Longitudinal shrinkage, kiln-drying defects, and lumber grade recovery of red pine (Pinus resinosa Ait.) from a 125-year-old natural stand and a 57-year-old plantation

Longitudinal shrinkage, out-of-plane warp or distortion, and lumber grade recovery of red pine (Pinus resinosa Ait.) were investigated in a 125-year-old natural stand and a 57-year-old plantation in eastern Maine. Shrinkage measurements from short, clear specimens showed no age-related differences between the two stands when the samples were dried from the green condition to 12.4 percent moisture content and from green to 0 percent moisture content. In both stands, shrinkage decreased until age 15. In contrast, out-of-plane distortion was greater in 4/4 boards sawn from the plantation than in boards sawn from the natural stand. The greatest difference between stands occurred in pith-centered boards, with out-of-plane distortion of boards from the plantation exceeding that of boards from the natural stand by 0.06 in./ft. The overall grade recovery of lumber from the natural stand was higher than the grade recovery of lumber from the plantation. Thirty-one percent of the boards from the natural stand were graded as select, whereas only 9 percent of the lumber from the plantation was graded as select.

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