Often overlooked, Lichens serve many functions in the
natural environment. Not only are they good indicators of environmental health,
but they also support wildlife. Known as a “keystone” species, lichens are
vital to the well-being of the entire ecosystem. Late winter/early spring is a
great time to take a walk and keep an eye out for the many different types
growing in New Jersey.
Lichens come in different shapes, sizes, and
colors.
Photo Credit: Alyson Ricketts, Rutgers Master Gardener of Burlington County
Lichens can be found growing on trees, rocks, soil, metal,
plastic, cloth, etc. They are living organisms that function as a symbiotic
combination of fungus, algae, and yeast. The algae provides nutrients through
photosynthesis, the fungi protects the algae from drying out, and the yeast
allows the lichen to produce an acid that protects it from microbes.
Lichens can be beautiful and take on many shapes depending
on the type. The three main groups of lichens include: crustose (crusty),
foliose (leafy), and fruticose (bearded or tubular).
Perhaps the biggest reason for lichens’ likability is that
lichens are indicators of good air quality. They are used as bio-monitors and
give scientists clues about environmental pollution levels. Most lichens will
not tolerate air pollution, they require clean air. They may die if exposed to
elevated levels of sulfur or heavy metals. According to the National Park
Service, “Lichen trap particulate
matter in the air like dust, while also absorbing smaller pollutants like
sulfur, mercury, and nitrogen. This means cleaner, healthier air for us to
breathe.”
In 2015, two species of lichens were removed from the Rutgers
Pinelands Field Station and moved to the New York Botanical Garden in New York
City. But, more than two years after the move, the lichens met their demise.
Researchers attributed their non-survival to both disturbance and exposure to higher levels of air pollution than was present in their previous habitat in southern New Jersey.
Group of boulders with crustose lichens.
Photo Credit: Karen Dillman, U.S. Forest Service.
Contrary to a popular misconception, lichens do not harm
trees. They do not feed on tree bark. Lichens are not a sign that a tree is
damaged, dying, or diseased. They are found, however, on slow-growing, often
mature trees. In this way, they can be an indicator of declining health of the
tree because the bark has become brittle and cracked or the tree has defoliated.
The lichens are not damaging the tree, simply using the bark as a place to
exist and collect sunlight.
Foliose type lichen growing on a pine tree.
Photo Credit: Alyson Ricketts Rutgers Master Gardener of Burlington County
Fun Facts about Lichen:
- Lichens occur in all habitats,
including arctic, rainforests and desert.
- Ruby-Throated Hummingbirds use
lichen to line their nests.
- Lacewing insects carry lichen on
their backs as camouflage.
- Lichens are a food source for
deer, birds, and rodents.
- Scientists can use certain
slow-growing lichens to estimate the age of rocks, glacial retreats, and
landslides.
- Humans throughout history have
used lichens in food, to dye clothing, and as medicine.
- Some lichens can live for
centuries.
- There are approximately 3,600
species of known lichen in North America.