The Mineral Leasing Act of 1920 and its amendments govern the location and extrac- 

 tion of energy and some industrial minerals. Nonenergy minerals on acquired lands, 

 which would otherwise be subject to the Mining Law of 1872, are covered by the 

 Mineral Leasing Act. This law, too, was intended to encourage mining activities. 

 Individuals and firms may explore the public lands; however, discovery does not lead 

 to a transfer of ownership. Mineral locations are leased, with the lessor having an 

 exclusive right to extract the deposit ore to exhaustion. Royalties are paid to the 

 Government, based on the value of energy or mineral resource extracted. 



Trends in the Resource Base 



The forest and rangeland resources of the Nation have been substantially altered as 

 a result of human development (fig. 10). These resources are resilient, but their 

 condition has changed over time in response to changing human demands and 

 resource management. A review of historical resource trends provides a context for 

 evaluating the prospective future for renewable resources. We initiated two studies to 

 compile information on resource trends. The first study compared the forest situation 

 in 1900 with the current situation. The second study looked at the status and trends in 

 biological diversity in the United States. 



Figure 10— The forest and rangeland resources of the Nation have been substantially altered as a result of 

 human development. 



Issue Highlight— 

 Long-Term Trends in the 

 Condition of U.S. Forests 



American society in the 20th century changed from rural and agrarian to urban and 

 industrialized (MacCleery, 1992). Although this change has been accompanied by a 

 corresponding physical and psychological separation of people from the land and 

 resources, today's urbanized nation is no less dependent on the products of its 

 forests and fields than were the subsistence farmers of America's past. The current 



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