According to scientific estimates, the dual organism, lichen, covers 7% of the earth’s surface and number 18000 (and counting) variants. This fungi-algae hybrid cannot exist without one another, in-fact, the word symbiosis was coined to describe their unique union. Lichen are critical to our world as they fix hydrogen, break down rock material and provide habitat, food and shelter for an array of other organisms. Since their identification in the late 19th century, much has been learnt however recent developments about the nature of lichen suggest there is still much to learn.
Critically, many lichens are sensitive to pollution and shifts in global temperature so they are considered reliable indicators of environmental change and substantial distribution and density changes have been identified in the last two decades. It is considered that shifts in lichen communities could profoundly impact other essential forest processes.
