Lichen 101 for Arborists

Summary

How’s your ability to distinguish lichens that grow on tree trunks and branches from mosses and algae? A lichen is a mutualistic symbiotic relationship composed of two or more organisms (from up to three entirely different Kingdoms!). A mycobiont (fungus) makes up the majority of the “body” (thallus) of the lichen, while the photobiont (algae or photosynthetic bacteria, or both) typically resides inside the lichen’s thallus. Together, as a lichen, these organisms are able to live in environments where, individually, they would be unable to survive. Lichens play important roles in every terrestrial ecosystem on earth, including the urban ecosystem. With a brief biology lesson on lichen, you can change your client’s (and the public’s) skeptical disposition to one of understanding, acceptance, and even appreciation. But first, we need to educate the arborist. This presentation will explain the who, what, where, when and why of common lichens that grow on tree trunks and branches.