Scientists at the Missouri Botanical Garden, Kansas State University, and Southern Illinois University–Carbondale have completed an analysis of the effects of climate change on a dominant and economically important grassland plant.
Big Bluestem (Andropogon gerardii) is a common grass in natural and restored prairies that extend across the central Midwestern region (Kansas, Nebraska, Oklahoma, Missouri, and Iowa) and is an important component of forage for the region’s $10 billion livestock industry. It is also commonly used as an ornamental owing to its size and showy, purplish flowers and seed heads. Within the Midwest Big Bluestem can grow to 4-6 feet tall, but the researchers found that climate change could reduce height by up to 60% in the next 75 years. As a result, the form of Big Bluestem that grows in the central Midwest could come to resemble the form that currently inhabits eastern Colorado on the edge of the species’ range. Meanwhile, the tall forms of the Midwest could shift to the Great Lakes region where Big Bluestem is currently smaller and less common.
The authors are concerned the dramatic reduction in size of Big Bluestem foretells a fundamental shift in the nature of the Midwestern grassland ecosystem. “It was said in the past that the tallgrass prairies were so tall that a person riding a horse could literally get lost,” says Dr. Adam Smith, lead author of the study and researcher in the Global Change Lab of the Garden’s Center for Conservation and Sustainable Development.
“Big Bluestem is an iconic species in this system owing in part to its stature. If smaller forms come to dominate it could cause a fundamental shift in the habitat and ecosystem services prairies provide,” Smith continues. Most of the change was due to alterations in rainfall expected to occur across the area, not increases in temperature. “Our study also highlights why the term ‘global warming’ is inadequate—all aspects of climate are changing and affecting the natural world—not just temperature,” says Smith.
Photo: Jessie Harris