. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Age 20 Years (800 Trees Per Acre) Age33Years (580 Trees Per Acre) Valley region the first general period ends somewhere between the ages of 40 and 50 years, depending upon the local situation; in the central Atlantic coast belt apparently between 55 and 70 years. Figure 6, showing progressive stages of natural thinning and crown, classed according to age, represents actual numbers of trees and outlines of crowns as the}' existed in four fully stocked stands in Arkansas measured for growth and yield. The 20-year-old sta
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Age 20 Years (800 Trees Per Acre) Age33Years (580 Trees Per Acre) Valley region the first general period ends somewhere between the ages of 40 and 50 years, depending upon the local situation; in the central Atlantic coast belt apparently between 55 and 70 years. Figure 6, showing progressive stages of natural thinning and crown, classed according to age, represents actual numbers of trees and outlines of crowns as the}' existed in four fully stocked stands in Arkansas measured for growth and yield. The 20-year-old stand contained 800 trees per acre; the 33-year-old stand, 580 trees; the 42-year-old stand, 400 trees; and the 52-year- old stand, 320 trees per acre. Shortleaf pine shows progressive changes in the character of the forest canopy other than the mere reduc- tion in number of trees. These changes are well illustrated in figure 6 for stands from 20 to 50 3rears old. In early life the tree crowns are approximately circular in outline and closely approach each other, leaving very little un- occupied space. At the age of 50 years, however, the tree has become less tolerant, the crowns are quite irregular in outline, and crown isolation leaves relatively large light spaces in the canopy. The slow rate of natural thinning after about 50 years undoubtedly is accompanied by relatively small changes in the tolerance of the tree. The climax of lateral growth or spread of the branches characteristic of the species seems to be closely ap-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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