Usnea Lichens
Introduction
"Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs. The genus is in the family Parmeliaceae. It grows all over the world. Members of the genus are commonly called old man's beard, beard lichen, or beard moss." - Wikipedia: Usnea
Benefits
Indicator Species
"Like other lichens, Usnea often grows on sick or dying trees due to the pre-existing loss of canopy leaves, allowing for greater photosynthesis by the lichen's algae; this leads some gardeners to mistakenly blame the lichen for the tree's leaf loss and illness.[17]
Usnea is very sensitive to air pollution, especially sulfur dioxide.[18] Under poor growing conditions, such as areas high in pollution, they may grow no larger than a few millimetres, if they survive at all. Where the air is unpolluted, they can grow to 10–20 cm long. It can sometimes be used as a bioindicator, because it tends to only grow in those regions where the air is clean,[19] and of high quality." - Wikipedia: Usnea
Biodiversity
"Lichens on trees provide valuable microhabitats, shelter and food for various small invertebrates.
These in turn are prey for larger insects and birds. They can also be hosts for other species of parasitic fungi. Lichens also provide many other ecosystem services such as carbon cycling and water retention." - The Woodland Trust: Beard Lichens
"Usnea hesperina is a rare forage lichen. Squirrels, chipmunks, voles, pikas, mice, and bats and about 45 species of North American birds eat forage lichens or use them in nest building. A large variety of invertebrates including bristletails, barklice, katydids, grasshoppers, webspinners, butterflies, moths, lacewing larvae, mites, spiders, snails, slugs, and many beetles live on, mimic, or eat lichens (McCune and Geiser 1997). Fallen lichens are winter survival food for large animals such as deer and elk when snow depth prevents browsing. After windy periods and after snow melt, large quantities of forage lichens in the genera Alectoria, Bryoria and Usnea may be found on the ground (Esseen et al. 1981, Stevenson and Rochelle 1984). During conditions of deep snow, they provide critical winter nutrition to deer (Stevenson and Rochelle 1984)." - BLM: Management Recommendations for Usnea hesperina
Carbon Cycling
Water Retention
Medicine
These have been used for thousands of years for their antibacterial properties. They are also high in vitamin C.
"According to Paul Bergner, Author of Medical Herbalism. "The usnic acid in Usnea is effective against gram positive bacteria such as Streptococcus and Staphylococcus, making Usnea a valuable addition to herbal formulas for sore throats and skin infections. It is also effective against a bacterium that commonly causes pneumonia"[20]
There is reason to believe that Usnea, in high concentrations, could possess some toxicity.[21] The National Toxicology Program is currently evaluating the issue.[22]" - Wikipedia: Usnea
Dye
These have long been used for orange, purple, yellow, green, and blue textiles.
Threats
Air Pollution
"Beard lichens once occurred on trees throughout the UK. But the impacts of past sulphur-dioxide pollution and continued nitrogen air pollution from agriculture have resulted in their loss." - The Woodland Trust: Beard Lichens
Reliant Species
Birds
Northern Parula
"The northern parula, a species of New World warbler which breeds in North America, uses Usnea lichens in the construction of its nest in some parts of its range. Where these lichens have declined due to air pollution, the bird has also vanished.[29]" - Wikipedia: Usnea
