HUNTSVILLE, Texas (AP) _ Environmentalists chained themselves to trees and a giant machine Tuesday to protest the U.S. Forest Service's plan to clear and burn areas damaged by pine beetles. At least three people were arrested.

In Oregon's Williamette National Forest, three people perched in trees slated for cutting in the second day of a protest over logging.

In Texas, more than a dozen members of Earth First armed with signs and chains converged on part of Sam Houston National Forest where a 52-ton tree- crusher was mowing down trees.

''We want to stop the devastation of forests. This is public land,'' Pat Ellis Taylor said after she and her husband, Chuck, chained themselves to a tree.

Earth First members were protesting the Forest Service's decision to cut down trees where pine beetles have struck and then burn them with a substance some of the demonstrators likened to napalm. They said healthy trees and wildlife are being sacrificed in the process.

''There's still an intact forest there,'' said group spokeswoman Barbara Dugleby. ''They should maintain a diverse forest that won't invite more pine beetles back.''

Protesters gathered near the tree-crushing machine where acres of trees already had been mowed down. After shouting at the operator, several people strode alongside and in front of the machine, forcing it to stop.

Immediately after it stopped, one man climbed on top and chained his neck to part of it. Three others chained themselves to trees and another man climbed a nearby tree.

The Taylors vowed to stay chained to the tree as long as they could, but they were cut loose by Forest Service law enforcement officers.

They sat handcuffed in a van while officers tried to cut the others loose. Later in the day, Christi Stevens of Austin also was taken into custody. The three were taken to the Walker County Jail.

During the past two months, about half of the 2,582 acres that need to be cleared have been mowed, said Doug Wilder, of Wilder and Wilder, the Corrigan- based company contracted to clear the land.

Wilder said he was told to expect protesters and had advised the machine operator ''to stop the machine once they got in front of it.''

Once trees are knocked down and the areas are burned, about 2,500 acres will be replanted with pine trees, said Forest Service spokesman Dave Oates.

In Oregon, the area around the logging site, 16 miles northeast of Detroit, was closed in an effort to thwart the protest that began Monday.

Two of the protesters remained in two trees overnight after four other protesters were arrested for blocking a logging road. The four were charged with misdemeanors and released.

''The other person climbed the tree this morning, before the area was posted (for no trespassing),'' said John Fertig, a forester with the Detroit Ranger District.

Fertig said logging would continue around the three trees occupied by the protesters.