Equally unassuming and complex—lichen often go undeservedly unnoticed. Open your eyes to these delightful organisms, and an entire world unfolds before you. And here’s a shock, this world has been there all along hiding in plain sight. On the branch of a tree, or on the ground, or attached to a rock—lichen are everywhere.
Heck, spend enough time in the “world of lichen,” and they may even change your life. At least that is what happened to lichenologist Joseph (Joe) R D Meglio, whom I met on a cold, wet morning in January to hike and talk lichen.
The Hike
- Trailhead: Baker Creek Trailhead, McDonald Forest (Corvallis, OR)
- Distance: varies
- Elevation Gain: varies
- Details: This is one of many trailhead in the McDonald Forest, which offers a variety of hiking options on trails and logging roads. Limited parking is available.
Joe’s Story
Our hike began as we walked across a bridge and onto a wooded logging road, with cold pelts of mixed snow and rain falling on our heads and shoulders. Joe and I slogged up the gravel path making small talk along the way.
After a few minute’s time, I asked: “Why lichen? How did you end up here— with a career in lichen?”
Here is Joe’s story:
The Early Years
Despite being fascinated with living things from a young age, and an early interest in fungi and lichen, Joe didn’t become a lichenologist straight out of high school. He went to college for a term, and as he put it, “I flunked out.”
College “wasn’t an expectation in my family,” explained Joe. So it wasn’t a big deal when Joe dropped his academic pursuits, opting instead to learn a trade. Joe worked as a mechanic for a few years, and later as a high rigger for a logging company.
Epiphany
Then one day while on a break from rigging up cables, Joe found himself amongst the branches of a Douglas-fir tree in the Mckenzie River Valley. Looking around, he noticed two contrasting worlds—a clearcut landscape in the distance, a product of the logging industry of which he was a part, juxtaposed against the miraculous biodiversity of lichen dripping off the trees in the surrounding forest. He knew at that moment he needed a change.
Joe immediately climbed down from his perch and told his boss—“I don’t want to do this anymore. I am leaving.”
And he did. Right then and there.
A Whole New World
Not long after, Joe enrolled at the local community college and eventually made his way to Oregon State University to work with lichenologist extraordinaire, Bruce McCune.
Joe still works in the McCune lab on lichen taxonomy, and contracts with the U.S. Forest Service on Lichen related projects. He even married a lichenologist, whom we met up with later in the hike. So, yeah, Joe is really into lichen.
Pairing up
As we followed the road uphill, we continued to chat about Joe’s work and lichen-filled life. Then I asked him the all-important question, “What exactly is a lichen?”
Joe explained, “Lichen are composite organisms” containing a mycobiont (fungal component) and photobiont (photosynthetic partner) or two. The most common photobiont is green algae, followed by cyanobacteria. A tripartite lichen will contain both, like Lobaria pulmonaria (sometimes referred to as lung lichen), commonly found in lowland to mid-elevation forests of the Pacific Northwest.
Whatever the pairing, a “symbiotic” relationship, or cooperation, exists between the bionts. The photobiont provides food for the fungus due to its ability to photosynthesize. While the mycobiont provides shelter for the photosynthetic partner.
Pairing up also means physiological, chemical, and reproductive changes from the original forms of the individual bionts. Nearly nothing of the individual remains.
Hello Lichen
At this point, Joe stopped at the side of the road, grabbed a tree branch, and pulled it down to eye-level. It was time to take a look.
Joe began to point out all the different lichen species. “Stuff like this usnea is a chlorolichen,” he said pointing out a light green, stringy-looking lichen, “and this leafy species, Platismatia glauca is also a chlorolichen,” he continued.
On just a single branch, Joe pointed out at least a handful of different species— each with a unique color, shape, and form.
Growth Forms
Which begs the question— how does one even begin to keep all the different lichen straight? I asked Joe to provide some beginner tips.
One way to start to narrow things down, Joe explained, is by becoming familiar with the different growth forms lichen exhibit. There are three basic growth forms for lichen: fruticose (shrubby), foliose (leafy), and crustose (crust). Most species will exhibit only one growth form, and even within a genus, species typically share forms. Though there are exceptions.
When it comes to fruticose and foliose lichen (aka macrolichen), the bodies (or thalli) are organized internally into layers. Joe demonstrated this stratification by plucking up a Platismatia stenophylla species (a foliose lichen) off the ground and showing me how its ventral cortex (top side) and dorsal cortex (bottom side) differed. Sandwiched in-between, the photobionts are housed, just below the upper cortex amongst the loosely packed hyphae that make up the medulla.
In tripartite lichen, additional structures are needed, called cephalodia. Often wart-like in appearance, cephalodia create an anaerobic environment that cyanobacteria require “to fix atmospheric nitrogen, an important part of the forest ecosystem nitrogen cycle.”
Identifying Features
Of course, growth form will only get you so far when it comes to identifying lichen. Other characteristics that are helpful include the size, shape, and color of the thallus (the main body of the lichen) and lobes (branches), as well as the shape, position, and color of reproductive structures. There are also many specialized features, like cilia and pores (and the cephalodia mentioned earlier), that can help one distinguish between species and genera.
One of my personal favorites is that of the Usnea genus. Usnea has an inner cortex that when you pull on it, stretches like an elastic band. But beware, the band easily breaks.
This One is Not Like the Others
However, according to Joe, even members of the same species can exhibit a great deal of variability depending on the environment in which they reside.
He picked up a Platismatia from the trail and pointed to its frilly edges. Joe explained lichen will often exhibit “extreme dimorphism,” with fringed edges, dieback, and red spots, for example.
Even normal seasonal changes and variability in light exposure will alter the appearance of lichen thalli. Exposure to light often darkens the color, while shaded individuals may appear pale.
Cryptic Organisms
However, even lichen that superficially appear to be the same species, may vary substantially in other ways. As Joe described it—within the same fungal genus you might find individuals with different secondary chemistry, or an entirely different genome than you might expect. Lichen “are very variable, very adaptable,” Joe stated. “The closer you get the more you discover.”
In fact, looking into the less obvious differences between lichen is a big part of Joe’s work. By looking really close and comparing the genomes of different lichens that appear similar, he can parse out different species and determine who is related to whom.
A Closer Look
Currently, he is working on reevaluating the Sticta genus, a group of lichen that are distinguished by having cyphellae, “little windows,” usually found on the bottom of the lichen. Through his work, Joe has found that what was thought to be one species, Sticta fuliginosa s. l., is really three distinct species with different traits. “One has these really interesting lobules that are digitate,” for example.
We took a closer look at one of the new Sticta species Joe is describing—a small brown, unassuming lichen—with the proposed name: Sticta gretae sp. nov. Using a hand lens, Joe showed me the little white dots on its lower cortex, its cyphellae.
Biodiversity of Lichen
Walking along the trail it was not difficult to find lichen. Hanging from a branch or trunk of a tree, attached to a rock, or growing on the forest floor—no matter where we looked, there was plenty of lichen to look at.
Lichen are adapted to nearly every habitat on Earth, providing a symphony of biodiversity and plenty of eye candy. With our temperate rainforest and a diversity of habitats, it is no wonder that the Pacific Northwest is “the center for diversity for fungi in North America.” According to Joe, “there are approximately 580 genera and over 1400 species” of lichen in the region—a biodiversity hotspot.
Every Niche
However, every lichen species present in the Pacific Northwest isn’t going to be found in every location. Each lichen species is specialized for a particular niche, a particular home, and a way of life in the environment.
Joe pointed out a Peltigera species growing on the forest floor. “These are terricolous,” he said, “their medium is soil.” He went on to explain how each terricolous species needs specific soil chemistry, a certain acidity.
The same is true of species that depend on other substrates for a home. Lobaria oregana (Oregon lung lichen), for example, grows best in mid-elevation middle-aged to old-growth forests west of the Cascades. Conifer trees in these forests provide the perfect habitat for this species.
In addition, cyanolichen and tripartite lichen are limited by water and light requirements. They will “fall out at certain elevations,” explained Joe, as the environment is too harsh and dry. They also tend to be found where more light is present. In contrast, they can often be very abundant in riparian areas, where water and light are readily available
Dispersal, Growth, and Reproduction.
Despite their abundance, lichen still are relatively slow-growing organisms and don’t disperse or reproduce easily.
Though growth is pretty variable. According to Joe, crustose lichen typically grow only a few mm or ½ cm per year. Foliose or fruticose lichen may grow several cm, depending on conditions.
When it comes to reproduction and dispersal things don’t get much easier. Sexual reproduction is one possibility and is performed by the fungi. “A high percentage of our lichenized fungi are Ascomycota,” said Joe, when I asked about lichen reproduction. This sort of fungi produces disc-like fruiting structures called apothecia from which asci (spore-containing cells) can be found and lichen spores (ascospores) are released.
However, sexual reproduction can be challenging for lichenized-fungi that need to not only find a mate but a photobiont. Therefore, asexual reproduction is also common as it has a better chance of success. In the case of asexual reproduction, packaged “dispersal units” are released that contain all the parts of a functioning lichen. Isidia and soredia are the names of these dispersal units, both having some different characters, but function in a similar way. In addition, both isidia and soredia (and patches of soredia called sorelia) are observable, especially with a hand lens, making them also useful for identification.
What’s not to Lichen?
The snow was turning to a chilling rain when Joe and I decided to turn around. Joe’s wife and son were supposed to be meeting up with us soon. It was at this point that I asked Joe the all-important question—why should I care? For all their “good looks,” is there something more a person might appreciate about lichen?
“Lichens really tell you about the health of the ecosystem and the health of you and all the animals and all the plants,” Joe responded. “The more diverse the ecosystem and the healthier you will be…. without these organisms we wouldn’t exist.”
This might seem like an extreme view to some, but our dependence on the natural world (as part of the natural world) is well established. And when it comes to the mysterious world of lichen, the value that they provide is as diverse as the species themselves.
Fix it
One of the many benefits of lichen Joe shared with me early in the hike is their “important role in the nitrogen cycle.” The cyanobacteria in cyanolichen (including tripartite lichen) are capable of chemically changing nitrogen gas in the air (N2) into a form that is biologically available to plants and algae. This process is known as nitrogen fixation. Then as lichen fall to the ground and decompose, the nitrogen stored in their tissues becomes available to other life forms that need it.
In certain environments, this input of nitrogen may prove to be significant. Though more research is needed to better understand the extent of their contribution.
Lichen also plays a role in the hydrological cycle, and other mineral cycles, intercepting and storing water and atmospheric inputs of various nutrients—like with nitrogen, providing a catch basin and distribution system for these inputs.
Food and Fiber
Lichens also provide food and fiber to other living things. Deer, elk, and caribou feed on lichen, depending on it for winter forage. Squirrels, chipmunks, mice, and bats also take advantage of lichen for food and nesting material. Joe specifically mentioned flying squirrels, which rely on the lichen Bryoria sp. for food and nesting material during certain parts of the year. Flying squirrels are a major food staple for Spotted Owls; without lichen, the entire food chain would collapse.
Biological Indicators
Then there is their importance as biological indicators. The presence, and more often the absence, of biological indicator organisms, acts as an alarm system for environmental change. Like a canary in a coal mine, sensitive lichen will die off in areas where there is too much air pollution, while others may move in. Similar responses may occur with changes in precipitation and temperatures. Therefore the species composition in a location can tell you a lot about the health of the ecosystem and the stressors it may be facing.
Understanding lichen community composition and tracking it over time has been another large part of Joe’s work with the Forest Service. With over 3,000 plots scattered throughout forest service land, The National Forest Inventory and Analysis (FIA) Program tracks a plethora of forest-related data, including lichen community data.
Using this data, scientists are able to see which lichen species are present in various climate and air quality conditions. One of the startling patterns that emerged from this research is the changes in species composition as you move toward urban centers. “ A large number of species are dropping out,” said Joe, due to human impacts like poor air quality.
Changing Climate
In addition, Joe hopes that by observing changes in lichen communities, we might also be able to gain a better understanding of climate change. We know that lichens are sensitive to climate conditions, so it is likely that they will respond to climate change, especially in sensitive alpine and subalpine environments.
The arctic is already seeing a decline in lichen species as a result of climate change, so the question is how will this translate into other ecosystems? “Timelines for noticing the rate of change is gradual.” explained Joe, but “we have over 30 years of FIA plot community data” to work with.
Lichens to Know
As we continued our chat about climate change, Joe and I ventured our way back down the hill, eventually reaching a bridged creek crossing and an abundance of cyanolichen.
Joe held up a beautiful, deep brown colored lichen with ridges that ran along the upper cortex that reminded me of a river system and its tributary. Joe told me that the eruptions were soralia, soredia (asexual propogules) yielding structures and that the lichen was a Lobaria anomala (netted lungwort lichen).
Beautiful, bright green Lobaria pulmonaria (lungwort or lettuce lichen) littered the area, coating the bark of Ash and other riparian trees. And long strands of Usnea longissima (beard lichen) draped across the branches like a garland; a species common to the area, but rare globally. We even saw Joe’s “baby”—Sticta gretae sp. nov. growing on a tree branch.
With so many lichen around, I asked Joe for a shortlist of “ones to know” for the region. He suggested the following based on their abundance and distinctiveness: Platismatia glauca (ragged lichen), Parmelia sulcata (wax paper lichen), any Lobarias, and Caldonias. And almost instinctively, he continued to point each beauty in the vicinity out.
Cooperation
At this point, Joe and I caught up with his wife, Elisa and their young son. We were only a few minutes from the trailhead, but we took our time getting back, chatting about life and lichen along the way.
It was fun to watch the happy family together, harmoniously moving through life together as we walked along the trail.
It also reminded me of what interested me in lichen in the first place—the symbiotic relationship. The world of lichen is “rooted” (while not having actual roots) in cooperation; in give-and-take; in shared goals.
This sort of relationship might seem baffling at first—isn’t nature a battlefield? A competition with winners and losers?
Perhaps, or perhaps this view is too narrow. Lichen remind me that cooperation is natural—as natural as a family walking together through a lichen-filled forest.
What do you think? What’s not to lichen?
Joseph R Di Meglio is a Mycologist for MICROTERRA Analytical and Pathology Laboratories llc. and Molecular Lichenologist at Oregon State University. He also contracts with the U.S. Forest Service on lichen related projects. Joe studied mycology and lichenology at Oregon State University.