NURSERY PRACTICE FOR PRAIRIE-PLAINS PLANTING 113 



Every individual seedling was measured for height (from ground 

 line to tip of stem) and caliper and put into a specific grade. Caliper 

 was obtained in sixteenths of an inch at a point 2 inches above the 

 ground line, in order to make these measurements comparable with 

 those already presented regarding the effect of density of stand 

 (number of trees per lineal foot of row) on the size of stock produced, 

 which were also taken at 2 inches from the ground. Weights were 

 also measured on 25 to 70 representative seedlings of each species to 

 obtain data on the relation of caliper to weight, the stem-root ratios, 

 and the effect of top pruning on balance, and weigh t-caliper curves 

 were drawn. Height-caliper curves were drawn based on 100 to 300 

 measurements for each species. Both sets of curves are shown in 

 figure 42. The indication is that seedlings vary in form and taper 

 according to species, some being short and stubby, others long and 

 slender. 



The results of the first-year field survivals for representative species 

 are shown in figures 43 and 44. A few irregularities in survival are 

 attributable to differences in soil and the cultivation given after 

 planting. An examination of the bar charts brings out a definite 

 relation of size of planting stock to field survival. Small grades of stock 

 below %6-uich caliper are generally culls, trees between % 6 - and %6-inch 

 caliper are marginal grades, and those above % 6 -inch caliper are prem- 

 ium grades for most species. (Fig. 45.) 



Small trees of slow-growing species, or those with medium growth 

 rate in the nursery, have a higher survival than trees of the same caliper 

 class in fast-growing, succulent nursery or wnding stock. For 

 instance, a honeylocust, Osageorange, or American elm seedling of 

 ^6-inch caliper had a better survival than the same size tree of Chinese 

 elm. cottonwood. or catalpa. For practically all species, stock with a 

 caliper of Ke-inch, the best size for field planting, gave uniformly 

 good survival. 



There are, besides survival, a number of advantages in favor of 

 sturdy plants of good caliper. For one thing, they grow better and 

 more vigorously than small stock. For instance, seedlings of black 

 locust in the K 6 -inch-caliper class had an average height of 29 inches 

 at the end of the first season after field planting; whereas, those of 

 6 { 6 -inch caliper and over, even after having been top-pruned to 6 inches 

 at time of planting, had an average height of 50 inches. This 

 stand will close earlier, and cultivation can be dispensed with in 

 a shorter time. 



Larger trees are less likely to be plowed out or buried during culti- 

 vation. On very sandy areas they are not so likely to be injured by 

 the blowing away of soil from the roots or by having the bark cut 

 away by the moving sand. Survival examinations in Oklahoma 

 showed rather high loss in small seedlings where the rows crossed over 

 sandy knolls, mostly from the blowing away of several Laches of soil 

 from the roots. In large stock the loss was much lower. 



Again, their greater supply of stored food aids the Larger plants to 

 establish their root systems sooner, making them less suseeptible to 

 midsummer droughts and other ill chances. Examination of the root 

 systems of 1-year-old seedlings in the middle of the first season in the 

 field showed that large planting stock had a much wider spread oi 

 roots and usually had penetrated deeper than small stock. In case 



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