HÜMMEL, Germany — IN the deep stillness of a forest in winter, the sound of footsteps on a carpet of leaves died away. Peter Wohlleben had found what he was looking for: a pair of towering beeches. “These trees are friends,” he said, craning his neck to look at the leafless crowns, black against a gray sky. “You see how the thick branches point away from each other? That’s so they don’t block their buddy’s light.”

Before moving on to an elderly beech to show how trees, like people, wrinkle as they age, he added, “Sometimes, pairs like this are so interconnected at the roots that when one tree dies, the other one dies, too.”

Mr. Wohlleben, 51, is a very tall career forest ranger who, with his ramrod posture and muted green uniform, looks a little like one of the sturdy beeches in the woods he cares for. Yet he is lately something of a sensation as a writer in Germany, a place where the forest has long played an outsize role in the cultural consciousness, in places like fairy tales, 20th-century philosophy, Nazi ideology and the birth of the modern environmental movement.

After the publication in May of Mr. Wohlleben’s book, a surprise hit titled “The Hidden Life of Trees: What They Feel, How They Communicate — Discoveries From a Secret World,” the German forest is back in the spotlight. Since it first topped best-seller lists last year, Mr. Wohlleben has been spending more time on the media trail and less on the forest variety, making the case for a popular reimagination of trees, which, he says, contemporary society tends to look at as “organic robots” designed to produce oxygen and wood.