I n v estment T imin g . A classic problem in management of forests is determining when it is most

I n v estment T imin g . A classic problem in management of forests is determining when it is most economically advantageous to cut a tree for lumber. When the tree is young, it grows very rapidly. As it ages, its growth slows down. Why is the NPV-maximizing rule to cut the tree when its growth rate equals the discount rate?