The tech-free way to preserve California’s state weed


Although it is dying out, California’s official state grass has the ability to live for 100 years or more. New research shows that sheep and cattle can help him achieve this longevity.

Purple needlegrass in the foreground. (Loralée Larios/UCR)

The purple aiguillette once dominated the state’s grasslands, serving as food for Native Americans and more than 330 land creatures. Today, California has lost most of its grasslands, and the aiguillette occupies only a tenth of what remains.

It is drought resistant, promotes the health of native wildflowers by attracting beneficial root fungi, burns slower than non-native grasses, and speeds recovery from scorched land fires. For these and other reasons, many of those working in habitat restoration hope to preserve the aiguillette.

“Where it grows, those tall, slender clusters become focal points, beautiful and beneficial to the environment,” said Loralee Larios, plant ecologist at UC Riverside. “However, identifying effective management strategies for a species that can live for a few hundred years is a challenge.”

To tackle this challenge, Larios partnered with University of Oregon plant ecologist Lauren Hallett and the East Bay Regional Park District in Northern California. They tracked the health of nearly 5,000 individual needlegrass clumps over six years, including a year of El Niño rain as well as a historic drought.

plant ecologists in the field
Plant ecologists Loralee Larios, UCR, and Lauren Hallett, University of Oregon, monitor the purple aiguillette in Northern California. (Stella Cousins/University of Michigan)

Researchers measured plant health, including growth and seed production. They placed small bags over many clumps of grass to capture seeds and quantify the number of seeds they produced.

Their discoveries, now published in the Journal of Applied Ecology, were that the purple aiguillette did best in places where sheep were allowed to graze. The positive effects of grazing were amplified during periods of wetter weather.

Previously, the park district spent a decade trying to gauge the success of its grassland maintenance techniques. However, the district’s method of applying a strategy like grazing and then measuring the percentage of needle grass clumps in a given area yielded data that did not follow a discernible year-to-year trend. .

“By tracking each plant over time, rather than sweeping an area broadly, we got a lot more clarity on how grass responds to grazing,” Larios explained. “Perhaps counterintuitively, we saw that the aiguillette generally died when sheep were not allowed to graze on it.”

tuft measurement
Measure the size of an individual clump of grass to gauge its health. (Loralée Larios/UCR)

When the sheep were removed from the study sites, the aiguillette in all but two sites became less healthy. The researchers would like to know if the two sites that remained healthy have genetically distinct needle grasses.

Grazing is a controversial grassland restoration strategy. Some conservationists believe that sheep eating the targeted grass, especially in already stressful drought years, does not improve their survival. As early as the 1800s, some researchers hypothesized that the combination of grazing and drought resulted in the loss of perennial grasses.

Although the drought was not beneficial to any of the plants in this study, the researchers believe grazing helped the needle grass survive in at least two ways. First, by trampling leaf litter and other organic debris, the sheep created space for new needle grasses to grow.

“Sometimes you get trash as deep as a pencil – so much dead, non-native grass builds up. It’s hard for a small seed to get enough light through it all,” Larios said.

Second, sheep eat non-native grasses that generate debris that suppress growth and compete with purple grass for resources.

When the Spanish colonized California, they brought forage grasses like wild oats which they thought would be beneficial to livestock. These introduced grasses have spread and now dominate the state’s grasslands.

“Our grasslands are known to be one of the greatest biological invasions in the world,” Larios said.

California has up to 25 million acres of grassland, which is equal to the areas of Massachusetts, Connecticut and Rhode Island combined. While Larios doesn’t think it’s possible to rid the state of all non-native grasses, she said it’s possible to maintain or even increase the amount of purple needles.

“It’s great for storing carbon, mitigating climate change, not being used as fuel for wildfires, and cultivating space for wildflowers that pollinators can then use,” Larios said. “We want to keep all these advantages.”

(Cover image: Pedro Carrilho/iStock/Getty)


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