Regeneration Patterns on Some Modified Staggered-setting Clearcuts on the H.J. Andrews Experimental Forest PDF Download

Author: Jerry F. Franklin
Publisher:
ISBN:
Category : Forest regeneration
Languages : en
Pages : 104

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Book Description
A survey of natural regeneration of Doug1as-fir and associated species was made on 15 staggered-setting cuttings four and five years after logging. These areas were on the H.J. Andrews Experimental Forest which is located in the McKenzie River area of western Oregon. Five types of cuttings were represented: (1) four north-south oriented strip clear cuts varying from 50 to 330 feet in width; (2) three east-west orientated strip clear-cut varying from 100 to 300 feet in width; (3) six patch or group clear-cuts varying from one fourth to four acres in size; (4) a shade-seed-tree cutting on which residual trees were left to provide shade and seed; and (5) a typical staggered-setting clear-cut. The modified cuttings were designed to utilize shade from the residual stand to favor regeneration by reducing high surface, soil temperatures, a major deterrent to the establishment of tree seedlings in this area. Results of the survey showed that all of the modified cutting units were better stocked than the typical staggered-setting clearcut and with two exceptions had at least 500 we11-spaced trees per acre. The east-west orientated strips regenerated best with 69 to 89 percent of milacre plots stocked. The small group clearcuts also regenerated well; stocking varied from 8 to 72 percent of milacre plots stocked. The north-south orientated strips were the most poorly stocked group of small cuttings with from 35 to 61 percent of milacre plots stocked. The shade-seed-tree cutting had 61 percent of plots stocked and the staggered-setting clearcut 28 percent of plots stocked. The statistical analysis indicated that the parameter of shade hours per plot was consistently related to regeneration of all species together and of Douglas-fir alone. The degree of this relationship varied considerably between types of units and to a lesser extent among units of a particular type. In addition there was some evidence that intermittent shading was more effective in favoring regeneration than a similar amount of shade received in a single period of time. Distance from seed source was not found to be related to stocking on the small cutting units studied. This author concludes that consideration should be given to the use of special cutting methods such as east-west orientated strip clearcuts, small patch clearcuts, and shade-seed-tree cuttings, to aid in natural regeneration of Douglas fir, especially on severe sites. These cuttings should be laid out primarily to provide shade rather than from the standpoint of seed dispersal.