UVA Today

Landscape architecture students and volunteers plan the controlled burn at Milton Field.

“The old grassland remnants usually contain dozens of plant species that are not very tolerant of plowing and require long periods of full sun conditions, and groupings of these plants are easy for a botanist to see,” said Devin Floyd, founder and director of the Center for Urban Habitats in Charlottesville. “The reason the fire is important is because for most of the last 8,000 years, fire was a normal and regular occurrence in our region, and in some areas the fire return interval was as great as two to three years. What that did was allow for long periods, and perhaps even hundreds or thousands of years, of open-space conditions. The ongoing sunny conditions and lack of plowing allowed for diverse prairies and savannas to establish.

“Grasslands cannot persist if forests replace them. Grassland plants require lots of sunlight, and the ecosystem that results is the one that supports at-risk and endangered species such as the monarch butterfly, the northern bobwhite, the North American bumblebee and countless other grassland species. Without Piedmont prairies and savannas, the thousands of animals that depend upon them cannot survive.”

Floyd was clearly visible, even in the thickening smoke, in his bright yellow shirt of fire-resistant fibers and his bright hard hat. Floyd drizzled fire from an igniter carrying a 50/50 mixture of diesel fuel and gasoline onto a heavy thatch of dried grass. He started a stream of fire in the thatch, letting it burn for a few minutes. He then walked several feet away and started another stream of fire, and he let the wind push the second stream toward the first. After a few minutes, he started a third stream.

The grass popped as it burned and the whiteish smoke rolled upward from the flame to dissipate into the clear blue sky. Small, orangish tongues of flame flickered in the blackened ash of the burned thatch.

Matthew Seibert, an assistant professor of landscape architecture, was one of the fire tenders. Seibert features Floyd as a guest lecturer in his Ecology and Technology 3 class.  

“I would say it was a resounding success,” Seibert said later of the field burn. “It was a flawless execution by Center for Urban Habitats’ team. The burn went completely according to plan, with great thoroughness and precision. This will suppress the threat of invasive species and facilitate the robust growth of Piedmont prairie species.”

This was the second recent prescribed burn at Milton Field. Floyd, Seibert and the graduate students conducted one on an adjacent parcel in December. These two patches were burned because of the sharp eyes of Sarai Carter, a Master of Landscape Architecture student who spotted a grassland indicator species there last spring.

“I’m the one who stuck my nose down into the field and found some interesting plants,” Carter said with a musical laugh. The plants she observed were narrowleaf mountain mint (Pycnanthemum tenuifolium), little bluestem (Schizachyrium scoparium) and Indiangrass (Sorghastrum nutans).

“We were just passing through that field and I wanted to take a closer look,” Carter said. “It was totally by chance, because it looks like a very normal, cosmopolitan lawn mix, just sort of a run-of-the-mill field, but I guess that in and of itself made me curious as to whether there was something more interesting to look at. There was nothing in particular that caught my eye. I just got down on my hands and knees and wanted to see what was in the mix.”

Carter, who previously had trained as a restoration ecologist in the Southwest, said she loves finding surprising things in mundane places.

“I noticed the narrowleaf mountain mint first,” Carter said. “Devin pointed out little bluestem, which is another indicator for high-quality Piedmont grasslands, and then he noticed it was accompanied by Indiangrass. Indiangrass, little bluestem and mountain mint growing together, in combination with dozens of species that aren’t market-available for planting, tends to suggest that the ecosystem hasn’t been planted, but is naturally self-assembled.

“Many of them are so-called ‘conservative’ species, so it is difficult to propagate them, and they require specific conditions for long periods of time in order to persist. When you find them growing together like that, it’s a green flag of something that may have preceded or survived the settlement period.”

Floyd said the diverse mix of grassland species at the Milton airfield survived for several reasons. While the general area has been heavily farmed and developed, there are many spots that are unsuitable for those purposes; it is in these locations that small bits of the old grasslands survive. Floyd said Indiangrass, little bluestem, splitbeard bluestem (Andropogon ternarius), green milkweed (Asclepias viridiflora), smooth penstemon (Penstemon laevigatus) and southern sneezeweed (Helenium flexuosum) are common prairie “indicator species at the Milton Airfield.”

“If you find that group together, you know there are probably a couple hundred other species there,” Floyd said. “They are all native and you probably have something special there worth conserving, studying. This is system that was not planted. This mix became established gradually over great spans of time.”

Last year, the Center for Urban Habitats received a grant to find old-growth remnant prairies, savannas, barrens and other grassland types in an eight-county area of Central Virginia. The researchers found 420 remnants, including the one at the Milton Field. The Milton site is unique among the them, however.

“It is the only high-quality remnant we found in close proximity to the Rivanna River,” Floyd said. “This particular grassland is made of a unique blend of plants and is firmly associated with the unique geology of the site.

“All the flood plains of the region have been heavily farmed. This spot, however, is in between agricultural production zones, being perched up on an older flood deposit, likely of Pleistocene origin. I think because of the age of the landform at this location, the sands and gravels have decomposed in place and consolidated to form an unusual grainy, clay-ey and concreted soil type that resulted in the unusual community of plants. This is the only grassland we identified during 2021 research that occurs in association with old alluvial deposits.”

The grouping of native plants found in this old remnant is a community that is not at all tolerant of plowing and other deep soil disturbances The grouping is also quite fire-dependent and tends to move very slowly about the landscape. It takes a long time to establish, and new research suggests the average age of old grassland remnants on many continents is more than 1,000 years.  

“They tend to be groups of plants that have slow dispersal rates, and require specific conditions to germinate, grow and reproduce,” Floyd said. “The plants have a variety of strategies to spread. Some make tons of seeds and some are carried on the wind or moved around by birds or mammals. Others, like the mountain mints, spread mostly by gravity seed dispersal and the creeping roots that send up new growth, so it moves across the land real slowly. They require sun across great amounts of time to move across the land, and that condition – one free of dark forest –­ is perpetuated by surface disturbance regimes such as fire, both natural and human-ignited.

“We find these little patches spread out and separate from one another, where once they were contiguous across the land. For them to get from one place to another, say a couple of miles, might take hundreds of years, and during that time the path of movement must be a sunny one.

“When we find these plants that move slow and need this soil stability and sunlit environment, we begin to see a story emerging that is counter to what most of us learned when we were growing up,” Floyd said. “Ecologists now call it the ‘virgin forest myth’  – unbroken forests stretching from the Atlantic to the Mississippi. Thankfully, we have the records of dozens of early explorers and cartographers that help explain some of what we are seeing in the grassland research data. In fact, one may imagine the Piedmont region hosting an incredible diversity of ecological systems, from wetlands to barrens, and forests to prairies. It is a safe bet to assume that about half of the region would have been forests and the other half grasslands, including barrens, prairies, savannas and woodlands –­ a lot more diverse than the government-driven forest and anti-fire campaign led us all to believe beginning of the early 1900s.”

Floyd’s work is part of a larger movement that hopes to draw awareness to forgotten grasslands that still exist. The focus is on restoring natural systems, so that native plant and animal diversity may continue to persist.

“These burns are about systems, or what ecologists call ‘natural plant communities,’” Floyd said. “It’s important that we begin to influence the public with education that discourages an obsession with individual species and so-called ‘gardening’ and allows them to think about systems and restoration in the lived-in landscape; communities, not individuals. If the community is healthy, the individual plants and animals thrive. And the same can be said for all of the diverse organisms that call these grassland systems home.”

Floyd said that in a healthy natural Piedmont prairie or savanna ecosystem, typically between 65 and 110 native species grow within a 100-square-meter area.

“These are among the most biologically diverse ecological systems in the Eastern temperate landscape of North America,” Floyd said. “We are reintroducing a lost and forgotten disturbance regime – fire – in order to allow these systems to simply wake up and breathe in their fullness.”

Aside from realigning the ecosystem at Milton Field, Seibert said he was pleased to offer the students an opportunity to participate in using fire as a landscape management tool.

“Perhaps the greatest element of success was the educational opportunity afforded to the Master of Landscape Architecture students and other observers,” Seibert said. “Prescribed fire is an incredibly powerful and important tool in land management, ecological regeneration and disaster mitigation, one that future designers can employ with great result.”

The education will go on. Seibert said that his classes would continue to allow fire to be on the landscape periodically and continue to monitor what was happening with those parcels.

“The continued engagement with this landscape is possible because of the advocacy, research and teaching conducted under the umbrella of the landscape architecture department’s Milton Land Lab,” Seibert said. “Organized around a pedagogy of immersive, embodied learning within the Piedmont, the land lab aspires to have landscape architecture students work with the medium of landscape itself.

“In a profession largely practiced in front of a computer, meaningful engagement with the plants, animals, hydrology, landform and fire is paramount for a discipline aiming to tackle the social and environmental crises of today.”

Seibert and Floyd credited the influence of landscape architecture alumna Rebecca Hinch.

“She wanted to burn part of her project in spring 2021, but we couldn’t pull that together,” Floyd said. “But the momentum started there. And I think her spark is an important part of the community’s stake in this, as well as the interest and awareness in teaching ecological practices at UVA’s Landscape Architecture Department.”

While she missed the December burn, Carter was among the fireproof-shirted students drizzling fire and keeping it in line.

“It was amazing,” she said. “If you are in a drought and then the rains come, you can just feel the earth soaking it up, breathing a sigh of relief. I feel it’s very similar with a burn, especially on a piece of land that has not been involved in burning and it hasn’t been burned in a very long time. You can almost feel the earth give a sigh of relief.”

After spending many years working as a conservation botany field technician, Carter did not know if people were making good land use decisions after reading her research. She came to UVA to study landscape architecture because she thought that would put her in a position to help make some of those decisions.

She would like to see prescribed burns like the one at Milton Field be more integrated into the culture.

“I went into learning about grasslands to learn what I was seeing at Milton, and it has been amazing,” Carter said. “Now, when I look at other sites in other places around the country, I am seeing these historic place names that say ‘savanna’ and ‘prairie’ and ‘meadow’ that tip you off that grasslands were really more prevalent than I think we realize. I think that underestimates how much of a mosaic the landscape was. The grasslands were really important, and could still be really important.”