ARIVACA, Ariz. -- Jim Chilton is one of hundreds of ranchers targeted by environmental groups for allegedly allowing cattle to despoil the West's backcountry. Now Mr. Chilton is showing ranchers how to turn the tables on the green groups by using their own playbook.

The Center for Biological Diversity in Tucson is known for its lawsuits against ranching practices -- and for its methods of posting photos on the Internet that it says depict land destruction. So when the Center came after Mr. Chilton, he struck back with a defamation suit in Arizona Superior Court in Tucson last year.

He produced his own photos of lands the group claimed he spoiled in order to argue that their photos had exaggerated the damage. He snapped one photo, for example, of a hillside featured on the Center's Web site to show that what looked like barren earth was just a tiny patch surrounded by lush grass.

After a jury trial this year, Mr. Chilton was awarded $600,000, including $500,000 in punitive damages against the environmental group. "I had to decide whether I was a cowboy or a wimp," Mr. Chilton says. "I decided to be a cowboy ... and not ignore people saying bad things about my ranch." The Center denies wrongdoing and has appealed the decision.

For years, environmental groups have worked to curtail grazing on national forests and other public ranges, arguing that cows eat too much grass, destroy young trees and turn streams into fetid mud holes. The groups have sued the government for generations-old grazing practices, seeking closure of grazing lands. Often, the environmentalists have won big-dollar awards, partly because of their highly persuasive way of showing damage to lands through photos.

A third of the Center's $3 million in income in 2003 mainly came from court awards and settlements. Center officials say much of the money from those awards covers the group's legal costs. Much of its other money comes from such things as membership dues, donations and foundation grants.

The 66-year-old Mr. Chilton's adoption of the green group's own methods shows how the environmentalists' techniques can be turned against them. His case, if upheld, could spark a legal uprising by ranchers against environmentalists, experts say. The suit "has given hope to a lot of ranching families," says C.B. "Doc" Lane, executive vice president of the Arizona Cattle Growers' Association.

Mr. Chilton's story resembles that of many others in the West's cowboy country. A fifth-generation descendant of frontier settlers, he often spends 12-hour days in the saddle in a patch of rugged mountains along the Arizona border with Mexico. Mr. Chilton purchased grazing rights on the 21,500 acres, known as the Montana allotment, under a 10-year lease from the U.S. Forest Service in 1991 for $750,000. When that lease expired, he renewed for another decade.

Besides ranching, Mr. Chilton is president of a Los Angeles municipal investment bank that he co-founded, which his oldest son now largely runs. Ranching, though, is his first love; he still keeps the first saddle he got as a child in a barn, where it is now used by his 4-year-old grandson.

Several years ago, Mr. Chilton got a taste of the kind of run-ins he would later have with the Center. The Center, founded in 1989, has a mission of protecting endangered species in the region from logging, grazing and other practices. In 1997, the Center filed a lawsuit against the Forest Service to curtail grazing on Mr. Chilton's allotment, among many others across the Southwest. The Forest Service settled with the Center by requiring a fence around a 20-acre stretch of the land that surrounds a part of a stream known as California Gulch, to protect threatened Sonoran chub fish.

In September 2002, while reading a local newspaper, Mr. Chilton came across a notice published by the Center. It described alleged destruction to Mr. Chilton's leased land and directed readers to the Center's Web site. When the rancher went to the site, he saw numerous photos of supposed land devastation caused by the 425 cows he usually runs on the Montana allotment. One photo showed two of his cows lazing on a dusty, bare stretch of earth that was apparently once a grassy meadow.

Mr. Chilton denies his cows cause extensive damage -- although he admits they impact isolated "hot spots," like some watering holes where they congregate. Mr. Chilton says terms of his lease allow for a few hot spots. Plus, he says he rotates herds around the allotment to give the land a chance to rest. After seeing the Center's photos, he got so mad "he said some cowboy words," his wife, Sue, recalls.

Mr. Chilton and his lawyer, Kraig Marton, went to many of the 21 locations that the Center had photographed, shooting new pictures to show their belief that the Center's images were exaggerated. Mr. Chilton also obtained photos of the barren meadow the two cows were lazing in that showed some of the damage was the result of a campout involving several hundred people two weeks prior. Witnesses in the trial said the campout was part of an annual May Day celebration. Mr. Marton said the photos were given to him and Mr. Chilton by someone who attended the event.

Mr. Chilton filed his defamation suit against the Center in January 2004, enlisting consultants and scientists to back up his assertion that cattle do minimal damage. In his suit, Mr. Chilton also named Center members A.J. Schneller, Shane Jimerfield and Martin Taylor as defendants.

A central exhibit of the two-week trial last January was photo No. 18 -- the meadow where the big encampment had taken place. Mr. Schneller admitted during testimony that he had attended the camping event. He testified in court that he had to rake away numerous cow paddies to make room for the campers.

The jury apparently wasn't convinced. On Jan. 21, it awarded Mr. Chilton $600,000. Kieran Suckling, a Center co-founder, acknowledges the group's photos weren't representative of Mr. Chilton's whole allotment. "But they're not supposed to be," Mr. Suckling says. "What law in the universe says I'm not allowed to take pictures showing (just) damaged areas?" Mr. Suckling calls Mr. Chilton a "litigious" wealthy banker and says payment of the award could financially devastate the group. The Center has retained a San Francisco law firm that specializes in First Amendment cases for the appeal.

Mr. Chilton says he was "stunned" at the size of the award but notes the case wasn't about the money. "I would've been happy with a dollar," he says. After recouping his expenses, including $350,000 in legal fees and costs to hire experts to verify his assertion the range was in good condition, he plans to use the rest as a legal fund for other ranchers to defend themselves against environmental groups.