The chunk of northwestern Colorado where Eisenberg works is called the High Lonesome Ranch. Bordered on the south by Interstate 70 and on the west by the rippling shale and sandstone curtain of the Book Cliffs, it encompasses desert flats, river valleys and high-elevation aspen stands. With the recreation, outfitting and grazing permits it holds on Bureau of Land Management land adjoining its property, the ranch operates on a roughly circular 300 square miles -- an area larger than Lake Powell at full pool.

"It's an overwhelming landscape," says Eisenberg, who, with conservation biologist Michael Soule, flew over the ranch in a helicopter last May. "Even from the air, practically everything you can see is the ranch. You think, 'How are we ever going to measure this?' "

On winter afternoons, fading light glows in the snowy fields and sagebrush near ranch headquarters. High, rocky ridges rise in every direction, silencing the nearby interstate. Despite the dense, almost palpable quiet, the High Lonesome Ranch is a busy place, with a full-time staff of 40, a commercial kitchen, a well-stocked gift shop, and enough pickup trucks and road equipment to outfit a small highway department. Experienced guides lead hunting and fishing expeditions into remote ranch valleys; masseuses knead sore muscles; chefs prepare elaborate multi-course meals. In the ranch dining room, leather-bound albums display photos of grinning guests posed with their trophies: bull elk, bears, mountain lions, colossal trout. "While you're here," one slogan goes, "you own the place."

Not really, of course. That privilege belongs largely to Paul Vahldiek Jr., the president, CEO and chairman of the board of High Lonesome Ranch. Vahldiek, a tall, heavyset Houston trial lawyer with a boyish face and an attitude of expansive hospitality, is a man of epic enthusiasms: for wildlife, for travel, for good food and drink. A dedicated outdoorsman since his seventh-grade basketball coach took him fishing for trout and redfish on the Gulf Coast in the 1960s, Vahldiek spends several weeks each year on the property -- yet he rarely leaves ranch headquarters, and almost never hunts. Instead, he conducts a whirlwind of meetings with business partners, contractors, scientists, architects and staff, often becoming so absorbed in conversation that he loses track of time. "When he drives," says his wife, Lissa, "my job is to say 'Paul, the road. Paul, the road.'"

Petite and blue-eyed, with arching eyebrows, Lissa Vahldiek grew up in the news business: Her father, the son of a sharecropper, rose from a bookkeeping position at a Florida newspaper to found Southern Newspapers Inc., now a chain of 17 small and mid-sized papers in Texas, Alabama and Georgia. Lissa has spent most of her career with the company, and now serves as its vice president and CEO. She loves the outdoors -- on her cell phone, she proudly displays a photo of one of her prize High Lonesome Ranch catches, a 14-pound rainbow trout -- and is supportive of Paul's work with the ranch, but the place is clearly his realm. "Where newspapers are truly my passion, I think it's truly his passion," she says.

Like so many heat-weary Texans, Paul dreamed of a mountain getaway. Unlike many, he and Lissa had the funds to buy one. A big one. He wanted snowy peaks, not desert cliffs and sagebrush, and at first the valleys of northwestern Colorado held little appeal. But he also wanted a property that could be managed for conservation, and a friend who had hunted in the area pointed out that lower-elevation lands were accessible year-round -- to humans and wildlife. In 1994, Vahldiek bought the first piece of what would become the High Lonesome, completing the purchase of one valley before going on to the next, and then the next. The North Dry Fork Valley, where ranch headquarters now sits, alone comprises 18 former homesteads. "In Texas, you can have a long fenceline, but there's always some guy in a truck driving along the other side, waving at you," he says. "Here, the Book Cliffs are our fence. There's no one waving at us."

From the start, Vahldiek says, he wanted to protect the land for the long term, so he set about learning how to be a good steward. The ranch sits in the gas-rich Piceance Basin, but Paul used his legal expertise to cut off oil and gas company access to mineral leases. ("I haven't been the normal rancher in dealing with them," he says.) He decided to run 400 head of cattle, a fraction of the number permitted by the BLM. After a misguided attempt at pond-building by a former ranch manager -- an undertaking that eventually led to a settlement with the federal Environmental Protection Agency -- Vahldiek hired a team of stream experts to repair the damage and plan a new large-scale stream restoration project. He funded a ranch-wide biodiversity survey by scientists from the Academy of Natural Sciences in Philadelphia, and commissioned detailed maps of his private and permitted lands. And he recently hired Jones and Jones, a Seattle-based firm of architects, landscape architects and planners, to come up with a conservation plan. Two years ago, he sold minority shares in the ranch to several partners, including conservationist David Ford, a former general partner of Goldman Sachs. Today, the official mission statement for the High Lonesome describes a "model of sustainability" that maintains biodiversity and open space while allowing a mix of uses -- primarily ranching and recreation -- for its financial support.
But in the midst of all his activity, Paul noticed that in the high reaches of the ranch, in the aspen stands, something was wrong. The trees were dying, and there were few young sprouts to replace them. The trees were on his mind in August 2007, when he traveled to Montana for a meeting of the conservation and education committee of the Boone and Crockett Club, the venerable hunting and conservation organization founded by Theodore Roosevelt. There, he met Cristina Eisenberg, who told a story about aspen, elk and wolves.