XAPURI, BRAZIL, DEC. 16 -- Rubber tappers today hailed the convictions Saturday night in the murder of environmentalist Chico Mendes, calling the verdict a landmark for those seeking to preserve the Amazon rain forest.

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 here.

A seven-member jury determined that rancher Darly Alves da Silva planned the Dec. 22, 1988, slaying and that his son, Darcy Alves Pereira, fired the shotgun that killed Mendes, an Amazon unionist and rain forest defender. The defendants drew 19-year sentences. Prosecutors said the two had "stained the forest" with Mendes's blood and urged the maximum 30-year sentence. The defense said it would appeal.

Mendes, 44, a rubber-tapper union organizer who led a movement to stop destruction of the world's largest rain forest, was gunned down on the back porch of his humble wooden house in this Amazon town 2,650 miles northwest of Rio de Janeiro.

The four-day trial drew world attention to a centuries-old battle over land in Brazil that has killed thousands of people. To many in the United States and Europe, Mendes became a martyr, because he was killed at a time of rising world concern for the rapidly disappearing rain forest.