Archives For Plant Science & Conservation

Conserving plants is one of the most significant challenges of our time—and a major focus at the Chicago Botanic Garden. From studying soil to banking seeds, from restoring habitats and protecting endangered plant species to developing new ones, Garden scientists are fighting plant extinction, pollution, and climate change through diverse and exciting research.

Home on the Prairie

Undercover Science

Julianne Beck —  September 15, 2014 — Leave a comment

A delicate prairie bush clover extends its pink flowers toward the sun, like an early settler attempting to plant a flag on a piece of land to call home. Competition for space is intense where the native herb stands on one of the state’s last remaining prairie landscapes, Nachusa Grasslands, located in north-central Illinois.

The species’ juvenile plants must establish themselves rapidly to avoid being overtaken by dominant native grasses, such as little bluestem. Even if the wispy young herbs live to maturity, they may still struggle to survive the often deadly wake of litter the grass leaves behind.

PHOTO: A view of Nachusa Grasslands taken from Dr. Vitt’s field site.

A view of Nachusa Grasslands taken from Dr. Vitt’s field site. Photo by Pati Vitt.

Chicago Botanic Garden conservation scientist Pati Vitt, Ph.D., has been studying the rivalry between the prairie bush clover and grass species at Nachusa over the past 14 years. Also the curator of the Dixon National Tallgrass Prairie Seed Bank, she has seen the herb species’ population rise and fall.

PHOTO: A tiny, spindly stalk of prairie bush clover in spring.

Prairie bush clover ( Lespedeza leptostachya) grows at Nachusa Grasslands.

In Illinois, Nachusa Grasslands is one of the few remaining places where prairie bush clover (Lespedeza leptostachya) can still be found. The issues it faces there are not unusual to the species.

“It is a unique component of this very small subset of North American grasslands that exist nowhere else,” said Dr. Vitt. “Its presence is an indicator of high-quality, well-managed gravel hill prairie. It serves to increase the biodiversity of those types of habitats.”

After years of working to define the ideal environment for the prairie bush clover and getting to know its adversaries, she feels it is time to bring in the big guys.

Bison, 2,000-pound behemoths that are naturally adapted to Midwest weather and vegetation, will soon be arriving to help save the tiny plant. The rust-colored creatures, standing up to 6½ feet tall at the shoulder, are rather particular grazers, explained Vitt. Unlike cows, which graze broadly and without much discretion, bison selectively eat grass. That makes them the perfect friend of the prairie bush clover, which, Vitt has documented, needs a little more room to grow on the limited rocky portion of the 3,000-acre prairie it calls home.

Vitt spent much of her summer at Nachusa, a preserve managed by the Nature Conservancy in Illinois. She was hustling to document the status of prairie bush clover populations there before the arrival of a herd of bison in the fall of 2015.

PHOTO: Schizachyrium scoparium 'Carousel'

Little bluestem (Schizachyrium scoparium ‘Carousel’) is a native grass.

Each morning of research she and her team, which included an REU intern, fellow Garden scientist Kay Havens, Ph.D., and additional technicians, were out in the field at daybreak. They worked in teams of two to count and identify all of the plants associated with Lespedeza leptostachya in six plots where it grows. They also took soil samples and did nutrient analysis to measure elements such as nitrogen, phosphorous, and potassium. Lastly, they documented the slope of the land on which the prairie bush clover plants grew, and the aspect—the incline and direction at which they faced the sun. The team spent evenings at their temporary residence inspecting more challenging plants under a microscope to confirm the species identification. All of the data they gathered was recorded into GPS units and later downloaded into a database.

What did they find? Prairie bush clover performs best in soil that has 75 percent versus 82 to 89 percent sand, though all populations grow on soil with low organic matter. It suffers where levels of grass, and especially the litter the grass produces when it dies back each year, are high.

These findings support her research from previous years. Vitt studied the before-and-after status of the species during a one-year trial run with a cow as a grazer. She also investigated the impact of fire as a management tool.

“The more [grass] litter there is, the fewer seeds the [prairie bush clover] plants produce, which is both a function of size and probably nutrient status,” she explained. “Litter may not only serve to suppress the growth of the plant, but because it is carbon heavy it may actually decrease the available nitrogen in the soil.” One of the benefits of prairie bush clover, she theorizes, is that the healthy plants add nitrogen to the soil. That is an asset for surrounding plants.

A research plot where little bluestem is growing over smaller prairie bush clover plants. Photo by Pati Vitt.

A research plot where little bluestem is growing over smaller prairie bush clover plants. Photo by Pati Vitt.

When alternated with fire, grazing is a natural and effective management tool, noted Vitt. Fire, she explained, decreases the biomass of grass above soil, resulting in less grass litter. At the same time, it encourages new growth by stimulating meristems in the roots below the soil—areas where new cells are produced. After fire, said Vitt, clumps of grasses such as little bluestem (Schizachyrium scoparium) tend to be larger. However, when they are also grazed, those clumps are less dense, and therefore less discouraging to growth of the prairie bush clover.

Vitt has collected seeds on other prairies in the Midwest where bison have been present. “I’ve seen firsthand how bison graze, and I’ve seen the results of bison grazing versus cattle grazing,” she said. “When they [the Conservancy] decided that they were going to release the bison, for me that was very exciting. It’s kind of an affirmation of the work that I’ve done there, and that’s really great. I can see the benefits of the management and I have every reason to conclude that it’s going to increase the population viability of Lespedeza leptostachya.”

Bison will soon graze the vast prairie. Photo by Pati Vitt.

Bison will soon graze the vast prairie. Photo by Pati Vitt.

Vitt is back at the Garden now, sorting through the data she collected this summer and writing about her findings. These data are essential, she said, because she will be back to check on the prairie bush clover after the bison have settled in. She is also planning for future experiments, such as building habitat models for prairie bush clover using remote sensed data.

For a little plant that exists in only four states and is federally threatened, a hero can come in many forms.


©2014 Chicago Botanic Garden and my.chicagobotanic.org

Rescuing Local Ravines

Renee T. —  July 30, 2014 — 1 Comment

At first, the tree-shaded ravines near Lake Michigan look inviting, a place of filtered sunlight in the Chicago area’s North Shore. But the ravines—with homes built on the bluffs above them—are in trouble.

Overgrown with invasive plants that block the sun, the ravines are losing the native plants that help keep their soil from washing into Lake Michigan. Although some erosion is natural, the rate of erosion is accelerating, partly because of runoff from urban areas atop the ravines. The Chicago Botanic Garden and the Park District of Highland Park have stepped in to try to keep the ravines from crumbling any further.

“These are systems that have been beaten up for a long time,” said Rebecca Grill, natural areas manager for the Park District of Highland Park.

PHOTO: A bike path along the bottom of Millard Park ravine, next to a small stream.

Millard Park is one of the many Lake County ravines that face challenges from erosion.

The Garden and the Park District have put together a scientific research and “ravine trauma” team to help reestablish native plant cover that will slow surface erosion. The team is developing a mix of native seeds that private landowners can sow to help restore vegetation to the slopes of ravine and bluff properties. The seeds will be sold commercially. In addition, the team will provide homeowners with a guide on how to care for the native plants.

“The Garden has a responsibility to partner with our neighboring communities to conserve and protect oases of biodiversity such as those found within the Lake Michigan ravines,” said Bob Kirschner, the Garden’s director of restoration ecology and Woman’s Board Curator of Aquatic Plant and Urban Lake Studies. “We’re pleased to be able to pair our ecologists’ knowledge with the Park District of Highland Park’s progressive approach of helping landowners help themselves.”

The project team includes Garden ecologist Jim Steffen. With 25 years of experience, Steffen has worked on other Lake County ravines, where the lake’s cooler, damper air is funneled to create a microclimate not found anywhere in Illinois. (The ravines also are home to some of the state’s rarest plants.) As part of the project, Steffen helped design a seed-trial experiment and develop potential seed mixes.

PHOTO: Jim Steffen.

Garden ecologist Jim Steffen in the field

For the next three years, the seed mixes will be tested in plots within Highland Park’s Millard Park, one of the district’s four lakefront parks with ravines adjacent to Lake Michigan. (Check pdhp.org for more information.)

After that, the next step will be up to homeowners near the ravines. “We hope to build a better awareness about the potential they have to regenerate the diversity of native plants,” said Grill.

This post was adapted from an article by Helen Marshall that appeared in the summer 2014 edition of Keep Growing, the member magazine of the Chicago Botanic Garden.


©2014 Chicago Botanic Garden and my.chicagobotanic.org

Interested in new perennials for your garden? How about ones that have proven to be exceptional—fragrant, colorful, drought tolerant, resistant to disease and pests, and hardy in the Midwest and similar climates? Just turn to our scientists, who have done the legwork for you through the Chicago Botanic Garden’s plant breeding and evaluation programs.

Breeding and selecting new perennials is a long, intense process that begins with cross-pollinating two plants, or moving pollen by hand from the flowers of one plant to the flowers of another plant with different traits. The two related plants—which ideally will produce exceptional offspring—are selected for breeding based on desirable attributes.

PHOTO: Jim Ault poses in a bed of bright pink- and purple-blooming asters he developed at the Garden.

Jim Ault, Ph.D., with Symphyotricum (aster) hybrids developed at the Garden

PHOTO: A closeup of the rich purple buds of Twilite false indigo.

Twilite false indigo (Baptisia × variicolor ‘Twilite’)

PHOTO: Using tweezers, Jim Ault hand-pollinates a Baptisia.

Pollinating Baptisia

“In the best-case scenario, from the first cross to the final plant worthy of introduction, it takes about seven years, maybe eight to ten. I have to think long-term in generation time, from seed to first bloom to maturity,” said Jim Ault, Ph.D., plant introduction manager and Gaylord and Dorothy Donnelley Director of Ornamental Plant Research.

The most promising new plants are propagated by cuttings or tissue culture and then scrutinized by the Garden’s Plant Evaluation Program, managed by Richard Hawke. He compares the plants to cultivars and species already in the trade to ensure that the plants from the breeding program are unique and worthy of introduction. Hawke also recommends plants for use as parents in the breeding program.

PHOTO: Richard Hawke crouches down, examining the progress of a cultivar planted at the Garden.

Richard Hawke at work

“The public can see about 80 percent of the breeding program plants as we are growing them in the ground in the evaluation gardens,” Dr. Ault said. Plants with the highest marks move to licensed commercial nurseries that also conduct field and container trials and then propagate the new plants for sale to home gardeners and the horticultural trade.

In recent years, popular offerings from the breeding program have included the first orange coneflower ever released, Art’s Pride coneflower (Echinacea ‘Art’s Pride’), and Forever Pink phlox (Phlox ‘Forever Pink’). “The interest in ‘Forever Pink’ has exploded,” Ault said. “It has three weeks of peak bloom in late May to early June and then it repeat-blooms on about 10 percent of the plant all summer and fall. It’s compact and, unlike other summer-blooming phlox, has had no powdery mildew whatsoever.”

You can expect to see more noteworthy perennials in coming years. Ault is hybridizing several types, including ground-cover phlox, asters, and other genera. “Something really wonderful should bloom this spring out of the hundreds of new seedlings that we’re growing,” said Ault.

Visit chicagobotanic.org/research/environmental/breeding for a full list of the perennials released commercially through the Garden’s Plant Breeding Program.

PHOTO: A closeup of the unusual bright orange color of Art's Pride coneflower.

Art’s Pride coneflower (Echinacea ‘Art’s Pride’)

PHOTO: A bed of a dozen plantings of Forever Pink phlox in full bloom.

Forever Pink phlox (Phlox ‘Forever Pink’)

PHOTO: Tidal Pool prostrate speedwell.

Tidal Pool prostrate speedwell (Veronica ‘Tidal Pool’)

Support for the plant evaluation program is provided by the Bernice E. Lavin Evaluation Garden Endowment, the Woman’s Board Endowment for Plant Evaluation Research and Publication, and the Sally Meads Hand Foundation.

This post was adapted from an article by Nina Koziol that appeared in the spring 2014 edition of Keep Growing, the member magazine of the Chicago Botanic Garden.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

What if the next plant conservation project wasn’t down the street, or in the neighboring county, or far away in the wilderness? What if it was right above your head, on your roof? In our increasingly urban world, making use of rooftop space might help conserve some of our precious biodiversity in and around cities.

PHOTO: Ksiazek bending to examine blooming sedums on Chicago's City Hall green roof.

The green roof on Chicago’s City Hall supports an amazing diversity of hundreds of plant species.

Unfortunately, native prairie plants have lost most of their natural habitat. In fact, less than one-tenth of one percent of prairies remains in Illinois—pretty sad for a state whose motto is the “Prairie State.” As a Chicago native, I found this very alarming. I thought, “Is it possible to use spaces other than our local nature preserves to help prevent the extinction of some of these beautiful prairie plants?” With new legislation at the turn of the century that encouraged the construction of many green roofs in Chicago, it seemed like the perfect place to test a growing hypothesis I had: maybe some of the native prairie plants that were losing habitat elsewhere could thrive on green roofs.

This idea brought me to the graduate program in Plant Biology and Conservation, a joint degree program through Northwestern University and the Chicago Botanic Garden. Here, I am investigating the possibility that the engineered habitats of green roofs can be used to conserve native prairie plants and the pollinators that they support.

PHOTO: Ksiazek examines plants in a prairie, taking data.

Which plant are you? In 2012, I surveyed natural prairies to determine which species live together.

Since I began the program as a master’s degree student in 2009, I’ve learned a lot about how native plants and pollinators can be supported on green roofs. For my master’s thesis, I wanted to see if native wildflowers were visited by pollinators and if they were receiving enough high-quality pollen to makes seeds and reproduce. Good news! The nine native wildflower species I tested produced just as many seeds on roofs as they normally do on the ground, and these seeds are able to germinate, or grow into new plants.

Once I knew that pollinator-dependent plants should be able to reproduce on green roofs, I set out to learn how to intentionally design green roofs to mimic prairies for my doctoral research. I started by visiting about 20 short-grass prairies in the Chicago region to see which species lived together in habitats that are similar to green roofs. These short-grass prairies all had very shallow soil that drained quickly and next to no shade; the same conditions you’d find on a green roof. 

PHOTO: Ksiazek poses for a photo among prairie grasses.

Plant species from this dry sand prairie just south of Chicago might also be able to survive on green roofs in the city.

PHOTO: Plant seedling.

A tiny bee balm (Monarda fistulosa) seedling grows on the green roof at the Plant Science Center at the Chicago Botanic Garden.

PHOTO: Hand holding a seedling; paperwork is in the background, along with a seedling tray.

One of my experiments involves planting tiny native seedlings into special experimental green roof trays. They’re now on top of the Plant Science Center. Go take a look!

I’m now setting up experiments that test the ability of the short-grass prairie species to live together on green roofs. Some of these experiments involved using seeds as a cheap and fast way of getting native plants on the roof. Other experiments involved using small plant seedlings that may have a better chance of survival, although, as any gardener could tell you, are more expensive and labor intensive than planting seeds. I will continue to collect data on the survival and health of all these native plants at several locations, including the green roof on the Daniel F. and Ada L. Rice Plant Conservation Science Center at the Garden.

Ideally, I would continue to collect data on these experimental prairies to see how they develop over the next 50 years and learn how the plants were able to support native insects, such as pollinating bees and butterflies. But I didn’t want my Ph.D. to last 50 years so instead, I decided to collect the same type of data on green roofs that have already been around for a few decades. Because the technology is still relatively new in America, I had to go to Germany to collect this data, where the history of green roofs is much older. Last year, through a Fulbright and Germanistic Society of America Fellowship, I collected insects and data about the plant communities on several green roofs in and around Berlin and learned that green roofs can support very diverse plant and insect communities over time. We scientists are just starting to learn more about how green roofs are different from other urban gardens and parks, but it’s looking like they might be able to contribute to urban biodiversity conservation and support.

PHOTO: Ksiazek collects insects from traps on a green roof in Berlin.

I collected almost 10,000 insects on green roofs in and around Berlin, Germany in 2013.

PHOTO: Closeup of a pinned bee collected from a green roof in Berlin.

I found more than 50 different species of bees on the green roofs in Germany.

Now that I’m back in Chicago and have been awarded research grants from several institutions, I’m setting up a new experiment to learn about how pollinators move pollen from one green roof to another. I’ll be using a couple different prairie plants to measure “gene flow,” which basically describes how pollen moves between maternal and paternal plants. If I find that pollinators bring pollen from one roof to anther, this means that green roofs might be connected to the large urban habitat, rather than merely being isolated “islands in the sky,” as some people have suggested. If this is true, then green roofs could also help other plants in their surroundings—more pollinating green roof bees could mean more fruit yield for your nearby garden.  

PHOTO: Aerial view of Chicago at Lake Michigan, with green rectangles superimposed over building which house green roofs.

The green boxes represent green roofs near Lake Michigan. How will pollinators like bees, butterflies, and moths move pollen between plants on these different roofs? This summer, I will be carrying out an experiment to find out.

There are still many questions to be answered in this new field of plant science research. I’m very excited to be learning so much through the graduate program at the Garden and to be collaborating with innovative researchers both in Chicago and abroad. If you’re interested in keeping up with my monthly progress, please visit my research blog at the Phipps Conservatory Botany in Action Fellows’ page

PHOTO: A wasp drinks water from a flower after rain.

A friendly little wasp enjoys the native green roof plants on a rainy day in Paris.

And if you haven’t already done so, I hope you’ll get a chance to visit the green roof at the Plant Science Center and see how beautiful plant conservation happening right over your head can be! 

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Pioneering Woodland Restoration

Undercover Science

Julianne Beck —  May 10, 2014 — 1 Comment

Tranquil, peaceful, and serene are words often associated with the McDonald Woods, which wrap around the northeastern edge of the Chicago Botanic Garden. But to Jim Steffen, senior ecologist at the Garden, the oak woodland is a bustling center for natural processes and species, and may hold answers to unsolved scientific questions.

PHOTO: Multi-flowered milkweed blooms.

Purple milkweed (Asclepias purpurascens) blooms in the McDonald Woods.

“Nothing out there exists by itself. It’s all a network,” said Steffen. Since he arrived at the Garden 25 years ago, he has used his powers of observation to document, study, and breathe life into the systems that sustain a healthy woodland.

In the late 1800s, most area native oaks were cleared for settlement, leaving behind a fragmented and altered landscape. Invasive plants, including buckthorn and nonnative critters, such as all of our present-day earthworms, moved in. The climate began to change. While many may have thrown up their hands and walked away from this complex puzzle, Steffen saw a treasure.

Taking Flight

At age 15, he began to explore the natural world in earnest and to grow the insight that guides him today. After taking a course in his community, he was federally licensed to band birds for research, a pursuit he followed for another 40 years. As he searched for hawks, owls, and other birds of prey, Steffen couldn’t help but notice the activity beneath his feet. Among the fallen leaves were scuttling rodents, insects, and blooming plants. He realized their presence was integral to the entire community of life in the woods.

PHOTO: A clump of blooming sedge grass.

Carex bromoides is one of many sedge plants essential to the woodland ecosystem.

“I started getting more into how those things are related rather than just narrowly focusing on the birds or the plants,” he said.

Steffen developed a broad ecological background as he pursued his education and worked toward a career in conservation science. He was hired to manage 11 acres of woods alongside a nature trail at the Garden. Now, that management responsibility includes more than 100 acres.

Master Plan

Although he does not expect to recreate the exact natural community of the past, Steffen does aim to grow an oak woodland of today. “My goal is to increase the native species diversity and improve the ecological functioning that is going on in the Woods,” he said.

Early in his career, he successfully advocated to expand the managed area to include adjacent acres. His management activities and detailed inventory work has grown the number of species there from 223 to 405. Of those species, 345 are native to the region.

PHOTO: The woods in winter, showing both cleared, walkable woods and unpassable buckthorn-infested area.

Invasive buckthorn plants are interspersed among the trees on the right, while they have been removed on the left.

The leaf canopy of the second-growth woodland was nearly 100 percent sealed when he arrived. It is now more open, allowing sunlight to punctuate the ground—encouraging the reproduction of oak species and promoting the flowering and seed-set of the native grasses, sedges, and wildflowers. The rewards of his work? Less carbon being released from the soil, improved water retention and nutrient cycling, and a place to bolster native species of plants and animals.

PHOTO: Jim Steffen in full protective gear including helmet and goggles, up in a tree with a chainsaw.

Jim Steffen begins to remove an ash tree infested with the invasive emerald ash borer insect.

Each season brings new challenges. This winter, Steffen, his crew, and hired contractors carefully removed nearly 600 ash trees killed by emerald ash borers, cleared three acres of mature buckthorn, and conducted a six- to seven-acre controlled burn.

“It’s a difficult thing to do,” he said of oak woodland management. Steffen is grateful for each helping hand. “I’d say I’d be about ten years behind if it hadn’t been for my dedicated volunteers who help with the physically demanding work.”

Springing Into Action

This spring, Steffen and his team will begin to collect seed from more than 120 native plants they nurture in the Garden nursery and from dozens more in the woodland.

The process continues through November. It includes plants like the cardinal flower (Lobelia cardinalis), which was once common in Glencoe’s natural areas.

Native woodland plants are grown for seed in the Garden nursery.

Native woodland plants are grown for seed in the Garden nursery.

Berries are collected for seeding.

Berries are collected for seeding.

Steffen also collects seed from external natural areas, bringing new genetic diversity into the Woods to strengthen existing plant populations. (This is an increasingly challenging task, as 50 percent of his collection sites has been lost.) Collected seeds are scattered in prepared areas of McDonald Woods, either in the spring or fall, or sometimes in the middle of winter on top of the snow.

Groundwork

“Everything you see growing, walking, or flying in the woodland is just 10 percent of the picture. In any native ecosystem, probably 90 percent of the diversity is at and below the soil surface,” he said. An entire network of plants and other living organisms exist and interact there, helping to sustain what grows above them. Oak trees and most other native plants rely on entrenched fungi, for example, to deliver nutrients and water or protect them from herbivores and disease.

PHOTO: Closeup of a tiny brown spider clinging to the back side of a leaf.

This tiny Pisaurina spider helps support the woodland ecosystem.

Microarthropods living in the leaf litter and soil, such as tiny springtails and mites, and larger organisms including spiders, also play important roles. Together with a volunteer, Steffen has dedicated 14 years of work to better understanding those interactions. They have found several species never found before in Illinois and some that even appear to be new to science. “We are still identifying some of the things we collected ten years ago,” Steffen said. And similar, rarely studied subcommunities exist higher up in the trees. “That’s another hint as to how complex the system is and how much we don’t know about it,” he added.

Some things are clear. A pioneer of oak woodland restoration, Steffen was among the first to notice that the natural layer of decomposing oak leaves and plant material was vanishing from the ground in the McDonald Woods and most other woodlands in the region. He attributes the effect to higher levels of nitrogen from the decomposing leaves of nonnative plants, and the presence of exotic, invasive earthworms. “Because so many organisms live in that layer and depend on it for survival, they are disappearing,” he cautioned.

But first, it is time to take in the rewards of winter. May is peak season for migrating birds in the Woods, including warblers and flycatchers. Sedges will bloom, along with spring ephemerals such as trillium.

PHOTO: A spare woods has dappled sunlight throughout.

The lush woodland landscape is healthy today.

Activity is everywhere, and it is a welcome sign of progress for Steffen. “It’s much healthier now than it was when I started,” he said. “All this diversity is able to function more easily now.”

The McDonald Woods are also an educational resource. Steffen will lead a rare off-trail hike there this year, and teach classes in bird watching and sedges through the Garden’s Adult Education programs.

Learn more about Jim Steffen and watch a video about his work.

©2014 Chicago Botanic Garden and my.chicagobotanic.org