Knock on Wood

Robert Moor’s award-winning On Trails, from 2016, earned him a reputation as a writer unafraid to cross boundaries. With his follow‑up, In Trees, he takes turns as nature writer, travel writer, adventure writer, explorer, amateur anthropologist, wannabe primatologist, experiential reporter, journalist-activist, and collector of stories. But Moor is really a diarist. That’s because his account of trees always returns to its authorial source. So while his subtitle includes the word “exploration,” it’s really an open-ended self-exploration. This focus will appeal to some readers, but it raises serious questions about the author’s ethics.

There’s a lot to learn from Moor, who has read a lot of books, met a lot of people, visited a lot of places, and climbed a lot of trees. His latest work is a humane, erudite volume about trees and our place in them, written by a good, curious, and progressive gentleman. However, it’s also a class-bound...