"Supply" is a word widely used, hence one with several meanings. A meaningful and unambiguous exchange of ideas between us on the subject of timber supply requires some initial difinitions of terms and concepts. At the minimum, we must distinguish between shortrun timber supply, or the ability to harvest timber from a presently available stock, and longrun supply, or the ability and willingness to grow timber for future harvests. I have preferred to call these "willingness to harvest" and "willingness to invest in growing" timber, to measure human reaction rather than biological potential. Some trees will grow without Man's help and indeed some will grow in spite of almost anything we may do to try to prevent them. But investment of capital, labor, and management capabilities will increase timber growth for potential future timber harvest. At any given moment, our timber supply is limited to that volume and those kinds of trees which have grown in the past and are now standing.