Application. Survival and height growth of Douglas-fir bareroot 2 + 0 seedlings during plantation establishment can be increased significantly by using seedlings with both large diameters and root systems. Specific criteria for culling seedlings with small diameters and root size will depend on the characteristics of each nursery crop rather than on the same absolute values for all crops.Abstract. The relationships between field performance of Douglas-fir (Pseudotsuga menziesii) 2 + 0 seedlings and their initial diameter and root mass were evaluated on five sites in Oregon in the early 1980s to identify opportunities for improving seedling grading prior to planting. Survival and height 3--5 years after planting were positively related to seedling size at the time of planting. On all sites, survival nearly doubled from the smallest to largest diameter classes. Root mass had a similar relationship to survival on sites with environmental stress. Increasing root size class increased survival more for the small diameter classes than for the larger diameter classes. On the other hand, increasing root size class increased total height more for the large diameter class than the smaller ones. Although height was not as strongly affected as survival on several sites, height differences among initial seedling diameter classes were still significant and increasing after five years. Root class effects on height were less important than diameter class effects.
Diameter and height growth of 7- to 11-yr-old Douglas-fir (Pseudotsuga menziesii) were examined in relation to bigleaf maple (Acer macrophyllum) competition. Growth models were developed for plantations in Oregon and Washington by joining a distance-dependent model with a model that excluded competition effects. The fitted equations were based on Douglas-fir size at plantation age 7 yr and distance from the stump and crown diameter of the bigleaf maple clump. The models suggest that bigleaf maple clumps between 5.7-14.6 m from planted Douglas-firs decrease the latter's dbh and height growth, and that this decrease becomes greater with increasing size of the clump. A procedure is suggested to use the models to guide vegetation management prescriptions on sites with bigleaf maple sprout clumps. West. J. Appl. For. 10(1):5-11.
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