72 BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



inadequacy of its seed supply. 15 The virgin stand, with a total of 20 

 trees per acre (estimated), about half of which are over 20 inches, 

 heads the list in number of seedlings. Plot 3b, however, with its 23 

 trees per acre over 11 inches, has a third less seedlings than 3a 

 with only 15 trees, and about the same number as plot 3 with only 

 12 trees. This discrepancy is at least partially explained by the 

 fact that plot 3b has a very large proportion of small trees (below 

 21 inches) and that they occur in unusually large groups. It is 

 evident that we must consider size, crown development, and distribu- 

 tion as well as total number of trees. Considering only the trees 

 above 20 inches in diameter, plot 3b still has a good margin over 

 plots 3 and 3a, but it has a smaller number of large, free-standing 

 trees than the other two plots. This relation is illustrated by the 

 number of yellow pines. Plot 3b has no yellow pines, whereas plots 

 3 and 3a have 1.4 and 1.5 per acre, respectively. As explained in 

 the chapter on seed supply, yellow pines as a class are better seed 

 trees than blackjacks, because of their greater size and better crown 

 development and because a yellow pine is rarely left unless it is a 

 good seed tree, whereas blackjacks are left indiscriminately unless 

 they are plainly diseased or defective. 



In comparing the areas in Group I, the number of seedlings 

 needed, as well as the number present, should be considered. If 

 an area has twice as many seedlings as are needed for full stocking, 

 there is a possibility that it has more seed trees than are necessary. 

 It is difficult to fix a definite standard as to the minimum require- 

 ment for full stocking, because of uncertainty as to survival. Eec- 

 ords of a number of seedling stands indicate that 10 per cent is a 

 conservative figure for survival between the second and the tenth 

 year. Assuming a minimum of 200 ten-year-olds per acre as full 

 stocking, all of the areas in Group V, excepting the " timber rights " 

 sections, may be expected to show a surplus at the end of the 10 

 years. This indicates that even the most lightly stocked area, 

 plot 3, has more seed trees than are absolutely needed. Before ac- 



15 An extensive survey of this region by M. W. Westveld in June and July, 1920, 

 covering 05 sections of alternating Forest Service and " timber rights " cuttings, gave an 

 average of 0,325 1919 seedlings per acre for the former and 3,113 for the latter. On 

 many of the " timber rights " sections the stand ran as high as 10 trees over 12 

 inches per acre. On such areas seedlings were almost as numerous as on Forest Service 

 cuttings. Considerable areas, however, bad as few as 2 trees per acre, and here seed- 

 lings were almost entirely absent. The figures for Forest Service cuttings average con- 

 siderably below those on sample plots 3, 3a, and 3b. This is due partly to fewer seed 

 trees and partly to the fact that on a considerable portion of the area covered by West- 

 veld the seed crop was lighter than in the vicinity of plots 3, 3a, and 3b. Assuming the 

 same rate of mortality on the sections examined by Westveld as on the sample plots, It 

 seems evident that even the Forest Service cuttings will scarcely have sufficient survival 

 for complete stocking, whereas the " timber rights " sections will certainly fall below the 

 standard. The entire area covered by Westveld's survey, as well as sample plot 3, has 

 been grazed by sheep, which have destroyed over 25 per cent of the 1919 seedling crop. 

 Sheep were excluded from the greater portion of this region in 1921. 



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