SEWANEE, Tenn. — It is afternoon in a hardwood forest on the edge of the Cumberland Plateau, and the cicadas are singing.

David Haskell, an ecologist and evolutionary biologist at the University of the South, is taking me through part of the 13,000 acres owned by the university, to a small circle of forest floor a bit over a yard in diameter. He visited this randomly chosen forest “mandala,” as he calls it, many times over the course of a year and recorded his observations in “The Forest Unseen: A Year’s Watch in Nature.”

He is pointing out flowers, salamanders, insects, trees, as we follow a well-worn hiking path, and stops for a moment to listen. These are swamp cicadas, he says, not the kind that hatch all at once after years underground and hammer the ear mercilessly.

“Was it last year or the year before we had the 13-year cicadas?” he says. “I took my sound pressure meter down to a place where they were really loud, and it came to over 90 decibels. At 85 OSHA says you need hearing protection in your workplace.