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Background. Fraxinus excelsior L. is a common forest species in the Central Russian Upland, used to produce valuable lumber and for landscaping. Mass mortality of this species due to fungi and insects determines the relevance of its detailed research. Tree crown development features play an important role in the tree’s life in both dense communities and open spaces. Materials and methods. Shoots and large branches were collected from the apical part of the crown for ten years in Belgorod and Leningrad Provinces. The lengths of internodes and shoots, the numbers of leaves and branchings, and shoot development patterns were analyzed. An unmanned aerial vehicle was employed to examine the treetops. The complexes of large branches on the crown periphery in different age states (g1, g2, and g3) were studied both by direct measurement and using photographs. The effect of temperatures on the length and number of leaves was assessed with a two-way analysis of variance (ANOVA). Results. Shoots of F. excelsior are significantly shorter at high mean temperatures in the second ten-day period of June. The number of leaves on them is significantly greater at high temperatures in the second ten-day period of May. Six-to-eight-leafed shoots make up the ascending part on the curve of the sequence of internode lengths for the most developed shoots. In ontogenetic states g1 and g2, the crown surface is represented by sections of large branches. In the g3 state, they break up into complexes of small weakly branching spherical structures. The apical branches of the umbrella-shaped crown of generative ash trees are inverted cone-shaped shoot complexes with a similar development pattern. Conclusion. The structure and development of F. excelsior branches characterizes the ecological features of the species, manifested through the absence of obvious branching orders and combined with the inverted conical shape of large branches.

Abstract Objectives To determine the relationship between different parameters (age, periodontal phenotype, contact point height, and crown shape) and the height of the interproximal papilla around the teeth of/in the maxillary anterior sector. Material and Methods A total of 45 subjects were involved in this study, with 315 interproximal papillae of the maxillary anterior sector. The interproximal papillae were clinically classified according to the Norland and Tarnow classification. The periodontal phenotype was assessed by periodontal probe transparency through the marginal gingiva. The height of the papilla, the height of the contact points, and the width/length ratio of the crown were also measured using the periodontal probe. The relationship between the variables was studied using Pearson's correlation. Statistical significance was set at a value of p

The apple tree is a leading fruit crop in Ukraine in terms of production volumes and planting areas and is a valuable food product with a high content of vitamins. In new modern plantings, fruit producers prefer intensive cultivation technologies that ensure the maximum amount of high-quality fruit yield per unit area. The main criterion for solving this problem is the design of plantings: a narrow-row scheme for planting trees and a low-volume crown shape. The purpose of the study was to establish the influence of the pruning period of different types of crown formations on the growth and productivity of apple trees of two varieties: Fuji and Honey Crisp. The study was conducted in the conditions of the central Forest-Steppe of Ukraine (Uman National University of Horticulture). The scheme of planting was 4x1 m, M.9 rootstock, chernozem sod-podzolic soil, drip irrigation. Field, statistical, and computational-analytical methods were used in the course of the study. It was identified that the growth pattern of the examined varieties differed substantially, and crown volume, projection area, and development of the feeding area prevailed in Honey Crisp trees. However, in terms of productivity, the plantings of the Fuji variety substantially exceeded the values of the Honey Crisp variety. Forming a ballerina crown with the removal of overgrown wood in a 25 cm zone on the central trunk above the lower tier of semi-cellular branches provided an increase in the growth activity of the examined trees by 3-5%. A substantial decrease in the values of crown parameters was provided by the formation of the French axis crown – there was a decrease in the crown diameter by 44%, the crown volume – by 67%, and the crown projection area and the development of the feeding area – by 69%. Performing additional summer pruning of trees also helped to reduce growth activity by 6-11%. However, the specific productivity of plantings doubled in plantings with the formation of the French axis and by 45-50% with the introduction of double pruning of trees. It is recommended that agricultural producers investigate the terms of pruning low-volume crown forms, considering varietal characteristics, to create compacted apple stands and increase the intensification of production

Objectives: To determine the relationship between different parameters (age, periodontal phenotype, contact point height, and crown shape) and the height of the interproximal papilla around the teeth of/in the maxillary anterior sector. Material and Methods: A total of 45 subjects were involved in this study, with 315 interproximal papillae of the maxillary anterior sector. The interproximal papillae were clinically classified according to the Norland and Tarnow classification. The periodontal phenotype was assessed by periodontal probe transparency through the marginal gingiva. The height of the papilla, the height of the contact points, and the width/length ratio of the crown were also measured using the periodontal probe. The relationship between the variables was studied using Pearson's correlation. Statistical significance was set at a value of p <.05. Results: A positive correlation was found between age and the papilla score. However, a negative correlation was noted between age and papilla height, with statistically significant values. A negative correlation was found between the papilla score and the rest of the studied clinical parameters. However, this correlation was not found with regard to the height of the papilla with the same parameters, except for the height of the contact points. Conclusions: A statistically significant relationship was noted between the appearance of the interproximal papillae and all the parameters studied. [ABSTRACT FROM AUTHOR]

Growth is a component of forest dynamics that encompasses changes in species composition, interactions between species, and stand structure. We evaluated the effect of the presence of lianas, crown shape, and light exposure on the periodic annual increment of trees (PAI) in two phytophysiognomies: the ombrophilous dense forest and the ombrophilous open forest with lianas. This study was conducted in the eastern Brazilian Amazon in 13 permanent monitoring plots of 50 m × 50 m (2500 m2) in the same annual production unit. The area has been subjected to reduced-impact logging from 2014 to 2016. The increment in tree diameter varied significantly between both forests (opens forests: 1.28 cm yr−1; dense forests: 0.82 cm yr−1). Light exposure influenced the increment in tree diameter in the ombrophilous open forest with lianas, while the crown shape and light exposure significantly affected the ombrophilous dense forest. Our study emphasizes the usefulness of the periodic annual increment in exploring the differences between contrasting phytophysiognomies in a single annual production unit in the Brazilian Amazon that is subject to reduced-impact logging. [ABSTRACT FROM AUTHOR]

The vigour of the variety-rootstock association, the crown shape, the planting distance, the age of the trees, and the tree pruning pattern have been examined. The studies regarding the establishment of sweet cherry orchards, as well as the growth and fruiting of the 'Valerii Cikalov', 'Record', 'Ferrovia', 'Kordia', 'Regina', 'Stella', 'Skeena', 'Bigarreau Burlat', 'Lapins', 'Early Star', 'Samba', 'Black Star' sweet cherry trees grafted on the Prunus mahaleb L., 'MaxMa 14' and 'Gisela 6' rootstocks, in different combinations and planting distances, have been carried out in the Southern and Central fruit-growing area of the Republic of Moldova. High vigorous trees are used on non-irrigated soils in association with self-fertile varieties at optimal planting distances that ensure high yields. The sweet cherry trees, grafted on the semi vigorous rootstocks ('Gisela 6') and the moderate vigour rootstocks ('MaxMa 14') are used on fertile soils and irrigated at high densities. They can provide medium vigour of trees, which can be handled completely from the ground level, produce early average yields, with low pruning and fruit harvesting costs due to increased labour productivity. The pruning done during the growing period resulted in the vegetative growth of the trees and the formation of fruiting branches that produced better flower buds compared to the pruning done during the dormant period. The rootstock-variety association should be chosen in accordance with the direct task, the growing system and the applied technology. [ABSTRACT FROM AUTHOR]

Crown shapes of common European urban tree species differ from tree species to tree species and are modified by the age of a tree and its local environment. A tree's crown shape has a great influence on the crown volume and thus on the ecosystem service provision of a tree such as the shade area or the shade density. We used the data of 3852 tree individuals from eight German cities and the crown shape data of 528 trees for the species Acer platanoides, Acer pseudoplatanus, Aesculus hippocastanum, Fraxinus excelsior, Platanus × acerifolia, Robinia pseudoacacia and Tilia cordata to analyze tree structural dimensions and the crown volume and shade dependency on a tree's crown shapes. Ovoid (57% of all tree individuals) and spherical (24%) crown shapes were mostly observed. However, columnar shape was observed for light-demanding R. pseudoacacia in close proximity of objects. The greatest shade areas were measured for spherical shape and the highest shade density for ovoid shape. Logistic regression analysis showed significant effects of age and distance to objects on crown shapes. Significant probability of crown shapes was found for different tree species, e.g., A. hippocastanum strongly showed half-ellipsoid crown shapes. [ABSTRACT FROM AUTHOR]

Objective To analyze the impact of the activation mode on the results of space closure in the mandibular arch using a double keyhole loop (DKHL) with a typodont model and reverse engineering technique to provide guidance for clinical treatment. Methods Nine normal mandibular typodont models after leveling were randomly divided into 3 groups, which then underwent three types of DKHL activation for space closure. Each model was assessed at the initial stage and after the warm water bath, and the images were superimposed to measure the displacement of special crown and root mark points. All statistical analysis of the data was performed using SPSS 19.0. Results After equal activation times, the root retraction of anterior teeth and the crown forward position of posterior teeth in groups activated at the distal loop (conditions 2 and 3) were much greater than those in the group activated horizontally (condition 1). Activation between mesial and distal loops (condition 3) induced significant anterior tooth intrusion, together with elongation and buccal inclination of posterior teeth. The displacement of mark points among the three conditions showed a statistically significant difference. Conclusion The movement of mandibular anterior and posterior teeth could be flexibly controlled through different DKHL activation modes, which should be chosen carefully according to individual conditions.

On the basis of randomized selection of common hazel (Corylus Avellana L.) in the natural population of the North-West Caucasus, crown polymorphism has been studied by shape, diameter, height, density and diameter of the bush base. Plants grow at heights of 250-1,500 m above the sea level. Classification has been carried out on the basis of the well-known methodology for the pomological description of varieties. 450 fruiting rames of various ages have been examined so far. Data processing has been performed using the «Stadia» computer program. It has been established that more than 74% of plants in the population have a rare and dense crown. Bushes of medium density are represented by one quarter. The proportion of individuals with a weeping crown shape, which is of the greatest value for decorative purposes, was found in 0.22 % of cases. The main part of the plants has a shoot distribution diameter at the base of the bush from 0.10 m to 0.5 m, they account for 60.22 %. The diameter of the hazel crowns in the population vary between 1-12 m, and has a significant coefficient of variation of 42.13 %. Fruiting plants have a height ranging from 2 to 15 m, coefficient of variation of 40.33 %. The presence of individuals with a height of up to 3 m and more than 12 m suggests the possibility of selection of both undersized and overgrown forms.

Growth is a component of forest dynamics that encompasses changes in species composition, interactions between species, and stand structure. We evaluated the effect of the presence of lianas, crown shape, and light exposure on the periodic annual increment of trees (PAI) in two phytophysiognomies: the ombrophilous dense forest and the ombrophilous open forest with lianas. This study was conducted in the eastern Brazilian Amazon in 13 permanent monitoring plots of 50 m × 50 m (2500 m2) in the same annual production unit. The area has been subjected to reduced-impact logging from 2014 to 2016. The increment in tree diameter varied significantly between both forests (opens forests: 1.28 cm yr−1; dense forests: 0.82 cm yr−1). Light exposure influenced the increment in tree diameter in the ombrophilous open forest with lianas, while the crown shape and light exposure significantly affected the ombrophilous dense forest. Our study emphasizes the usefulness of the periodic annual increment in exploring the differences between contrasting phytophysiognomies in a single annual production unit in the Brazilian Amazon that is subject to reduced-impact logging.

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to determine the frequency of different crown shapes and associated dental anomalies of the permanent maxillary lateral incisor (PMLI) and their impact on aesthetics and occlusion (function) in orthodontically treated patients. Materials and Methods: The records of 372 subjects, which consisting of study casts, panoramic radiographs and anamnestic data, were investigated for crown shape and associated dental anomalies of PMLI and potential dental treatment to achieve satisfactory aesthetics and function. Descriptive statistics, including means, standard deviations and percentages for the observed variables, were calculated. Data were analyzed using the chi-square test. p-Values < 0.05 were considered as statistically significant. Results: The results showed that the most common crown shapes of PMLI were trapezoidal-shaped (59.8%), followed by central incisor-shaped (26.7%), canine-shaped (11.2%) and peg-shaped (2.3%), without statistically significant difference between genders. Developmental anomalies were found in 86 (11.6%) PMLI. All subjects with developmental anomalies were included in orthodontic treatment, and 91.2% of them need interdisciplinary treatment to achieve satisfactory aesthetics and function. Conclusions: The morphological diversity and developmental anomalies of the PMLI may affect aesthetics and function and should be considered in treatment planning.

This work examines the growth and fruiting of modern cherry plantations according to the vigour of the varietyrootstock association, crown shape and planting distance. The impact of the crown formation system on the growth and fruiting of 'Ferrovia', 'Kordia', 'Regina', 'Stella', 'Skeena', 'Bigarreau Burlat', 'Lapins', 'Early Star', 'Samba' and 'Black Star' cherry varieties grafted on Gisela-6 and MaxMa 14 rootstocks in various combinations and at diverse planting distances was studied. During the first eight years of fruiting, the trees of 'Skeena' and 'Ferrovia' varieties, which had an improved slender spindle shape of their crowns, yielded the highest harvests. The yield produced by the variety of trees which had been planted at the distance of 5 x 1.5 m (18942-20074 kg/ha) was the highest; the smallest harvest was produced by the varieties planted at the distance of 5 x 2.5 m. During the ninth year of vegetation, the 'Kordia' and 'Regina' varieties grafted on the MaxMa 14 rootstock produced record harvests of 19221-19314 kg/ha. On average over three years, the 'Kordia', 'Regina' and 'Skeena' varieties were more productive as compared with the 'Ferrovia' and 'Stella' varieties. [ABSTRACT FROM AUTHOR]

3D crown shape and tree ring development are autobiographies of the growth conditions. With advancements in terrestrial laser scanning, modeling growth from 3D crown structure offers insights into trees' structural and functional responses in a non-destructive and repetitive way. However, how the trees in different growing conditions respond in 3D structure and manifest their responses into tree rings remains unexplored, which would help to better explain tree-level growth dynamics and forest management. To enhance this understanding, we tested a set of hypotheses: (HI) that 3D crown shape (CS) and tree ring (width) patterns (TRP) are correlated across different growing conditions or forest stands like monospecific, provenances trials, and mixed forest stands; (HII) that stand types influence the CS-TRP link; and (HⅢ) local neighborhood competition (LNC) modulates the CS-TRP link. (HⅣ) 3D crowns manifest local growth conditions; therefore, 3D crown structures can be used to predict tree ring growth. We assessed these hypotheses by employing terrestrial laser scanning-based 3D crown shape and dendrochronology-based tree ring width patterns from Norway spruce (Picea abies [L.] Karst.) trees growing in pure spruce (unthinned and thinned), provenances trial, and mixed-species trial (with European Beech, Fagus sylvatica [L.]) stands covering a large-scale competition gradient. We first show that 3D crown shape and TRP metrics differed significantly across forests (p<0.05) but were correlated (p<0.05). Neighborhood competition among the forest types influences the link between 3D crowns and tree rings. Pathway-based analyses revealed that neighborhood competition indirectly influences ring variability by modifying crown structure (p<0.05), suggesting local growth conditions are mostly manifested into crown shapes, leading to 3D crown shape-based low-error growth predictions (0.44 mm) across forest types. However, incorporating competition legacy information (competition over the last 30 years) in the model slightly improved the prediction performance (error reduced to 0.41 mm), further explaining that the crown likely loses growth information due to growing conditions (competition it faces and species with it is growing). This study reveals how trees in different growing conditions differed structurally and mechanized their responses in tree rings, providing crucial insights into tree-level growth dynamics and management. [Display omitted] • 3D crown structure (CS) and tree ring patterns (TRP) are significantly correlated across forest stands. • The CS-TRP link is influenced by neighborhood competition and stand types. • CS mostly manifested and indicated the local growing conditions (competition). • 3D crown shape is a good and novel predictor of tree growth. [ABSTRACT FROM AUTHOR]

A microwave scattering model is a powerful tool for determining relationships between vegetation parameters and backscattering characteristics. The crown shape of the vegetation canopy is an important parameter in forestry and affects the microwave scattering modeling results. However, there are few numerical models or methods to describe the relationships between crown shapes and backscattering features. Using the Modified Tor Vergata Model (MTVM), a microwave scattering model based on the Matrix Doubling Algorithm (MDA), we quantitatively characterized the effects of crown shape on the microwave backscattering coefficients of the vegetation canopy. FEKO was also used as a computational electromagnetic method to make a complement and comparison with MTVM. In a preliminary experiment, the backscattering coefficients of two ideal vegetation canopies with four representative crown shapes (cylinder, cone, inverted cone and ellipsoid) were simulated: MTVM simulations were performed for the L (1.2 GHz), C (5.3 GHz) and X (9.6 GHz) bands in fully polarimetric mode, and FEKO simulations were carried out for the C (5.3 GHz) band at VV and VH polarization. The simulation results show that, for specific input parameters, the mean relative differences in backscattering coefficients due to variations in crown shape are as high as 127%, which demonstrates that the crown shape has a non-negligible influence on microwave backscattering coefficients of the vegetation canopy. In turn, this also suggests that investigation on effects of plant crown shape on microwave backscattering coefficients may have the potential to improve the accuracy of vegetation microwave scattering models, especially in canopies where volume scattering is the predominant mechanism.

The purpose of this study was to practice and improve the use of low volume crowns in a high-density system in order to obtain qualitative cherry production that would be competitive on the market and to make efficient use of the labor force. The research was carried out in the intensive cherry orchard planted in the autumn of 2011 with “Ferrovia”, “Kordia”, and “Regina” varieties, grafted on Gisela 6 (Prunus cerasus × Prunus canescens) rootstock interspaced at 4x2.5 m and managed according to the Ameliorated natural crown systems with low volume, Ameliorated Slender Spindle and Vase shaped crown. Harvest, diameter, firmness, dry matter content and fruit weight were determined. The trees started to yield in the third year after planting. The harvest in the second year of yielding was 4-5 kg/tree. The average harvest in the third year of yielding was 9640-13290 kg/ha. For all three varieties the harvested quantity and fruit size were correlated with the crown shape. The Ameliorated Slender Spindle crown provided the highest production per hectare, while the Flattened Vase Shaped crown provided the lowest yield but had the highest values of the fruit size (28.2-28.4 mm) and of the soluble dry matter in the fruit (17.9-18.6 Brix%).

Cherry technology is permanently modernized due to new varieties, vegetal rootstocks and new tree management systems. The cherry varieties “Bigarreau Burlat”, “Ferrovia” and “Lapins”, grafted on Gisela 6 (Prunus cerasus × Prunus canescens) rootstock at distances of 5x1.5 m; 5x2.0 m; 5x2.5 m, were studied in the southern area of the Republic of Moldova. The trees were shaped by the Ameliorated natural reduced-volume crown and Slender Spindle Ameliorated form. Cherry trees start to yield in the fourth year after planting; the largest total fruit production from the tree was obtained in the variant with trees planted at a distance of 5x2.5 m and per hectare, when the trees were planted at a distance of 5x1.5 m. In the fourth year of yielding, the production of “Ferrovia” cherry variety, where the trees were shaped by the Ameliorated natural crown with low volume constituted 15368-18155 kg/ha, and at the time the “Slender Spindle Ameliorated” form, constituted 16904 -20074 kg/ha. Although the results are preliminary, it seems that high-density planting systems combined with low-power vegetal rootstocks and improved crowns can give higher yields of cherries in the first 4 years than the traditional improved crown system with low volume.

Cherry technology is permanently modernized due to new varieties, vegetal rootstocks and new tree management systems. The cherry varieties "Bigarreau Burlat", "Ferrovia" and "Lapins", grafted on Gisela 6 (Prunus cerasus × Prunus canescens) rootstock at distances of 5x1.5 m; 5x2.0 m; 5x2.5 m, were studied in the southern area of the Republic of Moldova. The trees were shaped by the Ameliorated natural reduced-volume crown and Slender Spindle Ameliorated form. Cherry trees start to yield in the fourth year after planting; the largest total fruit production from the tree was obtained in the variant with trees planted at a distance of 5x2.5 m and per hectare, when the trees were planted at a distance of 5x1.5 m. In the fourth year of yielding, the production of "Ferrovia" cherry variety, where the trees were shaped by the Ameliorated natural crown with low volume constituted 15368-18155 kg/ha, and at the time the "Slender Spindle Ameliorated" form, constituted 16904-20074 kg/ha. Although the results are preliminary, it seems that high-density planting systems combined with low-power vegetal rootstocks and improved crowns can give higher yields of cherries in the first 4 years than the traditional improved crown system with low volume. [ABSTRACT FROM AUTHOR]

The purpose of this study was to practice and improve the use of low volume crowns in a high-density system in order to obtain qualitative cherry production that would be competitive on the market and to make efficient use of the labor force. The research was carried out in the intensive cherry orchard planted in the autumn of 2011 with "Ferrovia", "Kordia", and "Regina" varieties, grafted on Gisela 6 (Prunus cerasus × Prunus canescens) rootstock interspaced at 4x2.5 m and managed according to the Ameliorated natural crown systems with low volume, Ameliorated Slender Spindle and Vase shaped crown. Harvest, diameter, firmness, dry matter content and fruit weight were determined. The trees started to yield in the third year after planting. The harvest in the second year of yielding was 4-5 kg/tree. The average harvest in the third year of yielding was 9640-13290 kg/ha. For all three varieties the harvested quantity and fruit size were correlated with the crown shape. The Ameliorated Slender Spindle crown provided the highest production per hectare, while the Flattened Vase Shaped crown provided the lowest yield but had the highest values of the fruit size (28.2-28.4 mm) and of the soluble dry matter in the fruit (17.9-18.6 Brix%). [ABSTRACT FROM AUTHOR]

Research on the interaction mechanisms between a bit and rock is a focus of the field of rock breaking theory in drilling engineering. The bottom hole shape, which directly affects the effectiveness of rock breaking at different positions around the bottom hole, is the key factor in research on the interaction between a bit and rock. This paper aims to discuss the influences of bottom hole shape on effectiveness of rock breaking. Firstly we established the mathematical model of rock breaking strength and used it as an evaluation index to analyze the influence of bottom hole shape on effectiveness of rock breaking. Secondly, the relationship between the rock breaking strength and cutting speed, cutting depth, rock lithology and bottom hole shape are verified by experimental approach and numerical simulation. The mathematical model of the relationship between the rock breaking strength and the bottom hole shape is established with a finite element method. Finally, this paper takes minimum rock-breaking energy consumption as the goal and introduces the “crown breaking work per revolution” as an objective function to optimize the bottom hole shape. This paper uses the fact that the shape of the bottom hole is symmetric and corresponds to the crown shape to determine the optimal design of a PDC bit crown profile by inverse design. This paper will help to expend the ideas of bit design and promote the development of research on rock breaking theory. [ABSTRACT FROM AUTHOR]

• A framework of allometric models for maximum knot size prediction is presented. • The model framework is valid for uneven-sized Norway spruce dominated stands. • Basal area of larger competitors is a significant predictor to branch length. • Branch length can be predicted with crown ratio as a proxy for competition impact. • Branch diameter is a function of age, length and relative position of the branch. The size of knots is negatively correlated with bending strength in sawn timber and it is therefore used as a quality grading criterion in national roundwood grading standards. Some standards even use the size of the largest knot as the sole estimate for individual log knottiness. The size of knots is determined by crown horizontal extension, which in turn is dependent on the impact of competing trees. Thus, with knot size models that are competition-dependent, roundwood quality due to knottiness can be simulated for different management alternatives. However, these types of models, calibrated on uneven-sized Norway spruce in Fennoscandia, are currently not available. Therefore, the objective of this study is to develop a competition-dependent model framework for prediction of the largest knot size per stem height section, for application within uneven-sized Norway spruce stands. Data from terrestrial laser scanning of an uneven-sized stand in southern Sweden are used to calibrate a modular prediction framework, consisting of interlinked allometric statistical models. Alternative framework sub-models are presented and the preferred model combination can be selected according to context and available input data. The flexible modular format enables further development of separate sub-components for adaptation to growing conditions not covered by the current calibration range. [ABSTRACT FROM AUTHOR]

There are 3 types of crown shapes of the maxillary central incisors: type I-rectangular, type II-triangular and type III-oval. 250 study models of orthodontic patients of both sexes (125 males and 125 females) on the Dental Clinic in Nis were tested, with an attempt to determine the existence of variations in the crown shapes of maxillary central incisors. Gingival and incisal width and the crown height were measured by a digital nonius, as well as the proximal sides angle slope (Ø) according to Goose. Slightly more than a half of the examinees (52.40%) have a rectangular shape of the central incizor crown and a third (34%) has a triangular shape. Fewest examinees have an oval crown shape (13.60%). Similar distribution of crown shapes is found according to the examinees sex: a rectangular shape in 52% of boys and 52.80% of girls, a triangular shape in 36.80% of boys and 31.20% of girls and an oval shape in 11.20% of boys and 16% of girls. (Ø) angle is 7.56° in the total examinee sample, which coincides with the European population values. (Ø) angle is 6.95°in the triangular shape (6.51°in females and 7.39°in males); it is 8.20° in the oval shape (8.55° in females and 7.93° in males).

Aims: The aim of this study was to investigate if there is a correlation between the shape of the crowns of the incisors and crowding. Materials and Methods: Plaster models of 100 individuals having class I molar relationship were chosen .By using the irregularity index, 51 individuals (22 males and 29 fe-males) were considered to be the crowding group(irregularity index >3mm),and 49 individuals (23 males and 26 females) were considered to be the normal group(irregularity index< 3mm).The casts were selected from the POP department at the college of dentistry in Mosul University. Repeated mea-surements of the maximum mesiodistal width of the incisal and cervical areas of the incisors were tak-en by means of a vernier caliper and a ratios of these measurements were calculated. Results:The mean value for the crowding group was significantly higher in the incisal area of lower incisors and upper central incisors than corresponding values in the normal group. A significant correlation was present between upper irregularity index and upper lateral incisor mesiodistal width ratio. Conclusions: The lower incisors were more triangulary shaped in the crowding group than those in the normal one.

OBJECTIVES: The aim of this study was to evaluate the influence of the crown shape on the outcomes of root coverage procedures. MATERIAL AND METHODS: Eighty patients with Miller class I gingival recessions in maxillary canines or premolars were selected. The recession areas were treated using the subepithelial connective tissue grafting. The following clinical parameters were analyzed: crown length (CL) and width (CW), recession height and width, probing depth, clinical attachment level, width and thickness of the keratinized tissue and percentage of root coverage achieved. These measurements were recorded at baseline and 6 months after the surgical procedure. The CW/CL ratio was calculated for each tooth and the median obtained (0.83). Patients were then ranked into two groups, according to the shape of the tooth with gingival recession: Group A - square crown shape (CW/CL values above 0.83) and Group B - long and narrow crown shape (CW/CL values below 0.83). RESULTS: No statistically significant differences (p>0.05) were found between groups in any of the clinical parameters at baseline. After 6 months, both groups presented improved clinical outcomes for all parameters analyzed compared to baseline (p>0.05). The mean percentages and standard deviations of root coverage achieved in Group A and Group B was 91.37 (16.75) and 85.49 (23.55), respectively (p>0.05). CONCLUSIONS: Crown shape did not influence the root coverage obtained with the subepithelial connective tissue graft technique.

Key message : Mechanical properties of wood constrain most conifers to an excurrent form and limit the width of tree crowns. Development of support tissue alters allometric relations during ontogeny. Abstract: Biomechanical constraints on tree architecture are explored. Torque on a tree branch is a multiplicative function of mass and moment arm. As such, the need for support rises faster than branch length, which leads to increased taper as branch size increases. This violates assumptions of models, such as the pipe-model theory, for large trees and causes changing allometry with tree size or exposure. Thus, assumptions about optimal design for light capture, self-similarity, or optimal hydraulic architecture need to be modified to account for mechanical constraints and costs. In particular, it is argued that mechanical limitations of compression wood in conifers prevent members of this taxon from developing large branches. With decurrent form ruled out (for larger species), only a conical or excurrent form can develop. Wind is shown to be a major mortality risk for trees. Adaptations for wind include dynamic responses of wood properties and height. It is argued that an adaptation to wind could be the development of an open crown in larger trees to let the wind penetrate, thereby reducing wind-throw risk. It is thus argued that crown shape and branching may result not just from optimal light capture considerations but also from adaptation to and response to wind as well as from mechanical constraints. Results have implications for allometric theory, life history theory, and simulations of tree architecture. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to determine the relationship between crown length as well as crown width and gingival morphotypes (primary aim) and their correlation with tooth shape and papilla height (secondary aim). Material and methods: Thirty-six adult subjects were evaluated in this clinical study according to their gingival morphotype (GM) defined by transparency of a periodontal probe through the buccal gingival margin. Eighteen subjects comprised the thin entity group and 18 the control group thick entity, respectively. Besides crown length (CL) and crown width (CW), two different methods to assess crown shape (CW/CL ratio) were compared and analysis of their relation to papilla height was performed. Results: Nineteen female and 17 male volunteers were enrolled in this study, with a mean age of 24.9 years (±3.4; minimum 18, maximum 35). A statistical significant difference for the crown length could be detected between both groups ( p < 0.05) but not for crown width. No significant difference was found for apical or coronal CW/CL ratio besides on tooth 22. Conclusion: Within the limitations of this study and within this young Caucasian study population, only crown length seems to have an association with different gingival morphotypes. Furthermore, papilla height and crown shape do not have a clear correlation on tooth level. Clinical relevance: Crown shape seems to be not a strong parameter in assessing the gingival morphotype. [ABSTRACT FROM AUTHOR]

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Platycladus orientalis (L.) Franco is a beautifully crown-shaped evergreen tree species used for ornamental cultivation. These trees are also important afforestation plants at hill sites containing calcareous parent rocks and exhibit high tolerance to drought and barren sites. However, Platycladus orientalis trees with abnormal crowns, such as fusiform and torch-form, have been identified at sites with extreme drought and barren hills in Shandong, China, although the abnormal crowns does not reduce the ornamental value of these trees. In the present study, we used the RGB imaging and geographical statistical analyses through the construction of meteorological indices. The results indicate that variations of abnormal Platycladus orientalis crowns are associated with both the internal metabolism of these trees and the external environment. Crown shapes are strongly affected by the local dry, hot and windy meteorological environment, particularly individuals planted at poor hill site conditions. In response to extreme events of drought, high temperature and strong winds, the twigs and scale leaves of Platycladus orientalis typically wilt from the lower part to the upper part of the crown. The fusiform and torch-form crowns are formed through the wilting of partial twigs and scale leaves to avoid the entire wilt of the trees, thereby saving the life of the tree at the expense of partial twigs and scale leaves. [ABSTRACT FROM AUTHOR]

Crown profile models were developed for Chinese fir (Cunninghamia lanceolata) in Shunchang County, Fujian Province. We used data from 360 trees located in 65 pure, even-aged, and unthinned temporary plots. The data were divided into three groups according to site index. Nine models, including models for upper crown, lower crown, and entire crown, were fit; the optimal ones in each group were validated and chosen to estimate crown shape. The optimal models explained at least 70% variability in crown radius (CR). In addition, models for crown width, height above ground to crown base, and height above ground to largest CR were also developed to facilitate the convenient simulation of crown profile models. These three models explained 85.4%, 85.1%, and 86.9% variability. All models also passed the F-test and residual test. The 3D images of a single tree and stands were presented by OpenGL technology on visual c++ platform based on the proposed models. Tree growth was compared and analyzed using crown profile curves under constrained conditions. The analysis results accorded with plant growth. [ABSTRACT FROM AUTHOR]

The quantitative parameters characterizing the esthetic and spatial characteristics of the tree species Sorbus domestica L., including the architecture and the crown size, were evaluated in order to assess the qualified sources of planting material for the urban environment. Five types of crown shape (spherical, hemispherical, umbrella-shaped, ovate, and conical) were identified during field assessment of trees growing in the open landscape. Conformity of the classification under specific phenotypes within field studies and classification of trees based on quantitative parameters were evaluated using discriminant analysis. The variables included in the discriminant analysis model (crown diameter, crown length, and stem girth) were obtained from direct measurement in the field. A statistically significant relationship was found between crown volume and diameter at breast height. Under the specific environmental conditions of an open landscape, high values of crown volume were recorded not only for the thickest trees but also for trees with diameters oscillating around the mean values of this parameter. Our results indicate that the environment has a greater effect on the stem diameter increment of trees, than on the crown size and crown architecture of S. domestica . [ABSTRACT FROM AUTHOR]

Background and Aims Proper characterization of the clumped structure of forests is needed for calculation of the absorbed radiation and photosynthetic production by a canopy. This study examined the dependency of crown-level clumping on tree size and growth conditions in Scots pine (Pinus sylvestris), and determined the ability of statistical canopy radiation models to quantify the degree of self-shading within crowns as a result of the clumping effect. Methods Twelve 3-D Scots pine trees were generated using an application of the LIGNUM model, and the crown-level clumping as quantified by the crown silhouette to total needle area ratio (STARcrown) was calculated. The results were compared with those produced by the stochastic approach of modelling tree crowns as geometric shapes filled with a random medium. Key Results Crown clumping was independent of tree height, needle area and growth conditions. The results supported the capability of the stochastic approach in characterizing clumping in crowns given that the outer shell of the tree crown is well represented. Conclusions Variation in the whole-stand clumping index is induced by differences in the spatial pattern of trees as a function of, for example, stand age rather than by changes in the degree of self-shading within individual crowns as they grow bigger. [ABSTRACT FROM AUTHOR]

The article presents information on a study conducted on the impact of climate on the height of trees. It is stated that increasing tree height poses both biomechanical and transportational problems for trees. In the study, the researchers studied forest canopy height based on satellite data in Sulawesi, Indonesia, the Pacific Northwest of the U.S., and the Himalayas. The study concluded that temperature distribution has a considerable impact on the distribution of the tallest trees.

In this review, we give an overview of recent cultivation systems in commercial plum orchards. The aspects of selecting the shape of the crown and the spacing of trees are discussed first and then growth characteristics and the structure of the crow are described in detail. Finally, the wound healing and regeneration characteritics of plum trees are detailed which have an influence on the applied pruning technique.

Abstract: Although trees in polluted areas often exhibit modified growth habits, the immediate causes of changes in crown architecture and their consequences for persistence of plant populations in disturbed habitats are not well understood. We compared individuals of mountain birch, Betula pubescens ssp. czerepanovii, growing in severely disturbed habitats (industrial barrens) surrounding a nickel–copper smelter in north-western Russia, with birches growing in unpolluted habitats. They were found to have shorter heights, a shrubby growth habit, lower depth/width and surface/foliar mass ratios of the crown, higher numbers of dead branches and twisted trunks and higher branching resulting from increased numbers of long shoots and more densely spaced buds than individuals in unpolluted forests. The increased production of long shoots was enabled by their formation not only from the axillary buds of previous-year long shoots but also from the apical buds of short shoots. These latter long shoots develop in the inner part of the crown, thus increasing the crown density. Additionally, birches from industrial barrens better compensated for mechanical damage, such as trunk/shoot removal, compared to birches from unpolluted forest and mountain tundra habitats, presumably due to the larger number of buds formed annually. The specific crown architecture of these birches can be explained by the direct effects of pollution combined with changes in microclimate due to pollution-induced forest decline. The seed progenies of birches from an industrial barren reared in a benign environment produced higher numbers of long shoots than seedlings from other habitats, suggesting that adaptive changes in crown architecture are partially shaped by the selection imposed by long-term pollution impacts. Nearly spherical and compact crowns minimise the impacts of unfavourable environmental conditions on trees and are therefore adaptive. We concluded that the development of specific crown architecture allows mountain birch to dominate in habitats that are severely disturbed by pollution. [Copyright &y& Elsevier]

Trees outside closed forest stands differ in the relation between stem diameter, height and crown volume from trees that grew with neighbours close by. Whether this plasticity in tree shape varies between species in relation to their light requirement is unknown. We purposefully sampled 528 trees ranging 5-100 cm diameter at breast height growing in a range of light conditions. Across ten broad-leaved species observed in Sumatra or Kalimantan, a generic relationship was found between light exposure of the crown and a light-dependent a parameter that modifies the height-diameter allometric equation ( H = a D) from those for closed stands. In our results, vertical stretching is well predicted by light availability. In fully open conditions, trees are on average 31% shorter for the same diameter than under (partial) shade. Most of the stretching response occurs in all species as soon as some degree of lateral shading occurs. The response, however, varies by species (8-44% reduction) in a way apparently unrelated to species' successional status. Crown volume varied less than stem height in its relationship with stem diameter across all light conditions tested. The scaling of crown volume with stem diameter, however, differed markedly between tree species. [ABSTRACT FROM AUTHOR]