The Non-Technical Way to Preserve California Grass

Newswise – Although they are disappearing, California’s state grass has the potential to live for 100 years or more. New research shows that sheep and cattle can help them achieve such a long life.

The purple needle plant dominated the state’s grasslands, where it was used as food for Native Americans and more than 330 wild creatures. Today, California has lost most of its grassland, and this herb occupies only a tenth of what is left.

It is drought tolerant, promotes the health of native wildflowers by attracting beneficial root fungi, burns slower than non-native weeds and speeds post-fire recovery of scorched lands. For these and other reasons, many who work for habitat restoration hope to conserve the needle.

“Where they grow, these tall, slender clusters become beautiful, ecologically beneficial focal points,” said Lorale Larios, a plant ecologist at the University of California, Riverside. “However, identifying successful management strategies for species that can live for hundreds of years is challenging.”

To meet this challenge, Larios teamed up with University of Oregon plant ecologist Lauren Hallett and the East Bay Regional Park in Northern California. They tracked the health of nearly 5,000 individual needle grass blocks over a six-year period, including an El Niño rain year as well as a historical drought.

The researchers took plant health measurements including growth and seed production. They put small bags on several clumps of grass to catch the seeds and to determine how many seeds they produce.

Their findings now published In the Journal of Applied Ecology, did the purple needle perform better in places where sheep are allowed to graze. The positive effects of grazing in times of wetter weather were amplified.

Previously, the park district has spent a decade trying to assess the success of grassland conservation techniques. However, the region’s method of applying a strategy such as grazing, and then measuring the percentage of needlegrass clumps in a given region resulted in data that did not follow a discernible pattern from year to year.

“By tracking each plant over time, rather than scanning widely across an area, we gained more clarity about how the grass responds to grazing,” Larius explained. “Perhaps unexpectedly, we saw that the needle generally died out when the sheep were not allowed to graze on it.”

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

Grazing is a controversial strategy for grassland restoration. Some conservationists believe that sheep eating their target grass, especially during already stressful drought years, does not enhance their survival. Since the 19th century, some researchers have hypothesized that the combination of grazing and drought led to the loss of perennial grasses.

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

“Sometimes you get a waste as deep as a pencil—a lot of dead, non-native weeds build up. It’s hard for a small seed to get enough light through all of that,” Larius said.

Second, sheep eat non-native weeds that generate growth-inhibiting debris and compete with the purple needle for resources.

When the Spaniards colonized California, they brought in forage grasses such as wild oats that they thought would benefit livestock. Those introduced grasses spread, and now dominate the state’s grasslands.

“Our territory is known as one of the largest biological invasions in the world,” Larius said.

California has up to 25 million acres of grassland, the equivalent of the combined areas of Massachusetts, Connecticut, and Rhode Island. Although Larius did not think that it was possible to get rid of the condition of all non-original herbs, she said that it was possible to maintain or even increase the amount of Purple Needle.

“It’s great for storing carbon, which mitigates climate change, isn’t used as fuel for wildfires, and it grows space for wildflowers that pollinators can then use,” Larius said. “We want to keep all these benefits.”