Lichen: Exploring Microecosystems in Your Backyard

Lichens are tiny farming biomes that live on rocks, soil and trees.

Fortunately, with a magnifying glass or macro setting on your smartphone, you can explore these systems within a few steps of your door.

A Lichen is a Symbiotic System

Lichen is composed of fungi, algae, and bacteria. The fungus captures plant cells, taking it inside its body where it nourishes and protects them. When the algal cells photosynthesize, they produce sugars that the fungus eats.

Very resilient, lichens have survived space experiments and can lay dormant for up to ten years in wetter California climates. Some species are over 1,000 years old!

 

What Lichens Need to Grow

Lichens need air, water, light, nutrients, and something to cling to (substrate).

Air: Like sponges, lichens absorb everything they need from nutrients to moisture. They’re so sensitive to environmental pollutants, temperature shifts and water conditions that the U.S. Forest Service uses lichen surveys as indicators of forest health, providing hot spot data and conservation priorities.

Water: Lichens don’t have the ability to regulate moisture levels (poikilohydry).  When they lack water, they dry out, go dormant and look dark. When water is available, they plump-up, look green, grow, and reproduce.

Light: The algal cells that the fungi farm need light to photosynthesize. Lichen species have different light requirements. Some prefer full sun on rocks while others like shady, cooler subclimates. Brightness and coloring are also affected by light. Species adapted to hotter and brighter conditions are generally more colorful.
 
Nutrients: Lichen nutrients include; oxygen, carbon, and nitrogen. Lichens use cyanobacteria to “fix” nitrogen from the air which is then used to organic acids and proteins. 
Species types – acidophyte & nitrophyte – that flourish or diminish under certain climate conditions are used in lichen surveys.
 
Substrate: Any non-moving object the lichen can hold onto – rocks, trees, soil, tombstones, houses, farm equipment, etc. 

Types of Lichen

Foliose: Leafy lichens that use tiny rhizines to attach to substrate.

Folios lichen – Plitt’s Xanthoparmelia plitti, Lettuce lichen/Lobaria oregana & Rhizine Photo by Ed Uebel – NOTE: Lichens are not parasitic. They  do not hurt trees.
 

Forage: Hair-like and hanging species that are eaten by animals and humans

Forage lichen – Willa/Bryoria fremontii – eaten by squirrels, western voles, wild turkey, slugs, snails, mites, springtails, certain caterpillars and Mule deer. Photo by Jason Hollinger

 

 

Crustose:  Lichens grow flat on their substrate surface

Crustose lichens – gold cobblestone/Pleopsidium flavum and Firedot/Caloplaca trachyphylla – Photos by Jason Hollinger

Fruticose: looks like a shrub, bush, or coral

Fruticose lichen – Old Man’s Beard/Usnea Photo by Rhododendrites & Wolf lichen/Letharia vulpina Photo by Jason Hollinger

Reproduction

Lichens have multiple reproduction methods. If they reproduce sexually (by way of fruiting bodies) they create spores. If they reproduce asexually, a powdery substance – soredia –  is released. Both methods use, wind, water, and animals to transport the newbies.

The fruiting body of the Pixie Cup lichen

MYTH: Lichen do not harm trees. 

Other Lichen Uses & Users

Clothing, wound absorbent, diapers, model train shrubbery, and an ingredient in concrete, perfume, and deodorant. Some lichens are being studied as new sources of antibiotics and medicines.

Camouflage for; lizards, moths, tree frogs and other insects.

Insect larva camouflage

 

Nesting Material

At least 50 bird species use lichens as nesting material.

 

 

 

 

 

 

 

 

If you enjoyed this post, you might also like Bird’s Nest Fungi – Spores Spread by Raindrops

 

 

 

 

 

 

 

 

 

 

 

Resources:

Acidophyte & Nitrophyte Lichen Species  (air quality indicators)

Bay Nature – Identifying with Lichens

California Lichen Society – Observations  |  California’s State Lichen

Consortium of North America Lichen Herbaria 

Field Guide To California Lichens 

 

Live Science – What are Lichens?

The Scientist – Not One, Not Two, But Three Fungi Present in Lichen 

Marin County Lichens (Introduction to)

National Lichens & Air Quality Database and Clearinghouse

North American Mycological Association

OPAL Identification Guide (PDF)

Sharnoff – Lichen uses by people: Perfume & Misc. | Dyeing

Sierra College Natural History Museum – California Lace Lichen

UC, Berkeley – California Lichen Society

University of Minnesota Extension – Non-harmful tree conditions

USDA – Lichen Bioindication of Biodiversity, Air Quality, and Climate: Baseline Results From Monitoring in Washington, Oregon, and California

U.S. Forest Service – About Lichens

U.S. Forest Service – Lichen Habitat 

Wikipedia – Lichens of the Sierra Nevada U.S.

Books

 

 

 

 

 

 

 

 

Lichen Photography

Lichen Photography by Stephen Sharnoff

Lichen Photography by Tim Wheeler 

 

 

 

 

 

 

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