The excise tax imposed under this chapter applies to forest trees harvested after April 4, 1986, from lands sold to any governmental agency by warranty deed or contract where the seller reserved to itself the right to take all merchantable timber for a specific period of years, or in perpetuity, and to forest trees harvested after April 4, 1986, that any governmental agency, by quit claim deed, as partial consideration for payment of the purchase price, conveyed for a specific period of years, or in perpetuity, all forest trees, standing, growing, or lying on the described land, to the taxpayer, regardless of the date on which the contract was entered.