Nutritional aspects of distorted growth in immature forest stands of southwestern coastal British Columbia

Abstract
Nutritional problems, deficiences of B and Zn in particular, have been tentatively identified as the cause of specific distorted growth symptoms in several young stands of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and Pacific silver fir (Abies amabilis (Dougl.) Forbes) in southwestern coastal British Columbia. The most common symptoms associated with these apparent micronutrient deficiencies include leader dieback and discolouration, multileadered and bushy crowns, and, in severely deficient trees, swollen and distorted stems. Visual symptoms of apparent B deficiency become obvious when foliar concentrations are < 5.0 ppm; visual symptoms of apparent Zn deficiency are less easily recognized, usually occurring when foliar Zn levels are less than approximately 9.0 ppm. Low foliar concentrations of B were often associated with low levels of Ca and Mg. Foliar B concentration was also correlated with total foliar S. Temporal variation in foliar nutrient levels, examined over 3 years, was quite high with an apparent strong relationship to growing season precipitation. This suggests that deficiencies of B and (or) Zn may be acute rather than chronic, with the appearance of periodic acute deficiencies being influenced by growing season soil moisture supply.

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