What’s Not to Lichen?

Virginia Spring Beauty (Claytonia virginica)

Cladonia cristatella (British Soldier Lichen)

If you have ever been outdoors, you have probably seen a lichen. In addition to visual appeal, lichens serve many functions in nature and are unlike any other species on this Earth. Like a snowflake, each is unique, and no two species are visually identical. Often mistaken for moss or other plant species, lichens are organisms that only exist due to mutualistic symbiosis – teamwork! They belong to the fungi kingdom and each lichen is made up of two or three organisms: a cyanobacteria or algae, yeast, and a fungus. The fungus provides a place to live for the cyanobacteria or algae and in turn, the cyanobacteria or algae undergoes photosynthesis and provides nutrients to the fungi. All organisms benefit from the relationship; thus, the relationship is classified as mutualistic. There are around 15,000 different species of lichen and about 3,600 of them occur in North America. Lichens range in size and are commonly found throughout forests growing on trees or fallen branches, and on rock outcrops all over the world. In more developed landscapes you can find lichens on older concrete and brick, and even headstones. They come in all shapes, sizes, and colors with some being shades of green or even bright yellows and oranges. Macrolichens are leafy or bushy, while microlichens are flat.

Examples of Macrolichen and Microlichen found on both living and dead tree branches.
Click to view series of larger images.

Lichens are beneficial for wildlife and provide a food source for animals such as rodents and deer as well as provide nesting material for various bird species. One of the strangest things about lichens is the fact they lack roots and are unable to obtain nutrients from anything other than the air itself. They are sensitive to air pollution and can be indicators of local air quality. For this reason, lichens are considered keystone species in many of the habitats they reside. A keystone species is a species that provides an irreplaceable service to their ecosystem which other species largely depend on such that, if the keystone species disappeared, the ecosystem would change drastically.

Cladonia cristatella (British Soldier Lichen)

Cladonia coniocraea (Common Powderhorn

In addition to being keystone species, they are also used as a biomonitor by the National Park Service and United States Forest Service. A biomonitor is a species which helps indicate the health of an ecosystem as a whole. When lichen samples are inspected by scientists, they are able to experience the air we breathe on a molecular level, down to each individual element.

Here at the Carolina Wildlands Foundation biological field station, we have extremely abundant and diverse populations of lichens. One walk through Halfmoon, the floodplain forest along Thompson Creek, resulted in twenty different species of lichens being found. These lichens were seen growing on a range of tree species from Loblolly Pines (Pinus taeda), to various oak species (Quercus), to Tulip poplar (Liriodendron tulipifera). So next time you are walking in the woods, walk a little slower, stare a little longer, and look for these irreplaceable organisms because, after all, what’s not to lichen?

By Brianna Bergamini, Southern 8ths Prairie Keeper