Phenomenon of Trunk Twist during the Growth of Woody Plants (Using the Example of Pinus sylvestris L. and Picea obovata Ldb.)

Abstract

The phenomenon of trunk twisting in Pinus sylvestris L. and Picea obovata Ldb. during a vegetation period has been revealed and described by direct measurements. The frequency of this phenomenon, magnitude, and direction of twists and their 2-year dynamics have been studied on five sample plots located in different forest-growing conditions. The average rotation angle is 0.2°–0.5°, while its maximum values reach 1.3°–1.7°. These characteristics depend on forest type and weather conditions. Next year more, than half of the trees change their twisting direction to the opposite one, whereas 8–19% of pine trees keep it unchanged. Based on an analysis of our results and the data of other authors, a qualitative model of morphogenetic processes has been proposed to explain the mechanism of this phenomenon.