Abstract Douglas-fir (Pseudotsuga menziesii Mirb. Franco) seedlings, planted in snowbrush (Ceanothus velutinus Dougl.) stands 0-15 years old, survived and developed significantly better than ponderosa pine (Pinus ponderosa Laws.), western hemlock (Tsuga heterophylla Raf. Sarg.). and noble fir (Abies procera Rehd.) under the same conditions. Capacity of all four species to dominate the site was greatest in snowbrush at age 0, decreasing with increasing age of the snowbrush. Snowbrush attains full occupancy of the site in about ten years, causing serious suppression after that time. Growth in height of six naturally developing conifers was reduced by one-half under suppression by snowbrush. Findings indicate that snowbrush is more detrimental than beneficial in forest regeneration on west slopes of the Oregon Cascades.
Zavitkovski et al. (Tue,) studied this question.
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