Nilsson U, Hallgren JE
Changes in Growth Allocation Owing to Competition for Light in Young Fertilized Norway Spruce Trees
Forest Ecology and Management: 1993 62:157-172
In order to study the effects of competition for light without the effects of below-ground competition, young Norway spruces were artificially shaded on plots where intraspecific competition for water and nutrients was minimized. The plots were fertilized with complete nutrient solution and irrigated to maintain soil water at field capacity. At the start of the experiment the stand was 26 years old, and the experiment lasted for 3 years. The average height increment of shaded trees was greater than that of control trees during the second and third year of the experiment. Decreases in stem growth for shaded trees were found during the first 2 years, but not during the final year of the experiment. Growth of needles and twigs was reduced by the shading treatment during the second and third year of the experiment, but not during the first year. The reduction in stem wood growth and shoot growth that was caused by the shading treatment was greatest in the lower part of the tree. Shaded trees allocated more of their above-ground growth to stem wood, and less to needles, than did control trees.
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