Apical and radial growth in trunk, branches, and roots, together with needle and cone distribution, were studied in a black spruce tree 31 years old andhigh. Growth of aerial parts was summarized as follows: (1) according to years of formation (oblique summation); (2) transversely on trunk inter-nodes (horizontal summation); and (3) according to the position of the annual rings, and the branch internodes (and needles) in relation to the pith or trunk (vertical summation). Root segments were classified on the basis of their diameter and distance from the trunk. Calculated on a dry-weight basis, the trunk accounted for 37, the branches for 24, the roots for 21, and the needles for 18 of the grand total of 81ensp;kg.The tree had 7.8 million needles when sampled in the fall of 1963, one-quarter of which were formed during the last 2 years of growth. Dry weight of individual needles varied with both position and age. While needles of the same season from the lower part of the crown exceeded those from the upper part in length, the reverse was true for the individual dry-weight content.In black spruce, cone periodicity, while distinct, is not as pronounced as in white spruce. The productive capacity of one "average" needle was estimated in terms of apical growth, trunk wood, and needle and root formation.
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