In economic theory, land clearance or land reclamation involves a market failure. The market does not value naturally occurring resources in the production process. Nature's "capital" is not assigned a value by the market. The externalities that lead to private individuals cutting trees and the real economic costs and benefits to the nation of doing so arise because some of the biosphere's products, especially environmental protection functions, are neither produced goods nor do they have clearly defined ownership. As a consequence, they are regarded as free goods.