For wrongful injuries to timber, trees or underwood upon the land of another, or removal thereof, the measure of damages is twice such a sum as would compensate for the actual detriment, except where the trespass was casual and involuntary, or committed under the belief that the land belonged to the trespasser, or where the wood was taken by the authority of highway officers for the purpose of a highway, in which case the damages are a sum equal to the actual detriment.

SOURCE: CC § 3346.