Conservancy Naturalist and Mycologist Makes Thrilling Lichen Discovery in Frick Park!
Pittsburgh Parks Conservancy Naturalist and Mycologist, Stephen Bucklin, recently made a thrilling discovery in Pittsburgh's backyard. He recorded a species of lichen previously undocumented in the state of Pennsylvania—right here in Frick Park! Bucklin shares the captivating story below in a special edition of our blog. Read on to get the full scoop about this exciting discovery!
THE PARADOX OF LICHENS
The discovery of a lichen species previously unreported from Pennsylvania in Frick Park was something I never expected. Lichens are paradoxical by nature – extremely abundant and found on most surfaces around us (trees, rocks, concrete, fences, and even street signs), yet poorly understood and under-studied (how many lichenologists do you know?). They are usually part fungus, part algae, part bacteria and so cannot be easily divided into “individuals” and challenge our very way of classifying the natural world into discrete species. They are also paradoxical in the way that they are incredibly resilient (some lichens have survived trips to the vacuum of space and simulated Mars-like conditions) and yet incredibly sensitive to air pollution and human activity. Finding a new state record in the middle of Pittsburgh simply adds another layer to their complexity. The following is the story of my finding, I hope it may inspire you to pay attention to the little things around you.
Along the northern facing slopes of Clayton Hill, a mature forest of cool-and-moist-soil-loving trees mostly composed of American beech (Fagus grandifolia), sugar maple (Acer saccharum), and tuliptree (Leriodendron tulipifera) has flourished following logging and farming on this land during the late 18th and early 19th centuries. Many of these trees are likely over 100 years old – the land was donated to the city in 1919 before becoming officially a park in 1927.
In the upper canopies of the towering tuliptrees, poking out above the dense shade cast by the beeches and maples, the sun-soaked bark is dripping with lichens. Typically inaccessible to humans, these forest canopies support numerous invertebrate species and provide food and nesting sites for songbirds. Lichens play key roles in feeding invertebrates and camouflaging both invertebrates and bird nests and are crucial components of forest canopy communities.
AN UNEXPECTED FINDING AFTER A STORM
Throughout the winter, the bare and exposed canopies get battered by strong winds during storms. Particularly strong gusts sometimes rip branches from these heights and bring them crashing to the forest floor. I take great delight in exploring these gifts from the heavens. As I made my way around the 1-mile loop trail participating in a mindfulness walk with my colleagues in late February, I wandered off the trail here and there to explore recent windfallen branches. Most contain primarily bright greenshield lichens (Flavoparmelia caperata), dense coatings of gray hammered shield lichens (Parmelia sulcata), and the occasional puffs of frilly and hairy powdered ruffle lichens (Parmotrema hypotropum). Occasionally, a surprise lies hidden amongst this coral reef of the sky.
As I rounded a bend and began to make my way back towards the environmental center, a large branch about 50 meters up the hillside caught my eye. I carefully meandered up the hill and began peering over every inch of the branch and the smaller pieces scattered across the ground. Suddenly, a large gray lichen caught my eye. The gentle waves of the large thallus made them recognizable as a type of ruffle lichen (Parmotrema), but their surface had what looked like an unusual texture and shading pattern. Upon closer inspection, the surface was covered with small finger-like projections called isidia.
My heart leapt out of my chest – the fine isidia are a relatively uncommon feature to observe on lichens and I had never seen a ruffle lichen with this structure in Pennsylvania before.
A HEART-POUNDING DISCOVERY IDENTIFIED
After completing the walk, I ran back to the site to get more photos and collect the lichen for further study. When branches fall from trees, the lichens slowly die and decompose. As a volunteer for the Pennsylvania Biological Survey on their Mycological Technical Committee, I knew this section of tree bark was more valuable stored in an herbarium than if it was allowed to return to the soil.
I’m part of the Lichens subcommittee, a group of dedicated scientists tracking all lichen species found in Pennsylvania. I took the specimen home to examine under a dissecting microscope with 10x-40x magnification, under which I performed chemical spot tests with bleach and potassium hydroxide. The medulla layer – a loose mat of fluffy white fungal tissue between the upper and lower cortex – immediately stained yellow when a drop of potassium hydroxide was applied. Over the next 30 seconds, the bright yellow slowly turned deep red. This color change indicated the presence of salazinic acid. Lichens produce hundreds of unique chemicals, and the identity of species often is based on the particular mixture of chemicals present.
Due to my uncertainty about this mystery lichen’s identity, I contacted James Lendemer, Curator of Botany at New York State Museum, who grew up in eastern Pennsylvania and volunteers on the committee. He confirmed my suspicion that this was unlikely to be a species previously known from Pennsylvania and asked me to mail the specimen to him. Within a month, he had performed an advanced chemical analysis, called thin-layer chromatography, and detected another lichen substance – norlobaridone. This combined with the physical features made the lichen identifiable as Parmotrema subtinctorium – a species much more common in the southeastern United States. The nearest other records of this species are in southern Ohio and the mountains of West Virginia, and no records occur further north in New England.
THE SIGNFICANCE OF THE REVELATION—A BIG MOMENT FOR PITTSBURGH
It feels incredibly significant for Frick Park in the formerly smog-laden industrial town of Pittsburgh to be the site of a state record species of lichen – organisms known to be indicators of air quality. Most likely, this species is not particularly sensitive to the types of air pollution we have in Pittsburgh. When it comes to particulate matter, ozone, and sulfur compounds, Pittsburghers who are paying attention know we still have improvements to make – for our health as well as for the lichens. Perhaps somehow, the buffer of the surrounding trees filtered enough of the air pollution to allow this lichen to survive.
Those who live in Pittsburgh or who have visited know that our parks are a huge part of what makes our city special. From river trails shaded by sycamores and silver maples to hilly forested parks filled with oaks and hickories, to smaller community parks with gardens and playgrounds – greenspace is abundant in this city. Frick Park has been known for its dense forest not broken by any roads – this interior forest supports specialist birds that only nest in this habitat such as pileated woodpecker, scarlet tanager, barred owl, wood thrush, and hooded warbler. Now we know this park also harbors species of fungi that also require dense stands of forest and vast stretches of time without disturbance from humans. I’m excited to see what other species can be found in the park, and with time what species can be invited to live in our city again.
- Stephen Bucklin, Naturalist, Mycologist, Lichen Specialist, Past President – Western Pennsylvania Mushroom Club
