Throughout most of the eastern United States, oak woodlands were once a widespread and dominant ecosystem. These woodlands experienced periodic fires, which prevented woody trees and shrubs from growing so densely that the overstory canopy became closed. The partly open canopy allowed light to reach the ground, supporting a diverse community of herbaceous plants including wildflowers, grasses, and sedges. However, over the past two centuries, human induced changes including fire suppression, invasion by non-native shrubs, and other factors have caused most woodlands to become overgrown, and lose much of the diversity of plant species in the herbaceous ground layer.
Research on how to manage and restore these woodlands has shown that cutting down some trees to thin out the woodland, as well as removing non-native shrubs, and reintroducing periodic fires, are all strategies that help improve the quality of these habitats. However, even after employing all of these management strategies, many desirable plant species may still not return on their own. Ecosystem restoration often involves re-introducing plant species as a seed mix distributed over a cleared area, and this method can be very effective for grassland and savanna habitats that contain few trees. Restoring wildflowers and grasses in wooded areas with the addition of a seed mix could drastically improve the diversity and quality of the herbaceous community, but this approach has not been experimentally studied, and little is known about how to select the right species for re-introduction this way.
To address these knowledge gaps, scientists and land managers at the Missouri Botanical Garden started an experiment at the Shaw Nature Reserve in 2016, where highly diverse seed mixes of native plants were added to a degraded woodland undergoing active restoration. Throughout late 2016 and much of 2017, crews of managers and volunteer land stewards worked to thin the canopy by removing less desirable tree species, especially the aggressively fast growing native conifer, Eastern Redcedar (Juniperus virginiana). After thinning the canopy, crews used a combination of mechanical removal and herbicides to control the dense non-native shrubs. Fire was reintroduced through controlled burns starting in late 2017.
After the woodland was thinned, in January of 2018, we added seed mixes to three different management units, along a gradient of lower/wetter to higher/drier parts of this landscape. The seed mixes contained between 79 and 93 species, and all of the seed was collected from plants growing at the nature reserve. In order to track how these seed additions influenced the establishment of the herbaceous community, we collected data on the composition of the plant communities in areas that received seed and areas that did not. We sampled the plant community in 2017 before the seed additions and in the following two years, 2018-2019.
In both the seeded and non-seeded woodlands, the effect of management actions was very clear and positive, since both the number and cover of herbaceous species dramatically increased from the sample in 2017 to later sample dates. This is consistent with previous research showing that thinning the canopy, removing shrubs, and reintroducing fire promote restoration of herbaceous plants.
We also found substantial benefits from reintroducing species with seed mixes. The areas that received seed had about 10 more plant species present within a one square meter area, than the areas that did not get seed. We were also interested in the quality of the kinds of species that were establishing based on coefficients of conservatism, which denote how sensitive species are to human disturbances. We found that areas with seed added, contained fewer plants that were weedy ruderals, and more that were conservative and generally found only in high-quality intact habitat. Interestingly, areas that got seed additions were also more dominated by grasses and the areas that did not receive seed, although less rich in species, tended to have more abundant wildflowers (forbs). Specifically, common grasses that were sown at high rates tended to dominate areas that received seed additions, including river oats (Chasmanthium latifolium), hairy woodland brome (Bromus pubescens), and bottlebrush grass (Elymus hystrix). The restored areas that did not get a seed addition were dominated by ruderal (low conservatism) forbs such as jumpseed (Persicaria virginiana), white snakeroot (Ageratina altissima), and common yellow woodsorrel (Oxalis stricta).
Our final goal was to examine the recruitment success of the over 100 different plant species that we added as seeds, to see if there were patterns in which kinds of species tended to establish best. Perhaps surprisingly, over half of the species we added were never detected in vegetation samples. These species might not have been sown into favorable conditions, or potentially, the quality of the seed might have been poor, since it came from wild populations and the seeds might not have been viable or mature. Still, some seeds may be dormant for many years, and more added species may break dormancy and recruit later. Among the species that did establish from added seeds, we found that recruitment was much higher for species that were sown at higher rates, suggesting that some species might have benefitted from a higher seeding rate. Both grasses and forbs tended to recruit well when sown at high rates, but the 25 sedge species we added had little or no recruitment success.
Based on our results, future research on woodland restoration should address why sedges are difficult to restore and methods to remedy this deficit. Additionally, it will be interesting to track the development of these herbaceous communities into the future, to examine how sown and unsown areas resist re-invasion by shrubs while they are continually managed with periodic burns. Our seed mixes dramatically improved the diversity and floristic quality of the herb layer in this woodland, however many species did not recruit, and key functional groups including sedges and forbs were underrepresented in their abundance. Future research should investigate what ratios of functional groups in seed mixes produce the best restoration outcomes, since conventions established for grassland restoration may not be the best approaches for restoring herbaceous species under a tree canopy. If you are interested in learning about this project in greater depth, the paper is freely accessible here. If you have any questions, feel free to contact Andrew (firstname.lastname@example.org).
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.
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 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.
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.
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.
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.
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.
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.
By Adam Cross. Western Australia faces a biodiversity crisis driven by climate change and inadequate conservation and land management. Rates of extinction here are already among the highest in the world, and government projects have struggled to improve the situation for most species. But as land management is increasingly being turned over to Indigenous Australians, successes have begun emerging from the ashes.
Western Australia is known internationally for its remarkable biodiversity and high levels of floristic endemism. It is a landscape of rugged natural beauty that supports among the most ecologically unique and highly specialised organisms on the planet, and in which occur some of the world’s oldest rocks, oldest living life forms, and oldest continuous human cultures. And, it is a landscape of extremes—not only environmental extremes, such as the contrast between the cool, wet forests of the southwest and the hot, dry deserts of the interior, but also extremes in human impact.
In the southwestern corner of the 2.6 million km2 state, the result of wholescale clearing of millions of acres of native forest and woodlands for broadacre agriculture, mainly in the 1940s–1970s but continuing today, can be easily seen from space. Flying over Western Australia’s Wheatbelt region can yield horizon to horizon views containing little more than scattered handfuls of trees in a vast ocean of yellow-brown. In large areas of the Wheatbelt, for example, less than 3% of the landscape remains covered by native vegetation. It is among the most extreme examples anywhere in the world of habitat destruction on an industrial scale in an astonishingly short time frame.
In contrast, in the remote north of Western Australia in a region known as the Kimberley, there remain vast wilderness areas of remote savannah woodland, among the most ecologically intact and least human-impacted ecosystems still in existence. Although globally some 70% of tropical savannah ecosystems have been lost, a vast 1.5 million km2 of them remain in northern Australia, mostly in good condition, of which nearly 350,000 km2 is in the state of Western Australia. Nestled within this seasonally-dry savannah are rivers and deep rocky gorges, extensive sandstone plateaus and uplands, rugged ranges, and a myriad of seasonal and wetland habitats, providing a complex suite of more mesic habitats supporting high levels of botanical endemism. Over half of the 3,000 plant species currently known from the region have been described scientifically in just the last four decades, highlighting how remote and inaccessible the Kimberley remains even today.
These extremes in human impact come with considerable challenges in how we manage, conserve, and restore biodiversity and ecological resilience. Not even the Kimberley region is immune from external anthropogenic threats: weed invasion and rangeland stocking levels are ongoing concerns, and mining activities impact some areas. Indeed, a copper mine proposed within 20 km of the iconic Horizontal Falls in the Kimberley archipelago is cause for concern. Apparently illegal track and exploration clearing at the site has already prompted outcry from tourism operators, environmentalists, and the general public. Conflict between development, industry, and environmental interests in this manner is common in Australia, and current approaches and legislation are far from doing a sufficient job of managing and maintaining the country’s unique natural environment.
One of the very few positives presented by the 2022 State of the Environment Report, however, is recognition that Indigenous land management and the incorporation of Traditional Ecological Knowledge in environmental programs is having real, genuine benefits for biodiversity and the integrity of Australia’s ecosystems. Native Title, recognition by Australian Common Law that Indigenous Australians have cultural and historic land rights and interests, has resulted in over half of the Australian landmass being recognised as Indigenous estate. This means that now 54% of the National Reserve System of protected natural ecosystems consists of Indigenous Protected Areas and conservation reserves that are jointly managed by Indigenous Australians in partnership with other groups. In many cases, traditional approaches are returning to the management of Australia’s land and seas for the first time since European colonisation.
Many around the world will have heard of the recent catastrophic bushfires spread across eastern Australia, caused by climate change coupled with changes in the way that we manage our native forests. These fires, impacting some 28 million acres, are estimated to have killed or injured over 3 billion native animals, and damaged many ecosystems to the point where their recovery remains uncertain. And, amid highlighting the growing urgency for improved management and increased efforts to undertake ecological restoration across the Australian landscape, they rekindled the vigorous debate over a controversial topic in Australia—prescribed burning. Many of the areas that burned intensely in the summer 2019/2020 fires had recently undergone prescribed burning regimes in an effort to reduce fuel loads, a practice undertaken throughout many Australian ecosystems despite mounting evidence of its inadequacy at achieving safety outcomes and significantly deleterious impact on native biodiversity.
Contemporary prescribed burning is often undertaken by dropping incendiaries from aircraft, complemented by drip burning around the edges of the target area to be burnt to ensure fire boundaries are maintained. It is also typically undertaken in winter and spring, when weather conditions are most conducive to ensuring that fires do not become uncontrollable, at fire return intervals of seven years (studies suggest natural fire return intervals in most Western Australian ecosystems are in the decades or centuries). Unfortunately, the reality of this strategy means that large areas of remnant bushland are repeatedly incinerated from the outside inwards, often during peak flowering and breeding season for most species of native flora and fauna. For example, a catastrophic prescribed burn in one of southwest Western Australia’s most biodiverse regions in March 2019 transformed over 2200 acres of biodiverse woodland into a desolate, blackened ‘morgue’. However, in some regions, land managers are increasingly turning to the Traditional Owners of the land, Indigenous Australians, to understand how fire might be better managed.
Indigenous land management initiatives, including the highly successful Aboriginal Ranger Program, appear to be taking strides forward in appropriately managing Australia’s threatened ecosystems and biota where many other initiatives continue to flounder or fail. For example, in 2017 the Auditor General’s Conservation of Threatened Species Follow-up Audit examined whether progress had been made on a suite of recommendations made during an environmental audit in 2009. It found that progress by the State Government department tasked with managing Western Australia’s biodiversity had been “disappointing”, noting that the department has “considerable work to do” and will “continue to struggle to show… that scarce resources are being effectively targeted to conserve our world-renowned biodiversity”.
In 2009, 601 Western Australian species were threatened with extinction and 37% of these had recovery plans (strategies for improving their conservation status) in place. By 2017, another 71 species had been placed in the threatened list and 55% of all threatened species had recovery plans. But, as the threats to our environment have increased, staffing and expenditure on conservation and threatened species management by the State Government has fallen. Fortunately, this contrasts with an increase in funding for Indigenous land management programs, with nearly $AUD 37 million ($USD 25.8 million) committed to develop new Indigenous Protected Areas between 2018 and 2023 and over $AUD 746 million ($USD 521.5 million) allocated to support Indigenous Ranger Programs until 2028. There are lessons to be learned by Australian land managers around the country from the success of returning traditional Indigenous land management approaches to areas like the Kimberley, as the 2022 State of the Environment Report implies. We need to find a mixture of modern ways with the old ways. We need to adjust, or completely change, the way we approach land management in Australia across the board: not only in fire management but in appropriate stocking levels, weed control, regenerative farming practices, sustainable mining, conservation, and the restoration of areas that have already been degraded or destroyed. Unlike the Kimberley, where we are lucky that so much remains so intact, so many other ecosystems around Australia are in increasingly dire need. Hopefully, with Indigenous Australians leading the way, there is still enough time to conserve or restore them before it is too late.
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.”
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.
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.
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.
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.
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.”
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 – email@example.com) 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.
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.
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.
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.
James Trager lights a fire in a woodland at Shaw Nature Reserve.
One of several thousand red cedar stumps from trees that were harvested from the Dana Brown Woods in 2005-2006.
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.
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%.
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.
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.
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.
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.
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 (firstname.lastname@example.org). You can also tune in on April 21 for a webinar on this work. Register here.
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.
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.
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.
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!
This post is contributed by Dr. James Aronson, a restoration ecologist at MBG’s Center for Conservation and Sustainable Development, and his son Thibaud Aronson. James is also a researcher with the CNRS (National Center for Scientific Research) in Montpellier, France.
In Sinhalese Sri Lanka means “Resplendent Isle”, a fine name indeed for this tear-shaped island off the coast of southeastern India, just north of the equator. Last month I travelled with my son on a self-guided Natural History + Ecological Restoration visit, we are finding and photographing cloud forests and birds galore, like the endangered endemic Sri Lanka whistling thrush, Myophonus blighi, and the Kashmir flycatcher, Ficedula subrubra, which over-winters exclusively in the Sri Lanka highlands, from its very restricted breeding grounds in Kashmir, northern India.
We were also looking at the mosaic of grasslands, cloud forests, and lowland forests we find here from a restoration ecology perspective. That means we’re trying to “read” the landscapes we see in terms of known transformations carried out during the British colonial era (1815 and 1948, when Sri Lanka was known as Ceylon), and since independence. The remarkable Horton Plains National Park is a mosaic of montane grassland (ca. 35%) and cloud forest (ca. 65%), encompassing the headwaters of three major rivers. It was declared a sanctuary in 1969 and elevated to national park status in 1988; it became part of a large UNESCO World Heritage site in 2010. In the central highlands of Madagascar, grasslands appear to occupy about 99% and most people assume they are anthropogenic…. This month, I’m travelling with Leighton Reid in the Central Highlands of Madagascar, and we will be blogging about this soon.
Horton Plains National Park, where the grassland – cloud forest mosaic shows some sharp edges where human land use has had impacts, but otherwise with high species diversity and landscape scale heterogeneity.
Tree ferns (Cyathea sp.) in the Horton Plains cloud forest.
But, the history of preservation in the highlands here goes back a lot further, to the days when the Isle was part of the British empire, along with all of India. According to information we gathered at the extraordinary, and poorly known Hakgala Botanic Gardens, the great English botanist and explorer Joseph Dalton Hooker had advised the British government to leave all montane forests above 5000 ft. (ca. 1300 m) above sea level “undisturbed” and after 1873 the administration prohibited clearing and felling of forests throughout the central highlands. What a great idea that was! It is too bad there were not enlightened laws on hunting of wild animals as well. One Scottish officer in colonial service in Sri Lanka bragged he had shot and killed over 1400 elephants in Horton Plains and nearby. Today, there are none left there and, so far as we could determine, no plans to reintroduce them from the other remarkable parks, including Yalla and Uda Walawe….
So, what is the significance of the absence of elephants in this park? And, what else can we learn from past regimes and historic periods in Sri Lanka? For starters, we discover that conservation, and respect for other organisms goes back much further than the 19th century. Consider the sign at the entrance to Udawattakele Forest Reserve, near Kandy, one of the historic capitals from the long period of successive kingdoms the island had known prior to the European colonial chapter in Sri Lanka’s history:
“O Great King, the birds of the air and the beasts have an equal right to live and move about in any part of this land as thou. The land belongs to the peoples and the other beings and thou are only the guardian of it.”
-Arahath Mahinda (a son of the emperor Asoka the Great, who brought Buddhism to Sri Lanka)
How would it be if we could revive that approach to the Web of Life in our own day and age?
So, what has Horton Plains National Park, with its grassland-forest mosaic, its tourists, and its absent elephants got to do with the Central highlands of Madagascar? For one thing, we can see that fire is a big ecological driver in both areas. The abundant arborescent Rhododendrons in Horton Plains tell a vivid tale in this regard.
On the grand scale of things, Sri Lanka’s Central highlands also resemble those of Madagascar’s since both are the crowns of a poor, emerging tropical island with small and very similar human population size (21 million vs. 24 million), despite being much nearly ten times smaller, and with over 30,000 years of human history, as compared to merely two millennia for Madagascar.
Horton Plains also has remarkable conservation value both for its biodiversity and the ecosystem services it provides to people. Also, as I said, it’s a mosaic of grasslands and cloud forest, that in the past was certainly much affected by both elephants and fire.
Finally, both Sri Lanka (along with the Western Ghats of southern India) and Madagascar count among the world’s biodiversity hotspots, easily visible in their fauna and flora, which is one of the main reasons why MBG researchers, and many others travel and work in Madagascar.
Now, let’s turn back to fires. A big fire hit Horton Plains in 1998, and there are serious invasions of two noxious, cosmopolitan weeds, namely Gorse and Bracken fern. Some control work is underway on the Gorse, but the Bracken fern is apparently not seen as being a problem. Rainbow trout were introduced in the 19th c. and apparently have displaced all native fish, and are taking a toll on native shrimp and no doubt other fauna.
Gorse (Ulex europaeus) – a spiny invasive introduced as an ornamental in the colonial period for its pretty yellow flowers and now a noxious weed throughout the highlands of Sri Lanka.
Horton Plains grasslands infested with Bracken fern (Pteridium aquilinum).
Explanatory sign at Horton Plains National Park, in English, Singhala and Tamoul. Text on Rainbow trout and what it does when it swims where it shouldn’t be.