Why Lichens Matter
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CONTRIBUTIONS TO NUTRIENT AND WATER STORIES ABOUT LICHEN LINKS TO THE WHY LICHENS MATTER CYCLING ECOSYSTEM AND ECOSYSTEM SERVICES Lichens play significant roles in mineral and In functioning, resilient ecosystems, plants The Benefits of Lichens to hydrological cycles, notably nitrogen fixation. and animals are interdependent. The Cyanobacterial lichens “fix” atmospheric nitrogen following are two examples. Humans and Nature into forms useable by the lichen and by other WHAT IS A LICHEN AND WHAT IS IT WORTH? plants and animals. When abundant, lichens and Lichens are symbiotic organisms consisting of a fungus and a green alga (or bryophytes growing on trees intercept and hold cyanobacterium—or both!) growing together. Lichen lovers are not afraid to moisture, moderating humidity and temperature within the canopy. They also capture and slowly admit that they simply enjoy seeing the variety of forms and colors growing release nutrients from rain, dew, fog, air-borne on the trees, rocks, and soils wherever they go. Many also know that lichens fine particles, and gases, which might otherwise are indicators of air pollution and that both lichens and humans depend be lost or unavailable. Desert crusts of lichens, on clean air and a healthy environment. Less well known is that lichens fungi, cyanobacteria, and moss reduce soil erosion play integral roles in keeping our natural world working. They provide food, by intercepting surface run-off and regulating cover, and nesting materials for a variety of birds, mammals, and insects, infiltration of water into dry soils. and contribute to forest and rangeland water and mineral cycles. Lichens also have many traditional human uses as food, medicines, and textiles and The Oregon lung lichen dominates the lichen biomass produce unique compounds with promising pharmaceutical potential as of old-growth, temperate rainforests of Northwestern North America, where it contributes significant amounts antioxidants, anti-cancer drugs, and antibiotics. of new nitrogen to nitrogen-limited forest ecosystems. HOW DOES A LICHEN SYMBIOSIS WORK? LICHENS, FLYING SQUIRRELS, Algae and cyanobacteria produce food for the fungus, converting carbon ENVIRONMENTAL INDICATORS THE NORTHERN SPOTTED OWL, MYCORRHIZAL FUNGI, AND HEALTHY dioxide gas into sugars via photosynthesis. Cyanobacteria also convert Lichens are also important as indicators. TREES nitrogen gas into forms used to build proteins, nucleic acids, and other Lichen communities change with vascular Northern flying squirrels rely on air- essential molecules. The fungus, in turn, serves as a home for the food- plant succession. Land managers can use pollution sensitive, horsehair lichens as a producing partner(s) and provides water, minerals, and other nutrients lichens to show forest continuity and the distribution of specialized microhabitats and principal winter food source and nesting absorbed from the air, rain, and substrates. microclimates, to detect hotspots of biological material. These squirrels are a primary CONTRIBUTIONS TO diversity over the landscape, and to assess prey of the northern spotted owl, an BIOLOGICAL DIVERSITY water and air quality. Overall, lichens grow endangered species whose protection has Lichens contribute to the and disperse slowly compared to vascular redefined Federal forest management in Earth’s biological diversity. plants. Specialized habitat requirements, the U.S. Pacific Northwest. In summer, the the need for continuity in the availability of There are more than 5,500 squirrel’s main staple is underground- substrate, and sensitivity to air pollution make species of lichens and lichen- fruiting fungi. Scampering through the many lichen species vulnerable to habitat dependent fungi in North forest, the squirrels disperse fungal spores disturbance or degradation. America. Lichen diversity is in their droppings. The spores germinate promoted by good air quality, Rare, old-growth forest cyanolichens, and form mycorrhizal associations with habitat continuity, availability like the Rainier speckle belly lichen, tree roots critical for tree growth. The of preferred substrates, and indicate hotspots of rich biodiversity. trees, in turn, provide habitat for lichens, favorable climate. flying squirrels, spotted owls, and other A colorful diversity of lichens CLIMATE INDICATORS organisms; and they provide wood can be found on soil, rocks, products for people. trees, wood, human-made Climate strongly influences materials, invertebrates, and lichen community composition, even under water. i.e., which lichens are present. FORAGE AND NESTING MATERIALS FOR WILDLIFE A few lichens tolerate large Lichens are ecologically important as food, shelter, and nesting material for fluctuations in climate, but wildlife. Deer, elk, moose, caribou, mountain goats, bighorn sheep, pronghorn most require more specific antelope, and various squirrels, chipmunks, voles, pikas, mice, and bats eat regimes. Even a 1 °C shift in mean annual temperature can lichens or use them for insulation or in nest building. drastically increase or decrease the probability of finding certain lichens. Climate change and biodiversity can be tracked and indicated by monitoring lichen community composition. Northern flying squirrels, the primary prey of the endangered northern spotted owl (above), eat lichens in winter and underground fungi in summer. LICHENS, INSECTS, AND SONGBIRDS Shifts in lichen species indicate that climate is warming forest in Oregon’s As a forest matures, canopy lichens Left: Many North American birds, like this Anna’s hummingbird, use leafy and hairlike lichens high Cascades and that humidity is increase and support larger, more diverse as nesting material. Right: A deer grazes on tree beard lichens plucked from the ground after increasing along the Pacific Coast. insect populations. Most song birds are a wind storm. Shifts in lichen species indicate that climate is warming fastest in Oregon’s high insectivorous, and a rich supply of insects Cascades and that humidity is increasing along the Pacific Coast. AIR QUALITY INDICATORS helps ensure their breeding success. FOOD AND HABITAT FOR Two properties make lichens useful air quality indicators—they are especially Songbirds consume copious quantities of INVERTEBRATES sensitive to some important pollutants, and they concentrate many pollutants insect pests across their migratory ranges, in proportion to environmental availability. The first property can be used to providing a valuable ecosystem service that Bristletails, barklice, katydids, grasshoppers, demonstrate that air pollution is causing environmental harm and warn of webspinners, butterflies, moths, moth enhances the production of wood, fruit, incipient broader ecological effects; both properties are useful for assessing and other crops. larvae, lacewing larvae, mites, spiders, relative pollution levels over geographic space and time. When lichens are snails, slugs, and many beetles live on, wetted, pollutants deposited to their surfaces as gases, vapors, or fine particles camouflage themselves as, or eat lichens. dissolve and are absorbed. Lichen algal and cyanobacterial partners are especially vulnerable to air pollutants like sulfur dioxide, ammonia, fluorine, and nitric and Various insects, like this moth, hide from sulfuric acids. These highly reactive gases and acids interrupt essential processes predators by mimicking common bark like photosynthesis and respiration. Lichens are also sensitive to excessive lichens. nutrients, especially nitrogen, which favor smaller, fast-growing weedy species LICHENS AND MICROBES over the larger more ecologically valuable species. Air quality can be tracked Distributions of soil, leaf, and aquatic using changes in lichen community composition, indicator species distribution, microbes and invertebrates can be shaped physiology, or appearance. by lichen-dominated habitats and their LINKS BETWEEN LICHENS, ECOSYSTEMS unique chemical compounds. AND ENVIRONMENTAL CHANGE A variety of fungi, algae, and bacteria As nitrogen- and sulfur-containing air grow on or parasitize lichens; some are very pollutants increase, the ecological impacts specific to particular species. increase too. Sensitive lichens, diatoms, Lichens provide great habitat for a variety of insects bryophytes, ectomycorrhizal fungi, and sought as food by birds. HUMANS USE THEM alpine plants are among the first affected. Throughout history, people have used Because these air pollution-sensitive Sitka black-tailed deer photo by Karen Dillman; flying lichens for food, clothing, dyes, perfume organisms are completely woven into the squirrel photo by Marshia and Mike Crowley; downy additives, medicines, poisons, tanning ecosystem, harm to them can adversely woodpecker photo by Bob Armstrong; owl photo by agents, bandaging, and absorbent impact more tolerant or economically John and Karen Hollingsworth, U.S. Fish & Wildlife materials. Compounds unique to valuable species that need the sensitive Service; and all other photos by Stephen Sharnoff. Text lichens are used in perfumes, fiber dyes, species for food, habitat or cover. by Linda Geiser. Map by Doug Glavich. Artwork and and in medicines for their antibacterial design by Emily Underwood. and antiviral properties. Ornate lichens are harvested around the world for use in floral displays, decorations, and USDA is an equal models. opportunity provider, employer, and lender. The wolf lichen makes a bright yellow Air pollution and habitat alteration dye valued by the Chilkat people of south- threaten prize forage species like the long eastern Alaska for traditional blankets. beard lichen. United States Department of Agriculture Lichens are widespread, evolutionarily ancient, composite organisms comprised by members of two, and sometimes three, biological kingdoms. CELEBRATING LICHENS They provide food and habitat for wildlife and are important environmental quality indicators. Turn over this poster to learn more about these amazing organisms and why they matter. Forest Service FS-1071 June 2016.