Crown Width Research Articles

Models of linear dimensions necessary for constructing the correct shape of the dental arch in boys and girls with a wide face type depending on the characteristics of teleradiometric indicators

Annotation. One of the key tasks of modern orthodontics is the development of individualized approaches to modeling dental arches taking into account the morphological and functional characteristics of patients. Studying the influence of teleradiometric characteristics and three-dimensional parameters of teeth allows to significantly increase the accuracy of orthodontic treatment and the stability of the obtained results. Particular attention should be paid to age and gender differences that affect the structure of the face and the ratio of its structures. The expansion of scientific knowledge in this area contributes to the improvement of methods for predicting and constructing correct forms of dental arches. The aim of the work is to develop and analyze regression models of linear dimensions necessary for constructing the correct shape of the dental arch in Ukrainian young men and young women with a physiological bite and a wide face type depending on the features of teleradiometric indicators according to the Ricketts method and computed tomography dimensions of the teeth. An analysis of primary computed tomograms of 25 Ukrainian young men and 25 young women with a physiological bite and a wide face type was conducted. According to the Ricketts method, “dental”, “skeletal and dento-skeletal” indicators, indicators of “soft tissue aesthetics”, indicators of “craniofacial relationships” and indicators of “internal structures” were determined on lateral teleradiograms. Morphometric parameters of the teeth of the upper and lower jaws in the mesio-distal and vestibulo-oral directions were determined on computed tomograms; as well as the distances necessary for constructing the correct shape of the dental arches. Regression models were constructed using the Statistica 6.0 license package. It was found that both in Ukrainian young men with a wide face type and in young women, all 18 possible reliable regression models with a coefficient of determination greater than 0.6 were constructed (respectively in young men R2= from 0.799 to 0.960, p<0.001 in all cases, in young women R2= from 0.660 to 0.950, p<0.001 in all cases). The following percentages of occurrence in the regression equations of teleradiometric indicators and computed tomography dimensions of teeth were established: in teleradiometric indicators according to the Ricketts method (37.50 %), the width of the tooth crown in the mesio-distal direction (18.75 %), the distance from the cutting edge to the dentino-enamel border line of the tooth in the mesio-distal direction to the apex of the tooth root (9.82 %), the width of the dentino-enamel border of the tooth in the mesio-distal direction and the distance from the cutting edge to the apex of the tooth root (8.04 % each). The following percentages of occurrence in the regression equations of the corresponding teeth were also established: in young men – upper incisors (17.09 %), upper canines (11.11 %), upper premolar teeth and lower incisors (10.26 % each); in young women – upper incisors (27.68 %), lower incisors (10.71 %) and lower canines (8.93 %). The constructed highly informative regression models will allow dentists to reasonably approach the interpretation of the results obtained in patients and implement a more correct approach to orthodontic treatment.

Evaluation of CBCT reconstructed tooth models at different thresholds and voxels and their accuracy in fusion with IOS data: an in vitro validation study

BackgroundThis study aims to evaluate the impact of different thresholds and voxel sizes on the accuracy of Cone-beam computed tomography (CBCT) tooth reconstruction and to assess the accuracy of fused CBCT and intraoral scanning (IOS) tooth models using curvature continuity algorithms under varying thresholds and voxel conditions.MethodsThirty-two isolated teeth were digitized using IOS and CBCT at two voxel sizes and five threshold settings. Crown-root fusion was performed using a curvature continuity algorithm. Volume, surface area, and crown width of tooth models were compared to laser scanning models, and RMS error was measured. Data were analyzed using Wilcoxon signed-rank test, paired t-test, and one-way ANOVA.ResultsVolume amplification errors of CBCT with 0.15 mm and 0.3 mm voxels ranged from 1.22 to 19.07%, surface area errors from 0.18 to 7.78%, crown linearity errors ranged from 2.47 to 7.69%, root linearity errors ranged from − 1.02 to 2.26% and RMS from 0.0691 mm to 0.2408 mm. Crown-root fusion of IOS and CBCT data reduced volume error to -0.90–5.10%, surface area error to -0.66–4.15%, and RMS to 0.0359 mm to 0.0945 mm.ConclusionsVoxel size and threshold settings significantly affect the accuracy of CBCT reconstruction and crown-root fusion. Smaller voxel sizes yield higher reconstruction precision, and different voxel sizes and tooth regions correspond to distinct optimal segmentation thresholds. The validated semi-automated crown-root fusion algorithm significantly enhances overall model accuracy, offering new possibilities for clinical applications.

Retrieval of Chinese fir tree parameters under different understory conditions with the integration of handheld and airborne Lidar data

ABSTRACT Accurate extraction of tree parameters is vital for the calculation of high-quality forest volume or biomass. The Light Detection and Ranging (Lidar) technology with its ability to acquire three-dimensional forest stand structures is an important data source for extracting tree parameters. However, complex forest stand structures due to dense canopy and abundant understory vegetation can seriously affect the extraction performance of tree parameters. This study selected Chinese fir plantations to examine how different forest stand structure conditions affected tree parameter extraction based on the integration of handheld laser scanning (HLS) and airborne laser scanning (ALS) data. This study also explored the ability of developing models using extracted tree height and crown width, or directly using the calculated variables from point clouds to estimate the diameter at breast height (DBH) and stem volume. The methods mainly consisted of two parts: (1) Selecting appropriate height to identify seed points for tree segmentation, and subsequently extracting tree parameters; (2) Taking tree height, crown width, and tree-level point cloud metrics as independent variables to establish regression and random forest models for estimating tree DBHs and stem volumes. Results showed that (1) tree DBHs were accurately extracted with relative root mean square error (RMSEr) of 7.1%−10.5% and stem volume with an RMSEr of 12.3%−16.8% under different understory conditions; (2) As stand structure became complex, direct extraction of tree DBHs from HLS data became a challenging task. However, developing a DBH estimation model using tree height and crown width proved feasible; (3) In the complex-understory condition, the volume estimation model utilizing point cloud variables achieved good performance with RMSEr of 28.0%. This research provides new insights for extracting tree parameters using HLS and ALS data, offering a potential replacement for field measurements of tree DBH, height, and stem volume for Chinese fir plantations.

Optimizing Low-Efficiency Robinia pseudoacacia Forests on the Loess Plateau Based on an Evaluation of the Ecological Functions of Soil and Water Conservation

The vegetation for water and soil conservation on the Loess Plateau has resulted in the formation of large areas of low-quality and inefficient forests during its growth process, thereby hindering the high-quality development of such vegetation and compromising the sustainability of the ecological functions of soil and water conservation. This study focuses on Robinia pseudoacacia forests in the Caijiachuan watershed in the Loess region of western Shanxi. A comprehensive evaluation system for the ecological functions of soil and water conservation has been established to conduct a comprehensive assessment of the Robinia pseudoacacia forests. Additionally, the study identifies low-efficiency Robinia pseudoacacia forests and proposes reasonable regulation and control measures. The main research conclusions are as follows: (1) There are significant differences in the water and soil conservation functions among different Robinia pseudoacacia forests. The degree of inefficiency in these forests increases with forest density, and Robinia pseudoacacia forests with slopes between 35° and 40° are all low-efficiency forests. (2) The average density of high-efficiency Robinia pseudoacacia forests is 1655 trees per hectare, medium-efficiency forests average 1780 trees per hectare, and low-efficiency forests average 1927 trees per hectare. By substituting forest density, diameter at breast height (DBH), tree height, and crown width into the low-efficiency forest discrimination function, low-efficiency forests can be identified. The main influencing factors of low-efficiency forests are the Margalef richness index of shrubs, the total soil nitrogen content; and the nitrate nitrogen content. (3) Regulation measures for low-efficiency forests include controlling forest density to 1655 trees per hectare, increasing the richness of understory shrubs, and enhancing total soil nitrogen and nitrate nitrogen content by planting leguminous plants such as Lespedeza bicolor, Sophora davidii, and Vicia sepium. The research results can construct a comprehensive evaluation system for the ecological functions of Robinia pseudoacacia forests for water and soil conservation, identify low-efficiency forests, and provide precise regulation based on the causes of inefficiency, ensuring the sustainable function of Robinia pseudoacacia forests for water and soil conservation.

Biomass Allocation in Gentianella turkestanorum is Driven by Environmental Factors and Functional Traits.

Exploring the elevation distribution characteristics, biomass allocation strategies, and the effects of elevation, soil factors, and functional traits on the biomass of Gentianella turkestanorum (Gand.) Holub is of great significance for the production, development, utilization, and protection of the medicinal material resources. In this study, we investigated the biomass and functional traits of the root, stem, leaf, and flower of G. turkestanorum, analyzing their elevation distribution patterns, allometric growth trajectories, and their correlations. The results showed that the biomass of different organs of G. turkestanorum decreases with increasing elevation, and the belowground biomass/aboveground biomass increases with elevation. The flower biomass accounts for 59.24% of the total biomass, which was significantly higher than that of other organs. G. turkestanorum biomass follows the optimal allocation theory, adopting a 'pioneering' growth strategy at low elevations and a 'conservative' strategy at high elevations. Chlorophyll content and leaf thickness of G. turkestanorum were positively correlated with elevation, but leaf dry matter content and the number of flowers were negatively correlated with elevation. Compared to functional traits, elevation and soil factors have a stronger explanatory power regarding the biomass of G. turkestanorum. Elevation, soil moisture content, pH, available phosphorus, total nitrogen, and ammonium nitrogen significantly affect the biomass of G. turkestanorum, with only pH showing a positive correlation with biomass. Among these factors, elevation, soil moisture content, and pH significantly impact the accurate prediction of G. turkestanorum biomass. The number of flowers, crown width, root length, root diameter, and leaf dry matter content all have a significantly positive correlation with the biomass of G. turkestanorum, with the number of flowers and root diameter making significant contributions to the accurate prediction of biomass. Elevation can directly affect the biomass of G. turkestanorum and can also indirectly affect it through other pathways, with the direct effect being greater than the indirect effect.

An Algorithm for Determining Pith Position Based on Crown Width Size

To accurately estimate the pith position, a method was proposed for estimating the pith position by the crown width. The crown widths of 120 trees and radiuses of each disc extracted at the height of 1.3 m from these trees were measured in four directions. The crown and radius ratios of the length of each direction to the total length in that direction and the opposite direction were calculated. Using the crown ratio as an independent variable, as well as the radius ratio as a dependent variable, the linear, logarithmic, exponential, and polynomial models were built. The model with the highest R2 was selected as the radius ratio model. The geometric center method and the crown width method were applied to estimate the pith position, and the estimation errors were calculated, respectively. The R2 of the linear, logarithmic, exponential, and polynomial models were 0.405, 0.379, 0.403, 0.404, respectively, and the linear model was chosen as the radius ratio model. The prediction error based on the crown width was 7.6%, and that of the geometric center method was 10.1%. The findings indicate that the crown width method can improve the accuracy of estimating the pith position.

Динамика биометрических и углеродных показателей сосновых насаждений на залежных землях Красноярской лесостепи

Today, the overgrowth of woody and shrubby vegetation on former agricultural lands is a serious problem. The aim of this research has been to investigate age-related changes in the forest inventory indicators of forest stands on abandoned farmlands. Taking into account the temporal factor when monitoring the carbon budget allows identifying a number of processes in the dynamics of carbon sequestration that cannot be estimated in a single study. To address this issue, data from permanent sample plots have been analyzed in 2011 with repeated measurements in 2023. The sample plots are located on the abandoned farmlands on the border of the Krasnoyarsk forest-steppe area. The dynamics of the process of Today, the overgrowth of woody and shrubby vegetation on former agricultural lands is a serious problem. The aim of this research has been to investigate age-related changes in the forest inventory indicators of forest stands on abandoned farmlands. Taking into account the temporal factor when monitoring the carbon budget allows identifying a number of processes in the dynamics of carbon sequestration that cannot be estimated in a single study. To address this issue, data from permanent sample plots have been analyzed in 2011 with repeated measurements in 2023. The sample plots are located on the abandoned farmlands on the border of the Krasnoyarsk forest-steppe area. The dynamics of the process of overgrowth and development of plantations has shown that as the abandoned farmlands form, in addition to the dominant Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth) and aspen (Populus tremula L.), Siberian larch (Larix sibirica Ledeb.), Siberian spruce (Picea obovata Ledeb.) and goat willow (Salix caprea L.) are also found. The dynamic process of pine abandoned farmlands has been established over a period of 15 to 27 years after land abandonment. The mixed plantations of various successional origins have ranged in age from 10 to 30 years old. Various processes have been observed in the research plots in terms of changes in the density of abandoned farmlands (overgrowth, thinning). The reforestation of abandoned farmlands occurs from the forest border and at a distance of up to 50 m continues after 30 years. The abandoned farmlands are characterized by various forms of overgrowth: clumps, biogroups, complete and by single trees. The average quantitative assessment has shown that that the most intense changes in height, diameter, height to the crown base, height to the largest crown width, and crown diameters have occurred in the test area where the minimum density has been observed, which has been decreasing dynamically. In the plot with the maximum density, morphological indicators have been characterized by an average increase. Minimal changes have been recorded in the sample plot where the density has increased significantly over 12 years. The growth rate of trees of the same diameter in height has been greater in 2023 compared to 2011. It is possible that this has been influenced by a combination of external and internal factors, including climate change. To assess the carbon productivity of forest stands growing on the abandoned farmlands, it is advisable to use regression equations developed for a specific area. The results of the study of the dynamics of carbon sequestration by young forests growing on the abandoned farmlands indicate the feasibility of using postagrarian lands for the implementation of forest climate projects.

Effects of plant crown characteristics on dispersal kernels of wind-dispersed seeds under low wind speeds

Abstract Plant crown can affect the seed dispersal process. Clarifying the influence of plant crown type on seed dispersal kernel is important for predicting species distribution. However, the impact of different plant crown types on seed dispersal has rarely been tested. To determine the effect of plant crown type on seed dispersal kernel, we conducted wind tunnel experiments in which we investigated seed dispersal average distance, range, kurtosis and skewness of 29 species with different diaspore traits (type of appendage, mass, projected area, shape index, wing loading and terminal velocity) under 3 wind speeds (2, 4 and 6 m•s-1) for seed passing through different crown types (classified based on crown size, branch density and with or without leaves). We fit functions to the seed dispersal distance and found that the Gaussian function had the best fit. Plant crown type had significant effects on dispersal kurtosis and skewness, but not on dispersal average distance and range, of seeds passing through it under low wind speed condition. Width and branch density of plant crown affected dispersal kurtosis, and leaves of plant crown influenced kurtosis and skewness. Increase in wind speed reduced the influence of planting crown on the dispersal kurtosis and skewness. Plant crown had no significant effect on average seed dispersal distance but affected seed dispersal kernel shape, so, the dispersal range of seeds through different plants is invariant while the density of dispersal varies greatly. The information could be helpful for understanding plant metapopulation dynamics.

Patterns of Congenital Tooth Agenesis and Crown Width in Patients with Alveolar Clefts in Guizhou, China: A Retrospective Study

Objective This study aimed to investigate the prevalent pattern of congenital tooth agenesis and the development of crown width in patients with alveolar clefts in Guizhou, China. Methods The imaging data and complete medical record information of 222 patients who met the criteria were studied. The rate of tooth agenesis, tooth agenesis patterns, type of cleft, gender, and crown width in patients with alveolar cleft were counted. Results Twenty-two congenital tooth agenesis patterns were statistically identified in patients with alveolar clefts by the tooth agenesis code method. The rate of congenital tooth agenesis in patients with alveolar cleft was 72.5%, and the most common missing teeth were lateral incisors. The rate of tooth agenesis was higher in bilateral alveolar cleft (87.1%) than in unilateral alveolar cleft (67.4%). No correlation was found between gender and tooth agenesis patterns, tooth agenesis rate, or number of missing teeth. Crown width in patients with alveolar clefts is less than normal. No correlation was found between the number of missing teeth and crown width. Conclusions The congenital tooth agenesis patterns and tooth agenesis rates in patients with alveolar clefts in Guizhou, China, were related to the type of cleft, independent of gender. The crown widths in patients with alveolar clefts were smaller than normal, irrespective of the number of tooth agenesis.

Prenatal Exposure to a Human Relevant Mixture of Endocrine-Disrupting Chemicals Affects Mandibular Development in Mice.

Mandible is a bony structure of neuroectodermal origin with unique characteristics that support dentition and jaw movements. In the present study, we investigated the effects of gestational exposure to a mixture of endocrine-disrupting chemicals (EDCs) on mandibular growth in mice. The mixture under study (Mixture N1) has been associated with neurodevelopmental effects in both a human cohort and animal studies. Pregnant mice were exposed throughout gestation to 0.5× (times of pregnant women's exposure levels), 10×, 100× and 500× of Mixture N1, or the vehicle, and the mandibles of the male offspring were studied in adulthood. Micro-CT analysis showed non-monotonic effects of Mixture N1 in the distances between specific mandibular landmarks and in the crown width of M1 molar, as well as changes in the mandibular bone characteristics. The alveolar bone volume was reduced, and the trabecular separation was increased in the 500× exposed mice. Bone volume in the condyle head was increased in all treated groups. Τhe Safranin-O-stained area of mature hypertrophic chondrocytes and the width of their zones were reduced in 0.5×, 10× and 100× exposed groups. This is the first indication that prenatal exposure to an epidemiologically defined EDC mixture, associated with neurodevelopmental impacts, can also affect mandibular growth in mammals.

Groundcover improves nutrition and growth of citrus trees and reduces water runoff, soil erosion and nutrient loss on sloping farmland.

Groundcover management plays a crucial role in improving water retention and soil nutrition in orchard systems, thereby preventing environmental constrains by non-point source pollution. However, effectiveness of groundcover management in citrus orchards developed on sloping farmland with eroded purple soil has not been studied in detail. In particular, information on the soil nutrient losses, e.g., nitrogen (N) and phosphorus (P), through interflow and its effects on growth and nutrition of citrus plants has not been reported. The present study evaluated the effects of different cover crops, i.e., Lolium perenne L. (Lolium), Vicia villosa Roth (Vicia) and Orychophragmus violaceus (Ory), on nutrition and growth of citrus trees as well as water, soil and nutrient retention in an orchard developed in sloping farmland during two consecutive years. The results show that the groundcover species Lolium and Vicia mediated nursing effects on nutrition and growth of citrus trees. These nursing effects included enhanced foliar levels of carbon(C), N and P as well as increased tree height, stem diameter, and crown width. Groundcover management generally reduced the annual surface runoff, interflow, soil loss, total N loss and total P loss. Among the cover crop species studied, Lolium and Vicia were overall more efficient than Ory in this context. Lolium reduced the average annual total loss of N and P by 42.53% and 49.23%, respectively, compared with clean tillage. The estimated annual reduction potentials of soil, N and P losses in Southwestern China were 16.3, 3.4 and 8.5 million tons yr-1, respectively. Obviously, Lolium and Vicia provide highly beneficial ground coverage on sloping farmland and, thus, can be used for future sustainable development of citrus orchards.

Genetic Diversity of Native Provenance and Plantation Populations of Pinus sylvestris var. mongolica Based on SSR Markers and Morphological Traits.

Pinus sylvestris var. mongolica plays a crucial role in the ecological restoration and industrial raw material production of arid and semiarid regions in northern China. The widespread degradation of its near-mature plantation (over 30 years) is a significant concern, having been a topic of interest in recent decades. In this study, the genetic diversity and population genetic structure were assessed using 12 simple sequence repeat (SSR) markers within 11 native provenance populations and eight plantation populations. Additionally, variations in eight morphological traits of their offspring were evaluated at three sites in northern China. The results revealed high genetic diversity and weak genetic differentiation among the native provenance populations. The mean number of alleles (N a), allelic richness (A r), expected heterozygosity (H e), and Shannon-Wiener diversity index (I) were 5.492, 4.679, 0.550, and 1.120, respectively, and the genetic differentiation coefficient (F ST) was 0.022. Significant population effects of tree height and height to live crown base (HCB), as well as interactions of population with site and block within site, were observed in tree height, HCB, stem diameter at breast height (DBH), stem volume (VOL), crown shape (CS), and disease grade (DG). The genetic diversity parameters based on SSR markers and breeding values of tree height, DBH, HCB, VOL, and stem form (SF) of plantation populations were found to be lower than those of native provenance populations. Significant positive correlations were identified between the mean effective number of alleles per locus (N e) and VOL as well as H e and crown width (CW). Furthermore, the maximum temperature of the warmest month (BIO5) and the silt content (T_SILT) were identified as significant factors influencing genetic diversity parameters and morphological variation, respectively. The findings provide scientific support for the reduction of plantation degradation, the effective restoration, and the sustainable management of forests for this species.

MANEJO DO SORRISO GENGIVAL ATRAVÉS DO USO DA TOXINA BOTULÍNICA TIPO A

An aesthetically pleasing smile results from the combination of several factors, such as the position, size, shape, and color of the teeth, as well as the exposure and characteristics of the gingival tissue. When evaluating the gingival tissue in a smile, several important factors must be considered: excessive vertical growth of the maxilla, reduced length of the upper lip, excessive contraction of the upper lip, and disproportion between the length and width of the clinical crown of the anterior teeth. A minimally invasive approach that can be used as a complement to dental treatment is the application of botulinum toxin, a neurotoxin produced by the anaerobic bacterium Clostridium botulinum. This toxin blocks the release of acetylcholine in the presynaptic vesicles of neuromuscular junctions, inhibiting muscle contraction. The aim of this literature review was to analyze the use of botulinum toxin type A (BTX-A) in the management of gummy smile. The search was conducted in the databases Google Scholar, PubMed, Latin American and Caribbean Health Sciences Literature (LILACS), and Scientific Electronic Library Online (SciELO). The descriptors used for the search were "botulinum toxin," "gingiva," "periodontology," and "dental aesthetics," combined using the boolean operators AND and OR. Although the evidence demonstrates favorable results, the use of botulinum toxin to correct gummy smile has limitations. It is a temporary solution, and patients should be informed about the need for periodic reapplications and the potential side effects, such as facial asymmetries. The reviewed studies indicate that this technique is particularly effective in cases of gummy smile resulting from hyperactivity of the upper lip elevator muscle, providing a significant reduction in gingival exposure, with results lasting up to 12 weeks. The combination of different therapeutic approaches, along with a careful evaluation of the causes of gummy smile, allows dental professionals to offer more integrated and personalized solutions for each patient.

Analysis of Influencing Factors of Green View Index Based on Street View Segmentation

Abstract. The calculation of green view index in street view image has become an emerging choice for many researchers. This article proposes a PSAT-Net semantic segmentation model and specifically designs a pyramid pooling attention module. This module cleverly integrates channel and spatial information, implicitly implementing a three-dimensional attention mechanism, and significantly improving performance indicators. By performing detailed semantic segmentation on street view image, this article deeply analyzes the impact of different street view parameter configurations on green view index, and studies in detail how these parameters affect the visual perception of urban greening. The experiment found that: (1) The Green view index(GVI) of most sampling points decreases as the FOV increases. The increase in GVI is mainly affected by the crown width and pitch angle, and the high-value points of GVI are more easily affected. (2) Pitch angle usually causes a slight increase in GVI, which is mainly affected by the distribution of tall trees and low vegetation. Tall trees cause an increase in GVI, while low vegetation causes a decrease in GVI. Similarly, high value points of GVI are more likely to produce larger differences. (3) The Heading parameter has no obvious impact on the overall visual impact of GVI. The difference in independent sampling points comes from the angle between the lens acquisition direction and the road forward direction.These findings not only enrich the theoretical connotation of green view index research, but also provide valuable references for practical applications.

Dimensions of Posterior Implant Restorations Related to Intra-Coronal Cantilever and Occlusal Forces: An In Vitro Study.

The aim of the present study was to investigate the relation of the implant position to the implant crown and analyze the location and magnitude of bite force. The dimensions of 49 posterior implant-supported restorations were recorded in terms of: 1. implant diameter, 2. crown length, 3. crown width, 4. crown height, 5. occlusal surface of the restoration. The crown/implant height was measured and the distance between the implant center and the restoration center revealed the size of intra-coronal cantilevers. The occlusal force analysis determined the point and magnitude of loading. Correlation coefficient r was used for the statistical process and statistical control was carried out with the aid of t-test with minimum level of significance p < 0.05. - The mean crown-to-implant ratio was 0.9 and in short implants (< 10mm) the ratio was 1.28. - Intra-coronal cantilever extensions ranged from 2.1 mm to 6.35 mm depending on crown size. - Occlusal loading was identified in cantilever areas of the crown. - Implant center deviates from crown center in 71%-82% of the cases depending on site location. - Implants with non-ideal position may support a functionally occluding crown. Intra-coronal cantilevers are a critical factor to avoid clinical complications and should be taken under consideration both in the planning and fabrication phase of implant restorations.

Key factors influencing street tree root conflicts with planting pits and sidewalks in old Guangzhou, China

Urban street trees improve urban life quality, but their root systems can conflict with infrastructure, especially in densely populated areas. Guangzhou—one of the world’s most densely populated cities—experiences significant challenges related to street tree root-damage, which impacts urban infrastructure and public safety. This study examined factors affecting root-damage in 1227 street trees in Guangzhou’s old urban areas, focusing on tree phenotypic parameters, planting environment, and root characteristics. Variables recorded included Tree height (TH), Crown width (CW), Diameter at breast height (DBH), root distribution, presence of buttress roots, and planting pit size. Logistic regression identified key factors influencing root-damage occurrence and severity. Results showed 30.9 % of trees exhibited root-damage. Shallow-rooted species such as Ficus microcarpa and Ficus altissima had higher root-damage rates (41 % and 47 %, respectively). Key predictors included DBH, planting pit size, and buttress roots. DBH was positively correlated with root-damage; larger planting pits reduced root-damage risk; and buttress roots increased root-damage likelihood. Trees with buttress roots were more likely to cause severe damage, and trees with DBH > 40 cm were prone to moderate and severe damage. These findings offer valuable insights for urban planners and forestry managers to optimize tree selection and planting strategies, mitigating root-damage and enhancing urban infrastructure resilience.

ALS-Based, Automated, Single-Tree 3D Reconstruction and Parameter Extraction Modeling

The 3D reconstruction of point cloud trees and the acquisition of stand factors are key to supporting forestry regulation and urban planning. However, the two are usually independent modules in existing studies. In this work, we extended the AdTree method for 3D modeling of trees by adding a quantitative analysis capability to acquire stand factors. We used unmanned aircraft LiDAR (ALS) data as the raw data for this study. After denoising the data and segmenting the single trees, we obtained the single-tree samples needed for this study and produced our own single-tree sample dataset. The scanned tree point cloud was reconstructed in three dimensions in terms of geometry and topology, and important stand parameters in forestry were extracted. This improvement in the quantification of model parameters significantly improves the utility of the original point cloud tree reconstruction algorithm and increases its ability for quantitative analysis. The tree parameters obtained by this improved model were validated on 82 camphor pine trees sampled from the Northeast Forestry University forest. In a controlled experiment with the same field-measured parameters, the root mean square errors (RMSEs) and coefficients of determination (R2s) for diameters at breast height (DBHs) and crown widths (CWs) were 4.1 cm and 0.63, and 0.61 m and 0.74, and the RMSEs and coefficients of determination (R2s) for heights at tree height (THs) and crown base heights (CBHs) were 0.55 m and 0.85, and 1.02 m and 0.88, respectively. The overall effect of the canopy volume extracted based on the alpha shape is closest to the original point cloud and best estimated when alpha = 0.3.

Gender wise comparative study of mesiodistal width of crown among patients attending Dhulikhel Hospital

Gender wise comparative study of mesiodistal width of crown among patients attending Dhulikhel Hospital

Crown Width–Tree Height Models for Magnolia grandiflora, Prunus cerasifera, and Acer negundo Growing in Cities in Northeastern Greece

The objective of this study is the development of crown width–tree height (CW-H) models in cities in northeastern Greece, for better urban vegetation management. In the cities of Kavala, Xanthi, Komotini, Alexadroupolis, and Orestiada, in total, 700 trees of Magnolia grandiflora L., Prunus cerasifera Ehrh., and Acer negundo L. were selected. For each selected tree, the total height as well as the minimum and maximum crown diameter were measured, and the average of the minimum and maximum diameter was considered the crown width. The selected CW-H models exhibit satisfactory R2 values of 0.60 and above. There is not a common pattern in the value order (or rank) of R2 among the M. grandiflora, P. cerasifera, and A. negundo CW-H models in the studied cities. A medium-sized tree such as M. grandiflora, a small-medium sized tree such as A. negundo, and a shrub or small tree such as P. cerasifera did not exhibit substantial differences in estimated and observed crown widths. The results of this study will increase our understanding of CW-H allometries. The main use of these models will be in the selection of the proper above-ground spacing of tree lines and in the spatial planning of a tree’s establishment so that no problems arise from its proximity to infrastructure.

Enhanced Estimation of Crown-Level Leaf Dry Biomass of Ginkgo Saplings Based on Multi-Height UAV Imagery and Digital Aerial Photogrammetry Point Cloud Data

Ginkgo is a multi-purpose economic tree species that plays a significant role in human production and daily life. The dry biomass of leaves serves as an accurate key indicator of the growth status of Ginkgo saplings and represents a direct source of economic yield. Given the characteristics of flexibility and high operational efficiency, affordable unmanned aerial vehicles (UAVs) have been utilized for estimating aboveground biomass in plantations, but not specifically for estimating leaf biomass at the individual sapling level. Furthermore, previous studies have primarily focused on image metrics while neglecting the potential of digital aerial photogrammetry (DAP) point cloud metrics. This study aims to investigate the estimation of crown-level leaf biomass in 3-year-old Ginkgo saplings subjected to different nitrogen treatments, using a synergistic approach that combines both image metrics and DAP metrics derived from UAV RGB images captured at varying flight heights (30 m, 60 m, and 90 m). In this study, image metrics (including the color and texture feature parameters) and DAP point cloud metrics (encompassing crown-level structural parameters, height-related and density-related metrics) were extracted and evaluated for modeling leaf biomass. The results indicated that models that utilized both image metrics and point cloud metrics generally outperformed those relying solely on image metrics. Notably, the combination of image metrics obtained from the 60 m flight height with DAP metrics derived from the 30 m height significantly enhanced the overall modeling performance, especially when optimal metrics were selected through a backward elimination approach. Among the regression methods employed, Gaussian process regression (GPR) models exhibited superior performance (CV-R2 = 0.79, rRMSE = 25.22% for the best model), compared to Partial Least Squares Regression (PLSR) models. The common critical image metrics for both GPR and PLSR models were found to be related to chlorophyll (including G, B, and their normalized indices such as NGI and NBI), while key common structural parameters from the DAP metrics included height-related and crown-related features (specifically, tree height and crown width). This approach of integrating optimal image metrics with DAP metrics derived from multi-height UAV imagery shows great promise for estimating crown-level leaf biomass in Ginkgo saplings and potentially other tree crops.