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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 ...
Usnea is a genus of fruticose lichens in the large family Parmeliaceae. The genus, which currently contains roughly 130 species, was established by Michel Adanson in 1763. Species in the genus grow like leafless mini-shrubs or tassels anchored on bark or twigs. Members of the genus are commonly called old man's beard, beard lichen, or beard moss.
This lichen prefers to grow on large coniferous trees; especially Douglas Firs, in forests. This lichen prefers growing on Douglas Fir so much that it makes up about 5% of the weight of foliage on Douglas Fir trees. It prefers cool places, and is sensitive to living in areas that are about approximately 15 degrees Celsius. [4]
They are often epiphytic, growing on trees in forested areas, but are also common in some alpine zones. [30] Lichenologists tend to consider filamentous lichens to be a type of fruticose lichen. [31] This is an uncommon growth form, found in only a handful of genera. [32]
Other common growth forms are crustose, crustlike lichens that grow tight against, even into, the substrate, and fruticose lichens, which grow as free-standing branches like tiny trees.
The lichens usually grow on the bark and wood of coniferous trees. Hypogymnia was proposed by lichenologist William Nylander , first as a subgenus of Parmelia in 1881, and 15 years later as a distinct genus of two species, including the widespread and common type species , Hypogymnia physodes .
A forest is really a community of plants and animals. Within this large community are smaller groups of living things that grow together.
The map lichen (Rhizocarpon geographicum), the lichen most used in lichenometry. Lichenometry can provide dates for glacial deposits in tundra environments, lake level changes, glacial moraines, trim lines, palaeofloods, [9] rockfalls, seismic events associated with the rockfalls, [2] talus stabilization and former extent of permafrost or very persistent snow cover. [10]