The convictions and 19-year prison sentences handed down for the murder of environmentalist Chico Mendes are an important victory in the fight to preserve the dwindling Amazon forest, rubber tappers say.

"This conviction is a landmark" for environmentalists, prosecutor Sueli Bellato said over the weekend.A seven-member jury determined late Saturday that rancher Darly Alves da Silva planned the Dec. 22, 1988, slaying and that his son, Darci Alves Pereira, fired the shotgun that killed the Amazon union leader and rain forest defender.

Prosecutors had said the ranchers had "stained the forest" with Mendes' blood and urged the maximum 30-year sentence. Brazil has no death penalty.

"Now (landowners) know that every brother rubber tapper or environmentalist who dies will be avenged," said Francisco Barbosa de Aquino, president of the Rural Workers Union in this remote town.

Defense attorney Ruben Torres said his clients would appeal.

Mendes, leader of the rubber tappers' union, became internationally known in his fight against ranchers, who sought to expand their pastures by cutting down the rain forest. The rubber tappers gather latex from forest trees.

He was gunned down on the back porch of his wooden house in the Amazon river town 2,650 miles northwest of Rio de Janeiro.

The four-day trial also drew world attention to a centuries-old battle over land in Brazil that has left thousands of people dead. Too often, the perpetrators have gone unpunished.