Would you be able to recognize a healthy forest if you walked through one? We begin our course in “Forest Health” every summer with this question to our students. Of course their answer almost always is no. They are surprised to learn that neither can we! The reason, we explain, is because there is no widely accepted, clear, and concise definition of a “healthy forest.” Why not? … is almost always the next question. Human health is a relatively easy concept. Arguably, it is the absence of disease. But is a healthy forest one without diseased or dead trees? Following about 10 years of unsuccessfully trying to answer these questions from our students, we decided to attempt to develop our own definition.

Fortunately, during the past 10 to 15 years or so, Paul Manion, Professor Emeritus of Forest Pathology at SUNY-ESF, and his students, were developing the baseline mortality concept of sustainability and forest health. The logic of this concept as the foundation for a concise definition of a healthy forest was so compelling that we adopted it for our course, and decided to write this text. So, the essential concepts that form the basis of this book are his, not ours, and we are grateful for, and readily acknowledge, his lucid thinking. Our contribution is the blending of sustainability (i.e., a sustainable diameter distribution) with productivity (i.e., meeting landowner management objectives) to create our two-part definition of a healthy forest.