Thinning Pine Stands
by James B. “Jim” Kea
Area Extension Forestry Agent – now retired
Thursday, February 9th, 2006
Planting pine trees is often thought of as something to do for the next generation. While it’s true pines take about thirty-five years to mature, income can be generated after about seventeen years through a thinning operation.
As many as eight to nine hundred trees per acre were planted on older pine plantations while currently six to seven hundred trees per acre are being planted. At age thirty-five less than one hundred trees per acre remain. While over five hundred trees per acre died they served a number of useful purposes. They shaded out lower limbs making more knot free lumber earlier than on more open grown trees. They shaded out some competing under growth making more nutrients and water available to the survivors. Extra trees also resulted a greater number of superior or faster growing trees being found on an acre.
While nature will thin out trees naturally, trees too crowded may cause stress related insect problems. Thinning by man will salvage wood that would normally rot, reduce chances of insect problems, provide income early in the timber growing cycle remove poor quality crooked, forked or diseased trees and increase the size and therefore value of the final crop. Trees too crowded will actually have too few limbs to put on good diameter growth. Thinned trees will have enough green top to maximize growth. An acre of pines will only produce so much wood. If that wood is on fewer, larger trees it will be worth more than if it was on many small trees. An acre of small pulpwood trees would only bring two thirds of the value of the same age, larger chip’n’ saw trees produced by thinning. A thinned stand would also produce about a third more income at the final cut.
It has been difficult to sell thinnings until the last three or four years. Now pulp mills are set up to handle this wood that is slightly different from older wood found in tops, defective logs or other mill residue.