about 175 species of invertebrate inside them, including 53 species of beetle, 21 flies, 13 butterflies and moths, 13 mites, 9 lice, 7 bees, 5 wasps, 5 cockroaches, 5 spiders, 4 ants and a number of other groups.<ref name="Kelcey" /> In warmer climates, termites are serious pests in the urban habitat; 183 species are known to affect buildings and 83 species cause serious structural damage.<ref name="Abe,Bignell,Higashi" />
 
==Microhabitat types==
==Microhabitats==
A microhabitat is the small-scale physical requirements of a particular organism or population. Every habitat includes large numbers of microhabitatsmicrohabitat types with subtly different exposure to light, humidity, temperature, air movement, and other factors. The [[lichen]]s that grow on the north face of a boulder are different from those that grow on the south face, from those on the level top, and those that grow on the ground nearby; the lichens growing in the grooves and on the raised surfaces are different from those growing on the veins of quartz. Lurking among these miniature "forests" are the [[microfauna]], species of [[invertebrate]], each with its own specific habitat requirements.<ref name="ngpNx">{{cite web |url=https://www.anbg.gov.au/lichen/ecology-habitatshabitat types-micro.html |title=MicrohabitatsMicrohabitat types |access-date=18 May 2016 |publisher=Government of the Commonwealth of Australia |work=Australian National Botanic Gardens, Centre for Australian National Biodiversity Research (An Australian Government Initiative) |archive-date=14 April 2016 |archive-url=https://web.archive.org/web/20160414150015/https://www.anbg.gov.au/lichen/ecology-habitatshabitat types-micro.html |url-status=dead}}</ref>
 
There are numerous different microhabitatsmicrohabitat types in a wood; coniferous forest, broad-leafed forest, open woodland, scattered trees, woodland verges, clearings, and glades; tree trunk, branch, twig, bud, leaf, flower, and fruit; rough bark, smooth bark, damaged bark, rotten wood, hollow, groove, and hole; canopy, shrub layer, plant layer, leaf litter, and soil; buttress root, stump, fallen log, stem base, grass tussock, fungus, fern, and moss.<ref name="Offwell" /> The greater the structural diversity in the wood, the greater the number of microhabitatsmicrohabitat types that will be present. A range of tree species with individual specimens of varying sizes and ages, and a range of features such as streams, level areas, slopes, tracks, clearings, and felled areas will provide suitable conditions for an enormous number of biodiverse plants and animals. For example, in Britain it has been estimated that various types of rotting wood are home to over 1700 species of invertebrate.<ref name="Offwell" />
 
For a parasitic organism, its habitat is the particular part of the outside or inside of its [[Host (biology)|host]] on or in which it is adapted to live. The [[Biological life cycle|life cycle]] of some parasites involves several different host species, as well as free-living life stages, sometimes within vastly different microhabitatsmicrohabitat types.<ref name="Lewis" /> One such organism is the trematode (flatworm) ''[[Microphallus turgidus]]'', present in brackish water marshes in the southeastern United States. Its first intermediate host is a [[Gastropoda|snail]] and the second, a [[Palaemonetes pugio|glass shrimp]]. The final host is the waterfowl or mammal that consumes the shrimp.<ref name="InVitro" />
 
==Extreme habitatshabitat types==
{{main|Extremophile}}
[[File:Cryptoendolith.jpg|thumb|right|An Antarctic rock split apart to show [[endolithic]] lifeforms showing as a green layer a few millimeters thick]]
Although the vast majority of life on Earth lives in [[Mesophile|mesophyllic]] (moderate) environments, a few organisms, most of them [[Microorganism|microbes]], have managed to colonise extreme environments that are unsuitable for more complex life forms. There are [[bacteria]], for example, living in [[Lake Whillans]], half a mile below the ice of Antarctica; in the absence of sunlight, they must rely on organic material from elsewhere, perhaps decaying matter from glacier melt water or minerals from the underlying rock.<ref name="94qKN">{{cite news |last=Gorman |first=James |title=Bacteria Found Deep Under Antarctic Ice, Scientists Say |url=https://www.nytimes.com/2013/02/07/science/living-bacteria-found-deep-under-antarctic-ice-scientists-say.html |date=6 February 2013 |work=[[The New York Times]] |access-date=18 May 2016 |archive-date=3 September 2019 |archive-url=https://web.archive.org/web/20190903173131/https://www.nytimes.com/2013/02/07/science/living-bacteria-found-deep-under-antarctic-ice-scientists-say.html |url-status=live}}</ref> Other bacteria can be found in abundance in the [[Mariana Trench]], the deepest place in the ocean and on Earth; [[marine snow]] drifts down from the surface layers of the sea and accumulates in this undersea valley, providing nourishment for an extensive community of bacteria.<ref name="Y9kb7">{{cite web |last=Choi |first=Charles Q. |title=Microbes Thrive in Deepest Spot on Earth |url=http://www.livescience.com/27954-microbes-mariana-trench.html |date=17 March 2013 |publisher=LiveScience |access-date=18 May 2016 |archive-date=2 April 2013 |archive-url=https://web.archive.org/web/20130402234623/http://www.livescience.com/27954-microbes-mariana-trench.html |url-status=live}}</ref>
 
Other microbes live in habitatsenvironemts lacking in oxygen, and are dependent on chemical reactions other than [[photosynthesis]]. Boreholes drilled {{convert|300|m|ft|-2|abbr=on}} into the rocky seabed have found microbial communities apparently based on the products of reactions between water and the constituents of rocks. These communities have not been studied much, but may be an important part of the global [[carbon cycle]].<ref name="boiY3">{{cite web |last=Oskin |first=Becky |title=Intraterrestrials: Life Thrives in Ocean Floor |url=http://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html |date=14 March 2013 |publisher=LiveScience |access-date=18 May 2016 |archive-date=2 April 2013 |archive-url=https://web.archive.org/web/20130402235647/http://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html |url-status=live}}</ref> Rock in mines two miles deep also harbour microbes; these live on minute traces of hydrogen produced in slow oxidizing reactions inside the rock. These metabolic reactions allow life to exist in places with no oxygen or light, an environment that had previously been thought to be devoid of life.<ref name="ztVC3">{{cite web |last1=Schultz|first1=Steven |title=Two miles underground|url=http://www.princeton.edu/pr/pwb/99/1213/microbe.shtml |publisher=Princeton Weekly Bulletin|archive-url=https://web.archive.org/web/20160113130655/http://www.princeton.edu/pr/pwb/99/1213/microbe.shtml|archive-date=13 January 2016|date=13 December 1999}}</ref><ref name="NYT-20160912" />
 
The [[intertidal zone]] and the [[photic zone]] in the oceans are relatively familiar habitatshabitat types. However the vast bulk of the ocean is inhospitable to air-breathing humans, with [[Scuba diving|scuba divers]] limited to the upper {{convert|50|m|ft|-1|abbr=on}} or so.<ref name="Cole" /> The lower limit for photosynthesis is {{convert|100|to|200|m|ft|-1|abbr=on}} and below that depth the prevailing conditions include total darkness, high pressure, little oxygen (in some places), scarce food resources and extreme cold. This habitat is very challenging to research, and as well as being little-studied, it is vast, with 79% of the Earth's [[biosphere]] being at depths greater than {{convert|1000|m|ft|-2|abbr=on}}.<ref name="DeepSea" /> With no plant life, the animals in this zone are either [[detritivore]]s, reliant on food drifting down from surface layers, or they are predators, feeding on each other. Some organisms are [[Pelagic zone|pelagic]], swimming or drifting in mid-ocean, while others are benthic, living on or near the seabed. Their growth rates and metabolisms tend to be slow, their eyes may be very large to detect what little illumination there is, or they may be blind and rely on other sensory inputs. A number of deep sea creatures are [[Bioluminescence|bioluminescent]]; this serves a variety of functions including predation, protection and social recognition.<ref name="DeepSea" /> In general, the bodies of animals living at great depths are adapted to high pressure environments by having pressure-resistant [[Biomolecule|biomolecules]] and small organic molecules present in their cells known as [[piezolyte]]s, which give the proteins the flexibility they need. There are also unsaturated fats in their membranes which prevent them from solidifying at low temperatures.<ref name="JetfZ">{{cite web |url=https://www.bbc.co.uk/earth/story/20150129-life-at-the-bottom-of-the-ocean |title=What does it take to live at the bottom of the ocean? |year=2016 |publisher=BBC Earth |access-date=19 May 2016 |archive-date=13 May 2016 |archive-url=https://web.archive.org/web/20160513205236/http://www.bbc.co.uk/earth/story/20150129-life-at-the-bottom-of-the-ocean |url-status=live}}</ref>
 
[[File:Dense mass of anomuran crab Kiwa around deep-sea hydrothermal vent.jpg|thumb|right|Dense mass of white crabs at a hydrothermal vent, with stalked barnacles on right]]
[[Hydrothermal vent]]s were first discovered in the ocean depths in 1977.<ref name="Vent" /> They result from seawater becoming heated after seeping through cracks to places where hot [[magma]] is close to the seabed. The under-water hot springs may gush forth at temperatures of over {{convert|340|°C|°F|-1}} and support unique communities of organisms in their immediate vicinity.<ref name="Vent" /> The basis for this teeming life is [[chemosynthesis]], a process by which microbes convert such substances as [[hydrogen sulfide]] or [[ammonia]] into organic molecules.<ref name="SnmYR">{{cite web |url=http://ocean.si.edu/ocean-videos/hydrothermal-vent-creatures |title=Hydrothermal Vent Creatures |work=Ocean Portal |publisher=Smithsonian National Museum of Natural History |access-date=20 May 2016 |archive-date=24 May 2016 |archive-url=https://web.archive.org/web/20160524171254/http://ocean.si.edu/ocean-videos/hydrothermal-vent-creatures |url-status=dead}}</ref> These bacteria and [[Archaea]] are the primary producers in these ecosystems and support a diverse array of life. About 350 species of organism, dominated by [[Mollusca|molluscs]], [[Polychaete|polychaete worms]] and [[crustacean]]s, had been discovered around hydrothermal vents by the end of the twentieth century, most of them being new to science and [[Endemism|endemic]] to these habitatshabitat types.<ref name="DesBruy" />
 
Besides providing locomotion opportunities for winged animals and a conduit for the dispersal of [[pollen]] grains, [[spore]]s and [[seed]]s, the [[atmosphere]] can be considered to be a habitat-type in its own right. There are metabolically active microbes present that actively reproduce and spend their whole existence airborne, with hundreds of thousands of individual organisms estimated to be present in a cubic meter of air. The airborne microbial community may be as diverse as that found in soil or other terrestrial environments, however these organisms are not evenly distributed, their densities varying spatially with altitude and environmental conditions. [[Aerobiology]] has not been studied much, but there is evidence of [[Nitrogen cycle|nitrogen fixation]] in [[cloud]]s, and less clear evidence of carbon cycling, both facilitated by microbial activity.<ref name="RSB" />
 
There are other examples of extreme habitatshabitat types where specially adapted lifeforms exist; [[tar pit]]s teeming with microbial life;<ref name="Liq" /> naturally occurring crude oil pools inhabited by the larvae of the [[Helaeomyia petrolei|petroleum fly]];<ref name="GByxc">{{cite encyclopedia|year=2004|title=Petroleum fly|encyclopedia=Grzimek's Animal Life Encyclopedia|publisher=The Gale Group|edition=2nd|volume=3: Insects|page=367|isbn=978-0-7876-5779-6}}</ref> [[hot spring]]s where the temperature may be as high as {{convert|71|°C}} and [[cyanobacteria]] create [[microbial mat]]s;<ref name="Ot0z9">{{cite journal |author1=McGregor, G.B. |author2=Rasmussen, J.P. |year=2008 |title=Cyanobacterial composition of microbial mats from an Australian thermal spring: a polyphasic evaluation |journal=FEMS Microbiology Ecology |volume=63 |issue=1 |pages=23–35 |pmid=18081588 |doi=10.1111/j.1574-6941.2007.00405.x|doi-access=free}}</ref> [[cold seep]]s where the [[methane]] and hydrogen sulfide issue from the ocean floor and support microbes and higher animals such as [[mussel]]s which form [[Symbiosis|symbiotic associations]] with these [[anaerobic organism]]s;<ref name="0YJr8">{{cite web |url=http://oceanexplorer.noaa.gov/explorations/10lophelia/logs/oct18/oct18.html |title=Gas-powered Circle of Life: Succession in a Deep-sea Ecosystem |author=Hsing, Pen-Yuan |date=18 October 2010 |work=Lophelia II 2010 |publisher=NOAA |access-date=22 May 2016 |archive-date=25 February 2014 |archive-url=https://web.archive.org/web/20140225105310/http://oceanexplorer.noaa.gov/explorations/10lophelia/logs/oct18/oct18.html |url-status=live}}</ref> [[Salt pan (geology)|salt pans]] harbour [[halotolerance|salt-tolerant]] [[bacteria]] and [[archaea]] and also fungi such as the [[black yeast]] ''[[Hortaea werneckii]]'' and [[Basidiomycota|basidomycete]] ''[[Wallemia ichthyophaga]]'';<ref name="Gostincar" /><ref name="Saline" /> ice sheets in Antarctica which support fungi ''[[Thelebolus]]'' spp.,<ref name="Gostincar" /> glacial ice with a variety of bacteria and fungi;<ref name="SciR" /> and snowfields on which [[algae]] grow.<ref name="0yqn0">{{cite web |url=http://www-es.s.chiba-u.ac.jp/~takeuchi/snowalgae_ak.html |title=Snow algae on Alaskan glaciers |author=Takeuchi, Nozomu |year=2014 |access-date=22 May 2016 |archive-url=https://web.archive.org/web/20180329200551/http://www-es.s.chiba-u.ac.jp/~takeuchi/snowalgae_ak.html |archive-date=29 March 2018 |url-status=dead}}</ref>
 
==Habitat change==
[[File:Mt st helens Johnston ridge 25 years later.jpg|thumb|right|Twenty five years after the devastating eruption at [[Mount St. Helens]], United States, [[pioneer species]] have moved in.]]
Whether from natural processes or the activities of man, landscapes and their associated habitatshabitat types change over time. There are the slow [[Geomorphology|geomorphological]] changes associated with the geologic processes that cause [[tectonic uplift]] and [[subsidence]], and the more rapid changes associated with earthquakes, landslides, storms, flooding, wildfires, [[coastal erosion]], deforestation and changes in land use.<ref name="Lindenmayer" /> Then there are the changes in habitatshabitat types brought on by alterations in farming practices, tourism, pollution, [[Habitat fragmentation|fragmentation]] and climate change.<ref name="Miller" />
 
Loss of habitat is the single greatest threat to any species. If an island on which an endemic organism lives becomes uninhabitable for some reason, the species will become [[Extinction|extinct]]. Any type of habitat surrounded by a different habitat is in a similar situation to an island. If a forest is divided into parts by logging, with strips of cleared land separating woodland blocks, and the distances between the remaining fragments exceeds the distance an individual animal is able to travel, that species becomes especially vulnerable. Small populations generally lack genetic diversity and may be threatened by increased predation, increased competition, disease and unexpected catastrophe.<ref name="Miller" /> At the edge of each forest fragment, increased light encourages secondary growth of fast-growing species and old growth trees are more vulnerable to logging as access is improved. The birds that nest in their crevices, the [[epiphyte]]s that hang from their branches and the invertebrates in the leaf litter are all adversely affected and biodiversity is reduced.<ref name="Miller" /> Habitat fragmentation can be ameliorated to some extent by the provision of [[wildlife corridor]]s connecting the fragments. These can be a river, ditch, strip of trees, hedgerow or even an underpass to a highway. Without the corridors, seeds cannot disperse and animals, especially small ones, cannot travel through the hostile territory, putting populations at greater risk of [[local extinction]].<ref name="StrongEffect" />
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==Habitat protection==
{{Main|Habitat conservation}}
The protection of habitatshabitat types is a necessary step in the maintenance of biodiversity because if [[habitat destruction]] occurs, the animals and plants reliant on that habitat suffer. Many countries have enacted legislation to protect their wildlife. This may take the form of the setting up of national parks, forest reserves and wildlife reserves, or it may restrict the activities of humans with the objective of benefiting wildlife. The laws may be designed to protect a particular species or group of species, or the legislation may prohibit such activities as the collecting of bird eggs, the hunting of animals or the removal of plants. A general law on the protection of habitatshabitat types may be more difficult to implement than a site specific requirement. A concept introduced in the United States in 1973 involves protecting the critical habitat of [[endangered species]], and a similar concept has been incorporated into some Australian legislation.<ref name="Klemm" />
 
International treaties may be necessary for such objectives as the setting up of marine reserves. Another international agreement, the [[Convention on the Conservation of Migratory Species of Wild Animals]], protects animals that migrate across the globe and need protection in more than one country.<ref name="A4iV3">{{cite web |url=http://www.cms.int/ |title=Convention on the Conservation of Migratory Species of Wild Animals |publisher=UNEP/CMS Secretariat |access-date=7 July 2016 |archive-date=7 March 2011 |archive-url=https://web.archive.org/web/20110307065602/http://www.cms.int/ |url-status=live}}</ref> Even where legislation protects the environment, a lack of enforcement often prevents effective protection. However, the protection of habitatshabitat types needs to take into account the needs of the local residents for food, fuel and other resources. Faced with hunger and destitution, a farmer is likely to plough up a level patch of ground despite it being the last suitable habitat for an endangered species such as the [[San Quintin kangaroo rat]], and even kill the animal as a pest.<ref name="endangered" /> In the interests of [[ecotourism]] it is desirable that local communities are educated on the uniqueness of their flora and fauna.<ref name="Honey" />
 
==Monotypic habitat==
{{Distinguish|Monotypic}}
A monotypic habitat-type is a concept sometimes used in [[conservation biology]], in which a single species of animal or plant is the only species of its type to be found in a specific habitat and forms a [[monoculture]]. Even though it might seem such a habitat-type is impoverished in [[biodiversity]] as compared with [[wikt:polytypic|polytypic]] habitatshabitat types, this is not necessarily the case. Monocultures of the exotic plant ''[[Hydrilla]]'' support a similarly rich fauna of invertebrates as a more varied habitat.<ref name="Theel2008" /> The monotypic habitat occurs in both botanical and zoological contexts. Some [[invasive species]] may create monocultural stands that prevent other species from growing there. A dominant [[Colonisation (biology)|colonization]] can occur from retardant chemicals exuded, nutrient monopolization, or from lack of natural controls such as [[herbivore]]s or climate, that keep them in balance with their native habitatshabitat types. The [[Centaurea solstitialis|yellow starthistle, ''Centaurea solstitialis'']], is a botanical monotypic habitat example of this, currently dominating over {{convert|15000000|acre|km2}} in California alone.<ref name="m9qmw">{{cite web|url=http://wric.ucdavis.edu/yst/images/none/nc4.JPG |title=1970 distribution of yellow starthistle in the U.S. |publisher=[[University of California, Davis|UCD]] |work=Yellow Starthistle Information |url-status=dead |archive-url=https://web.archive.org/web/20061231024708/http://wric.ucdavis.edu/yst/images/none/nc4.JPG |archive-date=2006-12-31}}</ref> The non-native freshwater [[Zebra mussel|zebra mussel, ''Dreissena polymorpha'']], that colonizes areas of the [[Great Lakes]] and the [[Mississippi River]] [[drainage basin|watershed]], is a zoological monotypic habitat example; the predators or parasites that control it in its home-range in Russia are absent.<ref name="RnZlu">{{cite web |url=https://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species/Invasive-Mussels.aspx |title=Invasive Mussels |publisher=National Wildlife Federation |access-date=29 June 2016 |archive-date=17 August 2016 |archive-url=https://web.archive.org/web/20160817005333/https://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species/Invasive-Mussels.aspx |url-status=live}}</ref>
 
==See also==
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* {{annotated link|Habitat fragmentation}}
* {{annotated link|Landscape ecology}}
* {{annotated link|Marine habitatshabitat types}}
* {{annotated link|Habitat destruction}}: the loss of habitat
{{div col end}}
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<ref name="Richards">{{cite journal |last=Richards |first=O.W. |title=The biology of the small white butterfly (''Pieris rapae''), with special reference to the factors controlling its abundance|journal=Journal of Animal Ecology|year=1940 |volume=9 |issue=2 |pages=243–288 |doi=10.2307/1459|jstor=1459}}</ref>
<ref name="Spitzer">{{cite journal |last=Spitzer|first=L.|author2=Benes, J.|author3=Dandova, J.|author4=Jaskova, V. |author5= Konvicka, M.|title=The Large Blue butterfly (''Phengaris [Maculinea] arion''), as a conservation umbrella on a landscape scale: The case of the Czech Carpathians|journal=Ecological Indicators |year=2009 |volume=9 |issue=6|pages=1056–1063 |doi=10.1016/j.ecolind.2008.12.006}}</ref>
<ref name="Sutherland">{{cite book |author1=Sutherland, William J. |author2=Hill, David A. |title=Managing Habitatshabitat types for Conservation |url=https://books.google.com/books?id=FcRZodbd9oQC&pg=PA6 |year=1995 |publisher=Cambridge University Press |isbn=978-0-521-44776-8 |page=6 |access-date=2016-05-24 |archive-date=2018-12-12 |archive-url=https://web.archive.org/web/20181212134623/https://books.google.com/books?id=FcRZodbd9oQC&pg=PA6 |url-status=live}}</ref>
<ref name="Breed">{{cite book|author1=Breed, Michael D.|author2=Moore, Janice|title=Animal Behavior|url=https://books.google.com/books?id=lGe6UzHNcp8C&pg=PT248|year=2011|publisher=Academic Press|isbn=978-0-08-091992-8|page=248|access-date=2016-06-02|archive-date=2018-12-12|archive-url=https://web.archive.org/web/20181212134407/https://books.google.com/books?id=lGe6UzHNcp8C&pg=PT248|url-status=live}}</ref>
<ref name="BBCNature">{{cite news |title=Habitatshabitat types |url=https://www.bbc.co.uk/nature/habitatshabitat types |newspaper=BBC Nature |archive-url = https://web.archive.org/web/20160704211559/http://www.bbc.co.uk/nature/habitatshabitat types |archive-date = 4 July 2016}}</ref>
<ref name="Cook">{{cite book|author1=Cook, C.D.K.|author2=Gut, B.J.|author3=Rix, E.M.|author4=Schneller, J.|title=Water Plants of the World: A Manual for the Identification of the Genera of Freshwater Macrophytes|url=https://books.google.com/books?id=uRFTK3T4WTUC&pg=PR7|year=1974|publisher=Springer Science & Business Media|isbn=978-90-6193-024-2|page=7|access-date=2016-06-02|archive-date=2018-12-12|archive-url=https://web.archive.org/web/20181212134407/https://books.google.com/books?id=uRFTK3T4WTUC&pg=PR7|url-status=live}}</ref>
<ref name="Roff">{{cite book |author=Roff, John |title=Marine Conservation Ecology |url=https://books.google.com/books?id=HSLGGARRtfYC&pg=PA105 |year=2013 |publisher=Routledge |isbn=978-1-136-53838-4 |page=105 |access-date=2016-06-02 |archive-date=2018-12-12 |archive-url=https://web.archive.org/web/20181212134407/https://books.google.com/books?id=HSLGGARRtfYC&pg=PA105 |url-status=live}}</ref>
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{{Wikisource1911Enc|Habitat}}
*{{wiktionary-inline|habitat}}
*{{commons category-inline|Habitatshabitat types}}
 
{{Biology nav}}
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[[Category:Habitat| ]]
[[Category:Habitatshabitats| ]]
[[Category:Ecology]]
[[Category:Landscape ecology]]
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