Density And Growth Ring Characteristics Of Pinus Taeda L. Following Thinning

William W. Moschler, Edward F. Dougal, Deborah D. McRae

Abstract


Sixteen experimental plots of loblolly pine (Pinus taeda L.) grown in plantations in Tennessee, USA, were thinned to basal areas of 13.8 m2/ha (heavy), 23.0 m2/ha (moderate), or 32.2 m2/ha (light) in 1963 at age 23. In 1980 12-mm increment cores were removed at breast height, and sections encompassing 8 years before and after thinning were examined for changes in average wood density, radial growth, earlywood and latewood density, and percent latewood. As expected wood density increased with tree age but was not significantly affected by thinning, even though individual tree growth was considerably improved. Although radial growth usually decreases with age, it actually increased in the heavily thinned plots compared to the less severely thinned or unthinned (control) plots. Trees in the moderately and heavily thinned plots produced wood with lower earlywood density and higher latewood density while percent latewood remained unchanged.

The timber strength and seasoning characteristics related to wood density should not be affected by thinning. However, the shift within growth rings of earlywood and latewood density distributions may adversely affect pulping qualities of wood.


Keywords


Pinus taeda L;thinning;growth-ring characteristics;gamma densitometer

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