Pattern of Diversity in the Vegetative and Generative Crown Structure of the Siberian Stone Pine on a Seed Orchard with Sparse Tree Planting

Abstract

Studies of the diversity of economically valuable traits in forest tree species are of great interest not only for forest selection and practical silviculture, but also important as a general biological problem. Among the objects of attention of breeders, a special place is occupied by cone-bearing species such as Siberian stone pine. Its cultivation through the forest tree plantations for wood and for cone-bearing will allow in the future to reduce the damage for natural ecosystems significantly. The purpose of this work was to analyze the structure of diversity in growth and generative development of the Siberian stone pine crown on a specially created plantation, where a low level of natural selection makes it possible to more efficiently select for early reproduction, growth and seed productivity. This plantation is located in the south of the area (Western Siberia, south of Tomsk region). It was created from stone pine seeds of the local population, that were sown in 1977 as forest crops with standard density (0,75 х 3 м). At the age of 10, they were planted out at a distance of 8 x 8 m. The vegetative and generative development of 89 trees aged 40 years was analyzed. We used a retrospective method that allows reconstructing of the tree organogenesis and growth on the scars on the bark of the shoots. The start of sexual reproduction has been reconstructed; a comparative characteristic of the vegetative and generative development of the tree crown has been carried out. The results show that, in general, the initial idea of the dependence of the efficiency of selection on the conditions in which the trees were formed is confirmed. In the natural dense stands, many of the leader trees in cone-bearing, which we found in our study, could fall behind due to slow growth and did not live to reproductive age. On the plantation where sparse tree planting was applied, they survived and became the leaders in cone-bearing. Early start of reproduction, even under conditions of sparse tree planting, is positively correlated with the growth rate in the pre-generative period of ontogenesis (r = + 0.65). The level of variations in the generative development of trees was much higher than in the vegetative one. The abundance of male shoots in the crown and the relative length of the male generative zone of crown were determined primarily by the height of the trees. On the contrary, the active growth of the tree in height did not have a noticeable influence on the development of the female shoots and the female generative zone of crown. Contrasting differences in the traits of male and female crown development with growth traits are very interesting result, in our opinion. Tall trees with a narrow crown are most promising for pollen productivity breeding, since they have a longer male generative zone and because of this they have more male shoots in the crown. Trees with a broad crown are promising for seed production breeding. Although seed productivity is not in all cases a direct function of the size of the crown, but depends on the specific genotype of the tree. This is confirmed by the fact that in each group (high, medium and low trees) there are individuals of high-cone-bearing and low-cone-bearing, which is promising for seed production breeding in groups of different growth levels. Using the calculated relative traits «1 m² of the area of the horizontal projection of the crown onto the ground surface» made it possible to select the best trees for seed production (combining the minimum size of the crown with the number of cones per unit area of the crown) and growth (combining greater height and narrow crown).
For citation: Velisevich S.N., Popov A.V. Pattern of diversity in the vegetative and generative crown structure of the siberian stone pine on a seed orchard with sparse tree planting. Lesnoy Zhurnal [Forestry Journal], 2019, no. 5, pp. 35–47. DOI: 10.17238/issn0536-1036.2019.5.35
Funding: This work is supported by the Russian Science Foundation under grant no. 18-16-00058.
⃰ The article is published within the framework of implementation of the scientific journals development program in 2019, based on proceedings of XIX International conference of the young scholars “Forests of Euro-Asia – The Southern Ural” (August 25-30, 2019. Chelyabinsk).