They are simply custodians of the resources. This is often part of the philosophy of traditional indigenous hunter gatherer communities. They believe that they have a responsibility to ensure that the land they leave for their descendants is in the same condition as when they took it over. Which is the most beneficial is not something that economists can make easy decisions over. That is left to the politicians.
Economists are only able to offer frameworks in which decisions can be then made.
Theories relating to productive and allocative efficiency attempt to do this.