Aldo Leopold (January 11, 1887 – April 21, 1948) was an American writer, philosopher, naturalist, scientist, ecologist, forester, conservationist, and environmentalist.

He was a professor at the University of Wisconsin and is best known for his book A Sand County Almanac (1949), which has been translated into fourteen languages and has sold more than two million copies.

His father, Carl Leopold, was a businessman who made walnut desks[5] and was first cousin to his wife, Clara Starker.

Charles Starker, father of Carl and uncle to Clara, was a German immigrant, educated in engineering and architecture.

"[11] He attended Prospect Hill Elementary, where he ranked at the top of his class, and then, the overcrowded Burlington High School.

Every August, the family vacationed in Michigan on the forested Marquette Island in Lake Huron, which the children took to exploring.

[13] His parents agreed to let him attend The Lawrenceville School, a preparatory college in New Jersey, to improve his chances of admission to Yale.

Leopold's career, which kept him in New Mexico until 1924, included developing the first comprehensive management plan for the Grand Canyon, writing the Forest Service's first game and fish handbook, and proposing Gila Wilderness Area, the first national wilderness area in the Forest Service system.

[22] Leopold and other members of the first Arboretum Committee initiated a research agenda around re-establishing "original Wisconsin" landscape and plant communities, particularly those that predated European settlement, such as tallgrass prairie and oak savanna.

One day after fatally shooting a wolf, Leopold reached the animal and was transfixed by a "fierce green fire dying in her eyes."

His rethinking the importance of predators in the balance of nature has resulted in the return of bears and mountain lions to New Mexico wilderness areas.

He was prompted to this by the rampant building of roads to accommodate the "proliferation of the automobile" and the related increasingly heavy recreational demands placed on public lands.

The concept of "wilderness" also took on a new meaning; Leopold no longer saw it as a hunting or recreational ground, but as an arena for a healthy biotic community, including wolves and mountain lions.

"[31] Science writer Connie Barlow says Leopold wrote eloquently from a perspective that today would be called Religious Naturalism.

[32] Though often forgotten, thinking about population dynamics and consumption also shaped Aldo Leopold’s ecological vision in profound ways.

One of the well-known quotes from the book which clarifies his land ethic is, A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community.

(p.262) The concept of a trophic cascade is put forth in the chapter, "Thinking Like a Mountain", wherein Leopold realizes that killing a predatory wolf carries serious implications for the rest of the ecosystem[36] — a conclusion that found sympathetic appreciation generations later: In January 1995 I helped carry the first grey wolf into Yellowstone, where they had been eradicated by federal predator control policy only six decades earlier.

By illuminating for us how wolves play a critical role in the whole of creation, he expressed the ethic and the laws which would reintroduce them nearly a half-century after his death.Thinking Like a Mountain was originally written during World War II and shows that Leopold's thinking was shaped by that global cataclysm.

[38] In "The Land Ethic", a chapter in A Sand County Almanac, Leopold delves into conservation in "The Ecological Conscience" section.

In short, a land ethic changes the role of Homo sapiens from conqueror of the land-community to plain member and citizen of it.

It provides interpretive resources and tours for thousands of visitors annually, distributes a curriculum about how to use Leopold's writing and ideas in environmental education.

[42] The film aired on public television stations across the nation and won a Midwest regional Emmy award in the documentary category.

The U.S. Forest Service established the Aldo Leopold Wilderness Research Institute at the University of Montana, Missoula in 1993.

It is "the only Federal research group in the United States dedicated to the development and dissemination of knowledge needed to improve management of wilderness, parks, and similarly protected areas.