Seed-stealing insects hinder prairie restoration

By Liam Tiernan

Bugs hinder prairie restorations more than previously thought, according to research conducted at Michigan State University.

The study, which awaits publication in the Journal of Plant Ecology, indicated that arthropods – which include insects, spiders and crustaceans – account for the majority of seeds removed from prairie restoration sites. The study could catch a lot of attention in the prairie restoration field, said Mary Linabury, an MSU plant biology researcher who authored the study with Lars Brudvig and Nash Turley of the same university.

“In the past I don’t believe that managers believed that arthropods had much of an impact on seed consumption,” said Linabury. “This study says otherwise.”

The findings have ramifications for every prairie restoration project, she said. It could prompt modifications of planting techniques and seed mixes that could drastically increase the number of plants that survive long enough to germinate.

North American prairies are extremely diverse grassland ecosystems that once spread over 200 million acres, according to the National Park Service. Only 1 percent of that habitat remains and many species that depend on it are on the brink of extinction as well.

“Prairies can fit in anywhere there’s space, and of course, there’s a lot of worry about bees, and just a lot of worry about losing biodiversity in general,” Linabury said.

Many Midwestern prairies began to disappear in the early 1900s to make way for farms, according to the American Prairie Reserve, an organization that works with the National Park Service to restore them.

“A lot of prairies were lost to agriculture,” said Ellen Anderson, a habitat restoration expert with the American Prairie Reserve. The massive sizes of farms in the American breadbasket restricted the amount of space prairies had to naturally grow.

Biodiversity, or the variation of life within an environment, is important to maintaining a stable, healthy ecosystem, according to the National Wildlife Federation. Biodiversity allows ecosystems to function properly and allows easier recovery from disasters.

The University of Minnesota has shown that areas with dozens of diverse plant communities are more stable during the extreme variations in weather so common in the Midwest,” according to “Going Native,” a Minnesota DNR handbook for growing prairies by Rebecca Kilde. “A lawn or farm field contains around five species, making them more susceptible to drought, pests and disease.”

“Prairies are a very important ecosystem that hasn’t been protected,” Anderson said. “There have been a lot of national parks to preserve other ecosystems.”

And they help fight climate change by capturing carbon from the atmosphere.

“Prairies do great things for carbon sequestration,” Anderson said. “They are resilient to drought and other large climate change issues, and the plants have resilient roots systems that help resist erosion and can do a lot to buffer runoff into waterways.”

The MSU study showed that arthropods are the primary granivores, or seed-eaters, that eat the grains and legumes sown into prairie restoration areas. It also showed that the later in the growing season, the granivores become more active and eat more seeds.

Other data also indicated that large seeds, such as common prairie legumes, were consumed at higher rates while smaller grass seeds and flower seeds were consumed at much lower rates.

The arthropods became much more active in the later months of the summer, the study said. They consumed only 28 percent of all seeds in May but by July consumed 46 percent. Linabury speculated that warmer temperatures may have caused the insects to become more active.

“In the future this could change the way that seeds are sown,” she said. “They should not be scattered, they should be drilled into the ground. It’s worth considering adjusting the planting dates and the mixes of the seeds as well.”