Conservation is the management of human use of the biosphere in order to achieve the greatest sustainable benefit to current generations while maintaining its potential to meet the needs and aspirations of future generations. Thus conservation is positive, embracing preservations, maintenance, sustainable utilization, restoration, and enhancement of the natural environment.
The conservation movement was born in the nineteenth century as a result of two developments: acceptance of the theory of evolution and the concept (later proved erroneous) of the balance of nature. It was estimated in that century that over 100 million acres of land in the United States had been totally destroyed through erosion of soil, caused by the reckless destruction of forests; Congress passed the Forest Reserve Act (1891) and the Carey Land Act (1894) but both were rendered ineffectual by commercial interests. The first genuinely conservationist president was Theodore Roosevelt, whose Newlands Reclamation Act of 1902 began the struggle for American conservation in earnest. More recently, where officialdom has been dilatory, conservation has been brought to the people by groups such as Friends of the Earth, earning through their efforts powerful international membership.