Effects of sclerophyllous shrub sprout competition on the morphological development of 1 + 0 containerized Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were monitored above- and below-ground for 5 years after planting. Seedlings were planted among dead shrub sprouts 0.25 m in height (treatment C1), stumps of mature shrubs slashed just before planting (treatment C2), and shrub sprouts 0.5 m in height (treatment C3). In treatments C2 and C3, stumps sprouted quickly and sprouts grew vigorously, whereas C1 seedlings grew initially without competition. Above- and below-ground growth were reduced substantially and similarly by increasing competition. Root and shoot biomass of C1 seedlings were approximately 9–10 times and 22–25 times larger than that of C2 and C3 seedlings, respectively. During the first growing season, root biomass of seedlings in all three treatments increased relatively more than did shoot biomass. This growth pattern was reversed during subsequent seasons, and over the 5-year period resulted in greater growth in shoot biomass than in root biomass. Both shoot/root and height/diameter ratios increased over time in C2 and C3 seedlings. In contrast, the shoot/root ratio increased and the height/diameter ratio decreased in C1 seedlings. Allometric regression analyses showed no significant difference in biomass allocation to shoot and root among treatments over time.
Bareroot 2-0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and ponderosa pine (Pinusponderosa Dougl. ex Laws.) seedlings were subjected to five undercutting treatments, which varied by number and depth of undercut and seedling phenology at time of treatment, so that morphological characteristics at lifting and field performance 4 years after planting on droughty south slopes in southwest Oregon could be evaluated. All undercutting treatments significantly reduced seedling top growth, but changes in root system morphology depended upon treatment severity and species. Treatment effects were generally more pronounced in ponderosa pine than Douglas-fir. Multivariate analysis of variance showed significant treatment effects for both species based on seedling morphology at lifting, but discriminant analyses revealed that these differences existed primarily between undercut seedlings, regardless of undercutting treatment, and controls. In Douglas-fir this separation was largely due to differences in seedling height and in ponderosa pine it was due to differences in tap root biomass. However, no treatment effects were detectable 4 years after outplanting for either species despite record high air temperatures during the first growing season, suggesting that morphological differences at lifting were probably not of sufficient magnitude to affect field performance.
A stepwise discriminant function analysis, based on soil chemical properties at the growing site, was used to differentiate conifers with root decay caused by Armillariellamellea (Vahl. ex Fr.) Karst. from conifers without A. mellea decay. Discriminant functions developed for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and grand fir (Abiesgrandis (Doug.) Lindl.) were significant. Low soil nitrogen and pH were associated with decayed Douglas-fir; low soil calcium and phosphorus and high soil potassium were associated with decayed grand fir.
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