Role of Dormant Buds in Crown Architecture in Coniferous and Deciduous Trees of the Temperate Zone

Abstract

The goal of this study is to investigate the localization of dormant buds and the features of the structures arising from the buds in coniferous and deciduous trees in response to age-related changes and various growing conditions. The crown is analyzed using architectural models and the reiteration concept. It is found that the dormant buds in deciduous trees are usually at the bases of annual growth. The dormant buds in conifers are at the bases of annual growth, in the axils of bud scales, or along the entire length of the shoot in the axils of needles and in the shoot distal part. It is revealed that the terminal buds of short shoots can function as dormant buds. The natural aging of skeletal axes is an endogenous factor of the development of shoots from dormant buds in deciduous trees. In evergreen conifers, it is the plant’s response to needle aging. This leads to the induction of the growth of dormant buds and to the acropetal appearance of the buds on the mother axis in conifers. The reiterated complexes of deciduous trees form in response to the completion of the axis development cycle, which initiates dormant buds in the centripetal direction. The reiterated complexes of conifers look like bundles: such structures form due to the easy initiation of dormant buds, which leads to the formation of the shoots of other orders. The reiterated complexes of deciduous trees are characterized by prolonged growth, acrotonicic branching, and orthotropic growth direction. The crown of the old generative and senile deciduous trees consists almost entirely of reiterated complexes. It has been found that conifers have a different degree of participation of dormant buds in the crown formation, which can vary significantly within the same genus. The reiterated complexes of Picea abies (L.) Karst. replace small twigs. In some other species (for example, Picea schrenkiana Fisch. et E. Mey., Abies sibirica Ledeb., Pinussibirica Du Tour.), the reiterated complexes can also replace the skeletal branches extending from the trunk. No secondary crown is formed in Pinus sylvestris L.