The practice of thinning works on the proven fact that most sites can produce the same amount of volume growth on fewer good stems as they can on many smaller ones. Thinning will occur naturally in a stand that is overcrowded, but the process will take many years and result in a reduced growth rate of all the trees, including the crop trees. The goal then is to take advantage of the volume in the trees that will die off before they die and maintain the growth rate of the crop trees. Pine thinning accomplishes multiple objectives; 1) increases or maintains the growth rate, 2) improves or maintains the health of the trees, 3) increases resistance to insects and disease, 4) provides earlier and more steady financial return, 5) improves wildlife habitat and 6) increases forest management options.
The optimal approach to thinning is to accomplish two of them in the life of the stand. Each one should concentrate on removing the smallest, least productive stems from the stand of trees, leaving the best trees as "crop trees". The first thinning should occur at age 16 - 20 and bring the number of trees down to 250-300 trees per acre dependent on the site and health of the trees. The second thinning should then occur at age 25 - 30 and reduce the stocking to 125 trees per acre. These are the trees that will be carried to the full rotation age of 35-45. Thinning pines can actually shorten the overall rotation length by growing a larger diameter tree in less time.
By thinning your trees, you will be selling the trees that are removed. Typically you should get $14 - $18 per standard cord of wood removed in the first thinning. Most first thinnings seem to yield an average of 10-12 cords per acre and the buyer usually pays per unit volume removed which is measured in weight as the trucks enter the mill. Loblolly pine pulpwood in Virginia averages about 5200 pounds per cord. This means each cord of pulpwood weighs approximately 2.6 tons and the price range above is equivalent to $5.38 to $6.92 per ton (or $0.27 to $0.35 per 100 pounds). The thinning sale contract often expresses the price you get in terms of weight received at the mill. Different mills use slightly different weight conversions so you should be aware of what your buyer is using.
Seldom is there a lump sum sale in a thinning. Sometimes a deposit may be paid by the buyer which represents a certain percentage of the estimated volume. This ensures the pines will be cut soon. The second thinning often results in both pulpwood and "chip and saw" wood (small sawtimber) that brings an even better price. A consulting forester may be hired to estimate the volume and administer the sale if you desire. I can provide you with a list of consulting foresters.
More often than not, thinning is done by mechanical row thinning. In this case they cut an entire row of trees every 45-60 feet apart. Then, certain trees are removed from between the rows. This has proven to be an effective and efficient way to operate a thinning. In some cases, on smaller tracts, the project can be marked for a thinning. This ensures that the better trees are left in the woods but many buyers prefer to avoid the constraints it imposes. You should be aware that not all loggers have the skill and experience to conduct a successful thinning. It is vitally important that care be exercised in both the selection of trees and the removal of trees so that the future crop trees are capable of responding to the increased space to grow and not damaged in any way. A list of local pine thinning operators is available upon request.