Crown form and harvest increment in pendulous Norway spruce.
Crown characteristics and the distribution of three years’ (1986–88) biomass production of 20 pendulous Norway spruce (Picea abies f. pendula (Lawson) Sylvén) trees with heritable narrow crown and 15 normal-growned spruces (Picea abies (L.) H. Karst.) were studied in a 19-year-old mixed stand.
The form of the crown is conical in normal-crowned trees, columnar and narrow in pendulous trees. The partitioning of aboveground biomass to stems during the studied 3-year period was significantly higher in pendulous (0.281) than in normal-crowned trees (0.255) and also the ratio between growth of stemwood and growth of needle biomass during three years was higher in pendulous trees (0.67 g g-1) than in normal-crowned trees (0.52 g g-1). The needle biomass was distributed higher in the crown in pendula than in normal-crowned trees and they had a higher needle biomass/branchwood biomass ratio than normal trees. The difference in harvest increment between the two crown types are mostly due to the significantly lower branchwood biomass values in pendulous than in normal-crowned trees. The higher needle ’efficiency’ in pendulous trees is probably connected with high partitioning of needle biomass to the upper part of the crown in pendulous trees.
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Published in 1991