Back in the Eifel in 2002, Mr. Wohlleben set aside a section of “burial woods,” where people could bury cremated loved ones under 200-year-old trees with a plaque bearing their names, bringing in revenue without harvesting any wood. The project was financially successful. But, Mr. Wohlleben said, his bosses were unhappy with his unorthodox activities. He wanted to go further — for example, replacing heavy logging machinery, which damages forest soil, with horses — but could not get permission.