Disappearing Lichens and a Southern Appalachian Stronghold

Disappearing Lichens and a Southern Appalachian Stronghold

New York Botanical Garden

James Lendemer, Ph.D., Assistant Curator – Lichenology

Imagine if most native plants had vanished or become rare a century ago. As an Easterner, I try to envision the explosion of spring wildflowers in Appalachia reduced to only the few and hardiest. You might think of the impact in Southern California deserts, high country of the Rockies, Midwest prairies, or swamps along the Southeast coast. It is not an easy task. Native plants are central to how humans perceive the natural world and appreciate its value and beauty. Because native plants are so important to us, such losses are difficult to conceptualize.

Background photo: Lichens are specialists and there are species adapted to grow on almost everything in every place. Many species in the tropics grow on the living leaves of plants. Some of these, such as Fellhanera bouteillei also grow in wet and humid parts of the southern Appalachians.  Photo credit: James Lendemer, courtesy of New York Botanical Garden.

Disappearing Lichens and a Southern Appalachian Stronghold

New York Botanical Garden | James Lendemer, Ph.D., Assistant Curator – Lichenology

Imagine if most native plants had vanished or become rare a century ago. As an Easterner, I try to envision the explosion of spring wildflowers in Appalachia reduced to only the few and hardiest. You might think of the impact in Southern California deserts, high country of the Rockies, Midwest prairies, or swamps along the Southeast coast. It is not an easy task. Native plants are central to how humans perceive the natural world and appreciate its value and beauty. Because native plants are so important to us, such losses are difficult to conceptualize.

Thankfully, although many native plants are imperiled, their absence is still a thought experiment. This is not the case for lichens.

Lichens are fungi that form beautiful, complex symbioses with algae and bacteria. They hold together soils, regulate the climate, allow seeds to germinate, and provide both food and shelter for all kinds of animals. These hubs of activity that bind nature together are incredibly important to nearly everything that lives on land. And many have vanished.

Understanding why they have vanished is simple: lichens are sensitive to change.  Attached to the substrates they grow on, lichens cannot rapidly move to avoid fires, floods, or changing climates. They passively soak up moisture from the environment and can’t keep pollutants from entering their bodies. They are made up of specialized, highly adapted partners and can’t live without the right conditions for all the partners. Finally, they do not disperse very far, with each generation only a short distance away from its parents. Ironically, these very factors that allowed lichens to diversify and thrive – as long as they had a bit of fog and a substrate to grow on – now leave them poorly adapted to the challenges of the modern world.

Photo of Cladonia cristatella

Cladonia cristatella, also known as British Soldiers, one of the iconic lichens of eastern North America. Photo credit: James Lendemer, courtesy of New York Botanical Garden.

Photo of branch covered with lichens

A typical branch covered with lichens, including Ramalina culbersoniorum and Myelochroa galbina. Fruticose lichens like Ramalina have been greatly impacted by air pollution and habitat fragmentation. Photo credit: Andrei Moroz, courtesy of New York Botanical Garden.

Photo of Xanthomendoza hasseana

Lichen coloration is primarily due to pigments produced in their outer layers and which serve many functions, including sunscreening. This orange species, Xanthomendoza hasseana, is rare in the southern Appalachians where it grows on canopy branches in old-growth forests. Photo credit: James Lendemer, courtesy of New York Botanical Garden.

The disappearance of the lichens has been chronicled by naturalists for nearly two centuries. An early naturalist noted their loss from Dickensian England as cities grew and air quality decreased. A lichenologist documented their loss in Paris during the Industrial Revolution. In the United States, urbanization, deforestation, and the Industrial Revolution have spurred the loss of Southern California lichens. There was once a lichen desert covering tens of thousands of square miles in Pennsylvania and the Ohio Valley. Nearly all of New York City’s hundreds of species were pushed out of the boroughs.

Happily, air quality across the U.S. has improved since the Clean Air Act was passed in 1972. Lichens have begun to return to areas where they once were numerous. But most have yet to recover.

Many species are rare and are commonly found only in unique areas that have been protected and remain relatively undisturbed. Although areas of conservation concern have been established for native plants, lichens do not follow the same patterns. Finding these areas for lichens and recognizing their value for conservation are now critical. I have the privilege of working toward this goal as a member of a small but dedicated group of lichenologists from across the United States and Canada.

James Lendemer and North Carolina National Forest Service Botanist Gary Kauffman surveying for rare lichen species on a windy cliff of Roan Mountain, North Carolina. Photo credit: Laura Bogges, courtesy of New York Botanical Garden.

The 2018 Highlands Biological Station field course in introduction to lichens on the culmination of their trip to study threatened endemic species in Great Smoky Mountains National Park. Cliff tops of Mount LeConte, Tennessee. Photo credit: Jessica Allen, courtesy of New York Botanical Garden.

One of the priority areas for lichen conservation is Appalachia, especially the southern mountains in Alabama, Georgia, North Carolina, South Carolina, Tennessee, and Virginia. For more than a decade, I have worked as a lichenologist for the New York Botanical Garden, together with colleagues and students, to build the case that this area is a global hotspot for lichen diversity and one that is critically imperiled.

The region is truly special. We have found dozens of species new to science. Some of these are restricted to mature individuals of specific tree species that grow in the largest remaining tracts of old-growth forest east of the Mississippi River. Studies with Dr. Erin Tripp and Dr. Christy McCain at University of Colorado, Boulder, have confirmed that patterns of lichen diversity in the region are driven by habitat quality and disturbance. My colleagues and I have found species still relatively common in the southern Appalachians that have declined greatly in other parts of North America. A team of lichen specialists, led by Dr. Jessica Allen at Atlanta Botanical Garden, have begun to rank and assess these species as part of a broader effort to increase representation of lichens among biodiversity recognized to be in need of conservation and protection. Appalachian Matchsticks (Pilophorus fibula), Hot Dots (Arthonia kermesina), Virginia Square Britches (Hypotrachyna virginica), and the Rock Gnome (Cetradonia linearis), are just a few of the lichens that have been assessed as endangered and added to the IUCN Red List as a result of these efforts.

Great Smoky Mountains National Park has long been recognized as central to protecting the vast diversity of life in the southern Appalachians. My colleagues and I have documented nearly a thousand species from the park – more than from any other national park in the United States. But it is difficult for the average person to access the hidden world of diversity where these lichens still abound and thrive. That is why, in addition to all of the efforts to document and conserve lichens that make the southern Appalachians so special, we have published a Field Guide to the Lichens of Great Smoky Mountains National Park – the only modern field guide for a North American region that covers more than just the most common and conspicuous species.

Photo of forest near Shuckstack, Great Smoky Mountains National Park, North Carolina

Foggy, hazy forest near Shuckstack, Great Smoky Mountains National Park, North Carolina. Much of the southern Appalachians are inundated by clouds and fog during some part of every day and this provides the moisture lichens need to thrive. Photo credit: James Lendemer, courtesy of New York Botanical Garden.

Photo of James Lendemer looking for aquatic lichens

James Lendemer looking for aquatic lichens at Slickrock Creek in Joyce Kilmer-Slickrock Wilderness, Cherokee National Forest, Tennessee. Photo credit: Andrei Moroz, courtesy of New York Botanical Garden.

The lichens in many areas of the United States have suffered steep declines. That is precisely why those that remain must be recognized and conserved. Lichenologists have shown that setting conservation priorities for these amazing organisms can be achieved and we hope that many more success stories will add to what we have accomplished in the southern Appalachians.

Photo of NYBG-CUNY graduate student Jordan Hoffman studying Cladonia

NYBG-CUNY graduate student Jordan Hoffman studying Cladonia (reindeer lichen) on Whiterock Mountain, Nantahala National Forest, North Carolina. Photo credit: James Lendemer, courtesy of New York Botanical Garden.

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2020-05-15T04:10:49+00:00