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Most lichens grow on stable rock surfaces or the bark of old trees, but many others grow on soil and sand. In these latter cases, lichens are often an important part of soil stabilization; indeed, in some desert ecosystems, vascular (higher) plant seeds cannot become established except in places where lichen crusts stabilize the sand and help ...
Lichen thalli provide a complex and varied habitat for lichenicolous fungi, characterised by biological gradients that range from actively growing to decaying parts. This diversity within a single thallus creates a spectrum of microenvironments, which may contribute to the diversification of fungal life strategies.
Lichens are symbiotic organisms that play an important role in the biogeochemical cycle on Earth. The characteristics of lichens, such as strong resistance to factors such as desiccation, ability to grow and break down rocks allow lichen to grow in different types of environment including highly nitrogen limited area such as subarctic heath.
With the exception of calicioid lichens, lichen growth forms are based on the appearance of the thallus, which is the vegetative (non-reproductive) part of the lichen. [5] In most species, this form is determined by the lichen's fungal partner, though in a small number, it is instead the alga or cyanobacteria (the lichen's photosynthetic ...
About one-third of all lichen photobionts are cyanobacteria, while the remaining two-thirds are green algae. [2] Some lichens host both green algae and cyanobacteria alongside their fungal component. These are known as "tripartite" lichens. In most lichens, the photobiont forms an extensive layer covering much of the lichen body (the thallus).
While many of the lichens found to date in Madagascar are relatively widespread, tropical species, [1] some are endemic. Isalonactis madagascariensis , for example, is known only from its type locality near Isalo National Park , [ 2 ] and new species continue to be found.
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. [2]
A cyanolichen is a lichen with a cyanobacterium as its main photosynthetic component . [12] Many cyanolichens are small and black, and have limestone as the substrate. Another cyanolichen group, the jelly lichens (e.g., from the genera Collema or Leptogium) are large and foliose (e.g., species of Peltigera, Lobaria, and Degelia. These lichen ...