GALT - Fairy shrimp, the rare tiger salamander, the solitary bee - rare critters that live in seasonal rainwater pools in California's grasslands - may actually benefit from having large, heavy-footed cattle grazing around their habitat.

Several biologists looking closely at what happens in these vernal pools say the diversity of the ephemeral fauna and flora in the water increases when cows keep weedy non-native grasses under control.

"The plants and the shrimp are very delicate, but it works," said Jaymee Marty, an ecologist at the Cosumnes River Preserve, which was created to prevent further development along the only undammed river that flows from the Sierra Nevada into California's Central Valley.

When cows munch on the invasive Mediteranean grasses that blanket the surrounding hills, vernal pool natives like the frothy white Meadowfoam and the tiny yellow Goldfields are more likely to bloom, Marty said.

She surrounded 72 pools with electrified wire and alternated periods of grazing for three years. In cow-free areas, a thick tangle of grass grew five feet tall, obscuring the ground. "The only thing that can grow in this situation is more grass," Marty said.

The 40,000-acre preserve just south of Sacramento is operated by the Nature Conservancy together with other environmental groups such as Ducks Unlimited, as well as the U.S. Bureau of Land Management and the California Department of Fish and Game. Its mission is to preserve the streamside habitat and restore wetlands while demonstrating the compatibility of human uses, including ranching, with wildlife.

Marty's observations, which she plans to submit to peer-reviewed journals, suggest that a partnership of ranchers and environmentalists - of cows and fairy shrimp - might be just what's needed to protect such seasonal pools.

Similar evidence has been gathered by Joe Silveira, a wildlife biologist working for the U.S. Fish and Wildlife Service at the Sacramento National Wildlife Refuge Complex in Willows. When cattle there were removed to manage water routes, the diversity of fauna found in a twice-monthly count went down.

And it wasn't just the little guys - the tadpole shrimp and the salamanders - that disapeared. The removal rippled all the way up the food chain. Silveira found fewer ducks, Sandhill cranes and Canada geese, and less waterfowl also meant fewer bald eagles.

"But it didn't surprise me, and it didn't surprise the cowboys," Silveira said.

The rare creatures found in the short-lived ponds are adapted to a unique regimen. The area floods completely in the winter, sprouting seeds, hatching salamander eggs and opening the cysts that hold the shrimp's eggs.

The shallow water then becomes a site of frenzied activity - the animals grow and mate, and the plants quickly flourish and bloom, surrounding the pools with splashes of fresh flowers that often attract visitors.

Marty found that cattle prefer eating imported grass over lower-lying native vegetation, clearing space for the native plants to sprout and preserving the water. Fast-growing grasses can suck up water like straws, drying up pools too quickly for the tiger salamander, an endangered animal that needs at least 90 days in a deep pool to lay its eggs and prepare for the dry season.

Ponds in grazed areas lasted an average of 105 days, Marty found. Those in areas where cattle was removed only lasted about 45 days.

Some experts hesitate to endorse these findings until they've been reviewed by other researchers. There's scant scientific literature on the topic - few studies have focused on the tiny plants that grow in vernal pools. One 1965 study determined that cattle in open ranges seemed to prefer eating native plants - but a 1996 article seemed to point out that vernal pool natives benefit from having cattle around.

"There is little or no compelling hard science published in peer-reviewed journals that would support the argument that livestock grazing is beneficial to native, vernal pool-dependent species," said Todd Shuman, California director of the Western Watersheds Project, an organization that works to restore watersheds.

"Having cattle hit the area might be part of the solution (for vernal pools), but using that approach might prevent other native plants from coming back," added Schuman, who would prefer to remove the cattle and replant grasslands with native plants - a solution he concedes is expensive and unlikely.

Other experts praised the research for testing what years of anecdotal evidence already suggested.

"In the past people have had concerns, and have taken grazing off, and found out that they end up with fields of weeds," said Carol Witham, president of the California Native Plant Society, and founder of vernalpools.org, a group dedicated to saving California's vernal pools.

Many of these pools rest on thick layers of clay that hold the water. But not far from Marty's neatly fenced-off squares of grazed and ungrazed land stand rows and rows of grape vines, growing in soil that has been deep-ripped to prevent standing water.

The gentle roll of the landscape also invites housing developments - neighbors that neither the environmentalists nor the ranchers want.

Researchers estimate that only 10 percent of California's vernal pools remain - and most of them are in privately owned ranchland. More intensive agriculture and urban development continue to threaten what's left.

One such development in the news lately is the University of California's 10th campus, to be built in Merced. In January, the U.S. Fish and Wildlife Service removed a possible hurdle to construction by declining to classify the Midvalley fairy shrimp as an endangered species that would merit greater protection.

The idea that cows might help protect shrimp pleases Jim Chance, 66, who grazes his cattle on the ranch in the preserve where Marty collected her data.

"I suspected that would be the case," he said, "because there was lots of fairy shrimp in those pools, and that's how the grass has been handled for 100 years."

On the Net:

http://www.cosumnes.org

http:www.vernalpools.org