Effect of Fertilization on the Branchiness and the Wood Quality of Scots Pine

1992

23 S.

46 Lit. Ang.

Bandaufführung

37298

Folia Forestalia ; Nr. 801, 23 S.

The study deals with the effect of repeated ferilizations on the branchiness and wood quality of Scots pine. The material was collected from four 2(hoch 3) factoral fertilization experiments, which were located in the eastern parts of Southern Finland. The sites were sub-dry mineral soils. The sample plots were fertilized with nitrogen, phosphorus and limestone as they were established. The nitrogen fertilization was repeated from two to seven times and the cumulative amount of applied nitrogen ranged from 354 to 1008kg N/ha. The phosphorus fertilization and liming were renewed 20 years after the establishment of the experiments. Thinnings were done once or twice. The material consisted of 150 felled sample trees. The differences between the treatments were tested by the analysis of regression. The volume growth of the tree stand, branchiness and the wood quality were affected only by the nitrogen fertilization. Nutrients that did not increase the volume growth did not affect the branchiness or the wood quality either. During vegetation season trees developed on average 4.6 shoots on the uppermost whorl. The amount of yearly formed shoots was not related to the nitrogen fertilization. The dying of branches was initiated on the tenth whorl from the top of the tree and was on average 0.35 branches per year. The dying was slight and occasional on upper whorl. Branches in nitrogen fertilized sites died within a shorter period than in unfertilized sites, except on the most heavily fertilized experiment. The diameter of living and dead branches and the length of living branches were increased by the increasing age of branches and the diameter of the stem. The nitrogen fertilization enhanced the branch growth even if the size of the tree and its relative size among other trees of the stand (competition index) were constant. The angle of branches was on average 50Grad - 60Grad. The angele was related to the competition index and the age of the tree. An increasing amount of applied nitrogen slightly increased the branch angle. The relationship between the angle and the properties of the tree and the stand was weak. Perhaps the angle of branches is mainly affected by genetic factors. The nitrogen fertilization increased the width of annual rings on average 0.33mm and diminished the basic density on average 2.2%. The heartwood contents were the greatest on 10% relative height. The heartwood contents were greater on nitrogen fertilized sites than on unfertilized sites, except the experiments where the greatest amounts of nitrogen were used. The nitrogen were used. The nitrogen fertilization did not, however, enhance the heartwood contents if other properties of the tree and the site were constant.