Crown structure in Siberian stone pine (Pinus sibirica Du Tour) young generative trees. Spatial organization of shoot diversity

In the 70-80-year-old Siberian stone pine forest in the southeast of Tomsk Region (56°15'N, 84°25'E), the crown structure of young generative Siberian pine trees (Pinus sibirica Du Tour) was studied. Five trees, average in height and DBH, were used to collect branches. The number of the first order branches was counted in each whorl. Then, eight of them, medium in size, were selected for analysis. There were branches from the 5th, 10th, 15th, 20th, 25th, 30th, 35th and 40th whorls, counting from the top. On these branches, all live shoots of all branching orders were counted. For each of them, the distance from the trunk, as well as the length of the last three annual shoots, was measured. The entire range of shoot diversity was divided into 5 unequal segments: up to 5, 6-11, 12-27, 28-62, and more than 63% of the maximum shoot length for a given tree. In each segment on each tree, 5 shoots were collected. On each of them, the number of stem units, the length of the internodes, and the width of the first xylem ring was determined. It was established that in the crown there is a clear predominance of small, some deficit of very small, and an acute deficit of medium-sized and, especially, large shoots (See Fig. 1). In the direction from the top and from the periphery of the crown, the level of diversity and the average size of shoots decrease, at first, very sharply, then very gradually (See Fig. 2, Fig. 3 and Table 1). Concentric domelike crown layers that differ in shoot size and are put into each other only exist if the average size of a shoot is used. As a matter of fact, only the most vigorous shoots in the peripheral part of a crown really form such a dome, which is symmetrical relative to the trunk of the tree. The smaller the size of the shoots, the more they are dispersed throughout the crown volume (See Fig. 4). However, they are located not chaotically, but are organized around the axes of lower order of branching. At the same time, the smaller the size of the shoots is, the higher the organizing value of the axes of lower orders and the more complex the configuration of the space occupied by such shoots are. All the morphological and morphophysiological features that characterize vegetative processes are determined by the size of shoots (the overall level of their growth) (See Table 1). With an increase in the shoot size, the beginning and ending of seasonal periods of morphogenesis and shoot growth move forward, their duration and intensity increase, the metameric structure of the shoot becomes more complicated, and its polar differentiation (acrotonia) increases. Correlations between any vegetative features are always either direct or inverse. The paper contains 4 Figures, 2 Tables and 54 References.

Keywords

Authors

References