Although it is dying out, California’s state grass has the ability to live for 100 years or more. New research shows that sheep and cattle can help achieve that longevity.
Purple needles once dominated the state’s grasslands, serving as food for Native Americans and more than 330 terrestrial creatures. Today, California has lost most of its grasslands, and needlegrass only contains about one-tenth of what remains.
It is drought tolerant, promotes native health by attracting beneficial root fungi, burns slower than native grasses, and accelerates post-fire recovery of burned lands. For these and other reasons, many people working to restore habitat hope to preserve the needle.
“Where it grows, these tall, slender clusters become focal points, beautiful and environmentally beneficial,” says UC Riverside plant ecologist Lorale Larios. But identifying successful management strategies for a species that can survive for two centuries is challenging.
To tackle that challenge, Larios teamed up with University of Oregon plant ecologist Lauren Hallett and Northern California’s East Bay Regional Park District. They tracked the health of nearly 5,000 individual needlegrass clumps over six years, including an El Niño rainy year and a historic drought.
The researchers took measures of plant health, including growth and seed production. They put small bags on several piles of hay to catch the seeds and measure the seeds they produced.
Their findings, now published in the Journal of Applied Ecology, show that grapevines do better in areas where sheep are allowed to graze. The positive effects of grazing increased during wet weather.
Previously, the park district spent a decade evaluating the success of its lawn care techniques. However, the district’s method of measuring pasture and then the percentage of needlegrass clumps in a given area yielded data that did not follow a discernible pattern from year to year.
“By tracking each plant over time, instead of surveying it extensively in every area, we get a much clearer picture of how the grass responds to grazing,” Larios explains. “Perhaps on the contrary, we have seen that the needle has generally died by not allowing the sheep to graze on it.”
When the sheep were removed from the study site, all needles were healthy except for two sites. The researchers wanted to see if the two sites that remained healthy contained genetically distinct needles.
Grazing is a controversial strategy for grassland restoration. Some conservationists believe that sheep do not increase their survival when they eat the target grass, especially during stressful drought years. In the year In the 1800s, some researchers speculated that a combination of grazing and drought was responsible for the loss of perennial grasses.
Although drought was not beneficial to the plants in this study, the researchers believe that grazing helped needlegrass survive in at least two ways. One, by trampling leaf litter and other organic debris, sheep make room for new needle grass.
“Sometimes you’ll find dirt that’s as deep as lead — lots of dead, non-native grasses piled up. It’s hard to get enough light for a small seed in all of this,” Larios said.
Second, sheep eat non-native grasses, which produce growth-suppressing debris and compete with purple needlegrass.
When the Spanish colonized California, they brought pasture grasses like wild oats that they thought would be good for cattle. The introduced grasses have spread, and now dominate the state’s grasslands.
“Our grasslands are known as one of the greatest biological invasions in the world,” Larios said.
California has up to 25 million acres of grasslands, equal to the combined areas of Massachusetts, Connecticut, and Rhode Island. Although Larios doesn’t believe it’s possible to eliminate all non-native grasses, she said it’s possible to maintain or increase purple needles.
“It’s good for carbon storage, it mitigates climate change, it doesn’t act as wildfire fuel, and it makes room for wildflowers, which pollinators can then use,” Larios said. “We want to keep all these benefits.”
(Cover image: Pedro Carrillo/iStock/Getty)