The Lichens Are Coming—Back!
Posted in Environment on February 19, 2019 by Becky Thorp
Becky Thorp is the Senior Plant Recorder at The New York Botanical Garden.
Do you like to breathe? If yes, then I have excellent news for you: lichens are easier to find in the New York metropolitan area today than they have been for decades, and this is an indicator of improved air quality.
Lichens are composed of a symbiotic relationship between photosynthetic algae or cyanobacteria, which create food from sunlight, and a fungus, which provides shelter. They can be found growing on the surfaces of tree trunks, rocks, lean soil, tombstones, and other surfaces on every continent and in every type of terrestrial ecosystem on earth. Able to withstand extreme variations of moisture and temperature, lichens have even survived long periods in outer space. What they can’t survive is air pollution here on earth, especially in the form of soot or sulfur dioxide, because they absorb nutrients directly from the atmosphere. Given this fact, it comes as no surprise that while they thrived in the New York area in the early 19th century, the number of local lichen species declined sharply in the 20th century with the growth of industry and population.