You're likely referring to the book "The Light in the Forest" by Conrad Richter. While there are many examples of personification in this book, one particularly strong example is the personification of the forest itself:

* The forest is described as having a "will" and a "life of its own." Richter writes: "The forest had a will of its own. It had its own ways of living, and its own way of dying, and it was wise and strong and patient. It did not hurry."

This statement gives the forest human-like qualities of intention and purpose, making it seem almost sentient and capable of independent thought.