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SCIENTISTS ANALYZE EFFECTS OF CLIMATE CHANGE ON A DOMINANT MIDWESTERN PLANT

 (ST. LOUIS): Scientists from the Missouri Botanical Garden, Kansas State University and Southern Illinois University-Carbondale completed a study on the effects of climate change on one of the Midwest’s most dominant and economically important grassland plants. The results have been published by the peer-reviewed journal Global Change Biology.

Big Bluestem (Andropogon gerardii) is a common grass in natural and restored prairies that extend across the central Midwestern region that includes Kansas, Nebraska, Oklahoma, Missouri and Iowa. It is an important component of forage for the region’s livestock industry. It is also commonly used as an ornamental owing to its size and its purple flowers and seed heads. Within the Midwest, Big Bluestem can grow to be 4-6 feet tall, but the researchers found that climate change could reduce height by up to 60 percent 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. 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 tall grass prairies were so tall that a person riding a horse could literally get lost. 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 such as forage for cattle,” said Dr. Adam Smith, of the Missouri Botanical Garden.

“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.”

Big Bluestem is commonly used in prairie restorations. However, individuals can live several decades, so restoration projects will need to consider the form of plants that would thrive at a site several decades into the future, not just now. Climate change creates a moving target making matching plants to their favored environments even harder.

The analysis also highlights the effects of climate change on common species that typically are not expected to be as vulnerable to anticipated climate change. Worldwide 1 in 5 plants is already on the brink of extinction and climate change is only expected to add pressure on species struggling to survive. This study indicates that common species may also be vulnerable.

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