Redwood burl poaching has spread to national forests in Northern California and Oregon.
The burls are knobby growths at the base of redwood trees. Their intricate grain is prized for furniture and decorations.
The poaching has been a problem in the Redwood National and State Parks for years. Two men were recently convicted in a case there.
Wendell Wood of the conservation group Oregon Wild says he was out hiking recently and found two redwood trees with burls cut off.
One was on the Six Rivers National Forest near Crescent City, California, the other on the Rogue River-Siskiyou National Forest near Brookings, Oregon.
Oregon Wild wants the forests to close old logging roads that poachers drive to reach the remote trees.
The U.S. Forest Service says it is investigating.