Crown organization in reproductive individuals of Quercus robur L. in the western spurs of the Volga upland

Abstract

Background. In recent centuries on the East European Plain massive degeneration of oak forests has been in progress. This is caused by a complex of climatic and anthropogenic factors. Since Quercus robur L. is a key species it seems to be necessary to research comprehensively its individuals and populations at different levels including the aspects of modern biomorphology. The purpose of the study is quantitative and structural analysis of crown organization of reproductive individuals of Q. robur within the Voroninsky nature reserve and its security zone. Materials and methods. The crowns of 335 young and middle-aged reproductive individuals in upland watershed, slope and terrace landscapes of the reserve have been analyzed. We measured meanings of morphometric parameters of individuals, determined its life forms and described a set of elements of architectural models, hierarchic to polyarchic organization plan ratio and expression of reiteration within an individual’s crown. Results. The tallest individuals of Q. robur grow in dense canopy stands on the upland watersheds. The lowest and at the same time the most spread individuals grow in the margins of oakeries and in the sparse oakeries on the slopes. In all habitats the Rauh architectural model-based individuals belonging to the one trunk life forms prevail. Besides in the studied individuals the elements of Troll, Leeuwenberg and Koriba architectural models were detected. In most individuals with aging trunk is replacing with systems of daughter axes having various growth directions. The processes of immediate reiteration contribute significantly to crowns. Conclusions. In all habitats of the Voroninsky nature reserve individuals of Q. robur reach a high level of crown plasticity when get established in middle-age reproductive ontogenetic state. Such level is realized mainly due to enhancement of polyarchic organization plan of crown. This points to the species’ wide adaptive possibilities in terms of the Western Volga upland forest-steppe.

Keywords

• quercus robur
• biomorphology
• life form
• architectural model
• organization plan
• reiteration
• voroninsky nature reserve