Schwinning Lab

Plant Ecology

Yang Tse

Invasive grasses

KR bluestem

Yellow bluestem forms nearly monocultures on Texas rangelands
Johnsongrass seedling

A Johnsongrass seedling grows faster than the seedlings of many native grasses our research showed

The invasion of American grasslands by exotic grasses poses a challenge to grassland management, but also some interesting questions for community ecology: Why is it that some grass species introduced from grasslands in Europe, Asia or Africa have been so exceptionally successful that they were able to dramatically reduce the occurrence of native grasses in American grasslands? For example, in Texas, yellow bluestem (Bothriochloa ischaemum) forms nearly pure stands where previously big bluestem, little bluestem and switchgrass were abundant. At the surface of it, there seems to be nothing special about the introduced species that would explain their competitive advantage over native species.

Our lab approaches these questions and challenges from two directions. In collaboration with Phillip Fay and Wayne Polley at USDA/ARS, and through funding from USDA, we have conducted greenhouse experiments to examine when and how invasive species establish competitive dominance over native species and what traits are involved. On the issue of combating invasive grasses in the field, we have been collaborating with Kelly Lyons at Trinity University in San Antonio to investigate if there are conditions under which invasive grasses such as yellow bluestem are especially vulnerable to grassland fire. By identifying such vulnerabilities we will be able to give management recommendations on how to target native species through prescribed burns while reducing collateral damage to native species.


Reichmann, L.G., Schwinning, S., Polley, H.W,, Fay, P.A. 2015. Traits of an invasive grass conferring an early growth advantage over native grasses. Journal of Plant Ecology DOI:10.1093/jpe/rtw014 pdf

Havill, S. Schwinning, S., Lyons, K.G. 2015. Fire effects on invasive and native warm-season grass species in a North American grassland at a time of extreme drought. Applied Vegetation Science 18:637-649 pdf




Lab News

Recent student presentations

Beth Crouchet and Nathan Custer presented on their research at the 2015 International Research Conference for Graduate Students at Texas State University, November 17 - 18, 2015:

Site factors influencing tree mortality during drought in Texas. Beth Crouchet, Susan Schwinning, Jennifer Jensen, Benjamin Schwartz.

Determining seed transfer zones for Mojave Desert shrubs. Nathan A. Custer, Susan Schwinning, Lesley A. DeFalco, and Todd C. Esque.

Highlighted publications

Scott Havill's paper on "Fire effects on invasive and native warm-season grass species in a North American grassland at a time of extreme drought" was highlighted in the October 2015 issue of Applied Vegetation Science (link).

Other lab news

The following students received awards and recognitions in the academic year 2015/16:

Beth Crouchet and Nate Custer received the Biology Department's "Certificate of Excellence"

Beth Crouchet was inducted into the National Honor Society of Phi Kappa Phi

Beth Crouchet received the the Graduate College Scholarship - Science & Engineering and the Lamar and Marilynn Johanson Graduate Endowment Award.

Wesley Collins received a Freeman Center Scholarship.

The lab was awarded two federal grants in 2015:

NSF proposal : DEB-1557176: "Collaborative Research: Hydrological tipping points and desertification of semi-arid woodlands".

The DOD Legacy Award HQ0034-16-2-0006: "Characterizing Mojave Desert shrub ecotypes to establish seed transfer zones for military range restoration".

Podcast interview

In September 2013, Susan was interviewed by Alan Knapp on a paper published in Functional Ecology. Listen to the podcast here.

Contact information
Susan Schwinning
601 University Drive
312 Supple Science Bldg
Texas State University
San Marcos, TX 78666, USA
Phone: (512) 245-3753
Fax: (512) 245-8713

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Biology Department
Texas State University

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