Development of the Shoot System of Young Loblolly Pine II. Dry Matter and Nitrogen Accumulation

Abstract Patterns of dry matter and N accumulation of the various parts of the shoot system of loblolly pine were characterized during the fifth year of the tree's development. The first of four flushes accumulated the most dry matter. The entire tree increased in mass throughout the year, and stem and foliage made the largest gains among the parts. The foliage mass doubled even though all the older foliage was lost during the year. Most of the branch accumulation was in the middle crown. During the calendar year, three different N accumulation rates were exhibited by the trees, the highest rate occurring between mid-August and October. Nitrogen accumulation generally paralleled foliar development, i.e., production of current foliage and the loss of older foliage. In contrast to other tissues, foliage accumulated N continuously. This continuity of accumulation was, in part, apparently maintained by transfer from other tree tissues. Net accumulation within individual trees was 7.6 g of N and 2.1 kg of dry matter. For the entire plantation this amounted to 34.1 and 9,400 kg/ha of N and dry matter, respectively. Forest Sci. 17:55-62.