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The grading of lumber starts with the growth of the tree. As the tree develops from a seedling branches are formed, some of which become large and remain in the tree as long as it lives, others die or are broken off and the stub eventually becomes covered by the wood of the tree. During the lifetime of the tree it may go through periods of drought, which affect the wood produced during that period; it may be affected by wind storms producing shakes, which are longitndinal separations of the wood fibers, and it may be attacked by fire. Pitch pockets and other variations of growth may be formed. As a result, the lumber produced from a log will vary from that which is clear and without defect to that having many defects. In addition, certain accidents of manufacture, machine damage, overstressed wood due to rough handling, cracks, broken pieces, etc., also appear in the lumber. All of these things affect the grade of lumber sawed from the tree.
Document Type: Journal Article
National Lumber Manufacturers Association
Publication date: May 1, 1938
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The Journal of Forestry is the most widely circulated scholarly forestry journal in the world. In print since 1902, the Journal has received several national awards for excellence. The mission of the Journal of Forestry is to advance the profession of forestry by keeping forest management professionals informed about significant developments and ideas in the many facets of forestry: economics, education and communication, entomology and pathology, fire, forest ecology, geospatial technologies, history, international forestry, measurements, policy, recreation, silviculture, social sciences, soils and hydrology, urban and community forestry, utilization and engineering, and wildlife management. The Journal is published bimonthly: January, March, May, July, September, and November.