In memoriam: Dac Crossley (1927-2024)

Allyson Mann

Deryee Ashton Crossley Jr., Research Professor Emeritus at the Odum School of Ecology, passed away at his home in Athens, Georgia, on Oct. 2 after a brief illness. He was 96.

Crossley was an internationally recognized pioneer in ecology whose research linked the abundance and diversity of organisms to the cycling of matter in ecosystems. Better known as “Dac,” he was renowned for his dry wit, generous nature and percussive guitar strum displayed when he performed the many folk songs in his repertoire.

Born in Kingsville, Texas, Crossley earned a Ph.D. at the University of Kansas, where he studied mite taxonomy. In 1956, he joined the Oak Ridge National Laboratory as an ecologist, pioneering applications of radioisotopes in ecological studies and the use of litter bags to measure leaf litter breakdown.

Dave Coleman had just taken a postdoctoral position at the Savannah River Ecology Laboratory when he was referred to Crossley for a radiation ecology class.

“I got a four-day, one-on-one immersion experience encompassing a huge amount of information. It was generous of him,” said Coleman, Distinguished Research Professor Emeritus at the Odum School of Ecology. “Dac had one speed—just whoosh.”

Crossley arrived at the University of Georgia in 1967, the year the Institute of Ecology was given official status by the Board of Regents.

Mark Hunter, dean of the Odum School of Ecology, was a faculty member during the third decade of Crossley’s career at UGA—a time when his earlier work was being recognized as a foundation for new directions in ecology.

Distinguished Research Professor Emeritus Dave Coleman (right) with Dac Crossley at the HorseShoe Bend Ecology Experimental Research Site. (Photo: Courtesy of Dave Coleman)

“His body of research with Dave Coleman laid the groundwork for a revolution in the mid-1990s,” said Hunter, “where the fundamental role of biological diversity in mediating ecosystem function exploded into the literature. In essence, they established that the identity and diversity of organisms matters to the flow of energy and the cycling of matter in ecosystems.”

Hunter added that “the quality of Dac’s work was matched only by the fun he had doing it.”

Tim Seastedt (PhD ’79), professor emeritus at the University of Colorado Boulder, called Crossley his “most valued role model.”

“Along with colleague David Coleman, he advanced a scientific vision of soil biology that was embodied into the earliest conceptual models for the Long-Term Ecological Research program, a framework that has survived largely unchanged to date,” Seastedt said. “His mentoring was unparalleled, providing a combination of theoretical ecology and stand-up comedy. Pondering ‘What would Dac do?’ continues to contribute to my decision-making processes.”

John Blair (PhD ’87), University Distinguished Professor at Kansas State University, said Crossley’s legacy will continue to have a positive influence for generations to come.

“I didn’t know Dac before joining the program, but he became a mentor, role model, provocateur, champion and life-long friend. I owe a great deal of any success I’ve had in academia to him,” Blair said. “He trained and inspired generations of ecologists, entomologists and invertebrate biologists to ‘do science and have fun.’ He was happiest when in the field or lab, or while sharing stories and insights over a beer with friends and students. His many scientific accomplishments were grounded in an innate sense of curiosity and wonder about the natural world.”

After retiring in 1998, Crossley continued to curate the Acarology Collection at the Georgia Museum of Natural History, serving on the board and as president of the Friends of the GMNH. He also authored five western novels and a memoir spanning his first 40 years. In 2018, he was named research professor emeritus.

Crossley was preceded in death by spouses Nettie Lou Keirsey and Dorothy (Dot) Money Blankenship. He’s survived by daughter Mary Freeman and her husband Bud Freeman, both faculty at the Odum School of Ecology, as well as stepsons Greg (Gail) and Steve Blankenship, two grandchildren, six great-grandchildren and four great-great-grandchildren.