As trees begin to come out of dormancy and start the growing season, tree health issues become apparent.  Bark beetles are the most common cause for dying trees around the Mid-Columbia region.  But OSU Extension Forester Glenn Ahrens says they have seen western redcedar dying in areas where it should thrive, along streams, in valleys, and along lower slopes.  He adds researchers have not found evidence of insects or disease as a cause.  The Oregon Department of Forestry, Washington Department of Natural Resources, and U.S. Forest service are involved in on-going investigations of the cedar dieback.