Some Comparative Characteristics of Second-Growth and Old-Growth Redwood

Old-growth and second-growth redwood are compared with respect to specific gravity, strength, shrinkage, and other properties. Silvicultural practices can aid in producing high-quality timber on the shorter rotations. Most old-growth redwoods have grown slowly; 20-50 rings per inch is common, and 8 percent of the trees sampled had 60 or more rings to the radial inch. Average specific gravity for old-growth trees was 0.38, with a wide range from 0.21 to 0.52. Moisture content in old-growth trees was 150 percent of the ovendry weight of the wood in the heartwood near the stump and decreased gradually upward to about 60 percent at 80 feet above the ground. In heartwood of second-growth redwood, moisture content varied from 150 percent at the stump to 60 percent at a height of 60 feet. Extractives present in redwood may influence shrinkage and compressive strength. Redwood is among conifers having very low volumetric and transverse shrinkage. Superior quality lumber is found in narrow-ringed, clear portions of large, old-growth trees. Production of this wood has taken one to two thousand years. Second-growth trees, less than 100 years old, have grown rapidly and have a very different natural appearance. It appears that for best quality, young stands should be densely stocked at first. Eight rings per inch produces desirable lumber. Young stands should also be pruned of lateral branches at an early age.

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