One of the most important aspects of the conservation of nature is its relation to a world problem: that of producing food and raw material in quantities sufficient to balance increases in population. This problem may, of course, be considered from various points of view. I shall consider it mainly from the point of view of an ecologist, starting from the fact that because the amount of highly productive land under cultivation is diminishing rather than increasing, it will be necessary to turn to regions at present marginal or undeveloped in order to produce any considerable increase in production.