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Difference between revisions of "Lichen"
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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'. | ||
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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. | ||
They can survive long unfavorable periods of drought in a dry and inactive state. In continental | 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== | ||