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