Ecologists fight for biodiversity

Rami Jameel University of Illinois

Imagine a prairie. How many plant species are seen? Maybe some yellow coneflowers, some little bluestem, perhaps a few asters. But plant ecologists at the University of Illinois Urbana-Champaign say those ecosystems are much more diverse than many people realize.

Midwest plant ecology specialists Jeffrey Matthews, assistant professor in natural resources and environmental sciences, and Jack Zinnen of the Illinois Natural History Survey recently published a database of thousands of plant species found in historic prairies — and that’s just one part of their comprehensive investigation of Midwest plant biodiversity.

Prairies are one of the most endangered native ecosystems in the region — only one percent of tallgrass prairie across Illinois, Iowa and Wisconsin has survived. To build their database, called RELIX, the team gathered and centralized existing data from studies of remnants. Remnants are small patches of ecosystems that survive otherwise widespread destruction. In that case, the researchers studied prairie remnants that have stayed relatively undisturbed since the arrival of Europeans to the continent.

Like prairies, most native wetlands, savannahs and forests have also been degraded or destroyed. Their future depends on intentional plantings, whether that’s in nature preserves, gardens or nature strips along roads and highways. People might even see prairie nestled between fields of corn and soy, as farmers cultivate native plants for the Conservation Reserve Program.

Whether people are landscapers, conservation managers or farmers, they need to buy those plants from somewhere. That means the future of Midwestern plant ecosystems depends on seed and plant vendors. By analyzing the gaps between the plants people can get and the plants that used to be available, Matthews and Zinnen hope to bring biodiversity back to the Midwest.

“Seed mixes are enormously valuable, even if they’re flawed or not very diverse,” Zinnen said. “But progress can be made by getting some more of these species in.”

In addition to uncovering the biodiversity of a bygone era, the project is helping ecologists understand whether restored ecosystems fill the same roles as remnants, especially whether they provide sufficient habitat and food for key species.

Survey native plant landscape

Matthews and Zinnen began by creating databases of commercially sold seeds and plants. In 2022, the team documented plants sold by more than 500 plant vendors, as well as all the species in more than 1,000 seed mixes commercially available in the Midwest. The databases revealed a significant lack of biodiversity -- less than half of regional native plants were commercially available, and many seed mixes overemphasized certain plants at the expense of others.

With a better understanding of who was selling what, the researchers could now dive deeper. In a 2024 paper published in Ecological Applications, they studied the influence of plants’ ecological characteristics on their commercial availability. They found that long-lived hardy species were more available than their more ecologically sensitive counterparts, and certain plant groups and families were heavily over- or underrepresented.

Matthews said, “There’s a typological mindset -- ‘A prairie is supposed to look like this.’ What we’re finding in all the remnants is that it's not just typical prairie species. There are forest species, wetland species creeping in at the edges from the adjacent forest or marsh — not just the standard species that were overrepresented in the commercial landscape.”

Informed by his previous career in the native plant industry, Zinnen also believes that commercial viability is a key factor. During his doctoral studies, Zinnen researched “conservative” plant species. Those plants are sensitive to environmental degradation and need high-quality ecosystems to grow. They might be difficult to cultivate and collect seeds from, so they’re less likely to be found in native plant nurseries or seed mixes.

As a result of the “typological mindset” and commercial restraints Matthews and Zinnen described, restored ecosystems are markedly less diverse than remnants. It’s a feedback loop, Matthews said.

“Most people’s experience of prairie ecosystems are restorations, not remnants. So when these low-diversity standard seed mixes are used, that reinforces the typical idea of what a prairie looks like,” Matthews said.

Why restore biodiversity?

Matthews' and Zinnen’s love for native Midwest ecosystems is clear, and they believe in the intrinsic worth of high-quality diverse restoration projects. However, they also emphasized the practical benefits of improved restoration -- plant diversity is the basis for overall biodiversity, they said.

The team revealed the potential implications of less-diverse restorations in another 2024 paper, published in Restoration Ecology, in which they compared pollinator seed mixes to prairie remnants across the Midwest. They found a critical lack of early-blooming species, meaning pollinators that become active in the spring might not find enough food to eat in plots planted with those seed mixes.

Diverse high-quality prairies and wetlands can support a dazzling variety of insects, including pollinators that are vital for maintaining the food supply. More plant species mean more diverse and numerous insect populations — a vital ecological need as insects decline worldwide. Those insects are also food for other animals, such as birds, mammals, amphibians and reptiles. Less diverse ecosystems, by contrast, support fewer animals.

Zinnen said, “As we say in ecology, diversity begets diversity."

And as plant diversity is lost, much more than animal habitat is lost. Most plant matter in prairies is underground, in deep dense root networks. Those roots are important food sources for insect larvae, but they also store carbon underground, prevent soil erosion, and are involved in a staggering number of interactions with fungi, bacteria and other soil creatures. Therefore, preserving prairie plant diversity is critical to the overall health of ecosystems and climate.

Matthews and Zinnen hope to continue studying the commercial availability of native plants and related restoration outcomes. RELIX will be fundamental to their work going forward, as they start to survey restored prairies and compare them to remnants. They’ve also narrowed down about 2,000 observed plant species to a list of the 900 most common ones — so prairie plant vendors and restoration practitioners can translate the team’s research into results on the ground.

The more that is known about Midwestern plant species and the communities they form, the better researchers will be able to bring them back to Illinois. Understanding the makeup of historic ecosystems is critical to inform restoration practices; vendors and planters can choose species that are resilient, easy to plant, and fill necessary ecological roles. Zinnen suggests rounding out pollinator mixes by adding hardy spring bloomers, like wild strawberry, wild garlic, golden alexander, spiderwort and wild indigo.

The study, “RELIX: A Dataset of Vascular Plant Species Presence for 353 Prairie Remnants in the Midwestern United States, with Prairie Remnant Metadata,” is published in Natural Areas Journal. Authors include Jack Zinnen, Marissa Chase, Brian Charles, Justin Meissen and Jeffrey Matthews.