What is it about?
Big Bluestem is the mist common grass in the Great Plains grassland ecosystem of the United States. The species provides important habitat for wildlife and forage for livestock. We took measurements of the stature of Big Bluestem from across the Plains and related them to the climate at those locations using mathematical models. We then forecasted the stature of the plant under scenarios of likely climate change. We found that by the 2070s in the core of the range where the species is currently most common the stature and biomass of individual plants could decline by 60% or more. Meanwhile, larger plants will be favored in the Great Lakes region, almost 600 miles (800 km) away.
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Why is it important?
Big Bluestem is a "workhorse" species commonly used in prairie restoration. It is also an important forage grass supporting the region's $10 billion livestock industry. Thus, knowing how climate change will affect Big Bluestem is important for anticipating how the prairie at large will respond. Individual plants live up to 50 years, so restoration practitioners should consider not only the plants that are favored in a location now but also the kind of plants that will be favored in the future.
Perspectives
Two lines of evidence give me concern for this species and its ecosystem. First, the physical size of Big Bluestem is strongly determined by its genes. Often the environment will affect a plant's height, but not so much in this case. Second, most reproduction in this species is clonal (ie, the plant sends out runners that emerge as genetically identical copies of the mother). Since all the offspring are genetically the same, there's not much opportunity for natural selection to help the plant adapt. And Big Bluestem can't really respond appropriately to changing climate unless it acquires the appropriate genes. All in all, I expect the genetic changes this species will need to adapt to climate change will have to be facilitated by humans moving plants to locations that become newly favorable as climate changes. The species can't disperse very far or evolve rapidly enough.
Dr. Adam B. Smith
Missouri Botanical Garden
Read the Original
This page is a summary of: Phenotypic distribution models corroborate species distribution models: A shift in the role and prevalence of a dominant prairie grass in response to climate change, Global Change Biology, March 2017, Wiley,
DOI: 10.1111/gcb.13666.
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