As a result, the fastest growing trees are the most successful competitors. Since pines cannot tolerate shade, their branches thin out and die from the ground up, as the trees become crowded or overtopped. This leaves progressively smaller live green crowns, so the trees become less competitive and eventually die. Most sites produce about the same total wood volume with either a lot of small trees or a few large ones. However, total wood volume is rarely a good indicator of market value.
Individual trees determine the market product, and value increases with diameter.
For example, the same volume of timber would approximately double in value if the trees were large enough to be used for chip' n' saw logs rather than pulpwood. That same volume in trees of sawtimber diameter would be about three times as valuable as chip' n' saw material. Diameter growth is greatly influenced by stand density. To produce sufficient food for vigorous diameter growth, each tree must retain at least one-third of its height in live crown. With normal, uncontrolled competition, the amount of live crown declines to less than one-third on all except the dominant trees in a stand.