Biomorphology of Quercus robur L. (Fagaceae) in the Upper Volga lowland (Based on the example of the Dubravna reserve in the Taldomsky city district of the Moscow region)

Abstract

The organization of the crown in Quercus robur individuals growing in the communities of the Dubravna nature reserve in the Taldom urban district in the north of the Moscow region was studied. We studied virginal, young reproductive and middle-aged reproductive individuals growing in a cleared area, in gaps of different sizes and in closed parcels of small-leaved spruce stands. The direction of growth, growth and relative position of the trunk and branches from the trunk were analyzed. Three main methods of crown formation have been identified. In the first method, the crown is formed by an orthotropic trunk with single forks (dichasia), and the largest branches have an ascending direction of growth. With the second method, the trunk deviates from the orthotropic direction, becomes arcuate and can move to the plagiotropic direction of growth. In this case, the branches on the “inner” side of the trunk grow plagiotropically, and on the “outer” side - obliquely upward or orthotropically. The third method of crown formation is that the trunk is divided into a complex system of monochasia and dichasia with multiple divisions and “turns” of the daughter axes. In addition, the structure of the crown is also influenced by the frequency of trunk reversal, the proportion and localization of plagiotropic branches, and the formation of false dichotomous structures within the branch. In all habitats, individuals with the first method of crown formation predominate. It is most pronounced in young reproductive individuals in the cleared area. In virginal and young reproductive individuals growing under the canopy of a tree stand, the extent of the crown zone formed by plagiotropic branches increases, and the trunk also more often turns over. In individuals that have entered the canopy, a significant portion of the branches die off, and the trunk is divided by several dichasia. Individuals with the second and third methods grow mainly under the tree canopy and in small gaps. They don't go out into the canopy.