Liking Lichens — Nature’s Air Quality Monitors
story and photos by Karen L. Monsen
Little things matter in nature, from the oceans’ tiny krill to the earth’s bacteria, fungi, and lichens. With approximately 15,000-20,000 species, 450 documented in Utah, lichens vary from leafy branching greenish growths to colorful green, yellow, and orange crusts on rocks. These desert survivors offer more than meets the eye, serve many purposes, exhibit a special form of species co-existence, and are useful for bio-monitoring air quality. We can learn from lichens.
Masters of Mutuality
Classified as fungi, lichens are actually two organisms—fungi and an algae or cyanobacterium. BYU botany professor Dr. Larry St. Clair describes lichens as, “symbiotic systems consisting of a fungus living in a complex and dynamic relationship with a photosynthetic partner (either a cyanobacterium or a green alga). The photosynthetic partner provides basic biological molecules through photosynthesis which the fungus uses to build and maintain a “greenhouse” like environment to accommodate its cyanobacterial/green algal partner.”
Lichens exemplify mutualistic symbiosis which differs from the symbiotic relationship in which ants capture aphids, clip their wings so they cannot escape, and induce them to produce nectar to feed the ants—definitely the ants dominate the aphids they “farm.” In lichens, fungi send fibers through the algal layer, provide color filters to regulate moisture and sunlight, and create sustainable growing conditions. With lichens, neither organism dominates—both mutually coexist.
Lichens are eaten by reindeer, antelope, mountain sheep, goats, and elk. They’re used to make brown and royal purple dyes, added to ferment beer, included in medicated lotions and perfume, and researched for antibiotic properties and anti-cancer drugs. Dr. St. Clair brands lichen as “pioneers—the first to occupy harsh and challenging environments such as bare rock” and being “sensitive to a wide range of air pollutants serve as effective bio-monitors of air quality.”
Air Quality Bio-Monitors
According to Weber State University botany professor, Dr. Heather Root, lichens are good air quality bio-monitors, “because lichens don’t have a skin or cuticle like animals and plants, they absorb pollutants roughly in proportion to their concentration in the air.” Lichen monitoring is accomplished in two ways, by counting species distributions and measuring pollutant concentration in lichen samples.
We know some lichens are sensitive and others more tolerant to specific pollutants. By observing species distributions, even non-scientists can assess air quality and contribute data useful to researchers. An Android app under development by Michigan Technological University (available at citizenscience.cs.mtu.edu/websites/lichen/dev/ ) helps individuals identify lichens and rate air quality in western Oregon and Washington, northwest California, coastal British Columbia and southeast Alaska.
Since 1980, the National Park Service and National Forest Service have used direct air sampling equipment. In 2001, the Forest Service launched the Lichens and Air Quality Workgroup to collect and share lichen data for assessing air quality and bio-monitoring air pollution-related effects on public lands. Along with direct sampling equipment, the lichen bio-monitoring helps evaluate the health of a forest or ecosystem, gauge forest fire conditions, and measure metals in rainfall.
In September 2016, Dr. St. Clair will retire, ending his 40-year teaching career at BYU, but he will continue working in the Bean Life Science Museum’s collection of lichens and bryophytes—one of the largest collections in North America with more than 100,000 lichens and mosses.
Another incredibly talented lichenologist, Dr. Heather Root is expanding Utah’s lichen research on the Wasatch Front where lichens have been dramatically impacted by air pollution. During the 2016 summer, Dr. Root set up 12 monitoring sites around Ogden and in the Uinta Basin and Mountains to measure air quality, collect lichen tissue samples, and calibrate the pollutant levels in lichen for a suite of heavy metals and nitrogen and sulfur—known acid rain components. By calibrating lichen findings with fixed air monitoring devices, she hopes to improve the reliability of lichen observation and samplings for air quality monitoring.
Per Dr. Root, “By monitoring lichens, we identify places where air pollution may affect human health at the same time as we are monitoring the effects
air pollution has on wild ecosystems. In Utah, we have made good progress using lichens to monitor in wildlands, but we haven’t really capitalized on this resource in urban areas. I’m hoping to develop more intensive monitoring in Ogden, where I live, to see whether this approach can help us solve some of our urban air quality issues. I also see lichen biomonitoring as a useful way to increase public involvement in air quality monitoring.”
Although small and often ignored, lichens are active participants in our interconnected living world. So, with or without a lichen identification app, lace up your boots, head for the trails, and try not to step on the lichens.