California Code, Revenue and Taxation Code - RTC § 436

On the lien date for the 1977-78 fiscal year and thereafter, all timber on both privately and publicly owned lands shall be exempt from property taxation, including possessory interest taxation, and shall not be assessed for taxation purposes. Nothing herein shall preclude the assessment of trees standing on land not zoned as timberland production under this article for purposes of property taxation based on their aesthetic or amenity value.