The Understory by Richard Powers is a beautiful novel that tells a part of the story of the chestnut tree and certainly deepened my appreciation for it.
Yes, The Overstory. The writing is great and Powers seems to have done a tremendous amount of beautifully presented background research (none of which he wants to leave out). But, somewhere in the middle, the book's focus shifts from its interesting characters to a strident narrative about our impending doom.