In search of a lost natural community: the Ozark savanna edition

Calvin Maginel is the Ecological Resource Scientist at Shaw Nature Reserve in Gray Summit, Missouri.

Anyone hoping to join the articulate stream of Missouri articles about natural communities ought to lovingly reference Paul Nelson’s “The Terrestrial Natural Communities of Missouri” (2010). In that vein, we will start our journey with page 233, the Savanna.

Paul differentiates savannas largely by overstory, topography, and light level characteristics. Primarily, savannas are grasslands that happen to hold little pockets, family clusters, of trees, that mosey through the swaying grass like the slowest of turtles. The natural history of these clusters is as such: a mature parent hosts numerous offspring around her perimeter that shelter her from the repeated onslaughts of prairie fires, while she in turn nurtures offspring on the lee side which will eventually replace her. They are separate from woodlands in that savannas exhibit a tree canopy of less than 30%, while woodlands can range from 30% to 90% canopy. Paul further describes the ground flora layer of savannas as being highly indicative of a prairie, holding the majority of a site’s diversity, and being strongly adapted to frequent fire.

Of the six savanna communities Paul describes, as nostalgia blurs the typeset, two are considered S1 (critically imperiled) and four are SH, or state historic. A glass of cold water to the face: no known examples remain when something is classified as state historic. To put numbers on this, an estimated 6.5 million acres of savanna in Missouri are now represented by <1,000 recognized acres. Robin Wall Kimmerer aptly wrote: “If grief can be a doorway to love, then let us all weep for the world we are breaking apart so we can love it back to wholeness again.”

Stylized drawings of the prairie-forest continuum, borrowed from The Tallgrass Restoration Handbook by Packard and Mutel.

Recognizing a savanna

As nice as it is to reminisce about and romanticize processes long devastated by European colonizers, if there are (nearly) no savannas left, then why does it matter? Well, there still is hope! While Missouri has a fair percentage of public land (11.2%), most of which has received extensive visits by ecologists throughout the years, the other 88.8% of private lands in Missouri often harbor as-yet-undescribed natural communities that may classify as savanna. In an effort to heighten awareness of these potential gems in the fire-starved hills, I offer a photo tour of a private site in southwest Washington County, near the town of Courtois, that could be described as a savanna. A few points about this site: it is currently being managed for its ground flora character, with repeated fire and herbicide, specifically to the detriment of encroaching cedars and woody re-sprouts. For 25 years prior to the current ownership, it received two fires and periodic mowing to maintain its relatively shrub-free character. Prior to that, it is assumed that this was a hay meadow, cut annually for livestock that were grazed in the valley nearby but not itself grazed. There is a rusty but strong sickle-bar mower still parked in the grass that is set up for a mule to pull, with patent dates from the 1920s.

Since Paul begins with the overstory, so too will this tour. Anecdotal descriptions of certain areas in the Ozarks by foresters refer to “wolf trees”, trees with spreading branches that were removed from the woodlot since those individuals were considered to be exhausting resources around themselves, much as wolves were believed to be harmful predators that exhausted prey species. An example of this can be found in Photo 1, where a large white oak shows the breadth of branches characteristic of an “undesirable” wolf tree. As mentioned in the caption, the health of the lowest branches can tell something about a site’s history. Overgrazing by cattle or other domestic animals often defoliates these branches until the tree sheds them entirely, so an observation of a tree similar to this one might mean that this site was hayed but not grazed intensively.

Now that photos have been mentioned, we’ll begin the photo tour in earnest. All photos are from August 22nd, 2021, unless otherwise stated. To the right side of Photos 1, 2, and 3, you will notice a young shortleaf pine (Pinus echinata) with a wolfish future, and in Photos 2 and 3, there is a distinctive Eastern Red Cedar (Juniperus virginiana) that seems to have lost half its top. All other photos will contain at least a blurry version of those two distinctive trees, in an effort to maintain scale. Speaking of scale, the distance between the white oak wolf tree and the red cedar is a little over 250 feet (76 meters). Photos 2 and 3, of almost the same area at different phenologies, hold the first real hope of a savanna classification. The structure is distinctively grass- and forb-dominated. While clearly the floral display is greater during June, this is not unexpected in an intact prairie system where suitable micro-habitats are dominated by the best-adapted competitors for those micro-habitats. For example, the glade coneflower in Photo 3 is distributed between the foreground of the photo and the base of the pine tree, but seems to decrease in abundance towards the red cedar in the upper left of the photo. Presumably, soil or other characteristics make the former area highly suitable for glade coneflower, despite the fact that no bedrock or other glade indicators occur in those areas. That said, it stands to reason that glade coneflower, currently relatively restricted to glade communities, must have had a mechanism to lay claim to those communities. Possibly this species was historically as ubiquitous in Ozark savannas and prairies as it currently is in glades.

Photo 1. Forgive the valiantly bolting hickory grubs and mowed path, but this white oak (Quercus alba) exemplifies the spreading nature of a relatively open-grown specimen. Note how the lower branches actually touch the warm season grasses: despite 5 recent years of annual dormant season fire, they are not set back. In fact, one telltale of current or historical colonizer-style grazing is that these perpetually-stretching side limbs are defoliated until they succumb and die. Trees with this character can tell a lot about a site’s history.
Photo 2. With the same white oak as in Photo 1 to the left of the frame, this photo shows the vegetative structure of the site. You will notice a handful of woody re-sprout clumps, but this area is largely dominated by warm season grasses and prairie forbs.
Photo 3. June 14, 2016 is the date on this photo. Note the profusion of wild quinine (Parthenium integrifolium) and glade coneflower (Echinacea simulata), the latter of which is commonly identified by its yellow pollen. The more westerly species with white pollen, E. pallida, does not occur on this site.

In addition to the striking summer floral display in Photo 3, there are distinct waves of blooms throughout the season. Each species, present in profusion in its preferred micro-habitat and scattered elsewhere, blooms en masse and then fades into the background, letting another take the stage like a carefully-choreographed dance.

At this point, you may be noticing that the common names for many of the plants listed in the photo captions refer to a habitat (eg “glade” coneflower, “upland” white goldenrod, “prairie” coreopsis). This name-relation to a community can serve to help with identifying that community, but the overall assemblage of species tells a stronger story. When you consistently encounter species that occur within multiple habitats (Ozark woodlands, glades, and/or prairies), which is true for most of the species shown in these photos, it may be a telltale sign of the missing connection between all of those communities. Similar to the previously mentioned glade coneflower, both downy gentian and the upland white goldenrod are commonly found in glades and open woodlands. They tend to fall out in areas with >60% shade. Almost all of these species are considered highly conservative; species that we expect to maintain high fidelity to intact ecosystems. Missouri is one of the states that maintains a coefficient of conservatism list, with values ranging from 0 to 10, where 9-10s are virtually only found in the highest quality habitats. For example, the downy gentian, white upland goldenrod, savanna blazing star, and southern prairie aster are all c=9 species. Most of the grasses are 4 or 5, as well as the prairie dock, prairie blazing star, and Canada lousewort. When visiting a natural community, generally the more intact, remnant sites boast a bell curve of c-values, with the peak being a good diversity of c = 4-6 species. The distinctive composition at this site, with conservative prairie and glade species present (yet located deep in the Ozarks in an area not considered historic prairie), triggers the savanna vibe.

Photo 4. Savanna blazing star (Liatris scariosa var. nieuwlandii), wild quinine, big bluestem, and ashy sunflower. Savanna blazing star is currently listed as a species of conservation concern in Missouri.
Photo 5. Southern prairie aster (Eurybia hemispherica, old name Aster paludosus), forms a colony with leaves reminiscent of a graminoid until it blooms with striking purple discs.

An additional, striking character of this site is the height of the vegetation (Photos 6 and 7). In particular, Photo 6 includes a species called ashy sunflower (Helianthus mollis). Various botanists and restorationists have used disparaging terms for this species, even the socially problematic term “thuggish,” since this species tends to form thick 2-4 foot tall monocultures to the detriment of other species. Surprisingly, the ashy sunflower at this site is a whopping 0.5 – 1 foot high and comfortably interwoven with other species. The matrix grasses, consisting of mostly of big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), prairie dropseed (Sporobolus heterolepis), and Indian grass (Sorghastrum nutans) are consistently knee-high or shorter, barring their flowering stems of around 5 feet. In many prairie reconstructions, the big bluestem and Indian grass commonly attain heights of more than 9 feet and encountering each clump of bunchgrass is like climbing up a small mima mound. Here, the grass ramets have presumably reached old age and no longer exhibit the mounding character. Many ecologists attribute the presence of hemi-parasitic species like Canada lousewort (Pedicularis canadensis), scarlet paintbrush (Castilleja coccinea), or blue hearts (c=10!, Buchnera americana) to decreased robustness of warm season grasses. All three of these hemiparasitic species are present at this site, yet the truth is that the science of ecology is still learning about what actually makes remnant sites look consistently different than reconstructed sites. Is it nutrient limitation, due to all niches being occupied in remnants? Maybe it’s mycorrhizal associations determining community composition and structure, since Arbuscular Mycorrhizal Fungi have been shown to strongly affect plant communities. What about beneficial or pathogenic bacteria, or soil structure, maybe parent material, or surely it’s the site’s aspect and moisture profiles? The obvious answer is that it’s a combination, and that we have much to learn about our natural communities. The quote by J. K. Rowling, “Understanding is the first step to acceptance, and only with acceptance can there be recovery,” might as easily have been about natural communities as it was directed at Harry Potter’s life.

Photo 6. Upland white goldenrod/prairie goldenrod (Oligoneuron album) blooms amongst two Silphium species, prairie coreopsis (Coreopsis palmata), and well-mannered ashy sunflower (Helianthus mollis) stems. Rarely is the term well-mannered used in conjunction with ashy sunflower.
Photo 7. Downy gentian (Gentiana puberulenta) looking disheveled prior to its glorious frost-triggered blooms, amidst prairie dock, prairie blazing star, and a grass/sedge matrix. A dominant sedge species here is few-flowered nut rush (Scleria pauciflora).

The last point regarding vegetative species groups are those considered woodland species. Just like in prairies and glades, there are a handful of woodland indicator species that assist with identification of the natural community we call a woodland in Missouri. As a reminder, woodlands have a canopy cover of >30%, all the way up to 90% cover, yet have an open mid-story maintained most commonly with frequent fire. Some characteristic species present at this site that are considered common woodland indicators include deerberry (Vaccinium stamineum), Samson’s snakeroot (Orbexilum pedunculatum), and stiff aster (Ionactis lineariifolia). The last species is especially striking, as botanists and plant geeks commonly observe it in acidic, poor-nutrient woodlands or power line rights-of-way. Yet keep in mind that glade coneflower, a known calciphile, is hanging out with the stiff aster. Whatever processes are allowing this site to host such a mish-mash of Ozark woodland, glade, and prairie flora, it seems to support the understudied idea that there really was a thriving prairie-forest ecotone amongst these aged hills.

Photo 8. Prairie willow in the foreground left (Salix humilis), vying for growing space with prairie dock (Silphium terebinthinaceum), tall tickseed (Coreopsis tripteris), little-leaf tick trefoil (Desmodium ciliare), and others.

Wrapping Up

As outlined above, there are few to no known savannas left in Missouri. While many agencies are trying valiantly to re-create open or closed woodlands, the sawdust of Missouri’s logging culture weighs heavily on our boots and generally there are fewer restoration practitioners aiming for savannas and their lack of timber products. The Nature Conservancy comes to mind, but the majority of their sites classify as true prairie, except maybe Bennett Spring Savanna. That site, like Ha Ha Tonka State Park, tends to maintain characteristics more similar to open woodland, but has lovely intact ground flora with a solid assemblage of prairie species. The critical missing piece is that for most natural community restorations, we have a goal in mind, dictated and informed by multiple examples of that community. With savannas and the lack of high-quality examples, we are left with a great deal more speculation. The hope mentioned in the beginning comes into play with each of you. There is a plethora of private lands that are largely inaccessible to state and federal biologists. If you get a chance to visit a friend’s farm, do so with a thought to some of the characteristics described above. Citizen science really does work, and maybe the next branch of citizen science is natural community identification! As Rachel Carson said, “The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.”

A prairie resurgence?

James Faupel is the urban ecology restoration supervisor at the Litzsinger Road Ecology Center, a suburban outdoor education site managed by the Missouri Botanical Garden. The property is a mix of reconstructed bottomland prairie and restored riparian woodlands in St. Louis County, Missouri.  

North American prairie remnants are invaluable pieces of a once vast grassland ecosystem, critical for the survival of so many plants and animals. Prairies are one of the most endangered ecosystems in the world, removed from existence by our agricultural development for crop production. According to the National Park Service, less than 1% of original prairies now remain in North America. The Missouri Prairie Foundation states that less than half of 1% of pre-settlement prairie is left here in my home state. These few remaining North American prairie remnants are vital seed banks for local ecotypes of thousands of native plant species, such as the federally endangered Mead’s milkweed (Asclepias meadii), and they are home to many species of animals that just cannot be found in any other type of habitat. Most prairie specialist species cannot survive once a fragmented prairie has been plowed or bulldozed under. Species such as the regal fritillary butterfly (Argynnis idalia) only occur on remnant prairies in Missouri and have not appeared in our human-made prairie reconstructions.

A now rare, prairie horizon view. This one is visible at the National Tallgrass Prairie Preserve in Kansas. Photo Credit: James Faupel.

Undiscovered remnant prairies are generally only spared thanks to practices such as consistent haying or grazing, and have sometimes been found protected in unused areas of historical sites, such as old cemeteries. Unfortunately, remnant prairies are now mostly found in rural settings far from the eyes of our growing urban populations. These sometimes small patches of prairie habitat do not have large dramatic features, such as mountains or canyons that draw vacationers’ attention from states away. Most remaining prairies are also no longer large enough to host their once charismatic herds of grazing megafauna, the American bison. The amazing views of these smaller, modern-day prairies must be experienced up close and personal. This is a problem if you want to educate the public on the importance of protecting these fragile habitats, that are now fragmented and spread far from each other across such a vast continent.

Middle school children getting to know prairies up close and personal, at a prairie managed by the Missouri Botanical Garden. Photo credit: James Faupel.

My home city of St. Louis was once 61% prairie pre-European settlement. The only remnant prairie still existing here is a small plot at Calvary Cemetery, which has had to have extensive restoration work done to remove trees, shrubs, and exotic invasive plants from smothering it out of existence.

The prairie remnant at Calvary Cemetery in St. Louis City looking very open after some much needed restoration work, consisting of tree and shrub removal. Photo credit: James Faupel.

Many organizations in St. Louis have begun to reconstruct prairies here over the years, to help regain this lost habitat for local wildlife and to be able to get these valuable grasslands back in view of the public. Some of the earliest prairie reconstructions in the Greater St. Louis Region started in the 1970s and 80s. Specifically within St. Louis City & County, this practice didn’t begin until the 80s. I have the pleasure of working on one of those prairies reconstructed in the 1980’s, at the Litzsinger Road Ecology Center, a prairie started and managed by Missouri Botanical Garden staff. The ecology center is a private education site dedicated to working with K-12 teachers, to improve upon their ability to engage their students in place-based education, using our local ecology as the framework.

Recent work at the Litzsinger Road Ecology Center suggests that St. Louis prairies are making a comeback. Our 2021 spring intern, Lydia Soifer, began work on an independent research project looking at prairie habitat connectivity within St. Louis City & County. Through this project Lydia and I generated a count of 58 small-scale, urban prairie reconstructions managed by various entities within this highly populated area. There are also many more prairie reconstructions in the 7 surrounding counties within Missouri and Illinois.  

With an increase of 58 small prairies slowly over 40 years, this may seem like a time to celebrate, but this prairie resurgence should not be taken lightly. Some of these new prairies are now at risk of failure. Prairie reconstructions cannot be left to their own devices in our modern, highly human influenced world. Investment in both ongoing habitat maintenance and the continued education of staff is a necessity, or these prairie reconstructions can quickly turn into fields of exotic invasive weeds or full of aggressive trees and shrubby growth. Even at 32 years old, the urban prairie I work at still needs continued maintenance to keep it a “native prairie”.

Challenges facing urban prairie stewards range from intense seed pressure from surrounding invasive plants, severe runoff and volatile urban waterways, minimal funding and educational resources, fire & smoke restrictions that limit the chance of using prescribed fire, and heavy browsing from oversized whitetail deer populations. Many businesses and organizations outsource with private contractors for their prairie maintenance, which can have some beneficial and detrimental outcomes. There is not a constant visual presence overseeing the land they hold, but it can be much more affordable than permanent staff. Sometimes the only maintenance is periodic visits from dedicated volunteers. The decision to reconstruct a prairie should be well thought out and planned for optimal long-term care. Placement should be targeted for areas where a new prairie could help connect existing fragmented habitats to improve urban wildlife corridors.

A prairie planting reclaims some space previously occupied by turf grass on a steep hillside at Bellerive Park, a St. Louis City Park. Photo credit: James Faupel.

Are these human-made prairies working?

So, it appears prairie reconstructions are gaining some ground within St. Louis and surrounding areas of the Midwest. How do we know if these reconstructions are being successful? What is success? Data collection of any kind is minimal to non-existent across these local sites, so assigning a value to these lands could be considered speculative at best.  

When I transferred to the Litzsinger Road Ecology Center in 2018, I took notice of data previously collected there relating to pollinators (I have a passion for animal associations with native flora.). There were collection records from around the year 2000, of the now federally endangered rusty patched bumble bee (Bombus affinis), the endangered (IUCN Red List) Southern plains bumble bee (Bombus fraternus), and the vulnerable (IUCN Red List) American bumble bee (Bombus pensylvanicus). This is the only confirmed record of the rusty patched bumble bee in St. Louis, and its range has now shrunk considerably in recent times and can only be found much farther to our northeast. After surveying the reconstructed prairies at my work, I was able to find these two latter bumble bee species of concern. I was curious. Could more of the prairies around St. Louis be supporting the potentially declining populations of Southern plains and American bumble bees?  

Left image – A Southern plains bumble bee queen nectaring on spider milkweed (Asclepias viridis). Right image – An American bumble bee worker visiting great blue lobelia (Lobelia siphilitica). Photo credits: James Faupel.

Previously, not much was known specifically about the rare Southern plains bumble bee in the St. Louis region. According to the Checklist of the Bees of St. Louis, MO (Camilo et al. 2017) only two records within the city had been collected, in addition to the collection I mentioned earlier from the Litzsinger Road Ecology Center in St. Louis County. According to many local bee specialists, the American bumblebee used to be commonly seen all around St. Louis, but the Checklist notes only 3 sites that it was recorded at during their recent surveys. After spending a lot of my free time surveying St. Louis prairies, woodlands, and gardens over the last three years, I have found very promising results in the prairies.  

Six of the larger and older prairie reconstructions in St. Louis City and County, with moderately rich species lists of native plants, were found to contain and support the Southern plains bumble bee, sometimes two to three years in a row. Many more of the prairies I visited supported the American bumblebee. Shutterbee, a local citizen science project I partner with, has recorded 3 Southern plains bumble bees and over a hundred American bumble bees from bi-weekly bee surveys in private home gardens in St. Louis City and County over the last two years. This shows there may be increased value in native plant gardens placed near prairies, for enlarging the foraging areas of bumble bees. 

I am also beginning to see a trend with these two species’ floral choices. These two species of conservation concern seem much more reliant on native prairie plants than some of their more common bumble bee counterparts, that are flexible enough in their diets to visit many more exotic flowers. For the moment, this is just observational data, but at least it is showing that there is value in the hard work being done bringing these grasslands back to urban spaces. There are many other ways we could begin to assign value to man-made prairies, but more data collection needs to be done across the board on urban prairies. 

All of these same prairie reconstructions containing milkweeds, blazing stars, sunflowers, asters, or goldenrods have also been recorded to attract in the majestic, migrating monarch butterfly (Danaus plexippus). Last December, the monarch was nearly put on the U.S. endangered species list. The US Fish and Wildlife Service put off this decision for a few years and will revisit it. If the well-known monarch butterfly does indeed get listed as endangered in the near future, will there be a vast new interest in prairie reconstruction? Will there be more investment in prairie protection and reconstruction from municipalities, utilities, corporations and other large land holders? If a quick surge of interest arises, education about these unique ecosystems and their management will be needed more than ever. 

There are current opportunities to capitalize on the revitalized interest in the outdoors that the pandemic brought about, and with urban populations projected to outpace their rural counterparts in the future, native ecosystems will need to be brought to the people, to spark their curiosity and passion with nature. Without urban prairie reconstructions, we won’t be able to inspire the future volunteers, donors, conservation voters, and land stewards needed to care for and protect remnant lands. Urban prairie reconstructions are therefore integral in the process of preserving our rural remnant prairies, while also being ecologically biodiverse and important in their own right. We need more prairie reintroduced into North America and we need continued investment in their long-term care and monitoring. We aren’t just hoping to save endangered species, we are also hoping to save our continent’s most endangered ecosystem.

A monarch butterfly visiting New England aster (Symphyotrichum nova-angliae) at the Donald Danforth Plant Science Center’s 5-year-old prairie reconstruction. Photo credit: James Faupel.

Conserving and restoring Missouri bladderpod, a US Midwestern endemic

Matthew Albrecht is a Scientist in the Center for Conservation and Sustainable Development at Missouri Botanical Garden. Here he describes a recent fieldtrip to the Ouchita Mountains to study outlying populations of the federally threatened Missouri bladderpod, Physaria filiformis.

Situated between Rocky Mountains to the west and the Appalachians to the east lies the often overlooked Ouachita (pronounced WAH-shi-tah) Mountains of central and western Arkansas and adjacent Oklahoma. Unlike the Rocky and Appalachian Mountains, the Ouachitas are a relatively small mountain chain that trends primarily east-west. Despite occupying a relatively small area, the Ouachitas harbor a large proportion of the region’s plant diversity and represent a remarkable center for endemism including many rare plants species with extremely narrow distributions.

On a recent spring afternoon, Christy Edwards and I had the opportunity to visit the relatively rare and poorly studied shale outcroppings of the Ouachitas with botanists Brent Baker and Diana Soteropoulos of the Arkansas Natural Heritage Commission. In the Ouachitas, shale formations outcrop on gentle to steep south- or west-facing slopes and occasionally on gently sloping drainages. Upon first glance, these outcroppings with exposed fragments of thin, black shale and patches of sparse vegetation cover appear somewhat other worldly. Upon closer inspection, one finds tucked between shale fragments a number of xeric-adapted herbaceous species capable of surviving in this harsh environment, where the dark, sun-scorched shale at the surface creates extreme ecological conditions.

Ouachita shale glade and barrens. Photo by Matthew Albrecht.
Xeric-adapted species specialize on the thinnest soil portions of shale outcrops. Photo by Christy Edwards.

Shale barrens and glades are mosaic plant communities consisting of a remarkable number of endemic, rare, and narrowly-distributed species. According to NatureServe, 36 plant species of state conservation concern and more than 20 globally critically imperiled, imperiled, or vulnerable species occur in this system. New species are still occasionally discovered and a few species remain undescribed in the Ouachita shale barrens. For example, we saw a striking purple-flowered undescribed species of wild hyacinth (Camassia sp. nova) during our visit.

An undescribed wild hyacinth (Camassia sp. nova) growing in a shale glade and barren complex owned and managed by the Ross Foundation. Photo by Matthew Albrecht.

The star of the show that day and the focus of our research expedition to the Ouachitas was the federally threatened Missouri bladderpod (Physaria filiformis).  Many members of the genus Physaria – commonly known as bladderpods due to their inflated seed pods – are recognized for their narrow distributions and edaphic endemism, or restriction to unusual soils. As a small-statured winter annual, Missouri bladderpod showcases brilliant yellow flowers in early spring and specializes on thin-soiled calcareous (dolomite and limestone) outcrops in northern Arkansas and southwestern Missouri. However, at its southern range limit in the Ouachitas, Missouri bladderpod is known from just a few isolated shale glades and barrens.

A profusion of flowering Missouri bladderpod (Physaria filiformis). Photo by Christy Edwards.
Missouri bladderpod (Physaria filiformis) displaying inflated fruits on a shale outcropping. Photo by Matthew Albrecht.

Prior to visiting the Ouachitas I wondered how a presumed calciphile like Missouri bladderpod existed on shale formations, which typically produce acidic soils. Perhaps like a few other species of rocky outcrops in the region – such as Sedum pulchelum (widow’s cross), and Mononeuria patula (lime-barren sandwort) which occur on both acidic and calcareous substrates – I surmised MO bladderpod may also tolerate a broader range of edaphic conditions than previously thought. However, I soon learned the shale outcroppings we visited were interbedded with limestone and supported other calciphilic indicator species such as Ophioglossum engelmannii.

A case of cryptic speciation in the Ouachitas

Once known only from limestone glades in southwestern Missouri, botanists over the years have discovered populations of Missouri bladderpod on limestone, dolomite, and shale outcroppings in scattered locations throughout Arkansas, denying Missouri’s claim of its only endemic species. A recent study led by Christy Edwards at the Missouri Botanical Garden examined range-wide (Arkansas and Missouri) genetic variation in Missouri bladderpod and the degree of genetic differentiation among populations on limestone, dolomite, and shale. Interestingly, genetic data showed isolation by distance – meaning that as geographic distance increased among populations so too did genetic differentiation. Most strikingly, the geographically isolated shale populations in the Ouachitas were highly genetically divergent from dolomite and limestone glade populations further north in Arkansas and Missouri. This strong pattern of genetic differentiation points to a possible cryptic speciation event in the Ouachitas and a previously unrecognized extremely rare species. On one hand, the genetic data was somewhat surprising given there are no obvious morphological differences among Ouachita shale populations and P. filiformis. Conversely, the data do support the remarkable pattern of narrow-endemism observed throughout the Ouachita Mountains. 

As we trekked across Arkansas for a few days – along with Brent and Diana who generously shared their time and expertise – collecting fresh material of Missouri bladderpod for a deeper research dive into whether morphological traits differentiate this previously unrecognized cryptic species in the Ouachitas, the need to conserve and restore glade habitat became ever clearer. At present, there are only three known Ouachita populations, making this cryptic species extremely rare and vulnerable to extinction. Many shale glade and barrens systems are now severely damaged or have been destroyed by mining activities. Fortunately, the largest population we visited consisted of thousands of plants scattered across a shale glade and barrens complex that has been restored and managed with fire and woody thinning by the Ross Foundation. In the absence of periodic, appropriately-timed prescribed burning, glades and barrens slowly become encroached with woody species that eventually choke-out sun-loving plants like Missouri bladderpod.

A large, restored shale glade and barrens complex in the Ouachita Mountains.

Other populations of Missouri bladderpod eek out an existence on small stretches of outcrops on roadsides or private property maintained as cattle pasture. These sites prove challenging to conserve and restore. Sadly, we did visit some sites where populations were barely surviving due to degraded habitat conditions. However, two sites we visited gave us a glimmer of hope that Missouri bladderpod will continue to survive and thrive. First was a newly discovered dolomite glade population on private property in north-central Arkansas. The property owners recently thinned woody vegetation and began prescribed burning to restore their glade and woodland ecosystem. When we visited, Missouri bladderpod was thriving after a recent prescribed burn. Similarly, the second site we visited on public property had been thinned and burned in recent years, resulting in a diverse plant community and flourishing Missouri bladderpod population. These success stories illustrate the importance of restoring degraded habitat to conserve our rarest components of biodiversity.

Population of Missouri bladderpod growing on a roadside dolomite outcropping and pasture in north-central Arkansas.
A degraded site with woody encroachment and a small, declining population of Missouri bladderpod.
A restored hillside glade with a thriving population of Missouri bladderpod.

To learn more about the Missouri bladderpod, read the new, open access paper by Christy Edwards, Matthew Albrecht and others.

Drought, flood, and fire: an unexpected habitat recipe for at-risk bats

Mike Saxton is an ecologist restoration specialist at Shaw Nature Reserve, a 10 km2 mosaic of restored and reconstructed woodlands, prairies, wetlands, and riparian forest along the Meramec River in Gray Summit, Missouri.

For most land managers, there aren’t enough hours in the day. Between invasive species management, native seed collection and prescribed fire implementation, there are never enough boots on the ground. Add in equipment break downs, erratic weather and administrative tasks and it’s no surprise that with so many balls in the air, something gets dropped. Far too often, we drop the ball on science and monitoring, which are critically important for biodiversity-driven ecosystem management and restoration. Research and monitoring can, in some cases, be expensive; usually they take a certain amount of specialization, and they most certainly take time. For these reasons and many others, land managers build partnerships with universities, collaborate with outside agencies, and engage the public in community science to meet research and monitoring needs.

What follows is an example of a highly successful partnership between non-profit organizations, a private consulting group, and a federal agency to better understand and protect a federally endangered species.

A female Indiana bat, “Celeste”, captured during mist netting surveys at Shaw Nature Reserve in 2017 and 2019. Photo credit: Cassidy Moody.

In 2017, Shaw Nature Reserve hosted a Bioblitz partnering with the non-profit Academy of Science, St. Louis. For two days, participants combed the area looking for as many plant and animal species as they could find. A single federally endangered Indiana bat (Myotis sodalis) was captured during an evening mist netting session along a riparian corridor, marking the first time this species was documented at the Nature Reserve.

Wildheart Ecology, the local consulting firm which carried out the Bioblitz bat survey, returned in the summer of 2018 to deploy acoustic detectors to further document bat populations at the Nature Reserve. The data revealed the presence of nine different species, including the Indiana bat, the endangered gray bat (Myotis grisescens), and several other species of conservation concern.

The audio signature of an Indiana bat, captured by detectors at Shaw Nature Reserve. Courtesy: Wildheart Ecology.

After these surprising and impressive findings, scientists at the U.S. Fish and Wildlife Service carried out mist netting in summer 2019 at the Nature Reserve to gather more information about the federally endangered population of Indiana bats. Netted individuals were tagged and fitted with tiny transponders. Using telemetry, USFWS staff were able to locate a maternal roost colony tree in the Meramec River flood plain. After multiple emergence sampling events conducted at dusk, the population is estimated to be 150+ individuals, making it one of the largest recorded in Missouri.

Indiana bat roost site at Shaw Nature Reserve. Photo credit: Cassidy Moody.

So how did Shaw Nature Reserve end up with one of the state’s largest populations of at-risk bat species? The story begins in fall 2015, when a major flooding event on the Meramec River deposited large amounts of woody biomass and created logjams in the Nature Reserve’s floodplain. Another major flooding event in the spring 2017 compounded these conditions. In the fall of 2017, moderate drought gripped the region, drying leaf litter and woody fuels on the forest floor. In November of that year and on a low humidity day in drought conditions, we conducted a prescribed fire that thoroughly burned the floodplain forest, which normally does not carry fire. The flames crept into flood-debris logjams, causing a major conflagration. Dozens of floodplain forest trees died — mostly silver maple, elm and cottonwood— leaving an open patch of larger-diameter snags, or upright dead trees. It is in these snags where the federally-endangered Indiana bats have found a home. Turns out, the serendipitous convergence of flood, drought, and fire created just the ideal conditions. Couple that with high-quality foraging areas across a healthy, diverse, managed landscape and this population is thriving.

Indiana bat roost habitat along the Meramec River at Shaw Nature Reserve in Gray Summit, Missouri. Photo credit: Cassidy Moody.

Current status of Indiana Bats

Unfortunately, like many bat species, the Indiana bat has been in decline and imperiled by human disturbance and disease. According to the U.S. Fish and Wildlife Service, hibernating Indiana bats are especially vulnerable to disturbance, since they often congregate in large numbers – from 20,000 to 50,000 – to overwinter. A large number of deaths can occur if humans disturb these caves during hibernation. While other factors are also responsible for their decline, the devastating wildlife disease known as white-nose syndrome — discovered in 2006 — is a serious threat to the long-term survival of the species.

According to the U.S. Fish and Wildlife Service population status update, the states with largest net loss of Indiana Bats since 2007 (% decline since 2007) includes:

1. Indiana: -53,220 (-22%)
2. New York: -39,367 (-75%)
3. Missouri: -18,157 (-9%)
4. Kentucky: -15,220 (-21%)
5. West Virginia: -14,125 (-96%)
6. Tennessee -6,509 (-73%)
7. Ohio: -4,739 (-62%)
8. Pennsylvania: -1,027 (-99%)

What Can Be Done

With thoughtful management and strategic planning, conservation practitioners can conserve and restore bat habitat. Providing a continuous supply of roosting trees and maintaining a habitat structure to facilitate foraging are key aspects of restoration and management plans for bats. According to the Beneficial Forest Management Practices for White Nose Syndrome-affected Bats, below are some best-practice guidelines for achieving these goals:

  • Harvest timber during the hibernation period to eliminate or significantly reduces the likelihood of direct fatality or injury to tree-roosting bats.
  • Create large-diameter snags and canopy gaps, via girdling or chemical (e.g., “hack and squirt”) methods, to increase sun exposure to existing and potential roost trees.
  • Increasing midstory openness to facilitate travel corridors and foraging opportunities via increased mobility and insect prey detection.
  • Retain or create large-diameter snags during forest regeneration harvests or when managing stands affected by windthrow or disease/insect outbreaks.
  • Limit aerial or broadcast spraying near known hibernacula, maternity sites, and surface karst features, unless it can be demonstrated that it would have no adverse impact on bat populations or habitat.
  • Avoid disturbances near maternal roost sites or colonies when possible.
  • Fell hazard trees that appear to provide bat roosting habitat and do not pose an imminent danger to human safety or property during winter (hibernation period) and avoid removing them during June and July when non-flying bat pups may be present.
  • Avoid burning during cold periods since this can be detrimental to colonies of some species if individuals cannot escape smoke and heat from fires.
  • Apply low-intensity fires when possible since high-intensity fires are more likely to cause injury.
  • Account for caves, mines, important rock features, bridges, and other artificial structures when developing burn plans since these locations are often occupied by roosting or hibernating bats.
  • Remove hazard trees and construct fire-lines during winter, when possible, to reduce chances of removing occupied roost trees or disturbing maternity colonies.
  • Protect known maternity roost trees and exceptionally high-quality potential roost trees (e.g., large snags or large-diameter live trees with lots of exfoliating bark) from fire by removing fuels from around their base prior to ignition.
  • Limit management activities and disturbances near cave entrances.
  • Eradicate and control invasive plants to improve habitat quality for bats.

A ten-year woodland restoration trajectory

Leighton Reid describes a long-term ecological research project at Shaw Nature Reserve (Franklin County, Missouri, USA). To learn more, read the new research paper (email the author for a pdf copy – jlreid@vt.edu) or tune in for a webinar from the Natural Areas Association on April 21 (register here).

In 2000, the Dana Brown Woods were dark and dense. Brown oak leaves and juniper needles covered the sparsely vegetated ground, and invasive honeysuckle was creeping in around the edges. Biologically, the woodland was getting dormant.

In contrast, the woods today are lit by sunlight everywhere except the lowest-lying streambanks, and the ground is hardly visible beneath a green layer of diverse, ground-level foliage. These changes were most likely caused by two actions: burning the woods, and cutting out invasive trees and shrubs.

Many practitioners have seen woodlands recover to some extent when they are burned, but few have documented the recovery as thoroughly and over so long a period of time as Nels Holmberg and James Trager.

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Nels Holmberg (left) discussing the finer points of Rubus identification with Quinn Long in the Dana Brown Woods.

Nels is an ecologist and sheep farmer in Washington, Missouri. He has inventoried the plants at several state parks and natural areas. In 2000, Nels teamed up with Shaw Nature Reserve’s resident natural historian, James Trager, and together they designed a study to describe how ecological restoration was changing the woodland flora at the reserve. They picked the Dana Brown Woods as their study area.

In a nutshell, Nels and James chose 30 random points on a map. They divided the points evenly across three ecological communities. They placed 10 points in mesic woodlands – the gently sloping parts of the property where white oak and shagbark hickory were most prevalent. Ten points were in areas dominated by eastern red cedar – mostly thin-soiled ridgetops that faced the south, and ten points were in forest – the lower, thicker-soiled toe slopes where northern red oak and Shumard oak were dominant in the canopy with paw paws and spicebush down below.

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Three ecological communities in the Dana Brown Woods: (A) red cedar dominated areas which, after removing red cedar, looked more like dolomite glades in some parts; (B) mesic woodlands with lots of oak and hickory in the canopy; and (C) forest – which had a much darker understory.

At each point, Nels hammered in a t-post, then walked 50 m in the steepest direction and hammered in another t-post. This was his transect. Every year for more than a decade (2000-2012), Nels walked the transects and recorded every stem of every species that was inside of 10 0.5-m2 study plots. Actually, he did this twice per year – once in the spring to capture the ephemeral plants, and once in early summer. Over the course of the study he spent more than 200 days in the field.

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Dana Brown Woods before (left) and after (right) red cedar removal, with Nels’s 30 transects. The horizontal axis of the image is about 0.9 km. Imagery is from Google Earth.

During this time the stewards at Shaw Nature Reserve were busy restoring the woods. From 2001-2012, they burned the woods five times. This amounted to about one fire every three years. In 2005-2006, they brought in a logging crew to remove all of the eastern red cedars.

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James Trager lights a fire in a woodland at Shaw Nature Reserve.

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One of several thousand red cedar stumps from trees that were harvested from the Dana Brown Woods in 2005-2006.

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One of Nels’s sampling quadrats in the Dana Brown Woods. Photo: Nels Holmberg.

I met Nels and James in 2014. I had just joined Missouri Botanical Garden’s Center for Conservation and Sustainable Development as a postdoc, and I was looking for a local research project. I heard that Nels Holmberg had a giant dataset about woodland restoration, so I called him and asked if I could look at it. Nels said “Sure!”. I imagined he would send me an Excel file. Instead he brought in a giant cardboard box full of yellow legal pads where he had recorded his data.

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One of hundreds of datasheets where Nels recorded his detailed observations.

It took a long time to digitize all of the data. There were more than 50,000 data points. But once we had it all together, this is what we learned:

After eleven years of restoration, the number of native plant species in Dana Brown Woods increased by 35%, from 155 species in 2001 to 210 species in 2012. This increase was linear. That is, the number of native species was still increasing at the end of the study. If we repeated the study today, we expect the number of native species would be even greater than in 2012.

The number of native species increased at different speeds and to different degrees in different ecological communities. In the lower and wetter forest areas, the numbers didn’t really shift very much. They jumped around but not in one direction. In the woodland areas, the number of native species increased by about 23% in the first three years and then leveled out. But in the higher and drier areas where red cedars had been dominant, the number of plants increased linearly by 36%.

Native Species Richness

Changes in the number of native plant species recorded over time in the Dana Brown Woods. On the left are overall changes for the whole management unit. On the right are changes for different ecological communities within the management unit. The management interventions are shown in gray.

The plant species that benefited from the restoration were mostly forbs and grasses. A couple of the biggest “winners” were black snakeroot (Sanicula odorata) and nodding fescue (Festuca subverticillata). There were also some “losers”: Virginia creeper (Parthenocissus quenquefolia) and spring beauty (Claytonia virginica) both declined over time. Relatively few of the species that became more common were “conservative” – i.e., dependent on intact habitat. Mostly they were more widespread and tolerant species.

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Co-author Olivia Hajek demonstrates a hog peanut (Amphicarpaea bracteata) – a good representative of the type of species that benefited most from the restoration. Hog peanut is an herbaceous legume that is common in many woodlands, including disturbed ones.

Our study did not include a control treatment, but counterfactuals exist at Shaw Nature Reserve (although they are becoming fewer and fewer with the excellent stewardship of Mike Saxton and many others). There are still thick patches of eastern red cedar covering remnant glades on parts of the property. Woodlands that have not been regularly burned are now filled with bush honeysuckle (Lonicera maackii), wintercreeper (Euonymus fortunei), and other invaders. And low-lying forest that has not been restored is very dark with fire-intolerant sugar maple (Acer saccharum) casting much of the shade. If we had included a control treatment in our experiment, these are probably the trends we would have found – definitely not a spontaneous resurgence of diverse native plants.

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Fragrant sumac (Rhus aromatica) was present at the outset of restoration and remained relatively stable.

Why does this work matter? The biggest value of this study is that it shows a relatively long-term restoration trajectory, and it does so in fine botanical detail. Many managers and scientists already have data to show that fire and tree thinning increase woodland plant diversity. This study adds another dimension. It shows how quickly plant diversity recovered. It also shows how the speed and shape of the recovery varied across the landscape. We hope that other scientists and practitioners will compare the recovery trajectories in the Dana Brown Woods to their own natural areas. To facilitate that, we have made all of the underlying data freely available online.

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Buffalo clover (Trifolium reflexum) is a conservative species that is present in Dana Brown Woods but was not detected in any of the survey plots.

One of the next steps for this research is to figure out how and when to re-introduce some more conservative plants. Although the Dana Brown Woods became much more diverse as it was being restored, most of the plants were early successional or generalist species. We found very few habitat specialists that cannot tolerate disturbance, which suggested to us that some of these species may have been lost from the site at some time in the past. To learn how conservative plants might be re-introduced, we have started a new experiment testing the effects of soil microbes, competition, and time since the start of restoration on the success of introduced seedlings from seven conservative plant species. In the next year or two, we hope to have new information and recommendations for restorationists looking to add more specialized biodiversity to their woodlands.

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Freemont’s leather flower (Clematis fremontii) is a restricted species occurring on dolomite glades in southeastern Missouri. Although it is present at Shaw Nature Reserve less than one kilometer from Dana Brown Woods, it has not colonized the restored glade habitats there. This photo is from Valley View Glade near Hillsboro, Missouri.

To learn more about this research, you can read the original research paper in Natural Areas Journal. Email me for a pdf copy (jlreid@vt.edu). You can also tune in on April 21 for a webinar on this work. Register here.

How does fire affect ant-mediated seed dispersal?

Eva Colberg describes her ongoing research at Shaw Nature Reserve. She is a Ph.D. student in the Biology Department at the University of Missouri St. Louis.

In the late 1940s, Ohio-born entomologist Mary Talbot spent her days crouched in the woods of St. Charles, MO, tracking ant activity in painstaking detail through the seasons. Similarly, last summer I tried my hand at watching ants in the woodlands of Shaw Nature Reserve, with the addition of crumbled pecan shortbread cookies and the help of my field assistant, Dayane Reis. Foraging ants flocked to the buttery feast, the contrast of the crumbs’ sandy color against dark soil and leaf litter allowing us to easily follow the cookie thieves back to their nests.

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A plot of flagged ant nests (found by following cookie-bearing ants) in the Dana Brown Woods, one of the management units at Shaw Nature Reserve.

We watched at least seven different species of ants run off with the cookie crumbs, but I was most interested in the winnow ant (Aphaenogaster rudis). Reddish-brown, long-legged, and narrow-waisted due to a double-segmented petiole (the connection between the abdomen and thorax), the winnow ant worker is an elegant lady. She is also remarkably swift-footed and strong, adept at carrying chunks of pecan cookie or naturally occurring analogs.

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A winnow ant (Aphaenogaster rudis) worker, with the petiole and post-petiole that give the species its svelte waist. From her head to the end of her abdomen, this ant is about 4.5 mm long.

To an ant, a cookie more or less resembles an insect carcass, a staple of many ant diets. Chemically and nutritionally, the seeds of many of Missouri’s spring-flowering herbs also resemble a delicious dead insect (or cookie). From an ant’s point of view, this means food for larvae. From a seed’s point of view, this means dispersal. Hitchhiking to an ant’s nest gives the seed a new location to germinate and grow away from the parent plant, and potentially a multitude of other benefits such as escape from predation or better soil conditions. In any case, this is ant-mediated seed dispersal, or myrmecochory.

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A field ant (Formica subsericea) grabs a bloodroot (Sanguinaria canadensis) seed by its elaiosome, the oily, nutritious appendage that most resembles a dead insect and attracts ants.

In other parts of the world, benefits of myrmecochory include enhanced survival and germination after fire. In arid, fire-prone areas of both Australia and South Africa, ants bury seeds deep enough to buffer the intense heat of fire, but shallow enough that the heat weakens the seed coat and increases the odds of germination. Thus, the ants protect the seed from the flames while still providing exposure to a Goldilocks level of heat.

Just as in Australia and South Africa, fire is (or was, and with the help of land managers is once again becoming) also a frequent occurrence in Missouri. At Shaw Nature Reserve, managers use prescribed burns to restore an open structure to the reserve’s oak-hickory woodlands. But, is ant-mediated seed dispersal interacting with fire the same way here as in those other fire-adapted ecosystems?

This is a key question of my dissertation research at University of Missouri St. Louis. Using cookies to find winnow ant nests last summer helped me test methods and plan out my experiments for this coming year. Specifically, I will be tracking where the ants take their seeds, whether ants disperse seeds more or less in the year after a fire, and whether the presence and timing of surface fire affects the germination of the seeds after dispersal. Stay tuned!

You can keep up with Eva Colberg on Twitter (@ColbergEva) or by checking out her science communication initiative Science Distilled STL.

It’s Complicated: Trees and Ecological Restoration

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The best time to plant a tree was twenty years ago. The second best time is now.
-Anonymous

Addendum: That is, unless the tree will grow just fine without your help or the tree doesn’t really belong there. In that case, the best time might be never.

Planting a tree is rejuvenating. It gets you outside, it’s good exercise, and it’s often good for the planet. Really, trees give us an awful lot and don’t ask for much in return. Among their many gifts are food, shade, animal habitat, building materials, erosion control, and fuel. Trees also filter our water and suck carbon out of the air. In cities, trees collect grit and grime that would otherwise coat our lungs.

But tree planting is not the same as restoration. Ecological restoration is the process of assisting the recovery of a damaged ecosystem. Trees are integral to many ecosystems, like forests…

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Notes on dolomite glade natural history and restoration

In early October, CCSD scientists Leighton Reid, Matthew Albrecht, and James Aronson and Shaw Nature Reserve naturalist James Trager toured several dolomite glades with Greg Mueller (Chicago Botanic Garden) and Betty Strack (Field Museum). We used the opportunity to discuss glade natural history and restoration.

In his book The Terrestrial Natural Communities of Missouri, Paul Nelson describes glades as:

“…open, rocky, barren areas dominated by drought-adapted forbs, warm-season grasses and a specialized fauna. They appear as small or large essentially treeless openings within landscapes primarily dominated by woodlands.”

Missouri glades are characterized by their geology. Many occur on southwestern-facing slopes with outcrops of sedimentary rocks, like dolomite and sandstone. But some also occur with igneous rocks in the St. Francis Mountains and Tom Sauk Mountain.

For some, glades seem like miniature deserts, complete with cacti, collared lizards, tarantulas, and even roadrunners in southwestern Missouri.

But glades are also like islands. To many of the organisms adapted to these sunny, rocky environments, the dark, duffy woodlands that surround them may seem like an oceanic barrier to movement. Dispersal events between glades can be rare. For collared lizards, dispersal is contingent on landscape fire to temporarily make the surrounding woodlands more easily traversable.

Glades are rarely cultivated, but many have been grazed. Cattle degrade glades by eroding and compacting their thin, precious soil. Some glades are also maintained by fire, which keeps woody trees and shrubs from crowding out the forbs and grasses. When people suppress fires, some glades become overrun with trees – especially eastern redcedar (Juniperus virginiana).

Shaw Nature Reserve contains a kind of chronosequence of glade restorations. Near the Maritz Trail House, Crescent and Long Glades were restored in the 1990s by clearing out the encroaching redcedar, establishing a fire regime, and reintroducing forbs and grasses – some of which were sourced from the remnant prairie at Calvary Cemetery in St. Louis. Other glades at Shaw Nature Reserve were restored in the 2000s and 2010s using similar techniques. So it might be possible to study changes in restored glades over time by comparing older restored glades to younger ones.

Could better-conserved dolomite glades serve as a reference to guide restoration at Shaw Nature Reserve? Beautiful dolomite glades are conserved at Valley View Glades Natural Area, Victoria Glades Conservation Area, and Meramec State Park. Some of these have plant species that are missing from Shaw Nature Reserve, possibly because they once existed at Shaw Nature Reserve and were extirpated, or possibly because glades at Shaw Nature Reserve lack appropriate ecological conditions for these plants. For example, prior grazing may have stripped the soil of some vital mycorrhizal fungi. Either way, the lack of some rare plants at Shaw Nature Reserve is probably exacerbated by fragmentation – a remnant plant population at Valley View Glades Natural Area would probably have trouble dispersing seeds 28 kilometers (17 miles) to Shaw Nature Reserve.

Further reading

Nelson P. (2010) Terrestrial Natural Communities of Missouri. 550 pages.

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Lines of woody vegetation on dolomite glades correspond to the local stratigraphy; plants like gum bumelia (Sideroxylon lanuginosum) and eastern redbud (Cercis canadensis) accrue on slightly deeper-than-average soils. (Crescent Glade, Shaw Nature Reserve)

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In this regularly burned glade at Shaw Nature Reserve, there is a fairly seamless transition between the open glade with abundant Rudbeckia and Silphium and the adjacent oak/hickory woodland. In other places, such glade/woodland transitions are marked by a dense thicket of vegetation, often with a strong component of eastern redbud or eastern redcedar. (Crescent Glade, Shaw Nature Reserve)

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Gattinger’s goldenrod (Solidago gattingeri) is an open-panicled goldenrod found on dolomite glades in the northern Ozarks and, disjunctly, in the cedar barrens of central Tennessee. This one was growing just above a transition from dolomite to sandstone substrate on Crescent Glade at Shaw Nature Reserve.

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A short-winged meadow katydid (Conocephalus brevipennis) rests on a seed head of Missouri coneflower (Rudbeckia missouriensis). These black seed heads were abundant across Crescent Glade in early October.

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Barn glade has been restored much more recently. A line of green, resprouting brush (including invasive Lonicera maackii and Ailanthus altissima) is visible where woody vegetation was recently removed. Blue flags in the foreground mark an experimental population of endangered Pyne’s ground plum (Astragalus bibullatus).

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A denizen of barn glade – the lichen grasshopper. (Shaw Nature Reserve)

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The quality of Valley View Glades Natural Area is evident in the abundant and diverse fall wildflowers that were present in early October. Could regional dolomite glades like this one serve as references to guide glade restoration at Shaw Nature Reserve?

 

 

Microstegium population distribution (and control) along Brush Creek

Restoration specialist, Mike Saxton, describes his observations on the distribution of invasive Japanese stiltgrass along a creek running through Shaw Nature Reserve.

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Brush Creek (blue) runs eastward through Shaw Nature Reserve in Gray Summit, Missouri. Gray Summit Road is in the upper right.

July 28, 2017

Yesterday, Adam and I put in to Brush Creek at the Old Gray Summit Rd. bridge and headed upstream spraying Microstegium vimenium (Japanese stiltgrass). This was the second time through this area this year and I made this sweep solo 3 times last season. My first outing last season, I used 3 gallons of herbicide before I finished the first wetland cell…this year it’s been much, much lighter. Last year, with only 1 person spraying, I was hard pressed to leave the creek bed because there was so much to spray directly along the accessible banks. And in our first outing this season, Catherine and I stayed completely within in the creek, rarely going up on the banks.

However, yesterday Adam and I abandoned the creek bed and went crashing through the brushy banks, finding more Microstegium than I had anticipated. What was interesting was that pockets of stiltgrass followed a predictable pattern of distribution. In many areas, one creek bank will be severely down cut, perhaps 15 ft sheer banks, while the opposite bank is tapered with a more gradual slope. This is where you find the Microstegium. I posit that floodwaters do not over-top the high bank but rush over the lower bank depositing sediment and seed. Almost without fail, the lower bank, if totally brushy, would have scatted Microstegium. However, if the lower bank was open or had open pockets of sunlight, those pockets would be dense thickets of stiltgrass. We observed a nearly 1-to-1 correlation between bank height and stiltgrass presence/absence and open sunlit patches having dense patches of stiltgrass on the lower banks.

I was covering a roughly 20 ft swath out from the bank edge before it dropped into the creek bed.  I did go further from the creek a number of times but wasn’t finding much (if any) the further I got from the creek.

Management considerations

Based on these observations, I believe that our current strategy of managing downstream from the “head waters” is prudent. Based on the diminished population this year and because the species has a 5-year seed viability, we should continue to see diminishing populations if we continue to be methodical and thorough with our management.

We repeatedly found dense patches of Microstegium in high light availability openings/tree fall gaps. This suggests to me that if we open up the brush creek corridor with forestry mowing/brush cutting, the increased light levels and soil disturbance might cause a spike in Microstegium populations.  While the brush creek corridor isn’t priority #1, I know we’ll get there some day. Before we aggressively start clearing brush in this area, I’d like to have 3-5 years of aggressive Microstegium management under our belts. We have observed diminished populations in the wildflower garden, along Paw Paw Creek, and along Brush creek with just one year of management. Coupled this with a short seed viability…and we might have a winning strategy.

 

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Large patch of Japanese stiltgrass (Microstegium vimenium) along Brush Creek at Shaw Nature Reserve.

 

 

Soil and vegetation recovery on burn pile scars at Shaw Nature Reserve

Claire Waldman is a senior at Centre College. This summer, she worked with CCSD scientist Matthew Albrecht to study the legacy of burn pile scars – the ashy leftovers from burning thinned tree trunks – in a restored woodland at Shaw Nature Reserve as part of MBG’s NSF-funded Research Experience for Undergraduates (REU) program.

In December 2016, the staff at Shaw Nature Reserve began a major restoration project focusing on 60 acres of woodland that were heavily invaded by bush honeysuckle (Lonicera maackii), Japanese privet (Ligustrum japonicum), and other invasive shrubs. This work, funded by the Institute of Museum and Library Services, commenced with removal of the invasive shrubs and thinning the canopy through selective tree cutting to promote a more open woodland structure. An open canopy structure allows for future use of prescribed burns in the area to help maintain the open canopy and facilitate diverse understory vegetation.

Canopy thinning left land managers with excess woody debris – that is, there were many large, fallen trees covering the forest floor. Rather than use heavy machinery to remove the logs (which often creates a large amount of soil disruption), the wood was stacked into piles and burned. These slash pile burns create an extremely localized but intensive disturbance. The soil at the burn site becomes sterilized and covered in a layer of ash. These sites are referred to as burn scars. The layer of ash that remains, as well as the absence of vegetation, make burn scars easily identifiable.

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Slash pile burn at Shaw Nature Reserve, December 2016 (left). Barren sampling plot in a burn scar six months later (right).

Slash pile scars were distributed across the restored site at Shaw Nature Reserve. Previous research has suggested the combustion of biomass and extreme temperatures of the burns can be lethal to the soil seedbank, alter soil structure, moisture, and nutrient availability. The rate of native vegetation recovery on slash pile scars depends on burn intensity, pile area, and properties of the surrounding plant community. The native plant community in burn pile scars, without active seed addition by people, are expected to recover slowly. If the native plant community recovers slowly over time, it raises the concern that slash pile scars could serve as foci for the reestablishment and spread of invasive or undesirable species.

This summer, as part of the NSF-funded Research Experience for Undergraduates program at the Missouri Botanical Garden, I worked under the guidance of Matthew Albrecht to further our understanding of these slash pile burn scars.

First we developed a field experiment focused on native vegetation recovery in slash pile burns. In order to characterize the changes in soil nutrients, compaction, and moisture that occur in these burn piles, we took soil samples from the burn piles as well as adjacent control areas and sent them to the University of Missouri Soil and Plant Testing Laboratory. The results we obtained from this soil analysis were dramatic. Soil pH, P, Ca, Mg, and K were all significantly higher in the burn pile. Soil compaction and soil organic matter were both significantly lower in the burn pile.

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Soil chemical properties from samples of the top 4 cm of burn pile and control soil (Albrecht et al. Unpublished data).

While there was an apparent flush of nutrients available in these burn piles, in the first growing season after a burn occurred, we found that burn scars remained essentially bare. We created experimental burn scar plots in which we seeded six native species. The six species sown into the plots were Bromus pubescens (grass), Chasmanthium latifolium (grass), Lespedeza violacea (legume), Senna marilandica (legume), Solidago ulmifolia (composite), and Symphyotrichum drummondii (composite).  We also seeded these species in adjacent unburned control plots. We then monitored plant occupancy in these plots over the course of eight weeks.

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Six native plant species seeded into the burn pile scars and adjacent control areas.

We found four of the six species established significantly better in the control plots relative to the burn scar plots. These results support that while there is a significant influx of nutrients in the burn scars, there are other factors that are limiting native species establishment in the burn scars.

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Vegetation cover in a burn plot six months after a slash pile burn (left) and an adjacent, unburned control plot (right).

PercentPlantCov

Average percent native vegetation cover (± 1 standard error) in burned plots and unburned control plots (Albrecht et al. Unpublished data).

There are restoration implications of our results. We found, of the six species sowed into the burn plots, native grasses established best. While the microenvironment created by slash pile burns presents a barrier to the restoration of native vegetation in burn pile scars, seed additions of native grasses provide a practical management strategy for promoting native vegetation recovery in burn pile scars.

PlotOccupancy

Average plot occupancy for six native herbaceous plant species in burned plots and unburned control plots. Error bars denote 1 standard error. P-values were derived from a generalized linear mixed effects model. Brpu = Bromus pubescens, Chla = Chasmanthium latifolium, Levi = Lespedeza violacea, Sema = Senna marilandica, Soul = Solidago ulmifolia, Sydr = Symphyotrichum drummondii. (Albrecht et al. Unpublished data).

Claire

Claire Waldman recording  plant occupancy in an experimental plot at Shaw Nature Reserve.