Two comprehensive studies by the University of California at Davis lend support to continued cattle grazing in the national forest.
The first study, published June 27 in Plos One, is billed as “the most comprehensive examination of water quality on national forest public grazing lands to date.”
The second, published in the same scientific journal, gave the results of a five-year study that concluded that cattle grazing in the national forest had no effect on the population of Yosemite toads. Scientists will have to look elsewhere for the cause of that toad’s decline, most likely disease similar to the fungus with which the Pacific chorus frog is infecting yellow-legged frogs.
The June 27 publication was a result of a study conducted June through November of 2011 in which nearly 40 UCD researchers, ranchers, Forest Service staff and environmental “stakeholders went out by foot and on horseback, hiking across meadows, along campsites and down ravines to collect 743 water samples from 155 sites across five national forests in Northern California.”
The study area included grazing areas, recreational lands and places where neither were found. The UCD researchers analyzed water samples for microbial content, including fecal coloform, E. coli, nitrogen and phosphorous.
“They found no significant differences in fecal indicator bacteria between grazing lands and areas without recreation or grazing. Overall 83 percent of all sample sites and 95 percent of all water samples collected were below U.S. Environmental Protection Agency benchmarks for human health.”
The importance here is that about 1.8 million livestock graze on national forest lands in the Western United States annually. In California there are 500 active grazing allotments serving 97,000 livestock across 8 million acres in 17 national forests.
The Yosemite toad study was a five-year study in which cattle were fenced off from toad habitat — basically marshes. Fencing the cattle off from toad habitat had no effect on the toad population.
“We basically found the Yosemite toad and cattle use the landscape differently,” said Ken Tate, principal investigator and rangeland watershed specialist for UC Cooperative Extension. “The toad uses water areas and the cattle use drier meadows, which provides better forage.”
The results of the study found “no benefit of fencing to Yosemite toad populations.” Also, it pooh-poohed previous studies that claimed negative impacts on toads from cattle grazing: Results “do not support previous studies that found a negative impact of grazing on amphibian populations.”
A five-year study is pretty comprehensive and definitive. What’s needed now is San Francisco State University researchers to apply the same research intensity to the Yosemite toad that they did to the yellow-legged frog, which they discovered was susceptible to a fungus carried by the Pacific chorus frog, which migrated upstream.