We noted in Chapter 1 that when the disciplines of forestry, wildlife management, and range management developed, their practitioners saw themselves as analogous to farmers, manipulating the environment to produce crops of desirable organisms. Their perspective led them to focus on the environmental requirements of species of interest, and they reasoned that by providing those requirements they could maximize production.

In seasonal environments, plants and animals are likely to have different requirements at different times of the year. In addition, the requirements of animals depend upon sex, age, and breeding condition. As managers came to understand this, they realized that in order to provide for a species of interest, it was necessary to understand that species' requirements throughout its entire life cycle (King 1938).

Although these developing disciplines emphasized economically valuable products, resource managers came to understand that meeting the habitat requirements of species of interest meant managing for the plant communities on which those species depended. This insight was a significant contribution. Managers realized that even the most stringent restrictions on grazing, hunting, and logging would not conserve future stocks in the face of severe habitat degradation.