HATO PINERO, Venezuela – For more than 50 years, the ranch at Hato Pinero has served as conservation land on which the unique wildlife of central Venezuela’s plains thrived. Tourists have come from around the world to marvel at Pinero’s wide array of flora and fauna, such as tapirs – hooved quadrupeds that look like a cross between a pig and an anteater. Ecologists praise the ranch for raising about 11,000 heads of cattle while preserving endangered species such as jaguars and Yellow Knobbed Curassows, a tropical bird with black and white feathers and a stripe of yellow above its beak.

Pinero has won the support of conservation biologists around the world, but it faces a new threat on the home front – a land-reform campaign that has promised to break up large properties and redistribute them. Led by leftist President Chavez, the Venezuelan government has decided to expropriate more than half of the 195,000 acres of Pinero, much of which will likely be turned over to landless low-income farmers. While government leaders insist that the campaign is meant to redress social injustices of previous corrupt governments, wildlife conservationists in and outside Venezuela say the area’s delicately managed ecosystem will be destroyed if the land reform measure passes.

“Most of landowners actually agree with the reform program – having large unused tracts of lands simply isn’t sustainable today,” the president of the company that owns Pinero, Jaime Perez, said. But he disagrees with the way in which the government is going about it.

The land-reform campaign comes as Mr. Chavez rides a wave of popularity following a resounding victory in a recall referendum last August that ended a violent two-and-a-half-year political crisis. Now the political champion of Venezuela, the world’s fifth largest oil exporter, Mr. Chavez is taking up the thorny issue of land reform – which has always been a central concern for Latin America’s leftist movements.

The government has already decided to expropriate land at five other major ranches, alleging that they are either not fully using their land or do not possess valid legal titles. It is a politically symbolic move for Mr. Chavez, who has promised to cut down the privileges of the country’s wealthiest families. The national land institute has already given campesinos – small farmers – land titles to property on other ranches, such as the 32,000-acre cattle ranch known as El Charcote. Critics say these land expropriations are based on a questionable interpretation of the law. Environmental experts add that a government takeover of Pinero could throw back decades of work in preserving a delicate ecosystem and an important group of endangered species.

“Carving up a ranch like Pinero into small holdings will destroy the conservation value of this area,” a research scientist specializing in tropical ecology at Duke University in North Carolina, Dr. Thomas Struhsaker, wrote in an e-mail message. “This will also mean the world will have lost one of the few remaining examples of the llanos [the Venezuelan plains] that is still reasonably intact.”

Pinero was founded in 1949 by Antonio Julio Branger, who dedicated himself to creating new breeds of Venezuelan cattle. In the early 1980s, he pioneered the concept of sustainable ranching that promoted conservation and tourism. Pinero has been the subject of dozens of doctoral dissertations by American students, and is widely acclaimed by America-based environmental NGOs such as the World Wildlife Foundation.

Such praise has not been echoed by Venezuelan government leaders. A former explosives expert who now heads the country’s land institute, Eliecer Otaiza, recently told reporters following the decision to expropriate Pinero’s land: “The supposed environmental conservation that they say they have in Pinero is not they way they describe it.” Land institute leaders accuse Pinero of massive deforestation and say its workers suffer under slave labor conditions. Pinero denies the accusations.

For many supporters of Mr. Chavez, Pinero serves as a playground for Venezuela’s richest and dollar-bearing foreign visitors. Tourists pay about $100 a night to stay at the ranch, – roughly the amount that an average Venezuelan makes in a month. As a result, poor landless people in the area view the conservation efforts as a ruse to protect privilege rather than a way to protect an ecosystem. Squatters such as Luis Alberto Garcia, 34, see the Branger family as wealthy landowners. Sitting beneath the awning of a makeshift zinc shack on a ranch neighboring Pinero, Mr. Garcia questioned the value of the Brangers’ conservation efforts.

“Sure, they have some animals there,” Mr. Garcia said, “but they want to control all of Venezuela, and things just aren’t like that, they have to learn to share.” Mr. Garcia complains that he and other farmers have been repeatedly threatened by landowners and their security forces during the six years they have lived on the Brangers’ property. He thanks Mr. Chavez for breaking up what he describes as a landowners mafia.

Antonieta Branger, the daughter of Pinero’s founder who grew up on the ranch and now lives in the Venezuelan city of Valencia, said that she is confounded by the government’s efforts in Pinero. Sitting on the stone porch of the ranch’s small hotel on a warm spring evening, she said Hato Pinero is in grave danger. “My father could have invested his savings in Caracas or in the United States, but he decided to build this ranch because he believed in the Venezuelan plains,” she said, gazing into the fields shrouded in darkness. “I just don’t understand why the government wants to roll back all the work he did.”