Cal. Pub. Res. Code § 4597.17

If a landowner with a nonindustrial timber management plan or a working forest management plan with less than 2,500 acres expands his or her total timberland ownership to 2,500 or more acres, the landowner may transition into a working forest management plan for more than 2,500 acres through an amendment to the plan. The board shall adopt regulations that establish this amendment process.