On graduating with a master’s in forestry from Yale in 1909, Aldo Leopold joined the newly established U.S. Forest Service. He achieved his life’s ambition by age twenty-five when he was appointed supervisor of the Carson National Forest in New Mexico. From the start he was deeply imbued with the utilitarian conservation philosophy espoused by Gifford Pinchot. But also from the start, he pushed foresters toward a broader definition of their responsibilities and more thoughtful consideration of the objectives of forest management.

At a time when the national forests were devoted by law to conservation of timber and water, Leopold laid out virtually the entire range of purposes—“timber, water, forage, farm, recreative, game, fish and esthetic resources”—in a 1913 letter to his fellow officers of the Carson. These ideas would be enshrined half a century later in the Multiple UseÐSustained Yield Act of 1960. All that was missing was wilderness, but Leopold would become the leading advocate for wilderness preservation as well.

Even more significant in his 1913 letter, however, was his emphasis on measuring successful management by “the effect on the forest,” rather than by mere adherence to official policies and procedures. It was this preoccupation with what we now call the forest ecosystem that marked Leopold as a person of vision.

For the remainder of his career in the Southwest, Leopold would serve in a succession of regional office positions in which he would seek to broaden the scope of national forest administration and improve the quality of forest ecosystems.

Perhaps his most far-reaching contributions came in the realm of ecological interpretation, as he sought to discern the interactions of grass, brush, timber and fire on southwestern watersheds in his capacity as a forest inspector. With an ever-open and inquiring mind, Leopold observed the marked increase in soil erosion, the continuing replacement of grass by unpalatable brush, the pattern of fire scars on ancient junipers and the growth of yellow pine in dense, stunted thickets.

In what was rank heresy in an agency dedicated to growing and harvesting trees, committed to absolute fire prevention and funded largely by grazing fees, he argued that grass was a more effective watershed cover than trees and that fire, which was necessary to maintain grass cover, was less destructive than grazing. And he drove home the point: “Fifteen years of forest administration were based on an incorrect interpretation of ecological facts and were, therefore, in part misdirected.”

The Forest Service in its early years was an enormously creative and vibrant institution, willing to respond to at least some of the prodding of a free thinker like Leopold because there was, in fact, relatively little demand for the timber that was its principal reason for existence.

Though some of his colleagues thought of him as highbrow, moving along “with his feet somewhat off the ground,” there is no question that he was well respected. Many of his innovations in game management, wilderness designation and inspection methodology influenced forest policy in his own time, though it would be years before his concern about the integrity of watersheds and the implications of ecology would be understood.

Leopold left the Southwest in 1924 to become assistant director of the Forest Products Laboratory in Madison, Wisconsin. Though the chemists, physicists and engineers on its staff were concerned primarily with research on utilization of wood products after the tree was cut, Leopold wrote a series of essays in an effort to shift the focus of research to the growth of forests, with a decided bent toward natural reproduction.

His frustration in this endeavor led him to resign from the Forest Service in 1928 to lay the groundwork for the new profession of wildlife management. The day before he left he published a parting shot in the in-house Service Bulletin: “Whether we like it or no, national forest policy is outgrowing the question of boards.” Consistent with his approach for nearly two decades, he asserted the claims of “sociology as well as silviculture” and the possibility of social evolution to a higher understanding of the ends—as well as the means—of forest management.

Aldo Leopold’s remarkable influence today on forestry, ecosystem management and environmental ethics is a tribute to the force of his spirit, embodied in simple prose grounded in personal experience. The most enduring of his writing, we now know, was in A Sand County Almanac, the little book that described his efforts to restore the health of the worn-out, abandoned farm he acquired in 1935 in the sand country of central Wisconsin. “I was made to live on and work on my own land,” he had written to his family a quarter century earlier, explaining why he was so eager to become a forest supervisor. “Whether it’s a 100-acre farm or a 1,700,000-acre forest doesn’t matter—it’s all the same principle.”