Figure 1.Product Yield for Loblolly Pine, Hypothetical Standon the map above.
SIZE IS CRITICAL
A log’s value, and therefore a tree’s value, depends on the value of the products that can be made from it. One of the most important parameters for softwood trees is size: a larger log can produce a wider variety of products and (usually) more valuable products can be made from larger logs.
The tricky part is that log products or grades are usually based on the diameter of the small end of the log, while tree diameters are measured 4.5 feet off the ground (DBH). The small end of a log will be anywhere from 6 feet to 100 feet higher than that. But, for most species, a minimum DBH can be determined that will yield a log with an acceptable minimum diameter for a product.
For example, Timber Mart-South uses the following specifications for products when reporting timber prices across the South:
This means, for example, that a tree with a 12-inch DBH is expected to produce a log that has a small-end diameter large enough to be sold to a sawmill.
Table 1. Distribution of Volumes and Value from a Hypothetical Stand of Loblolly Pine
High End, Rare Logs At the top of the size (and value) list are veneer logs and poles. Pole logs (used in making utility poles) are perhaps the rarest, because not only must they be large in diameter, but they must be long, sometimes over 100 feet long. Veneer logs (or ply logs) must be large in diameter, but don’t need to be nearly as long as poles.
However, as valuable as these logs are, they are usually not a significant component of most institutional investment forests. Intensive management and maximization of returns tend to lower rotation ages, which reduces the volume of larger trees suitable for these products.