Stunned by devastating floods along the Yangtze River, which experts said were intensified because slopes far upstream had been stripped bare, China has banned cutting of the old-growth forests that once carpeted these mountains in western Sichuan. No trees were to be cut after Sept. 1, and all logs must be trucked to timber yards by Oct. 31.

After a half-century of rampant clear-cutting, China's decision to save the remaining forests along the upper reaches of the Yangtze and other major rivers represents a dramatic shift in priorities in favor of environmental protection. Huge tree-planting campaigns have also been promised.But the change is certain to be wrenching for hundreds of thousands of people in Sichuan, Yunnan and Gansu provinces.

The thousands of former farmers or workers who scraped together as much as $10,000, a small fortune here, to buy logging trucks are chief among the casualties.

"No forest, no money," said Gu Yuefu, a private trucker.

He is deep in debt: no one wants to buy a logging truck and he does not know what he will do. "Maybe I'll just sit around drinking tea," he said.

Other truckers and timber workers said they would return to farming. That may only worsen another serious cause of erosion and silting of rivers: the widespread farming of steep mountain slopes.

Peng Huangshi, deputy director of forestry for Sichuan, said that "the timber resources have been approaching complete exhaustion" in the province.

About two years ago, national and provincial officials drew up plans to phase out most logging.

But last year, officials said there was not enough money to support displaced workers and pay retirees, to subsidize local governments dependent on logging revenues and to pay for tree-planting and other projects.

"The flooding this year pushed the government at last to implement this plan," Shen said.