How does prescribed fire affect a threatened terrestrial orchid?

By Leighton Reid and Ryan Klopf

Leighton Reid is an assistant professor of ecological restoration in the School of Plant and Environmental Sciences at Virginia Tech. Ryan Klopf is the Mountain Region supervisor and natural areas science coordinator for the Virginia Natural Heritage Program. They describe a new research project that aims to understand how an important restoration tool impacts the population dynamics of federally threatened small whorled pogonia orchids. This project has an open PhD position available to start in January 2023; details can be found at the end of this post.

Deep in the heart of Virginia’s Shenandoah Valley, nestled against the western edge of the Blue Ridge Mountains, two clusters of small, green orchids grow in the dappled sunlight of a woodland understory. The orchids are small whorled pogonias (Isotria medeoloides) – a rare species that is considered threatened by the United States government because its population is declining so quickly that it could become endangered in the foreseeable future. We have monitored these populations for the past two summers, keeping tabs on every individual, to learn how this species is affected by one of the most important restoration tools in North America – prescribed fire.

A small whorled pogonia orchid with two flowers at Mount Joy Pond Natural Area Preserve. Photo: Lindsay Caplan.

Small whorled pogonia

As their name implies, small whorled pogonias are small (≤25 cm) and whorled (their leaves radiate outward from the stem). This species is a member of the Pogonieae, an orchid tribe that includes species in Asia and eastern North America. Its closest relative is the large whorled pogonia (I. verticillata) which sometimes grows alongside small whorled pogonia, but is distinguished by its purplish stem (small whorled pogonia has a whitish green, glaucous stem).

Small whorled pogonia (left) with a whitish, glaucous stem compared to large whorled pogonia (right) with a purplish stem base. Photos: Sara Klopf (left) & JL Reid (right).

Small whorled pogonias emerge from the leaf litter in late spring and in some years produce one or two solitary greenish yellow flowers, particularly when plants are exposed to more sunlight. Their flowers do not require any help with pollination; they produce the same amount of seed whether they are cross-pollinated or pollinate themselves.

The seeds themselves are tiny – like vanilla seeds, which are in the same orchid sub-family (Vanilloideae). The parent plant (which is usually both a mother and a father) provides almost no resources at all to its offspring. Each seed’s fate is closely linked to whether or not it finds a mycorrhizal fungus in the Russulaceae family to help it acquire the resources that it needs to survive and grow. In a typical relationship between plants and mycorrhizal fungus, the fungus scours the soil for nutrients like nitrogen and phosphorus and provides them to the plant in return for energy in the form of carbohydrates, which the plant produces through photosynthesis.

A developing fruit on a small whorled pogonia orchid at Mount Joy Pond Natural Area Preserve in June 2022. Photo: Andres Cunningham.

Fire and water at Mount Joy Pond

The story of this research project begins about 80 years ago, in a DuPont chemical plant in Waynesboro, Virginia. In the 1930s-1950s, the DuPont facility used mercury to produce rayon – a synthetic, silk-like fiber. Some of the mercury escaped from the plant and leaked into the South River – a tributary of the Shenandoah River. Mercury is a neurotoxin, and in the environment it can accumulate to dangerous levels in animals that are higher on the food chain, like fish. For many years, people living along the South River have been warned about the poor water quality and advised not to eat the fish.

In 2016, DuPont reached a $50 million USD settlement with the United States Department of Justice, the Department of the Interior, and the Commonwealth of Virginia to restore habitat for wildlife in the South River watershed, enhance water quality, and improve recreational areas. This settlement represented one of the largest environmental damage settlements in United States history.

Some of the DuPont settlement money was allocated to the Virginia Natural Heritage Program, a division of the Virginia Department of Conservation and Recreation that uses science-based conservation to protect Virginia’s plants and animals. Specifically, funds were provided to allow the Virginia Natural Heritage Program to protect and restore woodland habitat surrounding a unique wetland at the Mount Joy Pond Natural Area Preserve in Augusta County.

Briefly, Mount Joy Pond is a Shenandoah Valley Sinkhole community; that is, it is a groundwater-controlled wetland that floods intermittently when water percolates up through underlying carbonate rocks and then floods over the top of a clay lens perched in a layer of soil derived from the overlying sedimentary rocks. When this happens, the water becomes trapped, like water in a saucer. This unique situation creates wetland habitats which have persisted for the past 15,000 years and contain numerous rare and disjunct species, including the globally rare Virginia sneezeweed (Helenium virginicum). There are several dozen Shenandoah Sinkhole ponds, but only a handful of them are protected.

Virginia sneezeweed, an endemic species in the southeastern United States with disjunct populations in Virginia’s Shenandoah Valley sinkhole ponds and in a similar wetland situation in the Ozark Mountains of southern Missouri. Photo: JL Reid.

In the past, Mount Joy Pond filled with water every few years, but in recent decades it has filled up less and less often. To restore the wetland’s hydrology, the Virginia Natural Heritage Program set out to thin the surrounding forest and re-introduce fire to prevent fire intolerant trees, such as red maple, from regenerating. This may sound counterintuitive to some, but the logic is this:

• Each tree is like a drinking straw sucking water out of the ground and releasing it into the air via transpiration. If there are a lot of trees, the groundwater may stay too low to fill up the pond.
• Fire used to be much more common in the Shenandoah Valley. Prior to European colonization, Indigenous People burned the landscape and maintained much of it as savanna and open woodland – ecosystem types that have fewer trees than present day forests.
• By removing some trees and reintroducing a regular fire cycle, land managers at Mount Joy Pond Natural Area Preserve can restore an open woodland and raise the groundwater level, causing the pond to flood more often.

The Virginia Natural Heritage Program began to implement this restoration project in 2017, and the first thinning operations and burn were a success. In the years since, the groundwater level appears to have gone up, suggesting that the hydrological restoration plan is working.

Small whorled pogonia discovery

In the first spring after that first fire, a botanist was surveying the burned woods near the pond and found something unexpected – a small population of small whorled pogonia orchids, which had not been seen previously in the preserve despite extensive surveying by the Virginia Natural Heritage Program’s inventory team. Were the orchids there all along and nobody noticed them? Maybe. Or maybe the fire helped the orchid population emerge after years of suppression in the dense leaf litter in the shady understory.

Our team uses a grid sweep survey to search for new small whorled pogonia individuals in June 2022. Photo: JL Reid.

The story became more complicated later that summer when a more intensive search turned up a second population of small whorled pogonia orchids on the preserve – this one in an area that had not been burned.

The immediate consequence of discovering the new pogonia populations was that the United States Fish and Wildlife Service expressed concerns that future fire management might be detrimental to this threatened species. Nobody had studied how small whorled pogonia responds to fire, and there was a chance that burning could damage the population, even if it was good for the nearby pond’s hydrology. Of course, there was also a chance that not burning could damage the population. With fire, inaction is still an action.

To help settle the issue, the United States Fish and Wildlife Service agreed to sponsor a PhD student to study the small whorled pogonias at Mount Joy Pond and figure out how their population dynamics are impacted by prescribed fire.

Lindsay Caplan and Jimmy Francis monitor a population of small whorled pogonias at Mount Joy Pond Natural Area Preserve in June 2022. Photo: JL Reid.

Effects of prescribed fire on small whorled pogonia orchids

The main goal of our ongoing research is to understand how prescribed fire impacts small whorled pogonias. To do this, we will map and monitor the two subpopulations and the woodland plant communities in which they live. Over the next two years, one of the two subpopulations will be burned during a winter or early spring prescribed fire, and we will continue monitoring to document changes in plant vigor, reproduction, and population size. We will pay special attention to the light environment, which seems to be important for small whorled pogonia reproduction, and to the diversity and composition of soil fungi, which are important for small whorled pogonia emergence. We will also conduct annual surveys of the entire reserve to search for additional populations.

Ethan Dunn uses a canopy imager to measure canopy cover, photosynthetically active radiation, and leaf area index over a tiny small whorled pogonia individual in July 2021. Photo: JL Reid.

This project is just beginning. To date, we have monitored the two populations for two growing seasons (2021, 2022). There is still much work to be done. One of the next steps will be to produce an accurate map of each plant’s location, which will require centimeter-level precision using high-quality GPS equipment under a forest canopy.

We are currently seeking a PhD student to lead this research project starting in January 2023. A description of this opportunity is below. This project is an excellent opportunity for a student to develop expertise in ecological restoration and threatened species conservation from both a scientific perspective and an on-the-ground land management perspective.

Ultimately, the results of from this study will inform management of natural areas and small whorled pogonia restoration projects throughout the species’ wide range – from Ontario to Georgia.

Major in Ecological Restoration at Virginia Tech

By Leighton Reid, Assistant Professor of Ecological Restoration in the School of Plant and Environmental Sciences at Virginia Tech.

Now is a great time to start a career in environmental restoration. Worldwide, society has degraded an area of land larger than South America with disastrous outcomes for biodiversity, climate, and human wellbeing. More than a million species face extinction, and ongoing deforestation is second only to fossil fuel emissions in driving global climate change.

Ecological restoration is the process of assisting the recovery of damaged ecosystems, and this profession is at the heart of a worldwide movement to solve the biggest challenges of the 21^st Century. During the past few years, dozens of countries, including the US, have pledged to restore an area of the Earth’s surface bigger than the state of Alaska. There are now three different initiatives to plant a trillion trees, and the United Nations recently launched the Decade on Ecosystem Restoration to amplify the critical role that restoration must play in preventing climate change and species extinctions right now.

Starting in December 2021, Virginia Tech offers a major in Ecological Restoration through the School of Plant and Environmental Sciences. Students who graduate with a BS in Ecological Restoration will be trained broadly in environmental science, ecology, botany, soil science, and human dimensions (download the course checklist). They will learn about ecological restoration projects happening in Virginia and around the world, and they will get hands-on experience designing restoration plans for degraded sites.

Undergraduates in Plant Materials for Environmental Restoration (ENSC 3644) plant an oak tree along Holtan Branch, a tributary of Stroubles Creek on the Virginia Tech campus. Photo: JL Reid.

Virginia Tech has deep roots in environmental restoration and continues to be in the vanguard. For decades Virginia Tech faculty have been research leaders in restoration monitoring, mine reclamation, river restoration, and endangered species recovery. Today faculty from across campus specialize in many more areas related to ecological restoration, including tropical forest restoration, grassland restoration, plant propagation, fire ecology, agroecology, environmental history, natural resource economics, and philosophy. Several faculty members and students have recently formed a Restoration Ecology Working Group to address the interdisciplinary nature of environmental problems.

A tropical forest restoration site in northwestern Ecuador. An undergraduate researcher in summer 2022 will measure the survival of native tree seedlings planted in this former cattle pasture.

Virginia Tech was the first university in the United States to formally align its Ecological Restoration curriculum with the Society for Ecological Restoration, the largest professional organization of ecological restoration professionals worldwide. This alignment means that students graduating with a degree in Ecological Restoration will have completed the knowledge requirements to apply for professional recognition as in the Certified Ecological Restoration Practitioner in Training (CERPIT) program. Professional certification clearly communicates to employers that graduates of this program are recognized within the profession as being knowledgeable in ecological restoration and committed to a high standard of practice.

A Virginia Tech research intern and staff of the Virginia Department of Conservation and Recreation search for a federally threatened orchid in a woodland restoration site in the Shenandoah Valley. Photo: JL Reid.

Undergraduate and graduate students at Virginia Tech can also get involved in restoration through a new student organization. The Society for Ecological Restoration Student Association at Virginia Tech (SER-VT) is student-led and aims to connect students with restoration projects and provide networking opportunities. For example, students who join SER-VT are eligible to apply for free membership in the Society for Ecological Restoration. Students can also get involved with the Virginia Tech Environmental Coalition, a student-run organization that advocates for a sustainable future and organizes events, including The Big Plant, an annual event to improve habitat and water quality in a local creek by planting native trees.

The Environmental Coalition is a student-led organization that organizes native tree planting events and other sustainability efforts on campus. Photo source: https://gobblerconnect.vt.edu/organization/ec.

Job prospects for ecological restoration professionals are already good and likely to improve given the huge scale of land and water degradation worldwide. As of 2016, the US restoration economy employed >126,000 workers and produced $9.5 billion USD in economic output. In terms of workers, there are more professionals working in ecological restoration than in iron and steel mills (91,000 workers in 2016) but somewhat fewer than in motor vehicle manufacturing (175,000). Many different sectors require restoration to comply with state and federal regulations. As such, ecological restoration professionals are hired by architectural firms, construction companies, state and federal government agencies, environmental consultancies, environmental education organizations, public/private/NGO land management organizations, state highway departments, mining companies, forestry companies, universities, and others.

PhD student Jordan Coscia measures plant community composition in a recently restored native grassland on the northern Virginia Piedmont. Photo: JL Reid.

Virginia Tech’s location in the New River Valley provides access to a wide variety of natural areas and restoration projects. One important site within walking distance of classroom buildings is the StREAM Lab, a restoration experiment designed to test different strategies for improving water quality along 1.3 miles of Stroubles Creek (watch a 7-minute video about StREAM Lab). Restoration courses also visit sites managed by the town of Blacksburg, The Nature Conservancy, the USDA Forest Service, and the Virginia Department of Conservation and Recreation to develop hands-on skills in plant identification, community ecology, seed collection, invasive species management, tree planting, and ecological monitoring.

Masters student David Bellangue sets up an experiment focused on improving native wildflower establishment at McCormick Farm near Raphine, Virginia. Photo: JL Reid.

An excellent way for students to get more out of their degree is to participate in a research experience or an internship. By working with a graduate student, a faculty member, or a local land manager, undergraduates develop new skills and perspectives as well as personal relationships with working professionals. Students can also broaden their horizons through a wide variety of study abroad programs.

Undergraduates who participate in research gain new skills (like plant community monitoring) and personal relationships with professionals in the field. Photo: JL Reid.

In a nutshell, the Ecological Restoration Major at Virginia Tech is designed to launch meaningful careers for students who are passionate about the environment and want to move the needle on climate change, biodiversity conservation, and ecosystem services.

To learn more about majoring in Ecological Restoration at Virginia Tech, contact Dr. Leighton Reid (jlreid@vt.edu) or Karen Drake-Whitney (kdrake@vt.edu).

Bee-friendly beef: rehabilitating cattle pastures to increase pollinator habitat

Dr. Parry Kietzman is a research scientist in Virginia Tech’s School of Plant and Environmental Sciences. Here she describes a new experiment aimed at improving Southeastern grazing lands to improve cow health, provide habitat for pollinators, and conserve plant biodiversity. A member of the bee-friendly beef team since 2020, her work focuses on the ecology and conservation of pollinating insects.

Across the world, pastures account for over 20% of the Earth’s land surface, an area roughly the size of Africa. Many of these pastures were once species-rich meadows, prairies, and woodlands that offered abundant and diverse food resources for pollinators, but are now limited to a handful of species that provide forage for grazing livestock.

Lanceleaf coreopsis (Coreopsis lanceolata), a native composite sewn into an active cattle pasture near Stuart, Virginia. Photo credit: Parry Kietzman.

Pollinating insects such as bees, flies, butterflies, moths, and beetles are currently in crisis, as habitat loss from development, intensive agriculture, and other human activities have diminished the food sources and nesting sites they rely on. The conservation of pollinators native to each particular region is especially important, as many plants depend on native specialists for pollination. The widely-kept, domesticated, European honey bee (Apis mellifera L.), though of great importance to modern agriculture, is often not successful or at least not as efficient at pollinating certain plants as the bee specialists that coevolved alongside each particular species. Landscapes rich in a diversity of plant species native to that location are therefore needed to provide habitat for these native pollinators.

Some types of beetles, such as the soldier beetles (Colanoptera: Cantharidae) pictured here, also visit flowers and can provide pollination services. Soldier beetles feed on nectar and pollen and do not damage their plant hosts. Photo credit: Parry Kietzman.

Researchers at Virginia Tech, the University of Tennessee, and Virginia Working Landscapes are currently collaborating on a multi-year rehabilitation project to plant native North American prairie grasses and wildflowers in cattle pastures in Virginia and Tennessee. The project is based on the idea that a landscape can be supportive of healthy cattle production while at the same time providing ecological niches for pollinating insects. Bringing back diverse food sources for pollinators in pastures, however, presents some significant challenges. First, the plants must not be harmful to livestock that may graze on them. Second, they must be hardy and practical to establish in new and existing pastureland. Finally, they should be native to the region in which they will be planted, as this will be most beneficial to that region’s native pollinators and help prevent the accidental introduction of invasive species.

Some of the wildflower species used in our experiment, such as this blanketflower (Gaillardia pulchella), are native to North America but not naturally found in Virginia or Tennessee. Photo credit: Parry Kietzman.

Our team is currently working to identify and successfully establish seed mixes that thrive in Virginia and Tennessee without becoming excessively weedy or crowding out grasses grazed on by cattle. Once established, pollinator diversity and abundance will be measured in plots with and without wildflowers introduced. Herds of cattle grazing in the pastures will also be monitored for health and body condition.

Bumble bees are common visitors at our wildflower-enhanced sites. Photo credit: Parry Kietzman.

Results from this study, including critical information about best practices for establishing the seed mixes, optimal grazing regimes to promote blooms, and wildflowers as forage will be disseminated to growers and other stakeholders through extension services such as published fact sheets, protocols, and workshops. This foundational work will help inform researchers and land managers around the globe how to transform pasturelands into landscapes that can help save our pollinators.

For more information on this ongoing study, visit the team’s website: beesandbeef.spes.vt.edu.

A wildflower-enhanced pasture in southwestern Virginia in mid-summer 2021. Photo credit: Parry Kietzman.

Virginia’s Piedmont grasslands: floristics and restoration

Jordan Coscia is a PhD student in the Restoration Ecology Lab at Virginia Tech and a graduate fellow at Virginia Working Landscapes, a program of the Smithsonian Conservation Biology Institute. She describes her research goals and includes a preliminary species list for natural and semi-natural grasslands on the northern Virginia Piedmont.

You may have heard the legend that before European colonization, a squirrel could get from the Atlantic Coast to the Mississippi by hopping from tree to tree. While the pre-European landscape of the eastern United States was indeed quite different from what we see today, the idea of a vast, all-encompassing forest is misleading. Particularly in the Southeast, open, grassy habitats such as meadows, pine and oak savannas, glades, and barrens were interspersed with hardwood forests. This mosaic of forests and open savannas was maintained by grazing elk and bison, variation in soil types and depth, and regular fires set by both lightning strikes and Indigenous peoples. All of these grassland-maintaining processes were disrupted by the introduction of European development and agricultural practices.

As a PhD student in the Restoration Ecology Lab at Virginia Tech and a graduate research fellow with the Smithsonian’s Virginia Working Landscapes program, I am researching native warm-season grasslands in Virginia. I have three main goals:

(1) To describe the plant species that characterize native warm-season grassland communities on the Virginia Piedmont;

(2) To determine which ecological processes and environmental conditions allow these grasslands to thrive and persist in tandem with forests; and

(3) To determine the best methods to restore and reconstruct these communities where they have been lost.

I am accomplishing the first of these goals, the description of Virginia’s Piedmont grassland communities, by surveying the plant species found in existing Virginia grasslands. Today, most high-quality grassland sites in Virginia are in areas where routine maintenance prevents the growth of shrubs and trees and keeps the habitat open for the sun-loving grassland plants. Many highly diverse sites, for example, are found in powerline rights-of-ways that are maintained by annual mowing.

Jordan Coscia surveys grassland plant vegetation in an experimental restoration in northern Virginia. Photo credit: Charlotte Lorick.

By surveying native grassland fragments such as those found in rights-of-ways, we can determine the plant species that are characteristic of these habitats. We can then include these species in planted grasslands and native grassland seed mixes to create more ecologically accurate restorations. In the summer of 2020, the Restoration Ecology Lab at Virginia Tech partnered with the Clifton Institute and Virginia Working Landscapes to identify and survey remnant and semi-natural grassland plant communities across northern Virginia. The results of these surveys will inform future grassland restoration projects in the area, including my own grassland restoration experiment that will test the effectiveness of different grassland installation and management techniques. While a full report of the survey results will be available in a future publication, you can find a sneak peak of the full list of the species recorded in our 2020 surveys below.

A semi-natural grassland bursting with scaly blazing star (Liatris squarrosa) blooms in a powerline right-of-way in Fluvanna County, Virginia. Photo credit: Jordan Coscia.

Across 34 sites, we identified 354 taxa (including subspecies and varieties), with an additional 53 groups only identifiable to genus or family. Of those identified to genus level or better, 330 (81%) are considered native, 41 (10%) are introduced, 11 (3%) are invasive, and 25 (6%) are of uncertain status in northern Virginia. The three most commonly recorded species were little bluestem (Schizachyrium scoparium), narrowleaf mountainmint (Pycnanthemum tenuifolium), and tapered rosette grass (Dichanthelium acuminatum).

Our species list is available for download below.

nova-piedmont-grasslands-species-list_2020_jordan-cosciaDownload

The final column is a count of occurrence, or how many sites a plant was recorded in, with a maximum possible value of 34. Plants are listed alphabetically by Latin species name in descending order of occurrence.

We are continuing this work in 2021 through a collaborative effort with the Center for Urban Habitats. This year, we have expanded our grassland discovery and characterization to an eight-county area centered on the city of Charlottesville in the central Piedmont. With a larger team and a refined protocol, we have already discovered more than 300 remnant grassland fragments this growing season. Both the 2020 and 2021 surveys are generously supported by research grants from the Virginia Native Plant Society.

Note: Part of this work represents a USDA NIFA Hatch project.

Torrey’s mountain mint – an oddball species?

In a state whose flora has been studied for hundreds of years, grassland conservation and restoration are still hindered by a need for better understanding of basic plant ecology and systematics. Leighton Reid, Jordan Coscia, Jared Gorrell, and Bert Harris contributed to this post.

All ecologists deal with puzzling groups of plants. In eastern North America, sedges (genus Carex) and panic grasses (genus Dichanthelium) are notorious for having many species with similar characteristics. In Central America, tree seedlings in the avocado family (Lauraceae) can be tricky to separate.

Sometimes we also encounter oddballs – plant species that it’s hard to see where they fit into the contemporary landscape.

Torrey’s mountain mint (Pycnanthemum torreyi) is a bit of both – an oddball species whose relationships to other mountain mints is not yet worked out.

Late-season aspect of Torrey’s mountain mint. Photo credit: B. Harris.

Like others in its genus, Torrey’s mountain mint is an aromatic herb that grows (mostly) in more-or-less open areas. Its crushed leaves have a delightful minty smell. In summer, it produces clusters of small, white flowers that are visited by a variety of pollinators.

Unlike some other mountain mints, Torrey’s is also rare. NatureServe ranks it as a G2, meaning that it is imperiled throughout its range – which extends sporadically from New Hampshire to Kansas.

Virginia has more Torrey’s mountain mint populations than the other states. The Flora of Virginia describes its habit as “dry, rocky, or sandy woodlands and clearings.” In some places, like the Piedmont, it occurs mainly on basic soils, whereas in other places, like the Coastal Plain, it lives in sandy, acidic soils. In the mountains it has been found also in limestone seepages.

An oddball species

While restoring natural areas in Chicagoland in the 1980s, Stephen Packard described some of the plants he saw as “oddball species”. Species like purple milkweed (Aslcepias purparescens) and cream gentian (Gentiana alba) grew neither in closed forest nor in open prairie, so where did they belong? These species preferred intermediate levels of light, such as would be found beneath a spreading burr oak. Packard’s observation that these species preferred savanna conditions sparked his realization that savanna had once been a frequent component of the Chicago landscape.

Matthew Albrecht has considered a similar possibility in Tennessee for Pyne’s ground plum (Astragalus bibullatus). This species grows on so-called cedar glades around Nashville, but it does not grow right in the middle. It prefers the edges where there is intermediate light. This suggests that these cedar glades may once have had softer edges that tapered slowly from exposed, rocky glade into open woodland. With modern fire suppression, these edges have become hard; many glades are now bordered by dense forests of eastern red cedar.

Could our own Pycnanthemum torreyi fall into the same category? An “oddball species” with a preferred niche that is neither full sun nor full shade? In our fieldwork on the northern Virginia Piedmont, we encountered several populations of Torrey’s mountain mint, all of which were growing in edgy sites, like powerline right of ways, or the edge of an old apple orchard.

A small population of Torrey’s mountain mint grows along one edge of this field near the forest edge, not in the open center of the field. Is this typical of this species’ preferred light environment?

Last summer, one of us (Leighton) tested P. torreyi’s habitat affinities inadvertently and with a very small sample size. He planted three seedlings in his small, Blacksburg, Virginia yard – one in an exposed spot on the south side of the house and two in a partially-shaded spot on the north side of the house. The plant in the more open, southerly spot grew okay, but it was somewhat stunted – like a spider plant that has been left out in the sun. Its stem and leaves grew short and tough. In contrast, the two plants on the north side of the house grew full and spread out, both flowering and fruiting in their first season. They also remained green late into the season, even after nearby P. tenuifolium and P. incanum had senesced. If this was a species desirous of full sun, shouldn’t it be doing better in the exposed position in the back by the parking lot?

Two Torrey’s mountain mints growing well and flowering in partial shade on the north side of JL Reid’s home in Blacksburg, Virginia.

Clearly Leighton’s sample is way too small to draw any conclusions, but it does make us wonder if Torrey’s mountain mint prefers and intermediate level of light, such as would be found in a savanna or an open woodland. These disturbance-dependent habitats were once widespread but are excluded today in much of the eastern United States. Maybe Torrey’s mountain mint is an oddball species whose habitat preferences will eventually lead us to design new restoration targets in Virginia, but we’ll have to study its ecology in a bit more detail first.

A “Problematic Species”

The Flora of Virginia also highlights that Torrey’s mountain mint is a “problematic species”, whose interpretation is “confounded by its similarity to Pycnanthemum verticillatum and its hybridization with other species.”

During our fieldwork in 2020, we were able to positively identify all of the individuals that we encountered, differentiating P. torreyi from P. verticillatum by characteristics of their flowers and leaves. Still, the possibility that Torrey’s mountain mint is not a well-differentiated species is troubling. Several landowners in our area are conserving open habitat in part because this rare species occurs there, so it would be nice to know if it is a good species.

I asked Gary Fleming, a Vegetation Ecologist for the Virginia Natural Heritage Program, for his thoughts. “Well, the entire genus Pycnanthemum is a bit problematic!” Gary wrote me in an email. He explained that the problem is that nobody has studied this genus using molecular phylogenetics, that is, using DNA to reconstruct the evolutionary relationships between species. As a result, our understanding of how species in this genus relate to each other is pretty fuzzy.

“Personally, I think P. torreyi is a good species,” Gary continued, “Over the years, I’ve observed it in numerous places state-wide and it appears to be morphologically very consistent.”

In a state whose flora has been studied for hundreds of years, apparently the Pycnanthumum nut has not yet been cracked. Hopefully some enterprising botanist will take this up soon (and maybe Packera while they’re at it).

Torrey’s mountain mint flowers. Photo credit: JL Reid.

Note: Part of this blog post represents a USDA NIFA Hatch project.

Botanizing a Central Appalachian Shale Barren

Leighton Reid describes a field trip to a unique, natural community with Tom Wieboldt, retired curator of the Massey Herbarium at Virginia Tech.

From southwestern Virginia to central Pennsylvania, ancient shale formations jut out of the mountains at wonky angles. Loose and crumbly, the rocks bake in the sun. Surface temperatures can reach 60° C (140° F) – comparable to a desert. Rocks slip and tumble easily on the steep slopes. Few eastern plants are tough enough to hack it under these conditions. Among those that can, a few are globally unique.

On a warm day in August, I had the opportunity to botanize one such place – a central Appalachian shale barren in Craig County, Virginia – with Tom Wieboldt, retired curator of the Massey Herbarium at Virginia Tech (VPI), and a leading authority on shale barren flora. As we hiked and photographed plants, we talked about the conservation and potential for ecological restoration of these rare communities.

Shale barren wild buckwheat (Eriogonum allenii), a central Appalachian endemic whose relatives are mostly west of the Mississippi.

The gems of the shale barrens are the endemics. Amazingly, 22 species are found mostly or exclusively on central Appalachian shale barrens. Another seven species are rare or disjunct from the rest of their range – typically far to the west. For example, the closest population of chestnut lip fern (Cheilanthes castanea) outside of Virginia and West Virginia is in Oklahoma.

Virginia white-haired leatherflower (Clematis coactilis), a Virginia endemic and one of three leatherflowers endemic to central Appalachian shale barrens.

Shale-barren ragwort (Packera antennariifolia) had already finished flowering by August, but its leaves lived up to their name, looking very much like pussytoes (Antennaria sp.). This plant is strictly endemic to shale and metashale barrens.

Kates Mountain clover (Trifolium virginicum) was long thought to be a shale barren endemic, but it also occurs (rarely) on other substrates.

Shale barren evening primrose (Oenothera argillicola), a strict shale barren endemic.

The teeny-tiny flowers of mountain nailwort (Paronychia montana), a plant that is not quite endemic to shale barrens. It also occurs on a variety of other substrates.

Shale barren plant communities exist in a dynamic equilibrium. The steep, brittle shale formations often are under-cut by rivers, which carry away rocks and cause further erosion. In essence, the entire slope is constantly slipping downwards. Successful plants find the most stable areas and send down deep roots to try to keep their place on the rocky conveyor belt.

Why do shale barrens occur only in the Central Appalachians and not also in the Southern Appalachians? Tom gave me two reasons. First, the shale deposits in the Central Appalachians get thinner south of Montgomery County, Virginia, where Virginia Tech is located. Second, the high Allegheny Mountains in West Virginia create a rain shadow over parts of the Central Appalachians, more so than the more southern and shorter Cumberland Mountains. Drier conditions in the Allegheny rain shadow contribute to the shale barrens’ uniquely western ambiance.

Inhospitable as they are, shale barrens are not immune from human pressures. They are sometimes crossed by roads or utilities, and shale banks are sometimes quarried for road-building material. Livestock and overpopulated white-tailed deer browse the plants and catalyze erosion, while also adding nitrogen and foreign seeds to the sparse soil.

Craig Creek undercuts several shale bluffs, hastening their erosion and creating the conditions for shale barren plants to flourish.

Can disturbed shale barrens be restored?

When Reed Noss visited a Virginia shale barren for his book Forgotten Grasslands of the South, he found traversing the slippery slopes, lurching from one scattered red cedar to another, “close to suicidal”. I had similar thoughts following Tom up the mountainside. He climbed like a mountain goat, wandering out on thin ledges to collect interesting looking mosses.

Tom Wieboldt collects an interesting-looking moss from the side of a crumbling cliff.

As we walked, Tom wondered aloud whether it would even be possible to restore such a fragile plant community if it was destroyed. Wouldn’t it be better just to leave these places alone?

Undoubtedly leaving these places alone would be better. But I enjoyed thinking about how one might restore a shale barren that had already been destroyed – by quarrying, for instance. A first step might be to recontour the slope, aiming to reestablish a dynamic equilibrium with some areas eroding more actively than others. Perhaps this could be done by a skilled operator with some of the same quarrying equipment that had previously exploited the loose shale.

To revegetate such a place would require a source of propagules. I am teaching a course on Plant Materials for Environmental Restoration, so I put it to my students to find out whether shale barren plants were available from two major conservation seed suppliers. The results were not promising. Out of 86 native, non-woody angiosperms found in central Appalachian shale barrens*, less than a quarter (23.3%) could be purchased from any major seed supplier, and only 2.3% were available as seed collected from Virginia. None of the endemics were available.

As far as I can tell, few shale barren restorations have been undertaken, but I did read about one attempt in a shale barren in Green Ridge State Forest, Maryland. Whereas some shale barrens are actively threatened by acute pressures, like quarrying, this small (0.6 ha) barren was passively threatened by steady encroachment from the surrounding forest. Trees, especially pignut hickory (Carya glabra), were growing into a formerly open barren, stabilizing the soil and cutting off direct sunlight to plants closer to the ground. Managers restored the site in 2010-2011 by removing some of the pignut hickories and by burning the area during the winter. Together, these actions resulted in greater herbaceous vegetation cover and greater species diversity.

Central Appalachian shale barren, Craig County, Virginia, with a mix of shale barren wild buckwheat (Eriogonum allenii) and hairy lip fern (Cheilanthes lanosa) dominating the foreground.

Thanks to Tom Wieboldt for a fun field day, an excellent guest lecture, and stimulating discussions about botany, conservation, and restoration. To learn more about this unique natural community, read Tom’s co-authored chapter about shale barren communities in Savannas, Barrens, and Rock Outcrop Communities of North America, or Reed Noss’s chapter on shale barrens in Forgotten Grasslands of the South.

*For the seed availability exercise, we used the list of plants recorded by the Virginia Natural Heritage Program in their description of Central Appalachian Shale Barren (Shale Ridge Bald / Prairie Type) CEGL008530. We excluded woody plants, non-native plants, and ferns.

Plant diversity, soil carbon, and ecological restoration in Virginia grasslands

Kathlynn Lewis is an undergraduate researcher in the School of Plant and Environmental Sciences at Virginia Tech. She is studying soil carbon storage as part of a larger project on grassland floristics, conservation, and restoration in northern Virginia. Keep up with her research on Twitter by following @KathlynnLewis.

How many rare or “cool” plants do you drive by every day without noticing? Do you brake for Buchnera americana? Do you pull over for Pycnanthemum torreyi? This is something not a lot of people think about, and I didn’t think about either until very recently. The answer is that there are more cool plants along roadsides than you would think. Some of the rarest grassland plants in Virginia have found a home in roadside clearings and powerline cuts where regular removal of trees has created an opening for them to grow and sometimes thrive.

This summer the Virginia Tech Restoration Ecology Lab team has been hard at work doing plant and soil surveys in several counties of northern Virginia. We are partnering with the Clifton Institute and Virginia Working Landscapes to find out where these rare grassland plants can be found and what are the greatest threats these populations face.

American bluehearts (Buchnera americana) – a charismatic hemiparasite and rare denizen of high-quality Virginia grasslands. Photo by JL Reid.

Many of the native vegetation surveys have taken us to the locations people might expect to find high-quality grassland plants, such as parts of Manassas Battlefield National Park where the soil and ecosystem have remained relatively undisturbed for almost 80 years. Other areas are much less expected. Rare plants also show up in power line right of ways and strips of roadside with tire tracks crisscrossing them in every direction and markers stuck in the ground indicating the soil was completely displaced to bury utility lines.

A flourishing native grassland at Manassas National Battlefield Park. In July, it was bedazzled with the hot pink inflorescences of scaly blazing star (Liatris squarrosa). Photo by JL Reid.

A hidden gem – high diversity native grassland along a back road in Culpeper County. The two lines show our 50 × 2 m sampling transect. Photo by JL Reid.

During June, we collected samples from 29 sites to compare plant species diversity with the amount of carbon stored in the soil. We also sampled soils from grassland restoration plantings and pastures “improved” with tall fescue (Schedonorus arundinaceus) to compare the effect of different management practices and ecological restoration on soil carbon sequestration. The soil work is my part of the project. My prediction is that soil carbon storage will be greatest in diverse, native grasslands and lowest in degraded fescue fields. I expect that restored grasslands will be intermediate.

A “blackjack” soil sample from a power line right of way in Culpeper County. This soil had so much clay you could pull it out of the probe and tie it in an overhand knot. Photo by JL Reid.

Power line right of ways are an interesting focus of this study because they present both opportunities and challenges for plant conservation. Power companies keep these areas open by cutting out trees and spraying young sprouts with herbicide. This management is the only reason that grasslands exist in these places today, but the rare plants that live there are at constant risk of collateral damage. At least two of the areas that we sampled in June were sprayed in July, harming populations of rare plants like Torrey’s mountain mint (Pycnanthemum torreyi) and stiff goldenrod (Solidago rigida).

Rose-pink (Sabatia angularis) next to a power line right of way in Prince William County. This plant can give away a good grassland even at 60 miles per hour. Photo by JL Reid.

The vegetation surveying team has already observed over 450 species across the 29 sites sampled. Not all of these species are a welcome presence though. Invasive species appear to pose one of the largest threats to Virginia grassland ecosystems we have observed in the field. A newly emerging and particularly aggressive invader is joint-head grass (Arthraxon hispidis) which we have found in many of the sites we are sampling. This annual grass is similar to Japenese stiltgrass (Microstegium vimineum) but there is very little information about its effects on grassland ecosystems or methods for controlling it.

Joint-head grass (tan-colored thatch) smothering one of the most diverse grasslands in northern Virginia. Photo by JL Reid.

The plant survey team is now doing a second round of sampling to identify later-blooming species, and they are collating information about the land use history at each of our study sites. The soil samples we collected are currently being analyzed (by me) in a lab at Virginia Tech. We will start analyzing data in the fall and hope this summer’s fieldwork will help inform future research projects and the conversation around land management in Virginia grasslands.

The author collects a panic grass (Dichanthelium sp.) for further observation. Photo by JL Reid.

To find out how ecological restoration affects grassland soil carbon storage in northern Virginia, follow the author on Twitter @KathlynnLewis.