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Difference between revisions of "Lichen"
added links to Antarctic lichens
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==Distribution== | ==Distribution== | ||
[[File:Lichenson Heard Island.jpg|thumb|right|Lichen covered rocks on Heard Island.]] | [[File:Lichenson Heard Island.jpg|thumb|right|Lichen covered rocks on Heard Island.]] | ||
Lichens occur from sea level to high alpine elevations, in many environmental conditions, and can grow on almost any surface. Lichens are abundant growing on bark, leaves, mosses, on other lichens, and hanging from branches "living on thin air" (epiphytes) in rain forests and in temperate woodland. They grow on rock, walls, gravestones, roofs, exposed soil surfaces, and in the soil as part of a biological soil crust. Different kinds of lichens have adapted to survive in some of the most extreme environments on Earth: [[Antarctica]], hot dry deserts, rocky coasts, and toxic slag heaps. They can even live inside solid rock, growing between the grains. | Lichens occur from sea level to high alpine elevations, in many environmental conditions, and can grow on almost any surface. Lichens are abundant growing on bark, leaves, [[moss|mosses]], on other lichens, and hanging from branches "living on thin air" (epiphytes) in rain forests and in temperate woodland. They grow on rock, walls, gravestones, roofs, exposed soil surfaces, and in the soil as part of a biological soil crust. Different kinds of lichens have adapted to survive in some of the most extreme environments on Earth: [[Antarctica]], hot dry deserts, rocky coasts, and toxic slag heaps. They can even live inside solid rock, growing between the grains. | ||
It is estimated that 6% of Earth's land surface is covered by lichen. There are about 20,000 known species of lichens. Some lichens have lost the ability to reproduce sexually, yet continue to speciate. Lichens can be seen as being relatively self-contained miniature ecosystems, where the fungi, algae, or cyanobacteria have the potential to engage with other microorganisms in a functioning system that may evolve as an even more complex composite organism. | It is estimated that 6% of Earth's land surface is covered by lichen. There are about 20,000 known species of lichens. Some lichens have lost the ability to reproduce sexually, yet continue to speciate. Lichens can be seen as being relatively self-contained miniature ecosystems, where the fungi, algae, or cyanobacteria have the potential to engage with other microorganisms in a functioning system that may evolve as an even more complex composite organism. | ||
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Lichens can be found growing in most areas of the Antarctic capable of supporting plant life. Currently four general distributional patterns of lichens are known. These are: species confined to the Maritime Antarctic; those found in the Peninsula and extending to the Lesser Antarctic; those with a Circum Antarctic distribution; and those with very disrupted or Disjunct distribution patterns. | Lichens can be found growing in most areas of the Antarctic capable of supporting plant life. Currently four general distributional patterns of lichens are known. These are: species confined to the Maritime Antarctic; those found in the Peninsula and extending to the Lesser Antarctic; those with a Circum Antarctic distribution; and those with very disrupted or Disjunct distribution patterns. | ||
The Maritime Antarctic lichens are restricted to the northern Peninsula and nearby islands. Many of the lichens found in Antarctica are restricted to this area. A number of the lichen species found here are also found in the subantarctic islands and the colder parts of the southern continents, and may represent a southern extension of these populations. This area has the greatest species diversity in Antarctica. | The Maritime Antarctic lichens are restricted to the northern [[Antarctic Peninsula]] and nearby islands. Many of the lichens found in Antarctica are restricted to this area. A number of the lichen species found here are also found in the subantarctic islands and the colder parts of the southern continents, and may represent a southern extension of these populations. This area has the greatest species diversity in Antarctica. | ||
Lichens have been collected from as far south as 86°30'. | Lichens have been collected from as far south as 86°30' and in the [[Caloplaca Hills]], which are named after the specific type of lichen found there. | ||
===Adaptations to Antarctica=== | ===Adaptations to Antarctica=== | ||
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Lichens have a number of adaptations that enable them to survive in Antarctica. They are able to exhibit net photosynthesis while frozen at temperatures as low as -20°C. They can absorb water from a saturated atmosphere when covered by snow. Additionally, snow cover affords protection from the elements and most growth appears to occur when they are buried beneath at least a thin protective layer of snow. | Lichens have a number of adaptations that enable them to survive in Antarctica. They are able to exhibit net photosynthesis while frozen at temperatures as low as -20°C. They can absorb water from a saturated atmosphere when covered by snow. Additionally, snow cover affords protection from the elements and most growth appears to occur when they are buried beneath at least a thin protective layer of snow. | ||
Like most [[psychrophiles]], they can survive long unfavorable periods of drought in a dry and inactive state. In continental [[Westarctica]], many lichens are able to absorb water vapor from snow and ice. | |||
==Effect of climate change on Antarctic lichen== | ==Effect of climate change on Antarctic lichen== | ||
According to a 2017 study published by Swedish University of Agricultural Sciences, short periods of increased temperature can push Antarctic lichens to their physiological limits, potentially threatening their survival. The observed effect is significant enough to lead the study group to conclude that a continued increase in temperature will lead to a severe species loss among Antarctic vegetation. | According to a 2017 study published by Swedish University of Agricultural Sciences, short periods of [[global warming|increased temperature]] can push Antarctic lichens to their physiological limits, potentially threatening their survival. The observed effect is significant enough to lead the study group to conclude that a continued increase in temperature will lead to a severe species loss among Antarctic vegetation. | ||
Lichen species native to southern latitudes appeared unable to adapt to rising temperature and were more likely to die out as opposed to lichen species which were native to northern latitudes, but had colonized Antarctic habitats. Those lichen were more readily adaptable to rising temperature. | Lichen species native to southern latitudes appeared unable to adapt to rising temperature and were more likely to die out as opposed to lichen species which were native to northern latitudes, but had colonized [[Antarctic]] habitats. Those lichen were more readily adaptable to rising temperature. | ||
==Lichens in Westarctica== | |||
* ''[[Caloplaca saxicola]]'' | |||
* ''[[Usnea antarctica]]'' | |||
==Human use== | ==Human use== | ||
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* [http://www.antarctica.gov.au/about-antarctica/wildlife/plants/lichens/ Australian Antarctic Division article on lichen] | * [http://www.antarctica.gov.au/about-antarctica/wildlife/plants/lichens/ Australian Antarctic Division article on lichen] | ||
[[Category:Plants of Westarctica]] | [[Category:Plants of Westarctica]] | ||