Natural History of Ecological Restoration

Tag: Grassland restoration

From Hayfield to Meadow: An Herbicide-Free Sod Removal Trial to Restore Native Meadows in Virginia’s Northern Piedmont Region, USA.

By Charlotte Lorick

Charlotte Lorick is the Head of Biodiversity Conservation at the Oak Spring Garden Foundation in Virginia, United States. She also leads the Forgotten Flora Project, an environmental and educational consulting initiative. In addition to this work, she serves as a co-lead of the Restorative Landscape Coalition, a working group of the Northeast Seed Network. In this blog, she shares her hands-on experience organically restoring a meadow in a former horse pasture and hayfield in the eastern United States.

Transformation of former hay fields (left) to native meadow (right) using sod removal for site prep. Photo by Charlotte Lorick.

In Virginia’s Northern Piedmont region, where rolling hills extend from the Blue Ridge Mountains toward the Atlantic Coastal Plain, sits the Oak Spring Garden Foundation (OSGF). Its mission is to support and inspire scholarship and public dialogue on the history and future of plants, including the art and culture of plants, gardens, and landscapes, and the importance of plants for human well-being. OSGF advances this mission through fellowship and residency programs, a renowned research library, and by cultivating a biocultural conservation farm and ornamental gardens. The foundation also convenes meetings and collaborations focused on botany, horticulture, and landscape conservation. In this capacity, OSGF hosted the inaugural meeting of the Restorative Landscape Coalition in 2024.

Among the foundation’s primary goals is conserving and promoting native plants and biodiversity across the 280-hectares (700-acres) of land under its care. This goal can often prove challenging because the land at OSGF, like much of the rich soils of the Northern Piedmont, has long been shaped by agricultural land use. The impacts of agriculture on soil and plant communities are long lasting and can be detrimental to native species richness and diversity. Heavy fertilization favors exotic species over natives and the common practice of heavy tillage forever alters the soil and seed bank, further decreasing native species richness. Indeed, the IUCN considers temperate grasslands the least protected, most heavily altered, and most endangered terrestrial biome in the world. In the southeastern United States in particular, an estimated 90% of pre-European grasslands have been lost due to agricultural practices and other factors. And the small amount that do remain are indicators of the incredible species richness that have been lost. A recent study of Virginia’s Piedmont grasslands demonstrates they are far more biodiverse than previously documented, with surveyed sites having over 100 plant species in a single 100 m² plot.

This ecological and land use legacy raises a common challenge for conservation landowners across our region: how to restore native meadows to ecosystems degraded by intensive agriculture? As agricultural abandonment has increased across the region, converting old pastures to native meadows by removing existing vegetation and seeding a regionally native seed mix has become a common practice to address that challenge. Meadow restoration as a practice can actually mean different things depending on the situation. In the context of the Society for Ecological Restoration’s (SER) Restorative Continuum of activities, most often these kinds of meadow plantings fall along the restoration continuum but are distinct from efforts to fully restore native biodiversity and ecosystem health based on a reference ecosystem. Instead, in our region and at OSGF these meadow restorations emphasize incorporating designed, site-adapted native plant communities into degraded grasslands. We are aiming to increase native diversity in our grasslands and this is one way to accomplish this. However, for several reasons, including lack of robust data on reference communities or access to hyperlocal native seed, we consider these projects as distinct from but complementary to a full-scale ecological restoration effort.

As every practitioner will tell you, restoring a native meadow is a challenging process in this region as the non-native weeds and pasture grasses (that had historically been introduced for cattle and hay production throughout the Eastern US) are tenacious. Removing them effectively to allow establishment from a native seed mix is arguably the most critical yet most challenging part of the meadow restoration process. Conventional methods rely on heavy use of herbicides or tilling, which both have considerable downsides. Yet data are lacking in this region specifically on alternatives. To address this gap and inspire formal research on innovative or alternative techniques to restore native meadows in the Eastern US, in 2023 we trialed a novel method to restore a meadow that could prove a viable alternative for small areas to the conventional herbicide and tillage approaches.

This post details our project, outcomes, and lessons learned. We outline the experimental approach, site preparation methods, and early establishment results, and reflect on the practical implications of this technique. This project is a case study rather than a formal experiment, but we believe that what we learned in the field and are sharing here can havevalue for generating hypotheses and informing land managers interested in applying this method on their land and researchers interested in conducting future studies.

Landscape Context and the Case for Meadow Restoration

The OSGF landscape includes a rich mosaic of open fields, meadows, forests, streams, and wetlands that have been shaped by a long history of anthropogenic influence. In Pre-settlement times, the commonly held theory is that the Piedmont was characterized by oak-hickory landscapes with patches of forest and savannahs often managed by controlled fire. Post European settlement, the land at OSGF was managed, including by enslaved people, for row crops and apple orchards, grazing cattle and hay production, and, in the last 50 years, horse pasture.

Today, through careful inventory of the landscape, we have identified several remnant and globally rare plant communities on the OSGF property that seem to have escaped much of the human impacts. These include a Piedmont upland depression swamp containing cypress-knee sedge (Carex decomposita), a species designated as critically imperiled in Virginia with fewer than five known populations remaining in the state, and false hop sedge (Carex lupuliformis), another exceptionally rare species.

However, most of the open fields on the property are now products of a two and a half century agricultural legacy and are low in diversity, dominated by non-native cool-season grasses and other exotic species. While these non-native grass dominated pastures are actually choice nesting areas for many declining grassland specialist bird species at OSGF (including Eastern Meadowlarks (Sturnella magna), Grasshopper Sparrows (Ammodramus savannarum) and Bobolinks (Dolichonyx oryzivorus), we are selecting areas carefully to convert to native meadow where these birds are not nesting to support other suites of species that benefit from native meadow conversion. These areas hold strong potential for ecological restoration and conversion to diverse native meadow habitat and have become high priorities for conservation for OSGF.  For example OSGF is also home to several threatened or declining bird species that depend on diverse grasslands and early successional plant communities. These species include Short-eared Owl (Asio flammeus), Northern Bobwhite (Colinus virginianus), American Kestrel (Falco sparverius), Savannah Sparrow (Passerculus sandwichensis), and Henslow’s Sparrow (Centronyx henslowii). Notably, the native meadows that OSGF has established over the years have become winter hotspots for Short-eared Owls and Northern Harriers (Circus hudsonius) and other birds.

Short eared Owls overwinter at OSGF every year and prefer roosting in clumps of native bunch grasses and in our restored native meadows. Pictured here in native broomsedge (Anatherum virginicus, syn. Andropogon virginicus) and purpletop (Tridens flavus) clump. Photo by Josh Rector, OSGF.

Can Sod Removal Replace Herbicides?

As OSGF transitions away from its historic use of the land for hayfields and pasture, we have initiated several native meadow restoration projects over the past decade, totaling roughly 24 hectares (60 acres). These projects have primarily used conventional installation approaches, including herbicide application or chemical-free methods such as repeated tilling and plowing. The most common conventional method is to apply a broad-spectrum herbicide, such as glyphosate, at least 3 times to create enough bare ground to seed the meadow. But chemical herbicides are not always effective on some of the most aggressive weeds, they are not effective on controlling weed seeds in the seed bank, they can alsonegatively alter the soil, and pose safety concerns for humans and wildlife. Unfortunately the common organic alternative relies on heavy tillage which comes with its own major downsides, including increases in noxious non-native weeds and negative impacts on soil health.

OSGF is particularly interested in restoration strategies that minimize or avoid the use of chemical herbicides. We are not alone. Across our region, many landowners are exploring herbicide-free approaches to meadow restoration. However, robust data on the efficacy of alternative methods are limited.

For this project we decided to try sod removal or scraping. Although this method of site preparation is often employed on small scales for garden installation or lawn conversion, we found little data on this method for large scale restoration plantings. However, we were encouraged by the results of some restoration studies from Europe and California involving topsoil removal.

Sod Removal Project Design: Methods, Site Preparation, Seeding, and Maintenance

The sod removal trial was designed with two main goals: to test an understudied organic approach to meadow restoration site preparation, and to share our case study to encourage further exploration of the approach, and perhaps formal research comparing this method with more common approaches.

The trial took place on a 0.8-hectare (2-acre) parcel of a former horse pasture and hayfield. Baseline vegetation surveys showed it was dominated by introduced cool-season pasture grasses: tall fescue (Lolium arundinaceum), orchard grass (Dactylis glomerata), and Kentucky bluegrass (Poa pratensis).

To track change over time, we established permanent vegetation monitoring plots across the site. Vegetation surveys were conducted at baseline (Year 0) before disturbance and twice per growing season following seeding (2024 = Year 1, 2025 = Year 2). Soil samples were also collected at baseline and in each subsequent year. In November 2023, we removed the top layer of sod using the bucket of a skid-steer at a depth of approximately two inches. Afterward, the soil surface was lightly raked to improve seed-to-soil contact. We hand-broadcast a native seed mix using pine shavings as a carrier at 13.5 kg per hectare (12 lb per acre) and seeded a temporary cover crop of 50% winter rye and 50% oats at 34 kg per hectare (30 lb per acre). The field was then lightly covered with straw using a straw blower. The seed mix included 28 regionally appropriate species, roughly 60% perennial grasses and 40% forbs.

Management during the first two years was intentionally light. In Year 1, the cover crop was flail-mowed once in the spring. Other interventions involved manual cutting or pulling of problem weeds, primarily biennial thistles (Carduusspp.), a single clump of Johnsongrass (Sorghum halepense) likely introduced during site preparation, and spot mowing of creeping thistle (Cirsium arvense). Additional mowing had been planned but proved unnecessary due to relatively low weed pressure. The most common weeds were the annual grass Setaria pumila, which we expected to decline naturally, and white clover (Trifolium repens), which remained low-growing and did not appear to inhibit germination of the native seed mix. In Year 2, the meadow was flail-mowed once in the spring, followed by two days of manual cutting of problem weeds—mainly biennial thistles—to prevent seed set during the growing season.

Progress photos

Year 0 baseline (left) dominated by cool-season pasture grasses with intermittent ruderal forbs. Site prep (middle & right) included sod removal with skid-steer, raking soil, hand seeding and covering with straw. Photos by Charlotte Lorick.

Year 1 from left to right, July, September, October. A lot of bare ground in year 1 (left) and complete removal of non-native grasses with pioneering black-eyed susan and mistflower (middle) already blooming. Slower-growing perennials such as hoary mountain-mint were abundant as well (right). Photos by Charlotte Lorick.

Year 2 from left to right, July, September, October. Abundant mountain mints and volunteer path rush dominating the wetter section with black-eyed susans in the background (left). Many perennials flowering and fruiting including the gray goldenrod and little bluestem (middle & right). Photos by Charlotte Lorick.

Preliminary but Encouraging Outcomes

Because native meadows take time to establish, we want to emphasize that these observations are preliminary, with only two growing seasons documented so far. We will continue monitoring the site over the coming years and hope to share longer-term results as the meadow develops.

Nevertheless, at this early stage, several encouraging patterns have emerged. Total native species richness approximately doubled in Year 1 and tripled in Year 2 compared to baseline conditions. Native forb richness increased even more dramatically, more than tripling from baseline to Year 2. At the same time, the three most abundant baseline species—all exotic cool-season grasses—dropped from nearly 100% cover in Year 0 to less than 5% cover by Year 2 when averaged across all survey plots. This is an important indicator that sod removal was extremely effective in removing existing non-native vegetation.

Figure 6. Total number of species documented across all survey plots and including incidentals encountered outside formal surveys. Plants were designated native or introduced rank based VA Digital Atlas and given invasive rank based off : https://www.dcr.virginia.gov/natural-heritage/invsppdflist

Figure 7. Total number of native forb species documented across all survey plots and including incidentals encountered outside formal surveys.

By the second year, 22 of the 28 species in the seed mix had germinated, with several species already fruiting in the first year. This is a highly successful germination result by year two. For comparison, some of our other meadow restoration projects that used herbicide did not have germination of many of these same species until after year 2.

Species seeded. P = Present but not seen flowering or fruiting, F = Observed flowering or fruiting, 0 = Not observed. *A small number of Midwestern species were included to provide early visual interest and occupy space in the first few years, but are expected to fade as the native perennial species establish. ** This species was only seeded in a small drift to prevent overabundance.

In addition to the seeded species, we documented a number of native volunteer species that were not part of the seed mix and were not recorded in baseline surveys. These included secund rush (Juncus secundus), path rush (Juncus tenuis), forked rush (Juncus dichotomus), sweet everlasting (Pseudognaphalium obtusifolium), green milkweed (Asclepias viridiflora), and sedges such as fox sedge (Carex vulpinoidea), straw-colored flatsedge (Cyperus strigosus) and globe flatsedge (Cyperus echinatus). The arrival of native volunteer species was an exciting bonus and good indicator that some of the legacy native seedbank was still intact and uncovered with sod removal.

Lessons Learned and Key Takeaways

While this project was not designed as a formal experiment, the results have been striking and our hypotheses can inform further studies. Compared to other meadow restoration efforts attempted at OSGF, this planting has performed exceptionally well. It has required far less maintenance and weed management, and the native seed mix established with noticeably higher germination, flowering, and overall cover. The method was also particularly effective at suppressing the dominant cool-season grasses that often make meadow establishment so challenging.

Before seeding, the site supported very little native diversity. And the few native plants that we did find were woody seedlings or ruderal species such as horse-nettle (Solanum carolinense) and pokeweed (Phytolacca americana). Following the restoration work, native forb diversity increased substantially, including the appearance of several volunteer species. Although non-native white clover became the dominant plant by percent cover, its low, spreading growth did not appear to suppress the emerging native seedlings.

Of course, many factors could have contributed to this success. The seed was broadcast rather than drilled, which may have supported quicker germination. Careful site selection, existing vegetation conditions, and even the drought that followed seeding may also have played a role. Still, after more than a decade spent surveying and working in meadows across Virginia, this site stands out as one of the most rapidly successful restorations I’ve ever observed.

Our working hypothesis is that scraping away the existing sod removed much of the weed pressure by removing the grassrhizomes in the uppermost soil profile and some of the associated seed bank. It also slightly reduced the organic matter and nutrient layer at the soil surface—conditions that may have favored native species during establishment by reducingweed pressure (which thrive in more fertile soil). Although a decrease in organic matter may not be ideal for overall soil health, the decline is likely temporary. A growing body of research suggests that over time, the increase in native plant diversity may ultimately improve soil health beyond what we observed at baseline. This is something we plan to monitor in the years ahead with continued soil sampling.

The primary drawback of this method is cost. Removing and relocating large amounts of topsoil requires significant upfront investment, which may be impractical in some situations and at larger scales. However, this material can be reused elsewhere on a property in areas not prioritized for restoration or offered as a resource to farmers or composting operations. It is possible that these higher initial costs could ultimately be offset by reduced long-term maintenance and weed control, but that would take further study to determine.

Another challenge we encountered was sourcing local seed. Ideally, we would have used seed with documented provenance sourced from populations occurring in Virginia’s Northern Piedmont ecoregion, but the native seed supply chain still has significant gaps. To help address native seed shortages, OSGF has partnered with the Northeast Seed Network’s Mid-Atlantic Seed Partnership and the Restorative Landscape Coalition, a working group of botanic gardens, arboreta, seed banks, and allied organizations working to expand the availability of diverse, source-identified native seed for ecological restoration across the Mid-Atlantic and Northeastern United States. For this project we purchased seed from Ernst Conservation Seed in Pennsylvania and although not all seeds were sourced from our ecoregion, we were pleased that all their seed was from very nearby ecoregions and states in the Eastern US.

We hope this project encourages others to explore sod removal for meadow restoration. There is much practical experience still to be gained and there are many questions worth investigating in controlled experiments to compare this method with other site preparation techniques, test different sod removal depths, or variations in seed mix compositions.

In the meantime, we plan to explore the further use of this approach in future restoration projects at OSGF. If you’re curious about the project or interested in collaborating, we’d be happy to connect.

Please feel free to reach out to me at charlotte.lorick@osgf.org, and stay up to date with the outcomes of this project—and more of my work—at https://www.osgf.org/conservation-biodiversity and https://forgottenfloraproject.substack.com/.

Acknowledgements: Special thank you to OSGF team Clif Brown, Josh Rector, Katharine Perkin, Sarah Krementz, Sam Terry and local contractor Virginica LLC for support of this project.

April 23, 2026
Native Plant Seeding Solutions for High Disturbance Highway Roadsides

By Wes Bollinger

Wes Bollinger completed his master’s in 2025 with Jeffrey Matthews lab in the Department of Natural Resources and Environmental Sciences at the University of Illinois. Wes is now a restoration ecologist in Chicago and runs his own restoration consulting business – Wildshape Ecological Design.

The modern American landscape is crosscut by millions of miles of roadways. This land that was previously part of intact ecosystems has been converted into impermeable pavement and ditches, reducing the quantity and quality of habitat. Roadways also lead to habitat fragments, which can impede the movement of animals around the landscape. Highways in the Midwest (Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin) amount to more than 100,000 centerline miles (160,934 km) of roadway, and their unpaved right-of-way (roadside margins, medians, interchanges, etc.) total over 1,010,000 acres (445,000 ha) of unpaved land and soil. Highway roadsides typically experience high rates of disturbance due to wind, vehicle traffic and pollution from oil, microplastics from tires and litter, and often agricultural additives like herbicides, insecticides, and fertilizers. These lands and similar areas adjacent to roadways may be either burden or boon to the local ecosystem depending on management regimes and use of disturbance tolerant plant species. Here I recommend an approach to identifying appropriate native species for roadside vegetation, but this perspective may also apply to a variety of marginal greenspaces, such as residential sidewalk strips.

Native species dominated restoration project on a highway roadside in Northern Illinois. Visible flowerheads are pale purple coneflower (Echinacea pallida), lanceleaf coreopsis (Coreopsis lanceolata), black-eyed Susan (Rudbeckia hirta), and Canada wildrye (Elymus canadensis). Photo by Wes Bollinger.

If poorly managed, rights-of-way can become heavily invaded by nonnative plants like common reed (Phragmites australis), teasel (Dipsacus fullonum, Dipsacus laciniatus), and Johnsongrass (Sorghum halepense) among many others. These invasive species inhibit the native grasses and forbs and reduce ecosystem functioning. When heavily invaded, roadsides also cause economic impacts, functioning as source populations of weeds that can impact adjacent agroecosystems. Typically, roadsides are seeded with a mixture of Eurasian turfgrasses like Kentucky bluegrass (Poa pratensis) and red fescue (Festuca rubra). These nonnative grasses are comparatively short both in their above- and below-ground growth. Their short roots do not inhibit the growth of undesirable nonnative species, resulting in more mowing and maintenance than a native plant community to keep areas appearing ‘pristine.’

However, roadsides can be restored with native species and managed using best practices to provide economic and environmental benefits to the region. Native-dominated vegetation can inhibit invasion, protect nearby remnant habitats, promote healthy soil, improve stormwater retention, absorb agricultural additives, sequester carbon, and provide forage and migration corridors for native animals. Though establishing native vegetation on roadsides may have these obvious benefits, there are many knowledge gaps pertaining to this practice such as how and what to seed in these areas to maintain the highest ecosystem fidelity and greatest economic benefits.

We conducted research to determine which native species to seed on highways and the best practices for establishment and maintenance of these areas, with the goals of lowering overall maintenance costs by reducing the frequency of mowing needed to maintain these areas. This work was funded through grants from the Illinois and Indiana Departments of Transportation (DOTs) in conjunction with the Illinois Center for Transportation and the University of Illinois.

I carried out three projects to gain empirical evidence on how to restore Midwestern roadsides with native species. Project 1) reviewed the native seeding practices of the DOTs of the Midwest to identify commonly seeded species and assessed establishment and management practices. For Project 2) we conducted experimental trials in Illinois comparing existing Illinois DOT mixes (non-native and partially native) with novel mixes that we designed to be more diverse and contain only native species. For Project 3) we conducted a field survey of existing native roadside plantings across Illinois and Indiana. Projects 2 and 3 sought to quantify the performance of individual species to determine which ones have the greatest establishment and persistence in roadside conditions, and what conditions lead to favorable native establishment generally.

Project 1) Current native seeding and management practices

My review of Midwestern DOT seeding practices revealed stark differences between DOTs among states, but some commonalities that are noteworthy for establishment and maintenance. Most interestingly was the disparity in native diversity between states. Michigan did not list any native species in their roadside manual, while Minnesota listed 108, the most of any Midwestern DOT. Further, Minnesota listed 11 majority or entirely native seed mixes and had the most comprehensive standard operating procedures for native seeding. Many mixes had average max heights under 3 ft (~1m) to avoid obscuring motorists views on roadsides; however, some states had mixes more than 5 ft (~1.5 m) for tallgrass areas and to increase the invasion resistance of an area by blocking light access with taller plants. Perhaps surprisingly, the states of Ohio and Indiana still list an invasive legume, crownvetch (Securigera varia), in mixes designed for erosion control.

Number of majority native species mixes listed by Midwestern Department of Transportation in order of most to least native species (n) listed.

Several establishment methods were common across states. Native seeds should be sown into low-fertility topsoil using a hydroseeding machine (a device that sprays a mixture of seed, water, and an organic adhesive agent directly onto soil) especially on sloped areas. Hydroseeders show remarkable success in soils with a seed bank containing invasive species, by avoiding tillage which can bring these seeds to the surface and increase their germination. Native straw can be applied as a mulch layer and may be harvested from areas scheduled for maintenance with mowing. Seeding should take place in the fall to allow for cold stratification. Local ecotype seeds are preferred to produce individuals with locally adapted phenotypes and avoid genetic contamination with seeds harvested outside the region. Mowing in the first year of growth is critical to reduce invasive species while native seedlings establish. Minnesota recommends three mows in year one, in May, June, and July, and a singular mow between July and August of year two. Controlled burning of these areas is ideal every 3-5 years but mowing at the same rate is also beneficial.

Project 2) Comparative performance of standard (mixed origin) and native-only mixes

As a method of direct comparison between existing DOT seed mixes and a fully native roadside, I established four trials across Illinois to test differences in seeded, native, seeded native, and nonnative unseeded plant cover and richness, thus also providing information on invasion resistance between four popular mixes (DOT lawn, roadside, north IL, south IL) and four corresponding fully native plant mixes I designed to meet the same general criteria (low growing, disturbance, and salt tolerant) while also being higher diversity (from 9 to 38 species depending on mix). These experimental plots were seeded in November 2023 and surveyed in May and August of 2024. I observed that plantings differed in degrees of success, but every trial showed at least one significant positive result for the native planting over the nonnative IDOT mix. Native richness was higher for all sites by August of the first growing year, and native cover was higher for three of the four experiments. My trial of the IDOT Class 3 North Slope mix against a mix of 38 native species yielded significantly higher seeded cover by August 2024, and higher richness and cover of all native species in both May and August, suggesting that this high diversity mix competed very well against an existing DOT mix which was a combination of native forbs and nonnative grasses. Based on preliminary data collected during 2025, the native species are continuing to outpace the nonnatives in these mixes.

Of the native species seeded in these trials, those with the greatest record of germination in year one are lanceleaf coreopsis (Coreopsis lanceolata), common milkweed (Asclepias syriaca), partridge pea (Chamaecrista fasciculata), Illinois bundleflower (Desma n thus illinoensis), pale purple coneflower (Echinacea pallida), common evening primrose (Oenothera biennis), golden Alexander (Zizia aurea), blue vervain (Verbena stricta), and plains oval sedge (Carex brevior), which were present in the first year between 50% and100% of plots they were seeded in.

Example paired plot before site prep and seeding (left) and August of the first growth year after establishment (right). IDOT mix on the left, native mix on the right of each image. Yellow flowers are golden Alexanders (Zizia aurea). Photo by Wes Bollinger.

Project 3) Identifying the most successful native species from field surveys

Lastly, I surveyed 34 native plantings on roadways across Illinois and Indiana at various distances from the road edge while collecting data on soil chemistry, surrounding land use, and soil compaction. Sites were more than two years old to avoid plantings early in their establishment. The purpose of this project was to identify which seeded species tend to germinate and persist, and what environmental factors contribute to higher native and invasive success. Of the 153 native species seeded in one or more sites, we found that 28 native species were observed in at least half of the planted sites and 84 species were never observed once despite being seeded in anywhere from one to 12 sites. Five species were found a total of 10 or more times each across all 34 sites: common milkweed (Asclepias syriaca), bee-balm (Monarda fistulosa), black-eyed Susan (Rudbeckia hirta), false sunflower (Heliopsis helianthoides), and switchgrass (Panicum virgatum). These five species along with Virginia wildrye (Elymus virginicus) were also the most observed species at sites where they were seeded. These surveys were not designed to be comprehensive given the size of many of these plantings and it is highly probable some other seeded species were present but unobserved.

I found that native diversity and cover were generally higher further from the road edge, in areas with less salt, more basic soil, lower nitrogen and phosphorous, and a higher seed mix diversity. The opposite was true for nonnative cover and diversity. Richness of the seeded native mix was one of the strongest determinants of both diversity and cover.

In summary, we recommend that seed mixes should be hydroseeded at a rate of 60-70 seeds per square ft. (650-750 seeds per square meter) into low-nutrient, unfertilized soils, and covered in native straw. High-diversity mixes with no more than 10% legumes and an otherwise equal ratio of grasses to forbs should be used. Several species (but no more than 10%) should be early-establishing annual forbs for first year cover. Select species so that there is at least one blooming at all times of the growing season, favoring plants like golden Alexander (Zizia aurea) and native Alliumspecies for early spring blooms. Seed in as large an area as possible to reduce edge effects, consider cloverleaf interchanges as ideal locations for large projects.

For maintenance in year one post-seeding, mow several times (May, June, July, potentially also August in warmer states) to a height of 6-8 inches. In year two, mow at least once between June and September. Controlled burning or mowing can be conducted as needed for persistent weed issues but generally are only required every three to five years. If mowing is needed, areas with low abundance of non-native plants can be harvested as native straw for future plantings.

Native species with the best establishment record and widest usage are as follows and should be prioritized in high disturbance roadside plantings: Asclepias syriaca, Asclepias verticillata, Bouteloua curtipendula, Carex brevior, Carex cristatella, Carex hystericina, Chamaecrista fasciculata, Coreopsis lanceolata, Dalea purpurea, Desmanthus illinoensis, Echinacea purpurea, Elymus canadensis, Elymus virginicus, Eryngium yuccifolium, Eupatorium perfoliatum, Helianthus grosseserratus, Heliopsis helianthoides, Juncus effusus, Monarda fistulosa, Oenothera biennis, Panicum virgatum, Penstemon digitalis, Physostegia virginiana, Pycnanthemum tenuifolium, Ratibida pinnata, Rudbeckia hirta, Silphium laciniatum, Symphyotrichum novae-angliae, Symphyotrichum puniceum, Liatris pycnostachya, Verbena stricta, Vernonia fasciculata, and Zizia aurea.

Further details and methods can be found in the thesis here or by contacting the author at info@wildshaperestoration.com

January 6, 2026
Natural History and Ecological Restoration in the Madrean Mixed-Grass Prairie of Southeastern Arizona

By Matilda Essig

Matilda Essig is an artist and agriculturalist who has lived in the grasslands of southeast Arizona since 2006. She uses visual art, hands-on restoration and public outreach to express the resilience of wild ecosystems. matilda@mindspring.com

Blue grama. Digital capture, archival inkjet print by Matilda Essig. Unless otherwise indicated, all images are by the author.

Nineteen years ago, I began a project to restore the native diversity of the grasslands on a badly damaged 5-acre residential parcel in southeast Arizona, in a region locally known as the Apache Highlands Grasslands, a.k.a. Madrean-Mixed Grass Prairie to botanists, naturalists and biogeographers. My journey was informed and inspired by landscape stewards throughout the American west – ranchers and conservation groups alike. My mission included restoring not just the amazing diversity of grasses in the region, but also using my experiences, expressed through the arts, to help restore the role of art as a visionary vehicle within our culture. Visual beauty, ecological, and spiritual beauty – we need to get in touch with all of them again.

San Rafael Valley Overview. A monsoon cloud unleashes its fury over Saddle Mountain, headwaters of the Santa Cruz River.

In 2008, I wrote an article for Ecological Restoration, with my friend, and then-editor Mrill Ingram, wherein I described the conditions and biological makeup of my land. This article, Portraits of Grasses, gave an in-depth description of the biological ingredients I had to begin with, and also the artistic process I learned to use to make direct images from nature, using digital technology.
At the invitation of my friend James Aronson, I am delighted to share an update here, in NHER, mentioning the methods that worked and failed, and highlighting native grass species, and sharing how my portraits of these grasses engaged new audiences. What I have borne witness to in my brief tenure as an artist and restoration steward on my small tract of land has given rise to meaningful dialogue across the spectrum of possible audiences, through exhibitions, residencies, studio visits, and the artist’s book that I produced, Native Grasses of the Apache Highlands, which is now available for use in five university library special collections.

Suite of five grasses. Blue grama (Bouteloua gracilis), Hairy grama (Bouteloua hirsuta), Little bluestem (Schizachrium scoparium), Sideoats grama (Bouteloua curtipendula), and Rothrock’s grama (Bouteloua barbata var. rothrockii). Digital capture, archival inkjet prints.

The Apache Highlands grasslands – also known as the Madrean Mixed-Grass Prairie, which derives its name from The Madrean floristic region (named after the Sierra Madre Occidental) that occupies the arid and semiarid areas in the southwestern US and northwestern Mexico, at the northern edge of the subtropics. Sandwiched between huge basins and the rocky mountains, it’s a biodiversity hotspot. The summer monsoon delivers the most annual precipitation and is the primary (warm) growing season for the grasses. The San Rafael valley, which spans the US/Mexico border, is home to the southwestern-most intact stand of Shortgrass prairie in North America.

The Apache Highlands Ecoregion, X marks Matilda’s property. Map by Robert Bailey, The Nature Conservancy.

According to the late, great desert ecologist Tony Burgess, who passed away in 2022, these were the most characteristic native grasses in my region: Black grama Bouteloua eriopoda, Blue grama, Curly-mesquite grass – Hilaria belangeri, Vine-mesquite grass – Panicum obtusum, Cane beardgrass – Bothriochloa barbinodis, Purple threeawn – Aristida purpurea, Poverty three-awn grass – Aristida divaricata, Plains lovegrass – Eragrostis intermedia, Giant sacaton – Sporobolus wrightii and Arizona cottontop – Digitaria californica.

Over the years, I’ve come to recognize many more grasses, some of which I’ll mention below. Sadly, a plethora of invasive grasses and other plants now compete with the natives on my property which is in a subdivision carved out of what was, until quite recently, open grassland.

Sideoats grama. Digital capture, archival inkjet print.

The slope is gently north facing, with the buildings situated on the flat area of the ridgetop in the SE corner of my 5-acre property. It has fenced pastures which had been overgrazed by an equine for 20 years, resulting in an abundance of amaranths (Amaranthus spp.) and various kinds of ‘tumbleweeds’ including Salsola spp. (Chenopodiaceae).

Among the invasive grasses I had to deal with were Johnson grass (Sorghum halepense), and Lehmann’s love grass (Eragrostis lehmanniana), Yellow bluestem grass (Bothriochloa ischaemum), and the infamous, cosmopolitan weed Skutch grass or Bermuda grass (Cynodon dactylon) that had been planted by previous owners for lawn and equine grazing. My first steps to control the invasives, and promote recovery of the pre-existing flora and vegetation, began with cattle and rotational grazing practices that I learned from neighbors. That was quite successful in knocking back the swarms of amaranths at the start of the monsoonal growing season, thereby allowing the slow-growing grasses to gain a foothold. While I had wanted to work with goats in subsequent years, I chose not to undertake the labor-intensive fencing that would be required to control them and their voracious grazing habits. The cattle had been easy to contain with single strand aluminum wire and a solar charged battery for electricity.

Five borrowed cattle – a British white park bull, and four criollo heifers – feasting on amaranth and other invasives at the start of the rains and growing season, early July.

Instead, I invested in a high-quality mower and did a lot of pulling by hand of all the invasive species that I could. In the first few years, my progress was great – eliminating the amaranth completely around the buildings and well into the pastures, and completely extirpating the tumbleweeds, without any chemical assistance. Instead, I set out to learn about the root strengths and soil moisture of each invader species, so as to be able to pull each plant at the most appropriate moment in order to remove the entire root system with minimal soil disturbance. Working to reduce the invasives, I also learned about the natives, as I watched them rebound in the absence of competition.

Sensing and observing the effects of my role as a player in this ecological equation gave me great inspiration for creating the artworks – to celebrate the grass species that I was learning about, and to share the story of healing the landscape. By healing, I mean restoring the native grasses which I knew, in turn, would be nourishing soil health and ecosystem health.

The Grasses

Out of the more than 100 native Poaceae in the Apache Highlands, the most prevalent and iconic is Blue grama, a recognized keystone species and, now, a keystone also in the communications programs based on my artwork. It was the favorite of my first local mentor, senior rancher John Donaldson, who first taught me about the role of grasses in assisting the recovery of soil and watershed health on the nearby Empire Ranch, now the Las Cienegas National Conservation Area. This species has persisted and rebounded from the impacts of overgrazing on my property, and is notably much beloved throughout the interior western USA and northern Mexico, for its role as a pillar of many kinds of grassland communities, and because it is palatable and provides high protein content for feed for livestock.

I had immediate success in portraying the character of this species, and through the strong imagery, it served as a common denominator in rangeland discussion amongst the agricultural communities with whom I met at conferences. In particular, the Quivira Coalition’s 2009 conference on the theme of American conservationist Aldo Leopold was a great opportunity to engage in the dialogue about the role of beauty in land conservation. As I mentioned above, visual beauty, ecological beauty and spiritual beauty are all players, so to speak, in the determination of future land usage decisions based on human values. Sideoats grama, Rothrock’s grama, and Hairy grama were all present and easy to portray, with their vertical postures and showy inflorescence, but Black grama was a far greater challenge to find and portray, with tiny its slivers of seed head, and prostate growth patterns.

Black grama. Digital capture, archival inkjet print.

I’d searched for this species after hearing Brandon Bestlemeyer, ecologist and research leader at the Jornada Experimental Range, describe it as a critical species in the future of grasslands conservation. Many such inspiring collaborative conversations came about in the context of annual science meetings convened by the Malpai Borderlands Group, whose legendary accomplishments in bringing ranchers and conservationists together have resulted in biological protection for vast tracts of open range grasslands in the Chihuahuan desert. My friend Ben Wilder, a biogeographer and communicator with the Next Generation Sonoran Desert Researchers, chose the image of Black grama to draw an audience for a fundraising event for the UA Herbarium and the vast resource of its collections. The image spoke to them about spirit and resilience.

While my original focus had been to learn everything I could about how and where the individual grasses grow, the point of understanding multiple species was to illuminate the strength that biodiversity creates within the fabric of ecological communities. When the Land Institute, the Kansas-based agricultural research organization working to develop sustainable food crops, invited me to present as Artist for the 30th annual Prairie Festival (2010), they wanted an image for the theme of perennial polyculture. This challenged me to portray a group portrait that was inspired by a series that I collected, just as it occurred, from a pasture of a neighboring rancher, Rukin Jelks, who practiced holistic management methods: a mature rotational cell system designed byAlan Savory thirty years ago.

Perennial Polyculture. Hairy grama, Plains lovegrass, Sideoats grama, Poverty three-awn, Bristle wolf’s-tail (Lycurus setosus), and the naturalized Afghani bluestem (Bothriochloa bladhii). Digital capture, archival inkjet print.

The Audiences

The audiences at conservation meetings and the Prairie Festival knew the subject and shared my love for it. I believe they even felt their passion for land and prairie conservation was being recognized and honored in a new way. At traditional art venues —museums and galleries —the subject matter was largely novel, reaching audiences in different, more intuitive ways. The resounding response was, ‘I will never look at grasslands the same way again’. The diversity of plant characters also brought out the diversity in my audience: some viewers related to chaotic images like Tanglehead grass (Heteropogon contortus) whereas others were repelled by it.

Tanglehead grass. Digital capture, archival inkjet print.

The audiences of the fine art world were ripe for the authenticity of nature based values, a light of climate change and then the pandemic. At Tucson Museum of Art, (2013) I worked with the curator to produce a large group exhibition called “Desert Grasslands”, which offered side events such as art-science panel talks about rangeland conservation, Buffelgrass (Pennisetum ciliare, formerly calledCenchrus ciliaris), the noxious and highly flammable invasive that now threatens the Sonoran desert.
At the Amerind Museum, I had a solo show for Native Grasses of the Apache Highlands,(2016) and was able to engage with Hopi and Navajo tribal members in a shared sense of spiritual and creative source in the natural world. At the Willa Cather Foundation my solo show focused on comparing the prairie grass characters to Cather’s meticulous human portraits of pioneer immigrants – studies in adaptation and resilience. At the Tucson Airports’ Center Gallery, in 2019, I was able to offer the work to the broadest audience yet, and also use the setting to meet with visiting classical composer Emerson Eads to discuss collaborative musical intentions, and also Indigenous author and botanist Robin Wall Kimmerer.

Over Time

While an extreme weather event in 2021 – 3 inches (75 mm) of rain in one hour – reversed years’ of hard work in a single episode, leading to the germination of an ‘avalanche’ of amaranth seed that had likely lain dormant for more than a decade, the subsequent two years of sustained drought allowed a favorite native grass of mine to appear – Sand dropseed (Sporobolus cryptandrus)- in uncanny abundance. Additionally, as I grew to learn the songs of grassland birds, my restoration priorities expanded to include the habitats of the avian species that also thrived from my work, Meadowlark and Scaled quail in particular. The meadowlark’s song is both ancient and evolving in this landscape, as we have eastern, western, and also a new Chihuahuan subspecies recently identified by its song. The invasive plants have also inspired their own folio, currently underway.

In conclusion, my intentions moving forward are to work with the folios in university settings, to challenge our culture-driven perceptual paradigms of the natural world, engaging the next generation with the inspiration of stewardship thinking, both from conceptual understanding through the stories of these many land managers, and also to inspire them to see their own potential hand in the process, to experience the role of healer, and to know that no matter how small or large a parcel or landholding they may be working on, five acres or fifty thousand, every gesture makes a difference. To that end, I look forward to further opportunities to collaborate with EHN and its partners, to help inspire acts of ecological restoration, and to offer the arts as a catalyst for all.

Matilda on Flecha, looking north across the San Rafael Valley, headwaters to the Santa Cruz river. Saddle Mountain and the Santa Rita Mountains in the background. Photo by Zay Hartigan.

I would like to express my gratitude to James Aronson and Lauren Shew for editorial and technical assistance in creating this post.

June 25, 2025
Ecological restoration of sandy grassland ecosystems in Kiskunság, central Hungary and combating the allergenic Common ragweed (Ambrosia artemisiifolia)

By: Katalin Török and Melinda Halassy

Katalin Török and Melinda Halassy are restoration ecologists specializing in sandy grasslands in Central Hungary. Katalin focuses on botany, ecology, and biodiversity monitoring. Melinda, formerly Katalin’s student, took part in their first restoration experiment and is likely Hungary’s first PhD in restoration ecology. Their research aims to identify barriers to spontaneous restoration and analyze long-term ecological processes triggered by various restoration methods to find the most effective approaches. Both contribute to international ecological research (eLTER) and restoration policy (SERE), working to link scientific knowledge with public policy in ecological restoration.

HUN-REN Centre for Ecological Research, Institute of Ecology and Botany, Restoration Ecology Research Group, halassy.melinda@ecolres.hu

KIskun LTER Restoration Experiments site is located in a unique sandy landscape of central Europe. Situated at the center of a vast sandy region, the core area of Kiskunság National Park represents one of the largest of its kind in Central Europe, spanning approximately 7,400 square kilometers. This unique environment is especially accessible near the village of Fülöpháza, where visitors can experience an impressive range of sand dunes. The landscape features both open sand steppes and  wind-blown dunes, offering a rare glimpse into one of the continent’s most distinctive and unusual natural habitats. Credit: Melinda Halassy, CER2021

The ecosystem

One of Hungary’s most distinctive geological regions is the Danube–Tisza Interfluve (Kiskunság), which is an important reservoir of biological diversity within the Pannonian Biogeographical Region of Europe. Situated at the westernmost edge of the vast Eurasian forest-steppe biome, this region is part of a bioregion that extends approximately 9,000 km from Central Europe to Eastern Asia, covering more than 4.7 million km² (Erdős et al. 2022). The Eurasian forest-steppe represents Hungary’s dominant vegetation type, covering more than half of the country. Although the grasslands in this zone are sometimes misinterpreted as being heavily deforested in historic times, ecological models that integrate climate variability, topography, soil conditions, herbivory, and natural fire regimes reveal that forests and grasslands naturally coexist in a dynamic mosaic within the forest-steppe zone (Erdős et al. 2022).

The largest and most ecologically diverse areas of the region preserve the characteristic ”puszta“, which includes both sandy and alkaline grasslands, sand dune forests, and remnants of former sodic pans, marshes, fens, fen meadows, and wet grasslands. The inland sand dunes, shaped by wind action, consist of coarse-textured, lime-rich soils that are low in water and nutrients, supporting unique vegetation, including specialist plant and insect species. The sandy forest-steppe of the “puszta” consists of poplar-juniper sand dune forests and thickets, as well as open oak-dominated woodlands forming complex mosaics with both open and closed sand grasslands, all of which are considered habitats of high conservation concern by the European Commission. The driest grasslands in the region, known as ”Festucetum vaginatae danubiale“ community, are found on the crests and southern slopes of sand dunes. These grasslands are characterized by tussock-forming grasses such as the endemic grass Festuca vaginata and the protected Stipa borysthenica, interspersed with cryptogam cover of mosses, ferns, lichens, etc. and frequent patches of bare ground.

Sandy Forest-Steppe Mosaic of the Puszta: Poplar-Juniper Stands and Open Sand Grasslands. Dominated by White Poplar (Populus alba), this landscape reflects the natural vegetation adapted to arid, sandy conditions.  Credit: Evgeni Dimitrov, eLTER 2023

Throughout the 19th and 20th centuries, the landscape underwent significant human modifications, beginning with river regulation and drainage, followed by agricultural intensification and plantation forestry. As a result, the region is now predominantly covered by agricultural lands, forest plantations, and fragmented remnants of semi-natural grasslands.  During the post-socialist transition (1987–1999), large-scale agricultural land abandonment occurred, particularly in low-productivity areas such as the Kiskunság (Valkó et al. 2016). While some native vegetation regenerated spontaneously, abandoned lands also became increasingly susceptible to invasion by non-native species. One of the most problematic invaders is Black locust (Robinia pseudoacacia), a fast-growing, nitrogen-fixing hardwood tree from eastern North America, which has spread extensively. Another notorious example is Common ragweed (Ambrosia artemisiifolia) that we will discuss below.  The expansion of invasive species not only threatens native biodiversity and ecosystem health but can also have negative impacts on human health.

Land abandonment presents a valuable opportunity for the spontaneous regeneration of native sandy grasslands, it also introduces significant ecological challenges. One of the most pressing threats to natural recovery is the aggressive spread of invasive alien plant species, particularly Common milkweed (Asclepias serica, formerly A. syriaca). Credit: Melinda Halassy, CER 2021

Restoration experiments

For the past 27 years, we have been conducting restoration experiments at the Kiskunság Long-term Ecological Research site to facilitate the recovery of sandy grasslands on lands degraded by Black locust plantations and arable cultivation. Our research focuses on the long-term effects of various treatments aimed at overcoming barriers to spontaneous grassland regeneration, assessing the positive and negative influences of the surrounding landscape, and enhancing invasion resistance through seed-based restoration.

Our findings indicate that active restoration interventions can significantly accelerate recovery. Specifically, sowing a mixture of locally sourced grass and forb species has proven to be the most effective method for initiating restoration in dry grasslands and controlling invasive species (Reis et al. 2023). Additionally, carbon amendments and mowing can serve as valuable complementary measures; however, they should be applied cautiously in invaded landscapes to avoid unintended ecological consequences (Reis et al. 2022).

Seeding Native Species: A Key Strategy for Restoring Sandy Grasslands. In the restoration of dry sandy grasslands, sowing a carefully selected mixture of locally sourced grasses and forbs has emerged as the most effective strategy for initiating vegetation recovery and suppressing invasive species. Although remnants of native sand grasslands remain in the landscape, their specialist species show limited natural dispersal capacity. As a result, abandoned agricultural fields are often colonized by weeds and invasive alien plants, which significantly hinder the process of secondary succession. Research has shown that even the low-rate seeding of as few as five native species can have a catalytic effect, facilitating the establishment of characteristic grassland communities and accelerating the recovery of degraded former croplands. Credit: Melinda Halassy, CER2021

The success of restoration efforts is further challenged by the presence of other aggressively invasive species beyond Black locust, including the tree of heaven (Ailanthus altissimus) and the herbaceous Common milkweed (Asclepias serica (formerly A. syriaca), which are particularly widespread in forest plantations (Csecserits et al. 2016). Even after the removal of dominant invasive species, new invasions may occur, likely due to legacy effects and the high dispersal capacity of these non-native species (Reis et al. 2023). To mitigate these negative impacts, restoration efforts should prioritize areas with lower invasion pressure or integrate early seeding of native species as a complementary strategy for invasion control (Csákvári et al. 2023, Halassy et al. 2023).

Managing Invasive Species: The Limitations of Mowing in Invasive Species Control. Mowing is widely used as a method to control the spread of invasive alien species. However, experience indicates that mowing alone often fails to deliver satisfactory results. This is largely due to the persistent legacy effects of previous invasions and the limited natural dispersal capacity of native grassland specialist species. While mowing can effectively suppress certain targeted invasives, it does not prevent secondary invasions—the establishment of other non-native species that quickly occupy the disturbed space. To ensure successful and lasting restoration, mowing must be combined with the active introduction of native species, which can stabilize the ecosystem and reduce vulnerability to further invasions. Credit: Márton Kállai 2023

Restoration – human health links; research in progress

Enhancing public health through ecological restoration efforts can be of significant importance. Ecosystem services and direct contact with nature may contribute to this improvement (Millennium Ecosystem Assessment 2005, Marselle et al. 2021), but robust evidence is needed to establish clear links between biodiversity, ecological restoration, and human health at landscape, regional, and national scales.

In Hungary, a national project has recently been launched to investigate these nature–health connections using ecosystem condition maps and health data (https://termeszetem.hu/en). This initiative aims to identify correlations between environmental factors and various health indicators, such as the prevalence of allergies, depression, autoimmune and inflammatory diseases, and self-reported well-being. The research focuses on detecting these relationships at the sub-regional scale and in urban areas, as well as assessing the economic impacts of health conditions. A key initial focus of the project is the highly allergenic Common ragweed (Ambrosia artemisiifolia), which poses significant public health challenges throughout Europe and elsewhere.

Restoration as a Tool to Combat Common Ragweed and Its Public Health Impact. Abandoned croplands provide favorable conditions for the establishment and spread of Common ragweed (Ambrosia artemisiifolia), a highly invasive species known for its allergenic pollen. This plant poses a growing public health threat across Europe and beyond. In 2015 alone, ragweed allergy adversely affected the health of an estimated 13.5 million people in Europe, resulting in public health costs exceeding €7.4 billion (US$8.1 billion). Common ragweed thrives in open, disturbed soils, making abandoned agricultural lands particularly vulnerable to colonization. However, as natural vegetation succession progresses and plant cover becomes denser, ragweed populations tend to decline. This succession process can be significantly accelerated through active ecological restoration, which helps close vegetation gaps more quickly, thereby limiting the window during which ragweed can release its pollen and spread. Credit: Anikó Csecserits, CER 2020

Battling Common ragweed – for ecosystem and human health

Successes so far with reducing invasion of Common ragweed (Ambr osia artemisiifolia) are noteworthy.   For starters, note that the disservices of Common ragweed are already serious and likely to get worse throughout Europe since its allergenic pollen affects one in ten people throughout the European continent. Schaffner et al. (2022) estimate that the health of 13.5 million people was adversely affected in 2015 by Common ragweed allergy in Europe alone, generating 7.4 billion euros (8.1 billion US$) in public health costs. Happily, our ecological restoration interventions have already demonstrated their effectiveness in battling this noxious annual weed (Fig. 1).

Figure 1. The decrease of cover of the highly invasive, and allergenic, common ragweed (Ambrosia artemisiifolia), under three different restorative treatments and control. The figure shows the pooled data of three experiments that included mowing (Reis et al. 2021), carbon amendment (Halassy et al. 2021) and seeding (Reis et al. 2023) between 1995 and 2019. Carbon amendment through addition of sucrose and sawdust reduced available N-levels in the soil. Mowing was carried out twice a year, and was followed by removal of dry plant biomass.

The successful reduction of Common ragweed invasion serves as a promising example of how ecological restoration can yield measurable benefits for human health. The new national-scale study aims to provide evidence-based insights into the potential interconnections between ecosystem health and human well-being. These findings could help inform policy decisions related to land management and restoration efforts not only in Hungary but also in other regions.

A potential next step is to investigate links between ecosystem conditions and asthmatic diseases. By analyzing data on general practitioner and specialist visits for asthma-related complaints, as well as the purchase of asthma-specific medications, we can correlate health trends with different ecosystem states across temporal and spatial scales (Nitschke et al. 2022). This approach will allow us to assess the broader health impacts of ecological restoration.

Moving forward, we plan to deepen our research on the relationship between ecological restoration and human health by collaborating with the Ecological Health Network and its member sites and hubs working on similar challenges. We believe that participation in an international social impact network will not only advance our research but also enhance its value and real-world impact.

April 16, 2025
Looking Back to Guide the Future: Evaluating 23 Years of Management History in Big Meadows, Shenandoah National Park

By Jordan T. Coscia

Jordan is a PhD candidate in the Restoration Ecology Lab at Virginia Tech and a Research Fellow with the Smithsonian’s Virginia Working Landscapes program whose research focuses on the characterization and restoration of Virginia’s native grasslands.

The western section of Big Meadows, Shenandoah National Park in June 2022. Photo by Wendy Cass.

Located at the heart of Shenandoah National Park, the Big Meadows landscape is a site of both natural and cultural history. The 134-acre meadow is the largest open area in the Park, and it is a popular visitor destination boasting numerous walking trails and proximity to campgrounds, picnic grounds, and one of the park’s two visitor centers. Ecologically, the Big Meadows landscape includes two globally critically rare Blue Ridge Mafic Fen plant communities, and hosts plant and animal diversity not found elsewhere in Shenandoah National Park.

Like other meadows and grasslands across the Southeastern United States, Big Meadows occurs in a climate that can support closed-canopy forests. Therefore, the open landscape and the species that rely on it only persist due to a combination of edaphic characteristics, such as shallow and poorly drained soils, and frequent disturbance, such as fires or the grazing of herbivores, that prevent the growth of woody trees and shrubs. In the post-colonial absence of large herbivores and the suppression of both cultural burning and wildfires, the open landscape of Big Meadows was maintained by livestock grazing before the establishment of Shenandoah National Park in 1935. Continuous efforts have been made to preserve the historic open landscape since the Park’s founding, including routine mowing, prescribed burns, and the targeted cutting and herbicide treatment of encroaching Robinia pseudoacacia (black locust) saplings and Rubus (blackberry) canes. While initially successful, management efforts appear to have become less effective over time, and the spread of woody and invasive species threatens the open landscape of Big Meadows.

A rare sedge, Carex conoidea, in Big Meadows. Common names for this species include the prosaic “field sedge” (Flora of Virginia) and the romantic “ancient prairie sedge” (Southeastern Flora). Photo by Leighton Reid.

Since 1998, botanist Wendy Cass and The Inventory and Monitoring program at Shenandoah National Park have recorded land management actions and collected plant community composition data in Big Meadows. Big Meadows was split into three major management zones, and all three zones were treated with prescribed fire each spring between 2000 and 2003. In 2004, a new management schedule was created with the goal of maintaining a three-year burn-mow-fallow cycle in each zone. To determine how these management changes impacted Big Meadows, Leighton Reid (Virginia Tech), Wendy Cass, and I assessed changes in the plant community composition from 2000 to 2023 using multivariate statistics and the creation of statistical models through regression analysis.

Jordan Coscia (second from left) and Inventory and Monitoring NPS staff measuring plant community composition in Big Meadows in June 2024. Photo by Wendy Cass.

We found that the plant community composition of Big Meadows shifted over the past 23 years, with the original mosaic of shrubs within a grass and herb-dominated community experiencing marked increases in low shrubs, young trees, and other woody plants. Though the average percentage of graminoids (grasses, rushes, and sedges) encountered along each survey transect experienced little overall change between 2000 and 2023, the average percentage of forbs (non-woody herbs that are not graminoids) encountered decreased by over 50%, while the average percentage of woody plants encountered increased by 200%-400%. This increase in woody plants was partially driven by native Rubus (blackberry) species, which increased from less than 1% of the plants encountered along each transect in 2000 to 15-20% of the plants encountered along each transect by 2023. Multivariate statistics revealed that the trajectory of change in the Big Meadows plant community shifted abruptly after the three-year burn-mow-fallow cycle was adopted in 2004. The direction of this shift was correlated with an increase in the time interval between prescribed burns.

Woody encroachment near the northern edge of Big Meadows. Bare stems represent Robinia pseudoacacia (black locust) top-killed by prescribed fire. Emerging beneath them is a green carpet of invasive bittersweet (Celastrus orbiculatus). Photo by Leighton Reid.

Our statistical models provided evidence that both climate and changes in the timing of land management actions have impacted the plant community in Big Meadows. There was moderate evidence that later springs (as indicated by the date of the last spring freeze) are correlated with desired increases in forbs, however, this positive effect may be lost as climate change brings milder winters with fewer frost days to Shenandoah National Park. There was strong evidence that longer intervals between prescribed fires are correlated with unwanted increases in woody plants and decreases in forbs and moderate evidence that longer intervals between mowings are correlated with unwanted increases in Robinia (black locust) and decreases in forbs. Together, this evidence indicates that these unwanted changes may be mitigated by increasing the frequency of prescribed burns and mowing in the future.

Overall, our analysis revealed that the changes in land management between 2000 and 2023 have negatively impacted the plant community composition in Big Meadows. Together, the shifts in community trajectory after 2004 and the evidence from our statistical models suggest that the change from annual burning to a three-year burn-mow-fallow cycle in 2004 has contributed to the declining landscape conditions in Big Meadows. Though ad-hoc changes to the three-year management cycle and gaps in the plant data make it difficult to determine an ideal burn or mow interval from the existing data, evidence from the past 23 years suggests that more frequent burning and mowing may aid the preservation of the Big Meadows landscape for future park visitors and wildlife alike.

A line of gray dogwoods (Cornus racemosa) accentuates a shorter canopy of narrowleaf meadowsweet (Spiraea alba) shrubs in the wet, central portion of Big Meadows. Photo by Leighton Reid.

July 5, 2024
The cost-effectiveness of fertilizing and irrigating tropical dry forest seedlings in an applied nucleation project

By Dr. Laura Toro

Laura is a Restoration Scientist at the Missouri Botanical Garden’s Center for Conservation and Sustainable Development, where her research focuses on dry tropical forest restoration (ltoro@mobot.org).

Tropical dry forests are among the most threatened ecosystems in the world. Commercial agriculture, livestock farming, and mining have damaged and reduced the extent of this ecosystem type globally. Now less than 10% of the original extension of this ecosystem persists. The conservation and restoration of tropical dry forests are often overlooked because they are not as lush and well-studied as rainforests. However, restoring tropical dry forests can ensure the survival of thousands of unique plant and animal species that only exist in this ecosystem, and the protection of food, medicine, and livelihoods for millions of people.

Colombia has been one of the few countries that has invested resources to study the diversity and function of tropical dry forests across the country to ensure the conservation and restoration of the existing remnants of tropical dry forests. Since 2013 the von Humboldt Institute has been leading most of the research initiatives, and all the knowledge compiled about tropical dry forests has motivated the creation of a biodiversity offsetting policy. This policy establishes that for every hectare of tropical dry forest that is impacted by any kind of development project, 10 hectares (25 acres) of land need to be restored and conserved.

Although our understanding of the ecology, function, and diversity of tropical dry forests has increased in the last decade, the unique characteristics of this ecosystem type including the lack of precipitation for up to 8 months, makes it challenging for seeds and seedlings to naturally establish in these forests. Therefore, restoring tropical dry forests requires extra investment, like seed purchasing, in situ seedling production, tree planting, irrigation, fertilization, and weed control. These extra steps translate into a large financial investment at the beginning of a restoration project. According to published estimates, the establishment phase (year 1) of a restoration project in a tropical dry forest can range from $105 – $25,830 ha^-1 (Bodin et al. 2022).

Irrigation and fertilization are among the most expensive management practices often implemented. When seedlings are planted in previously tropical dry forest areas, they are often irrigated to extend seedling access to water, and fertilized because most tropical dry forest soils are expected to be highly degraded from previous land uses. However, it is still unknown how much irrigation and fertilization seedlings need to be able to survive and grow. To answer this question, Fundación Natura, a Colombian nonprofit organization, Enel-Emgesa, an Italian electrical company, and researchers from the University of Minnesota established an applied nucleation project (where trees are planted in small patches to serve as focal areas of recovery) in a grassland area dominated by non-native species in southwestern-central Colombia that used to be a tropical dry forest. In this area, Enel-Emgesa built a dam, and as part of their biodiversity offsetting strategy the company committed to restore ~12,000 ha of degraded tropical dry forests in the next 10 years.

Ten-year-old grassland where tropical dry forests seedlings are not naturally establishing (photo: Laura Toro).

The grassland, where the research project we report on here was established, covered 7 hectares (17 acres) and had little evidence of spontaneous natural regeneration, so we implemented an applied nucleation intervention. To do that, we cleared the existing vegetation of the area with machetes and scythes, tilled with a tractor to reduce soil compaction, and set up 42 hexagonal plots that had an area of 1000 m² (0.25 acres) each. In each plot, we planted 271 seedlings belonging to 11 different plant species native to dry tropical forests of this region. Four of these species had the ability to associate with bacteria that can fix atmospheric nitrogen. The seedlings planted all received 1 kilogram of ant farm soil, 10 grams of hydrogel to extend the period of favorable soil moisture, and 50 grams of nitrogen – phosphorus – potassium (NPK) fertilizer, 25 grams of NPK, 43 grams of phosphoric rock, or no fertilizer, depending on the plot where the seedlings were planted. All seedlings were irrigated once they were planted to activate the hydrogel. The seedlings that received the irrigation treatments were watered two more times during the first month of the experiment. The control and the 50 grams of NPK without additional irrigation treatments did not receive any additional water. Once the seedlings were 6 months old, we started monitoring their survival and growth. In each plot,we recorded the height of every seedling that was still alive. Thereafter, we measured seedling height approximately every six months for two years.

Aerial image of the 42 nucleation plots established in 2019 in El Quimbo, Colombia. The extension of the restoration intervention was 7 hectares (17 acres) (photo: Fundación Natura).

A close-up view of the experimental restoration plot. The orange lines represent the limits of the plot (1000 m² = 0.25 acres), and each small dot represents a seedling planted (Photo: Fundación Natura).

Additionally, we decided to compare the costs among the different management strategies implemented. We documented the cost of seedling production, planting, fertilizers, irrigation, and monitoring. Finally, we estimated the cost-effectiveness of each treatment for any of the eleven species planted. We did that by first estimating the total cost of planting a hectare of grassland with a single tree species (a hectare is equivalent to six nuclei = 1,626 individuals) under a specific treatment, and then dividing that cost by the % survival of that species under that specific treatment after two years. The most cost-effective method was the one that yielded the lowest cost and had the highest % survival.

An employee from Fundación Natura fertilizing a seedling of Vachellia farnesiana a shade-avoiding plant species common in tropical dry forests in Colombia (photo: Laura Toro).

We found that during the first two years of the project seedling survival was on average 73% across treatments. The seedlings that received 25 grams of NPK plus irrigation treatment had the highest survival (76%), while the seedlings that were fertilized with 50 grams of NPK and did not receive additional irrigation had the lowest survival (69%). However, when we looked at the survival across species, we found that survival varied across species and treatments. The plant species with the highest survival was Ceiba pentandra (99%), while Handroanthus coralibe had the lowest survival rates (5%). In terms of costs of planting seedlings, we found that the cheapest strategy was to not fertilize or irrigate the seedlings ($7,313 per hectare, $2,961 per acre), while the most expensive strategy was 50 grams of NPK plus irrigation ($11,689 per hectare, $4,732 per acre). Finally, when we compared the cost-effectiveness of the six fertilization and irrigation strategies implemented, we found that the control treatment was the most cost-effective management practice across the eleven species planted ($19,522 per hectare, $7,903 per acre) in part due to the low costs of no additional management beyond planting and monitoring, and the modest benefits to survival of costly irrigation and fertilization practices.

Aerial image of nucleation plots in El Quimbo, Colombia in 2022. (photo: Fundación Natura).

Even though restoration practitioners deal with a lot of uncertainty and restoration studies still lack information about how fertilizers affect the growth of native tree species and non-native grasses, there are multiple ways to improve restoration outcomes in tropical dry forests. We encourage partnerships between scientists and restoration practitioners to test how fertilizers impact different plant species growth and survival, and to estimate the costs of this practice across different tropical dry forests. Additionally, paying close attention to the soil fertility of the area, planting species that are found locally, actively weeding during the first year of the project, and fencing the restored area to ensure herbivores do not browse the seedlings will increase seedling survival and the success of the restoration efforts. Based on our results, we suggest that restoration projects should spend less resources on irrigation and fertilization, and more on plant species selection and weed removal.

If you want to learn more about how fertilization and irrigation impacted the growth and survival of tropical dry forest seedlings, we invite you to read our recent paper in Restoration Ecology or contact Dr. Laura Toro.

May 31, 2024
Virginia’s Piedmont grasslands: floristics and restoration

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

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

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

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

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

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

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

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

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

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

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

Our species list is available for download below.

nova-piedmont-grasslands-species-list_2020_jordan-coscia Download

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

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

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

August 31, 2021
Restoring Tallgrass Prairies across Iowa

Andrew Kaul is a new Restoration Ecology Post-doc in the Center for Conservation and Sustainable Development at the Missouri Botanical Garden. Here he describes some projects from his dissertation work conducted with Brian Wilsey at Iowa State University.

Tallgrass prairies once covered most of the central United States, but much of this historic ecosystem was lost to agriculture during the 19^th and early 20^th Centuries. Iowa sits at the heart of the tallgrass prairie range and lost more of its prairie than any other state except Illinois.

Throughout the Midwest, prairie restoration efforts have become increasingly common, and after several decades of research, the practice of prairie restoration has become increasingly complicated. We now know that restoration outcomes can be highly variable, and it is difficult to predict the outcome of any given restoration because there are so many factors that have been documented to influence restoration success, in terms of species diversity and establishment of target species from the seed mix.

Nodding lady’s tresses (Spiranthes cernua) at Doolittle prairie in Story Co, Iowa. Conservative taxa from groups like orchids are common in remnants, but are often missing from restored prairie communities.

For my PhD at Iowa State I studied 93 grassland restoration projects across Iowa. Previous work on grassland restoration had included careful experiments and thorough investigations of novel restoration techniques. What hadn’t been done before was to treat existing restorations each as their own little experiment and to sample broadly across the wide diversity of restorations in the real world. This approach allowed us to describe general patterns across many sites and to investigate which of the many potentially important processes tended to drive restoration outcomes.

With this project, my advisor Brian Wilsey and I sought to test which factors are the best predictors of restoration success in terms of species diversity, degree of invasion, and establishment of sown species. We considered factors including management history, the diversity of the seed mix, land use history of the site, site size and shape, soil characteristics, and weather during the first couple years of vegetation development. We took a retrospective approach to answer these questions, using existing restorations, which were highly variable in their age and how they were undertaken. We sampled vegetation at 93 restoration sites across Iowa over two summers and interviewed the managers of each of those sites afterwards to get information on when the restoration was started, what seed was used, and how it had been managed. We also sampled 5 prairie remnants, as a reference.

Here I am squinting on a sunny day in July of 2015, posed next to a glacial boulder at one of the remnants in our study – Cayler prairie in Dickinson Co, Iowa. (Photo credit: Brian Wilsey)

We found that by far the strongest predictor of plant diversity and recruitment of species from the seed mix was the degree of invasion by exotic species, where the more heavily invaded a site was, the lower the plant diversity and recruitment of target species. The influence of exotic species was more important than soil type, site management, restoration age, or any other aspects of the restoration, indicating control of exotic species is key to restoring prairies, and other temperate grasslands. The degree of invasion was higher in more linear shaped sites, sites with higher soil organic matter, and sites with fewer species in the seed mix, so we found that these variables were negatively related to our restoration success measures because of their indirect effects through exotic species. More linear habitats tend to have more “edge effects” where there are more colonization opportunities for exotic species. The higher invasion rates we found in sites with greater soil organic matter indicate the exotic species are better able to take advantage of nutrient availability. The lower invasion rates in sites seeded with more prairie species indicate that these mixes contain species that together, occupy more niche space and leave less open niches for exotic species to colonize. We also found that sites mowed during the first two years of establishment had higher diversity and establishment of sown species. This practice is supposed to suppress the annual weeds, which start growing before the seeded prairie species can establish.

Roadside prairie plantings have become a common example of restoration in Iowa.

Sown natives, purple coneflower (Echinacea pallida), and beebalm (Monarda fistulosa) are seen in this roadside prairie planting, which has become mostly dominated by European smooth brome (Bromus inermis).

Another goal of this project was to examine the ecology of milkweeds in prairie habitats. Milkweeds are obligate host plants for larvae of the monarch butterfly (Danaus plexippus), and in recent years, conserving and restoring milkweed populations in service of monarchs has become a major conservation priority in North America, especially in the Midwest, where many of the migratory monarchs breed. We counted milkweed stems within a meter of our sample quadrats at each prairie, and used these count data to examine what prairie habitats have the highest milkweed abundances, and what features of a prairie habitat best predict stem density. Specifically, we tested whether stem densities were different between remnant prairies, roadside restorations, and the non-roadside “conservation” restorations, most of which are managed by the Iowa Department of Natural Resources.

Common milkweed (Asclepias syriaca) is abundant in roadsides, and often establishes in restored areas as a volunteer native.

Milkweeds were far more abundant in remnants than restorations. Among restorations, roadsides had higher milkweed densities. Remnant prairies also had a higher diversity of milkweeds, so they are clearly an important habitat for this forb assemblage. Most of the milkweeds we sampled in restorations were common milkweed, even though it is rarely planted. On the other hand, Swamp milkweed (Asclepias incarnata) and butterfly milkweed (Asclepias tuberosa) are often included in restorations seed mixes, but were not nearly as abundant as volunteer common milkweeds.

Across all the restorations, we tested whether milkweed stem density was related to management (burning and/or mowing) or environmental variables including soil characteristics, plant diversity, degree of invasion, and site shape (linearity). We found that milkweeds were more abundant in more linear and invaded sites, and sites with lower soil density, and higher soil pH. These factors indicate that milkweeds are more abundant in areas with more soil disturbance. This is not surprising, considering the “weedy” ruderal nature of many milkweeds, especially common milkweed. The relationship with pH was a novel discovery, and future work will be needed to experimentally test whether milkweed germination or growth is higher in more basic soils, which is what our study indicates.

I am continuing my research on tallgrass prairie restoration with new projects examining plant functional traits to help understand why certain species are under- or over-represented in restorations. We have collected data on plant and leaf functional traits for over a hundred prairie plants and will test how the mean traits of plant communities differ between seed mixes, restorations, and remnants. Additionally, I am working with the Wilsey Lab on a related project examining phenological differences between plant communities in remnant and restored prairies.

Bottle Gentian (Gentiana andrewsii) is being measured for plant height at Doolittle Prairie (Story Co., Iowa) as part of an ongoing project to examine how traits of prairie plants differ between remnants and restored communities.

To learn more, follow me on Twitter @andrew_kaul and check out our milkweed paper in Restoration Ecology. The prairie restoration study was recently accepted in Ecological Applications, under the title, “Exotic species drive patterns of plant species diversity in 93 restored tallgrass prairies.” Look for it to come out soon!

October 31, 2020