Lichen

Introduction

Delicate yet resilient, lichen are unique organisms often overlooked in the vast tapestry of nature. Not quite plants, lichens are complex life forms that arise from a symbiotic relationship between fungi and algae or cyanobacteria. Their presence, diversity, and abundance can tell us much about the world we live in, acting as vital indicators of environmental health. But beyond their role as environmental sentinels, why are lichens essential, and what functions do they serve in their ecosystems?

Lichens play a foundational role in the process of ecological succession. As some of the first colonizers of bare rock or disturbed areas, they prepare the way for future plant communities. By secreting acids, lichens break down rock surfaces, gradually turning them into a layer of soil. As this soil layer thickens over time, it provides a hospitable environment for mosses and, eventually, higher plants to take root. In this way, lichens serve as ecological pioneers, initiating the long process of turning barren landscapes into thriving ecosystems.

Furthermore, lichens offer food and shelter to various organisms and showcase adaptability by thriving in extreme conditions—from arid deserts to frigid tundras. Their importance in bridging gaps in ecosystems cannot be overstated.

On these pages, we will delve deeper into the multifaceted world of lichen. We'll explore their ecological significance, the intricacies of their symbiotic relationships, their vital role in ecological succession, and the pressing need for their conservation in the face of global environmental changes. Join us in celebrating and understanding these unsung heroes of biodiversity and ecosystem restoration.

Types of Lichen

Cladina Lichens

Cyanobacterial Lichens

Lung Lichens

Powdered Sunshine Lichen

Reindeer Lichens

Rock Tripe Lichens

These like to grown on rocks and vertical cliffs which puts them at risk of damage from rock climbers. 

They have long been a famine food, but can also be used as thickener in soups, but don't grow fast enough to be appropriate for general consumption. 

Usnea Lichens

"Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs. The genus is in the family Parmeliaceae. It grows all over the world. Members of the genus are commonly called old man's beard, beard lichen, or beard moss." - Wikipedia: Usnea

These have been used for their anitbacterial properties as medicine, to dye textiles, and even as food. In nature they are important microhabitats, and provide nesting materials. Their sensitivity to air pollution make them important bioindicators. 

Benefits of Lichens

Lichens aren't as well studied as vascular plants, mushrooms or mosses, but they fill some important ecological roles. 


Bioindicators

These are very sensitive to environmental changes, some even indicating the presence of specific air pollutants.

Camouflage

Certain species of amphibians have evolved to look like local lichen species and use lichens as camouflage.

Food

These can be edible to both humans and wildlife. 

Winter Forage

Unlike many plants and fungi they are present during winter months, helping to bridge the dietary gap for many species awaiting new spring growth. 

Lichens tend to have low protein content, but high carbohydrate contents, providing species such as caribou with extra energy during the cold months.

"Apart from their food value, lichens may be important as a source of free water during periods of cold temperatures. The arboreal lichens in the genus Bryoria are dark-colored and therefore a good absorber of solar radiation. They probably provide liquid for the northern flying squirrel and other animals (Thomas and Rosentreter, 1994.)" - Lichen Use By Wildlife In North America

Nesting Materials

"Both birds and small mammals who use lichens for nest building undoubtedly benefit from the lichens' insulating properties." - Lichen Use By Wildlife In North America

The softer, fluffier types of lichen are often used by birds and other species as padding for nests. 

Hummingbirds

Hummingbirds have been seen gluing lichen to the outside of their nests with spider webs, disguising them as little bumps on the outside of trees, so that they look like part of the tree itself.

Soil Health & Erosion Control

"Lichens enhance wildlife habitat in less direct ways as well: many species, especially the nitrogen-fixing lichens, increase nutrient availability for vascular plants, and lichens can be important in controlling soil erosion." - Lichen Use By Wildlife In North America

Benefit/Danger of Lichen

Lichen Absorbs Radioactive Fallout

"One disadvantage of eating lichens, particularly for human hunters who eat the meat of caribou and deer, is that lichens absorb and accumulate radioactive fallout far more than vascular plants and pass them along in the food chain. As Richardson and Young (1977) put it, "Liden (1961)...showed that reindeer meat contained 280 times the 137Cs level of beef produced in the same general area." In a study in Alaska (Viereck, 1964) it was found that "Lichens have concentrations of strontium-90 and cesium-137 of from 10 to 100 times that of most other plants from either temperate or northern regions...Caribou and reindeer have concentrations of strontium-90 in meat and bones that are about 25-30 times that found in meat in the average U.S. diet. Cesium-137 levels are from 3-300 times that found in beef...Strontium-90 in bone in caribou-eating Alaskan Eskimos is being laid down at about four times the rate of that of the average U.S. citizen...Inland Alaskan Eskimos at Anaktuvuk in the summer of 1962 had whole body counts of cesium-137 ...approximately 50-100 times the concentration of cesium-137 in people of temperate latitudes." After the Chernobyl disaster many reindeer in northern Europe had to be destroyed without their meat being consumed." - Lichen Use By Wildlife In North America

Dangers of Lichen

Natural Toxicity

Some species of lichen have toxic or psychoactive properties. 

Radiation

Lichens can be high in radiation and therefore unsafe to eat. Animals who have eaten radioactive lichen are also unsafe for consumption.

Threats to Lichen

Air Pollution

Lichen act as useful bioindicators because they are sensitive to certain air pollutants. If certain lichens are absent from their biomes, it may indicate the presence of pollution from nearby livestock farms or certain factories. Some top threats include:

"Losses of terricolous lichens in the Taimyr from pollution generated by the Norilsk metallurgical complex have been nearly complete within a 300,000 ha area...and damage and reduced growth extends over an area in excess of 600,000 ha. The Arctic also is a sink for atmospheric pollution generated in the heavily industrialized north temperate regions of the world." (Klein and Vlasova, 1992.) Schofield (1975) says, "...all of the ingredients necessary for lichen damage are present...The accelerated industrialization of the Arctic makes this possibility of more than academic interest." - Lichen Use By Wildlife In North America

Deforestation

"In many boreal forest regions, such as in northern Alberta, intensive logging for pulp wood is destroying the lichen communities upon which the woodland caribou depend. Oil and gas development, with its road building and increased access by hunters, is also stressing the herds. The number of woodland caribou in Alberta has fallen from approximately 8000 in 1966 to less than 2000 in 1990, and they may be in imminent danger of extinction in that province." - Lichen Use By Wildlife In North America

In Canada, toilet paper companies pose a particularly great risk to species including lichen due to the overharvesting of old-wood forests.

Wildfires

Lichens have a very slow growth rate, and impeding their return after wildfires.

Resources & Guides

Animals

Lichen as Indicator Species

Use the indicator species button to find general information on this topic, or the directory of "Indicator Species by Location". 

If you scroll down on this page, there's a smaller collection of lichen specific and lichen-inclusive resources of lichen which can be used as indicator species.

Lichens as Indicator Species by Location

Use these guides to determine local environmental health with lichens. Some of these guides focus on lichens only, while others are more diverse guides that also include lichens in general, or one or more specific lichen types.

North America

Canada

Ontario

Maps

Europe

UK