BARABOO (AP) - The humble shack that became the centerpiece of conservationist Aldo Leopold's "A Sand County Almanac" has been granted National Historic Landmark status.

The converted chicken coop and the farm on which it stands received the designation from outgoing Interior Secretary Dirk Kempthorne. He announced the designation of nine new historic landmarks just days before he and the rest of the Bush administration left office.

Leopold died in 1948 at the age of 61, before "A Sand County Almanac" was published.

The collection of essays detailed his observations of nature through changing seasons and also called for a new land ethic to guide humans in the way they deal with the natural world.

The shack is maintained in his memory by the Aldo Leopold Foundation, founded by his children in 1982 to carry on his legacy.

Leopold's daughter, 91-year-old Nina Leopold Bradley, remembers arriving at the shack when it was a weekend getaway spot for the family. They would go there with just a suitcase filled with clothes and toothbrushes.

"The shack was sort of an example of how you didn't need a palace and all these things surrounding you," she said. "The general effect was (showing) that you can be very, very happy with very little stuff around you."

She recalled summer nights in the 1930s and 1940s, sitting around a campfire with her father, mother and four siblings, singing songs and strumming a guitar.

Days were spent planting trees and restoring prairie areas.

"He didn't tell us this, but he was trying to restore this acreage to what it looked like before white men," Leopold Bradley said.

Buddy Huffaker, Leopold foundation executive director, said he hopes the National Historic Landmark declaration will increase awareness of the call for "human responsibility toward the land."

The Leopold site joins 2,500 other places nationwide and 39 others in Wisconsin on the National Historic Landmark list.

Leopold, considered the father of the modern-day science of ecology, worked with the U.S. Forest Service before being appointed a professor of wildlife management at UW-Madison, where he taught until his death. His career included advising the state's former conservation department.