Lichen, the gray-green growths on tree trunks and rocks, are a symbiotic organism of algae and fungi. The algae produces the food through photosynthesis, and the fungi provides the nutrients, water and foundation for growth. Their presence on the shady side of tree trunks and rocks is a sure sign the air is clean.
From the late 1960s to the mid ’70s, I was involved in studies and lawsuits concerning air-pollution damage to Christmas trees in Garrett County. At the time, power-generating stations and industries were burning eight to 10 percent sulfur coal.
In the mid-1960s, a new coal-burning power generating station had been built in West Virginia near the Maryland border. Within a few years, growers of Christmas trees began noticing a decline in the quality of trees. A high percentage of white pine trees were yellowing and dropping needles earlier than normal, while Scots pine trees had long and short needles with sparse branching. Christmas tree growers became desperate because they were unable to produce quality trees.
I soon became involved in solving the mystery. After walking through fields of trees on my first visit, I noticed the cuffs of my pants were full of fly ash. I suspected air pollution was the cause. Since I had limited knowledge of the effects of air pollution on plants, I took several trips to the library and to the air pollution laboratory in Beltsville to gain sufficient confidence to proceed.
After planting beds of summer squash near some of the growing fields and visiting family vegetable gardens in the area, I was able to confirm these suspicions. The foliage of the squash exhibited classic symptoms of sulfur dioxide injury.
In my review of literature on air pollution symptoms, I saw frequent references to the absence of lichens in areas with polluted air. In evaluating the affected area of Garrett County, I found dead lichen residue on rocks and tree trunks. I never saw a live lichen.
With the technical assistance from scientists with the Department of Health, Education and Welfare, we were able to prove in the court of law that air pollutants from the power plant in West Virginia caused the damage to the Christmas trees in Maryland. The 1972 air pollution abatement hearings in Keizer, West Virginia, mandated only three percent sulfur coal.
After several years, lichens reappeared. The quality of Christmas trees improved in a few years.
The University of Maryland at College Park had been burning Maryland soft coal, so I was able to monitor the regeneration of lichens on campus. They first appeared as small gray specks that eventually grew into larger characteristic lichen shapes.
The moral of the story: Appreciate the presence of lichens in your area.