I’m “Lichen” What I’m Seein’

I took advantage of a day off of school this winter to attempt a hike at Tabletop Mountain, which runs along a stretch of the PCT near Stevenson, WA.  This is a gorgeous hike that includes rapid changes in ecosystem type, which affords much to see along the way.

Unfortunately, there was no summit for us, as the conditions changed rapidly with the gain in elevation.











The foggy nature of the hike forced me to focus less on the destination and more on the journey. I began to look more closely at the smaller details to see right in front of me:











Namely, lichen. While we tend to overlook the humble lichen, once you see lichens you can never “unsee” them. Some look like frilly, green-grey bits with black undersides, others look like a fine, lime green confetti.  I began seeing lichens everywhere, on trees, rocks, old logs, patches of ground, the more I looked, the more lichens I saw. I started wondering about the many types of lichen we find in the Northwest and what their role is in the forest community. Here’s a little information I found on these fascinating organisms.

A lichen (pronounced “LIKE-in”) is much more than what meets the eye. Though to the untrained observer it may look like some moss or some kind of plant, it’s actually neither. In fact, it isn’t even a single organism. Lichens are formed by a symbiotic relationship between a photobiont and a fungus. A photobiont is just an organism that captures the energy from the sun through photosynthesis, like algae or cyanobacteria. A fungus, as we talk about in SECRETS, cannot perform photosynthesis, so it needs to obtain energy in other ways. The term symbiotic just means that both organisms are benefitting from the partnership. In lichens, the algae provide the fungus with food, and in exchange the fungus promotes conditions that the algae needs for growth. Now, of course, these two did not just decide to do this. Over the course of evolutionary history this relationship has been developed to give both an advantage.  And it certainly has given lichens an advantage. Lichens may be most obvious living on rocks, logs, and trees, but, in reality, there are few places on earth that lichens haven’t colonized. In fact, lichens are often some of the first organisms to appear after major disturbances, a receding glacier or a severe forest fire. Some studies suggest that lichens could even survive on mars! Lichens are able to live in these extreme habitats, including deserts and polar areas, due to their ability to withstand drought.  They can absorb moisture rapidly from their surroundings (including dew or fog) and hold onto that moisture for extended periods of time, allowing the photobiont to continue photosynthesis.

In the forest community, lichens contribute to species and habitat diversity, allowing ecosystems to be more resilient in the face of changes and disturbances. In the Pacific Northwest alone over 1,000 species of lichens have been identified, and there are over 25,000 known species worldwide. These lichens provide food, habitat, and nesting material for innumerable animal species, including elk, mountain goats, mice, birds, beetles, and moths. Lichens can be an especially important food source for survival in wintertime, when other sources of forage are scarce. Beyond supporting wildlife and invertebrates, lichens can also stabilize soils and reduce erosion, and some lichens can “fix” nitrogen from the air to biologically useful forms.









Many lichens grow at an extremely slow rate, often less than one millimeter per year. Some lichens are thought to be the oldest living organisms on earth, living from hundreds to thousands of years in some instances. They have been used to estimate the time frames of geological events. Lichens also are excellent chemists, and many of the chemical compounds produced by certain lichen have been used by humans in medicines. With such diversity in lichens, it’s exciting to think of the new chemical compounds that are still yet to be discovered, new advances in medicine still to be made, in these humble, hearty organisms.  Lichens have also had a number of traditional uses for groups of Native Americans in the Northwest, including in dyes, medicines, rituals, and as a culinary delicacy. Who knows, maybe in the future we’ll be eating lichen salads!

Despite their toughness, lichens are still vulnerable to human-induced changes in their ecosystems. Because lichens are excellent at absorbing moisture from the air, they are also incredibly sensitive to airborne pollutants. As such, changes in the lichen community of an area can be an early indicator of air pollution. Given the enormous role lichens play in ecosystems, it is important to be aware of our impacts on these often overlooked organisms.

For those of you who aren’t convinced that Lichens are pretty amazing members of the forest ecosystem, check out this cool application on lichens and climate change. Or look at this cool project you can do to study lichens and air quality in an area near you!

If you’re looking for more information on lichens, check out this site or this site. For some beautiful lichen photos, look here.

In the meantime, I’m out to hunt more lichens!


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