Fesenjan is believed to have originated in Gilan province, a temperate green swath of land along the Caspian Sea in the north of Iran, where wild ducks are plentiful.

WSJ: A Journey to Iran, by Way of the Kitchen

"Much of the world's population in North America, Europe, most of China and large portions of Russia live near temperate forests, so what happens in these forests has global importance, " said Jerry Franklin, a professor of forest resources at the University of Washington whose work was instrumental in maintaining the research plots.

CNN: Global warming threatens forests, study says