(1) If a forest is the subject of usufruct, both the owner and the usufructuary may require that the degree of use and the nature of the economic treatment be laid down in an economic plan. If a substantial change of circumstances occurs, then each party may require a corresponding amendment of the economic plan. Each party is to bear one half of the costs.
(2) The same applies if a mine or another installation designed to extract soil constituents is the subject of usufruct.