Oregon Revised Statutes Property Rights and Transactions § 105.030

The plaintiff shall only be entitled to recover damages for withholding the property for the term of six years next preceding the commencement of the action, and for any period that may elapse from the commencement to the time of giving a verdict, excluding the value of the use of permanent improvements made by the defendant. When permanent improvements have been made upon the property by the defendant, or those under whom the defendant claims, while holding under color of title in good faith and adverse to the claim of the plaintiff, the value of the improvements at the time of trial shall be allowed as a setoff against such damages.