| Abstract |
- Two studies were undertaken in search of a method or methods which might improve the survival of planted Douglas-fir seedlings on severe sites. The first, or preliminary study involved the planting of 2-0 Douglas-fir seedlings on southerly aspects, using nine techniques, including a control. The second, or main study involving 2-0 Douglas-fir seedlings planted on southerly or westerly aspects, was for the purpose of investigating in greater detail the most promising techniques in the preliminary study. In the pre1iinary study, the nine planting techniques were control (planting only); scalping before planting; fertilizer pellet in planting hole; simazine spray over area next to tree; paper sheet mulch over area next to tree; scalping plus fertilizer pellet in planting hole; scalping plus simazine spray on bared area; scalping plus fertilizer pellet in planting hole and simazine spray; scalping plus pulverized fertilizer on bared area, topped with sawdust mulch. There were two sizes of plots, or tree planting spots: one was approximately 18-inches square; the other was approximately ¼-milacre square. In both sizes of plots each treatment involving 25 plots was replicated twice, bringing the total number of plots to 900. After two growing seasons, observations showed that the large sized plots having the paper sheet mulch gave the best survival, with 38 percent. A statistical analysis of variance showed this was significantly better then all other treatments, except the one employing scalping, pulverized fertilizer and sawdust mulch (54 percent) and was nearly significantly better than the latter. In the main study, located on four adjoining aspects-southeast, south, southwest and west- the paper sheet mulch method of planting was investigated as follows: control (planting only); l8-inch paper squares; 27-inch paper squares; 36-inch paper squares. Rows of all four treatments (25 plots each) were replicated three times in four blocks on the four aspects, in completely randomized order. Therefore, except for differences in aspect row each row treatment was replicated 12 times. In all, there were 1200 plots. A time and cost study was also conducted. Because of poor stock, much of which was dead at mulching time and much of which did not burst its buds, survival results were based on the number of mulched and control trees that burst their buds rather than on the number of trees planted. After two growing seasons, best survival resulted from using the 36-inch squares, with 60 percent, which was followed by 27-inch squares, with 49 percent, 18-inch squares, with 33 percent and controls, with 10 percent. A statistical analysis of variance showed differences in percent survival due to sizes of squares to be highly significant (P=.01), whereas no significant differences were found due to aspects or the interaction of aspects and size of squares. In the time and cost study, it was found that ease of application decreased as size of paper increased and cost increased as size of paper increased. Conclusions were that it would take a square slightly larger than 27 inches to achieve a survival of 50 percent. Also, that by relating the cost of each treatment to the survival achieved under each, the optimum size square would be between 27 and 36 inches, which in the long run is cheaper than control or 18-inch squares. Finally, it was concluded that the paper sheet mulch method of planting offers a practical and much less expensive solution to the problem of planting trees on severe sites than do normal methods.
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