Structural features of the crown of young individuals of Quercus robur L. in Western Cis-Kama region

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.

The characters of Quercus robur and Q. petraea leaves are of main taxonomic value and the adult trees of both species can be distinguished on them. However, young individuals, mostly seedlings but also saplings, are told to be undistinguishable or only partly distinguishable on the leaf morphology. The aim of the study was to verify this hypothesis on the basis of biometrical analyses of leaf characteristics of adults trees and saplings in two mixed oak woods, one located close to the north-eastern limit, the other about 400 km inside of the Q. petraea range in Poland. The analysis of discriminations and minimum spanning tree on the squares of Mahalanobis distances were analysed to find differences between Q. robur, Q. petraea and intermediate adults and saplings. The differences between saplings of Q. robur and Q. petraea were found lower than between adult trees. Nevertheless, the biometrical analysis confirmed determination of saplings in the field.

Questions:1. What are the spatial patterns of all trees, individual tree species, trees within particular height classes, all gaps and gaps with specific properties across the study site in broad‐leaved deciduous forest at a range of scales? 2. Are patterns of the above features spatially associated? 3. Are these patterns indicative of gap creation mechanisms and phases of regeneration?Location:Frame Wood, New Forest, UK.Methods:Ripley'sK‐function analysis was applied to spatial information derived from airborne remotely sensed imagery to characterize the patterns of trees and gaps and to test for spatial interactions between these patterns. The patterns of trees and gaps with specific physical and spatial properties were analysed.Results:The pattern of all tree species combined was random for most scales;Quercus roburfollowed the same random pattern, whileFagus sylvaticaandBetula pendulawere clustered over most spatial scales. Large gaps (> 250 m2) and larger trees (> 17.5 m) were randomly distributed, while smaller gaps and smaller trees were clustered. Significant spatial relationships were demonstrated between the patterns of different tree species and between trees within different size classes, as well as between the patterns of trees and gaps with specific properties.Conclusions:Small gap patterns and field evidence indicated that progressive gap enlargement is the most likely creation mechanism for large gaps (> 250 m2). Clustered patterns of younger individuals were indicative of patches of past regeneration. As a complement to field‐based data, data derived from remotely sensed imagery provides spatially comprehensive information with which to further investigate woodland stand/community processes and gap dynamics.

Questions: 1. What are the spatial patterns of all trees, individual tree species, trees within particular height classes, all gaps and gaps with specific properties across the study site in broad-leaved deciduous forest at a range of scales? 2. Are patterns of the above features spatially associated? 3. Are these patterns indicative of gap creation mechanisms and phases of regeneration? Location: Frame Wood, New Forest, UK. Methods: Ripley’s K-function analysis was applied to spatial information derived from airborne remotely sensed imagery to characterize the patterns of trees and gaps and to test for spatial interactions between these patterns. The patterns of trees and gaps with specific physical and spatial properties were analysed. Results: The pattern of all tree species combined was random for most scales; Quercus robur followed the same random pattern, while Fagus sylvatica and Betula pendula were clustered over most spatial scales. Large gaps (> 250 m 2 ) and larger trees (> 17.5 m) were randomly distributed, while smaller gaps and smaller trees were clustered. Significant spatial relationships were demonstrated between the patterns of different tree species and between trees within different size classes, as well as between the patterns of trees and gaps with specific properties. Conclusions: Small gap patterns and field evidence indicated that progressive gap enlargement is the most likely creation mechanism for large gaps (> 250 m2). Clustered patterns of younger individuals were indicative of patches of past regeneration. As a complement to field-based data, data derived from remotely sensed imagery provides spatially comprehensive information with which to further investigate woodland stand/community processes and gap dynamics.

QuestionsAre there significant differences in the density and composition of natural regeneration among habitat types? Is the abundance of regeneration higher in patches more seriously damaged by a windstorm than in patches not affected by the wind? Is the species diversity of regeneration greater than the diversity of mature trees prior to disturbance?LocationSzast Protected Forest, NE Poland.MethodsThroughout the Szast P.F., 111 sample plots were distributed in a regular grid 13 years after a windstorm. In plots located in disturbed forests, we measured all the canopy trees and the 30 young individuals of each size class (seedlings, short saplings and tall saplings) closest to the plot centre. In non‐disturbed patches, we measured all trees within a plot of predefined radius. For statistical analyses of differences in the diversity between mature stands and young generation, we used the Kruskal–Wallis test followed by Dunn's multiple comparison test. The relationship between the canopy layer and the young generation of trees was analysed using Spearman's rank correlation and a classic negative binomial regression.ResultsNatural regeneration was more abundant in the coniferous and mixed coniferous habitat types than in the mixed deciduous type. The density of young trees was negatively correlated with the basal area of the trees that survived the windstorm and was positively correlated with canopy tree mortality. After the windstorm, Pinus sylvestris lost more trees than the other species; Picea abies and Betula pendula slightly increased their share; and the species that benefited most from the disturbance was Quercus robur. In the coniferous habitat type, the species diversity of the young generation of trees was higher than the diversity of the canopy trees prior to the windstorm.ConclusionsLeaving wind‐disturbed areas to natural regeneration could be a viable option for converting coniferous plantations into more diverse and species‐rich stands.

From the viewpoint of the hierarchy of shoot systems crown architecture in virginal and young reproductive individuals of Quercus robur L. in meadow steppes and various insular pineries in the Northern Voronezh refion is studied. The number of studied individuals is over 700. While systematized diversity of shoot systems categories of architectural model, architectural unit and architectural type (AT) were used. It has been established that Q. robur in the zone of the southern forest-steppe forms the same AT as in the mixed and broadleaved forest biomes in the Oka River basin. The individuals of the AT I prevail both under full light and canopy. Under shading most individuals of the AT I demonstrate decrease of growth processes and simplification of shoot systems. All AT of Quercus robur in the southern foreststeppe form a wider range of forms than in the mixed and broadleaved forest biomes. This is caused by realization of reduction and increasing processes and by forming new shoot structures of different levels.