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Vagrant Lichen
A vagrant lichen is a lichen that is either not attached to a substrate, or can become unattached then blow around, yet continue to grow and flourish. Some authors reserve the expression "vagrant lichen" for those lichens that never attach, that is, those that are ''obligately'' vagrant, referring to vagrant forms of other species as "erratic lichen".Rosentreter, Roger, "Vagrant Lichens in North America," Bryologist 96(3) (1993) pg. 333. Online at https://www.jstor.org/stable/3243861?seq=1#page_scan_tab_contents Vagrant lichens generally occur in open and windswept habitats, all over the world, in all kinds of temperature zones. Habitats include saltbush (mallee) vegetation zones in Australia, steppes of Eurasia, Arctic tundra, and the North American prairie. They range from the low elevations of the Namib Desert to the high altitude Andean páramo. There are under 100 identified vagrant species, most commonly in the '' Aspicilia'' and '' Xanthoparmelia'' genera Genus ( plural gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steppes
In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, savannas and shrublands biome A steppe may be semi-arid or covered with grass or with shrubs or with both, depending on the season and latitude. The term " steppe climate" denotes the climate encountered in regions too dry to support a forest but not dry enough to be a desert. Steppe soils are typically of the chernozem type. Steppes are usually characterized by a semi-arid or continental climate. Extremes can be recorded in the summer of up to and in winter, . Besides this major seasonal difference, fluctuations between day and night are also very great. In both the highlands of Mongolia and northern Nevada, can be reached during the day with sub-freezing readings at night. Mid-latitude steppes feature hot summers and cold winte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arctic Tundra
In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless mountain tract". There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra. Tundra vegetation is composed of dwarf shrubs, sedges, grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline. The tundra soil is rich in nitrogen and phosphorus. The soil also contains large amounts of biomass and decomposed biomass that has been stored as methane and carbon dioxide in the permafrost, making the tundra soil a carbon sink. As global warming heats the ecosystem and causes soil thawing, the permafrost carbon cycle accelerates and releases much of these soil-contained gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prairie
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay, and the steppe of Ukraine, Russia and Kazakhstan. Lands typically referred to as "prairie" tend to be in North America. The term encompasses the area referred to as the Geography of North America, Interior Lowlands of Canada, the United States, and Mexico, which includes all of the Great Plains as well as the wetter, hillier land to the east. In the U.S., the area is constituted by most or all of the states of North Dakota, South Dakota, Nebraska, Kansas, and Oklahoma, and sizable parts of the states of Montana, Wyoming, Colorado, New Mexico, Texas, Missouri, Iowa, Illinois, Indiana, Wisconsin, and western and southern Minnesota. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Namib Desert
The Namib ( ; pt, Namibe) is a coastal desert in Southern Africa. The name is of Khoekhoegowab origin and means "vast place". According to the broadest definition, the Namib stretches for more than along the Atlantic coasts of Angola, Namibia, and South Africa, extending southward from the Carunjamba River in Angola, through Namibia and to the Olifants River (Western Cape), Olifants River in Western Cape, South Africa. The Namib's northernmost portion, which extends from the Angola-Namibia border, is known as Moçâmedes Desert, while its southern portion approaches the neighboring Kalahari Desert. From the Atlantic coast eastward, the Namib gradually ascends in elevation, reaching up to inland to the foot of the Great Escarpment, Southern Africa, Great Escarpment. Annual precipitation ranges from in the most arid regions to at the escarpment, making the Namib the only true desert in southern Africa. Having endured Desert climate, arid or Semi-arid climate, semi-arid cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Páramo
Páramo () can refer to a variety of alpine tundra ecosystems located in the Andes Mountain Range, South America. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A narrower term classifies the páramo according to its regional placement in the northern Andes of South America and adjacent southern Central America. The páramo is the ecosystem of the regions above the continuous forest line, yet below the permanent snowline. It is a "Neotropical high mountain biome with a vegetation composed mainly of giant rosette plants, shrubs and grasses". According to scientists, páramos may be "evolutionary hot spots", that meaning that it's among the fastest evolving regions on Earth. Location The Northern Andean Páramo global ecoregion includes the Cordillera Central páramo (Ecuador, Peru), Santa Marta páramo (Colombia), Cordillera de Merida páramo (Venezuela) and Northern Andean páramo (Colombia, Ecuador) ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspicilia
''Aspicilia'' (sunken disk lichen) is a genus of mostly crustose areolate lichens that grow on rock. Most members have black apothecia discs that are slightly immersed in the areolas, hence the common name.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Most of the species of this genus grow on calcareous and acidic rocks and most of the taxa prefer temperate and arctic habitats. Some members of the genus ''Aspicilia'' are pioneer species on granite and other hard rock, after which members of other lichen species may grow on them, such as members of '' Acarospora''.ACAROPSPORA, Lichen Flora of the Greater Sonoran Desert Region. Vol 3., Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001/ref> Description Members of this genus are weakly cracked to distinctly areolate, with a scattered to whole thallus, thalli. Some of the species of this genus are disc-shaped with plicate lobes at the circumference; these lobes may appear chalky white, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthoparmelia
''Xanthoparmelia'' (commonly known as green rock shields or rock-shield lichens) is a genus of foliose lichen in the family Parmeliaceae.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, ''Xanthoparmelia'' is synonymous with ''Almbornia'', ''Neofuscelia'', ''Chondropsis'', ''Namakwa'', ''Paraparmelia'', and ''Xanthomaculina''. This genus of lichen is commonly found in the United States, as well as Australia, New Zealand and Ecuador. The name means 'golden yellow parmelia'. The photobiont (photosynthetic partner) is ''Trebouxia'' (a genus of green algae). Identification Distinguishing between species involves how much they are attached to the substrate, whether or not isidia are present, lower surface color, and chemical spot tests. All members of the genus react to spot test as K-, KC+ yellow, with medulla reaction varying from species to species. Species Species include: * ''Xanthoparmelia chlorochroa'' * '' Xanthoparmelia conspersa'' (''Parme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clearly demons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
