MADISON, Wis. (AP) — The last remaining child of famed conservationist and author Aldo Leopold has died at age 97.

Estella Leopold, a researcher and scientist who dedicated her life to the land ethic philosophy of her famous father, died on Sunday in Seattle after several months in hospice, the Aldo Leopold Foundation announced.

“She was a trailblazing scientist in her own right,” Buddy Huffaker, executive director of the foundation, said Wednesday. “She was a fierce conservationist and environmental advocate.”

Estella Leopold specialized in the study of pollen, known as palynology, especially in the fossilized form. She formed the Aldo Leopold Foundation along with her sister and three brothers in 1982. Now a National Historic Landmark, it is located along the Wisconsin River in Baraboo, about 45 miles north of Madison.

She and her siblings donated not only the family farm, but also the rights to their father’s published and unpublished writings, so that Aldo Leopold’s vision would continue to inspire the conservation movement, Huffaker said.

Aldo Leopold is best known for 1949’s “A Sand County Almanac,” one of the most influential books on ecology and environmentalism. Based on his journals, it discusses his symbiotic environmental land ethic, based on his experiences in Wisconsin and around North America. It was published a year after he died on the property.

Estella Leopold was born Jan. 8, 1927, in Madison. Named after her mother, she was the youngest of Aldo and Estella Leopold’s five children. She was 8 when the family moved to the riverside farm Aldo Leopold would immortalize in “A Sand County Almanac.”

Estella Leopold graduated from the University of Wisconsin-Madison in 1948, received her master’s at the University of California Berkeley and earned a doctorate in botany from Yale University in 1955.

She spent two decades at the U.S. Geological Survey in Denver, studying pollen and fossils. She led the effort to preserve the rich fossil beds in Colorado’s Florissant Valley, eventually resulting in the area being protected as a national monument.

She next joined the Quaternary Research Center at the University of Washington, where her work included documenting the fault zone that runs through Seattle.

Following the eruption of Mount St. Helens in 1980, she spearheaded the effort to make it a national monument so the area could be studied. The Mount St. Helens National Volcanic Monument was established in 1982.

She retired from teaching at the University of Washington in 2000. She published or contributed to more than a hundred scientific papers and articles over her career. But it wasn’t until 2012, when she was in her 80s, that Estella Leopold wrote her first book. Her second, “Stories from the Leopold Shack” published in 2016, provides insights into some of her father’s essays and tells family stories.

Huffaker called her death “definitely the end of an era,” but said the conservationism that she and her father dedicated their lives to promoting continues to grow and evolve.