Conservation vs. Preservation
What's the difference?

One of the central controversies of the twentieth-century environmental movement has been between those who want to preserve "wilderness" and those who support managed use of the material resources. The latter is sometimes referred to as the management of resources on a sustainable yield basis. "Conservation: The maintenance of environmental quality and resources or a particular balance among the species present in a given area. The resources may be physical (e.g. fossil fuels), biological (e.g. tropical forests), or cultural (e.g. ancient monuments). In modern scientific usage conservation implies sound biosphere management within given social and economic constraints, producing goods and services for humans without depleting natural ecosystem diversity, and acknowledging the naturally dynamic character of biological systems. This contrasts with the preservationist approach which, it is argued, protects species or landscapes without reference to natural change in living systems or to human requirements."

(Source: Michael Allaby, The Concise Oxford Dictionary of Ecology [Oxford: Oxford University Press, 1994], 92.)