Saving the Guadalupe fescue

West Texas is known for arid landscapes reminiscent of old Western movies rather than cool damp mountains 6000 feet in altitude. But this is what areas of the Chisos Mountains are like, and where UT researchers have been surveying a rare grass, the Guadalupe fescue (Festuca ligulata).

While once so abundant that cattle grazed on it, Guadalupe fescue was added to the endangered species list in 2017. It currently grows on protected acreage in its last known location in the US: Big Bend National Park.

Growing about a foot in height, the Guadalupe fescue is a rhizomatous perennial grass, sending out roots and shoots from underground stems and living for several years. It is considered a relict of the Ice Ages. This period in earth’s history began 2.4 million years ago and lasted until 11,500 years ago. During that time, West Texas was cooler and wetter than now, forests expanded downslope, and the Guadalupe fescue probably thrived at lower elevations than it does now. When the climate warmed after the last Ice Age, the region also dried and the grass “retreated” to the higher elevations of the Chisos and Guadalupe Mountains. It was first collected there in 1931. The population in the Guadalupe Mountains is likely gone as it was last documented in 1952.

Many factors have contributed to the decline of the plant, including livestock grazing, trampling by off-trail hikers, drought, competition from invasive species, and erosion. Not much is known about how the plant reproduces, but some theories suggest that because grasses are wind-pollinated, having small and scattered populations make successful pollination less likely.

Another factor in the decline is the loss of regular wildfires, wildfires being "nonstructural" fires that burn vegetation, not buildings. Throughout human history, humans have been practicing controlled burns, understanding the benefits to ecosystem health and ultimately to our natural resources. For much of the modern world, this practice has disappeared based on changing attitudes that all fires, natural or not, are bad. This has unintentionally caused destructive results to ecosystem health. Most of us remember Smokey Bear. While this animal in a ranger's hat gave out good advice about extinguishing campfires and cigarette butts, his PSAs should not be interpreted to mean that wildfires are always bad.

In reality, natural wildfires play a crucial and regenerative role for many ecosystems. Their benefits are many and include removing invasive species and returning nutrients to the soil, and for some plants wildfires are necessary for growth and reproduction. For the Guadalupe fescue, it’s possible that periodic wildfire clears leaf litter that otherwise inhibits growth.

Recently, concerned botanists from the U.S. Fish and Wildlife Service discovered some problems with older sampling methods of known Guadalupe fescue populations. In order to get a more accurate picture of this grass’ population, they brought out Dr. Norma Fowler and members of her lab in the Department of Integrative Biology to do statistically-valid sampling.

A grant from the Texas Parks and Wildlife Department, which distributed funds from the U.S. Fish and Wildlife Service for the study of endangered species, funded the research. Carolyn Whiting, a PhD student in Fowler’s lab, took the lead on the project. Her team took a different approach from the old permanent plot sampling methods used in the 1990s, which had introduced biases in estimates of the species abundance. Instead, her team counted plants within designated plots distributed randomly in the plant’s known range.

There is some good news from their work. They’ve discovered the plant’s population is much larger than previously thought. That number is about 2000 individuals versus the previous estimate of approximately 100 individuals. This difference is largely because the initial plots set up decades ago didn’t take into account the way a plant’s local distribution shifts over time: think of it as the plant population playing 'musical chairs' within a particular site.

As with so many other species, this grass is threatened by climate change. It manages to survive in challenging conditions with little rain, but in even drier weather, it may not be able to continue to survive.

Whiting’s work is included in a recovery plan for the Guadalupe fescue that was published in May of this year. Additionally, a wildfire from April of this year will allow Whiting and researchers from the U.S. Fish and Wildlife Service the opportunity to study its effects on the grass.

Want to learn more about the role wildfires play in healthy ecosystems? Dr. Fowler and Carolyn Whiting spoke with KUT's Rebecca McInroy for the Views and Brews series. Watch interview by clicking here.

Thanks to Dr. Norma Fowler and Carolyn Whiting for their edits to this piece.

SOURCES:

Buzek, Aubry. Researchers Discover New Individuals of Rare Plant at Big Bend National Park, May, 2021 (accessed online: https://www.fws.gov/southwest/stories/2021/GuadalupeFescue.html

“Ecological Benefits of Fire” National Geographic, January 15, 2020. (accessed online: https://www.nationalgeographic.org/article/ecological-benefits-fire/

“Endangered and Threatened Wildlife and Plants; Endangered Species Status for Guadalupe Fescue; Designation of Critical Habitat for Guadalupe Fescue.” Fish and Wildlife Service. Federal Register, the Daily Journal of the United State Government. September 7, 2017. (accessed online: https://www.federalregister.gov/documents/2017/09/07/2017-19001/endangered-and-threatened-wildlife-and-plants-endangered-species-status-for-guadalupe-fescue)

KUT’s Views and Brews: The Science of Wildfires, April 20, 2021. (https://www.facebook.com/watch/live/?v=731403167541208&ref=watch_permalink)

Robinson, Michael. Texas Grass is First Endangered Species Protected Under Trump. Center for Biological Diversity. September 6, 2017. (accessed online: https://www.biologicaldiversity.org/news/press_releases/2017/guadelupe-fescue-09-06-2017.php)