Lower Crown Research Articles

Effects Of Some Climatic Factors On Soil Moisture In Scots Pine Stands With Different Crown Closure

In this study, the effects of climate factors on soil moisture in Scots Pine stands with different crown closure were investigated. As a result of the study, it was revealed whether soil moisture values differ in Scots Pine stands in the same aspect, depth and slope group. The effects of some climate elements (air temperature, air humidity and rainfall) on the soil moisture values in the areas where the Scots Pine in different crown closures were investigated. We took 6 different forest plots in the same depth, slope and aspect group. The average soil moisture values was found 23.91% in Open forest plot (POF), 26.84% in P1 plot (Low crown closure scots pine stand), 16.72% in P2 (Medium crown closure scots pine stand), 16.00% in P3 (Full crown closure scots pine stand), 30.79% in Simulation plot (PS) and 28.62% in Erosion plot (PE). It was determined that the lowest average soil moisture values were found in the P2 and P3 plots and the highest soil moisture values were in the PS and PE plots.

No Field Evidence of Grass Fuel Structure effects on Postfire Tree Mortality in Juniperus virginiana

Prescribed fires are an important management tool for containing woody plant encroachment in rangeland ecosystems. Grasses are the dominant fuel type in rangelands. Past work has shown that grass canopy architecture, which varies among grass species, can influence flammability. Whether variation in grass fuel structure can influence postfire plant responses has not yet been tested. To bridge this gap, we set up field burning experiments with different fuel treatments and examined postfire mortality of Juniperus virginiana L. in a tallgrass prairie in southwestern Missouri. We sampled 60 trees and measured tree height and diameter at breast height before the fire. Fuels surrounding each tree were manipulated to vary independently in both fuel load and fuel structure. Flame temperatures were measured during the fire, and both stem and canopy injuries were evaluated 1 d after the fire. We surveyed tree mortality 7 mo after the fire. We found no effects of either fuel load or fuel structure on postfire mortality or on canopy injury in J. virginiana. Canopy injury was a critical fire severity measurement determining postfire mortality in J. virginiana, and taller trees are more fire resilient. Despite laboratory-observed fuel structure effects on flammability, this study finds no evidence for the importance of grass fuel load and canopy architecture in influencing postfire tree response. This result might arise from the low crown depth and low canopy water content of J. virginiana, which can promote canopy fire and result in a high mortality rate across fuel treatments. Notwithstanding the negative results, testing laboratory-based findings in field settings is important for further examining laboratory observations and upscaling individual-level processes to ecosystems to help identify the key ecological processes determining population dynamics and community assembly. Our study also suggests that prescribed fire is an effective tool to remove encroaching J. virginiana in tallgrass prairies at an early stage.

Effect of Model Resin and Shaft Taper on the Trueness and Fit of Additively Manufactured Removable Dies in Narrow Ridge Models.

A typodont model with a prepared mandibular molar was scanned to design virtual dies with different shaft tapers (0-degree (straight), 5-degree, and 10-degree tapered). Fifteen dies and one hollowed cast per taper were additively manufactured from two resins (G-PRINT 3D Model, GP and DentaMODEL, DM). Dies and casts were digitized to evaluate their trueness (root mean square (RMS)). The fit of the dies was evaluated with crown portion's RMS when seated in the cast and with distance deviations. Kruskal-Wallis and Mann-Whitney U tests were used to analyze data (α =.05). GP dies had lower overall, root, and base RMS, while DM dies had lower crown RMS (P≤.016). Straight dies had the highest overall, root, and base RMS within GP (P≤.030). Ten-degree dies had the lowest overall and base RMS, lower crown RMS than straight, and lower root RMS than 5-degree dies within DM (P≤.047). When the dies were seated, GP had lower crown portion RMS within 5- and 10-degree dies, and 5-degree dies had the highest RMS within DM (P≤.003). GP had lower distance deviations within 5- and 10-degree dies. Five-degree dies had the highest deviations within DM (P≤.049). GP dies mostly had higher trueness and better fit. Straight dies mostly had lower trueness within GP. Ten-degree taper mostly led to higher trueness within DM. The shaft taper affected DM dies' fit.

Leaf cluster morphology is altered along a local light gradient in different manners between young and old Fagus crenata crowns

ABSTRACT Leaf cluster morphological variation within and among Fagus crenata crowns was examined by analysing hierarchical leaf cluster structure. Leaf clusters were defined as a continuous group of leafy voxels, where each voxel was classified as part of a cluster if its effective leaf area density (eLAD) exceeded a threshold value. This threshold value ranged from sparse (10−1.3 m2 m−3) to dense (101.2 m2 m−3). Compared with young crowns, old crowns had a smaller effective leaf area index, a higher proportion of leafless space, more highly fragmented leaf clusters, and thinner clusters at all hierarchal levels, from smaller clusters with higher eLAD to large clusters with lower eLAD. Leaf clusters exhibited structural adaptability to the local light gradient within the crowns. For instance, we observed a positive correlation between leaf cluster thickness and inclination with relative light intensity. We hypothesized that the leaf cluster responses represented adaptations to changes in the light environment within crowns, particularly the increased light interception in lower crowns and the corresponding responses of leaves and twigs. However, cluster adaptation to local light conditions differed between young and old crowns. In young crowns, cluster thickness markedly varied with local light conditions, whereas cluster inclination did not respond. In old crowns, cluster inclination clearly adapted to local light conditions, whereas cluster thickness had little response.

COMPARATIVE ANALYSIS OF ABUTMENT TOOTH CONDITION WITH STUMP INLAYS OVER VARIED USAGE PERIODS

The aim of this study is to compare the condition of abutment teeth restored with stump inlays over different periods of use by applying periotestometry and radiography findings.
 Materials and methods. Ninety-six patients with extensively decayed dental crowns, including low crowns, were examined and treated. The patients were divided into two groups: Group A (main group, standard method for inlays) and Group B (control group, domestic ashless plastic used for modeling). Each group was further divided into three subgroups: A1 and B1 (single-rooted teeth with different crown types), A2 and B2 (collapsible cusp inlays with subsequent artificial crowns), and A3 and B3 (cusp inlays for bridge structures). The stability of the tooth was determined using a Periotest periotestometer (Germany), with scores ranging from -08 to +50 units. Radiological diagnostics and monitoring were conducted using targeted dental radiography with the X-genus DS apparatus. The degree of alveolar bone resorption was quantified using the Fuchs index of alveolar bone destruction.
 Result. In group A1, prosthetics with full cast crowns prior to orthopedic treatment initially improved stability by 2.93%, but this effect diminished by 3.39% after 12 months. Both metal-ceramic and all-ceramic crowns led to a decline in stability over the study period. Group B1 exhibited a stability increase of 1.42%, which reduced to 1.14% after 12 months. Metal-ceramic and all-ceramic crowns influenced tooth stability differently throughout the study. Within group B2, prosthetics with full cast crowns initially raised stability by 1.92%, yet this effect decreased to 0.28% after 12 months. Similarly, metal-ceramic and all-ceramic crowns indicated fluctuations in stability of supporting teeth over the study duration. In group A3, prosthetics with full cast bridges prior to orthopedic treatment initially increased stability by 0.86%, declining to a decrease of 2.07% after 12 months. Metal-ceramic bridges exhibited a smaller indicator at 6 months compared to pre-treatment, with this decrease persisting after 12 months. Conversely, all-ceramic bridges demonstrated stability enhancement by 0.61% after 6 months, persisting higher by 1.92% after 12 months. For group B3, prosthetics with full cast bridges prior to orthopedic treatment increased stability by 1.55%, maintaining a higher stability by 1.91% after 12 months. Metal-ceramic bridges indicated a decrease at 6 months compared to pre-treatment, persisting after 12 months. All-ceramic bridges showed a stability decrease by 2.42% after 6 months, yet remaining higher by 1.92% after 12 months compared to pre-treatment levels.
 Conclusions. The choice of prosthetic method for the manufacture of pin-and-stem inlays should be justified, taking into account the clinical situation and individual needs of each patient.

Relationship between Tree Girth and Forest Dieback Severity in Horton Plains National Park, Sri Lanka

Forest dieback changes the physiognomy, structure and floristic composition of montane forests leading to deterioration of ecosystem services. Although research has been conducted to investigate the etiology of forest dieback at Horton Plains National Park (HPNP), a direct cause for this phenomenon is yet to be identified. We investigated the relationship of plant maturity with forest dieback in montane forest species at HPNP. Two sites were selected considering the dieback percentages: less than 25% crown dieback as the healthy site and more than 75% crown dieback as the severe forest dieback site. The percentage crown dieback and girth at breast height was recorded in all individuals>10 cm in both plots. The mean GBH varied significantly among different crown dieback categories in five tree species in the healthy site and four tree species in the severe forest dieback site. In the healthy site, the mean GBH of healthy Cinnamomum ovalifolium trees was lower than that of dead trees while in the severe dieback site, it was higher for the severe crown dieback category than the healthy and rare dieback categories. In the severe dieback site, the mean GBH of healthy Symplocos obtusa trees was lower than that of the medium crown dieback category, while the mean GBH of dead Eurya chinensis trees was higher than that of healthy and rare crown dieback categories, in the severe dieback site. Furthermore, low crown dieback percentages were recorded in Syzygium rotundifolium, Vaccinium leschenaulti, and Litsea ovalifolia with the low mean GBH. A lower mean GBH was recorded for dead individuals of Symplocos cordifolia than healthy individuals. More research must be conducted to understand the relationships between forest dieback and site-specific factors to ensure the success of conservation efforts in tropical montane forests at HPNP.
 Keywords: Forest dieback, GBH, Plant maturity, Tropical montane forests

Dynamics of the forest cover of raised bogs in southern taiga: Zapadnaya Dvina forest peatland station as an example (Tver region)

The article is devoted to testing the hypothesis about the current increase in the forest cover of raised bogs in the forest zone, depending on changes in climatic conditions. To analyze the dynamics of forest cover using the example of raised bogs in the Tver region, a methodology was developed based on the use of different generations of Landsat satellite data. The methodology was tested on ground data and applied to analyze changes in forest cover between 1976 and 2022 in several raised bog areas, including undisturbed areas and areas drained for forestry. The study tested approximately 20 vegetation indices across a variety of surveys, including summer and winter (snow) conditions. The classification results were verified using planting taxation data on circular plots and assessed using error matrices. Moderate-resolution Landsat satellite imagery, especially winter imagery, has been found to be suitable for long-term analysis of afforestation dynamics in raised bogs. An optimal vegetation index SWVI (Short wave vegetation index) and classification technique are proposed. The results of the study showed that afforestation increases in all undrained areas of swamps, regardless of their initial state. The smallest changes are observed for areas with low crown density (0-0.1), to a greater extent for density 0.2-0.3, and the greatest changes occur in areas with high crown density (0.6-0.7 and higher).

The Dynastic Deity of the Liao Imperial Family -The White-robed Guanyin Statue from the Heavenly Palace of the Qingzhou White Pagoda

The Liao shi and the Qidan guo zhi contain intriguing records about the Liao imperial family’s faith in the White-robed Guanyin. One is that Emperor Taizong enshrined a statue of the White-robed Guanyin at Xingwang Temple in Mt. Muye and honored the bodhisattva as a dynastic deity who guarded over the imperial family. The other is that Emperor Xingzong had the statue worshipped before others during Ji shan yi, the most prestigious sacrificial ritual to Mt. Muye. This study linked these written records with the White-robed Guanyin Statue excavated from the Heavenly Palace of the Qingzhou White Pagoda, commissioned by the imperial family during the reign of Emperor Xingzong, and examined the overall development of the faith in the Liao imperial family and the statue’s style and historical and religious background. Consequently, this examination revealed that Taizong introduced the faith of the White-robed Guanyin to pacify the discontented Han Chinese population within the empire. Xingzong, in turn, elevated the deity to the supreme position. This move profoundly impacted the faith of the people and the imperial family in the late Liao. The statue from the Qingzhou White Pagoda, in particular, with its white robe, low crown, and lotus bud, does not stop at embodying the Buddhist teachings but also represents the intricate union between the Liao imperial family’s lineage, unique ritual customs, distinct faiths, and enshrinement rituals that originated from Yanjing area, present-day Beijing. Among the surviving examples, this statue is one that most closely follows the shape of the dynastic deity of the Liao imperial family, showing that it was likely created under careful considerations of the Great Master Xuanyan Yungui, who was well-versed in the particular faith of the Liao imperial family.

Crown die-back of peri-urban forests after combined heatwave and drought was species-specific, size-dependent, and also related to tree neighbourhood characteristics

The Rhine River valley of Germany has been facing recurrent and intense spells of drought and heatwaves threatening the health of trees in peri-urban forests. Crown damage intensified by climate change accelerates tree mortality, threatening its ecological, economic, and social benefits; however, the pattern of crown die-back in peri-urban forests remained unclear. We performed a field inventory to estimate the crown die-back of 2578 trees of 51 species from 68 randomly selected peri-urban forest plots in Karlsruhe region on the right bank of the Rhine, after the catastrophic summer heatwave and drought of 2018. We related crown die-back to species-specific drought tolerance, wood anatomical traits, tree size, canopy surface temperature, tree density, Shannon's diversity and Gini coefficient for tree height. Regression results indicate that small-size trees were found to be more susceptible to canopy damage than large trees, with a 1-meter increase in tree height associated with a 0.8 % reduction in crown die-back. This size-dependent process is also species-specific. Among the 12 species with significant (p < 0.05) linear relationship between height and die-back, 9 species demonstrated negative correlations and 3 species showed positive relationships. Species tolerant to drought or cavitation (e.g., trees with diffuse porous xylem, 21 species) had significantly lower crown dieback. For example, with a 1-point-scale increase in drought tolerance crown die-back declined 14.35 %. Trees that experienced high canopy surface temperature and grew with high tree density and species diversity (Shannon's diversity) had more crown die-back. However, high structural diversity (Gini coefficient) was related to lower crown die-back. Our results suggested that future research should focus more on tree species-specific hydraulic and thermal traits and tree density and structure management to improve tree health and species selection in peri-urban forests under future climate change.

Is magnesium deficiency the major cause of needle chlorosis of Pinus taeda in Brazil?

Needle chlorosis (NC) in Pinus taeda L. systems in Brazil becomes more frequent after second and third harvest rotation cycles. In a study to identify factors contributing to yellowing needle chorosis (YNC), trees were grown in soils originating from contrasting parent materials, and soils and needles (whole, green and chlorotic portions) from 1- and 2-year-old branches and the first and second needle flush release at four sites with YNC on P. taeda were analyzed for various elements and properties. All soils had very low base levels (Ca2+, Mg2+ and K+) and P, suggesting a possible lack of multiple elements. YNC symptoms started at needle tips, then extended toward the needle base with time. First flush needles had longer portions with YNC than second flush needles did. Needles from the lower crown also had more symptoms along their length than those higher in the canopy. Symptoms were similar to those reported for Mg. In chlorotic portions, Mg and Ca concentrations were well below critical values; in particular, Mg levels were only one third of the critical value of 0.3 g kg−1. Collectively, results suggest that Mg deficiency is the primary reason for NC of P. taeda in various parent soils in Brazil.

Effects of forest thinning on sap flow dynamics and transpiration in a Japanese cedar forest

Historically, forest thinning in Japan was conducted to obtain high-quality timber from plantations. Today, in contrast, thinning is also motivated by forest water balance and climate change considerations. It is in this context that the present study examines the effects of thinning on the ecophysiological responses of remaining trees, which are inadequately understood, especially in relation to changes in the magnitude and duration of transpiration. Sap flux densities were measured in both outer and inner sapwood to obtain stand-scale transpiration for two years in the pre-thinning state and three years post-thinning. The effects of thinning on transpiration were quantitatively evaluated based on canopy conductance models. The larger increases in outer sap flux density were found in the first year after the treatment, while those in inner sap flux density were detected in the second and third years. The remaining trees required a few of years to adjust to improved light conditions of the lower crown, resulting in a delayed response of inner sap flux density. As a result of this lag, transpiration was reduced to 71 % of the pre-thinning condition in the first year, but transpiration recovered to the pre-thinning levels in the second and third years due to compensating contributions from inner sap flow. In terms of more accurately chronicling the thinning effect, the distribution of sap flux density with respect to its radial pattern, is necessary. Such measurements are key to more comprehensively examining the ecophysiological response of forest plantations to thinning and, ultimately, its effect on the forest water balance.

Factors associated with bark beetle infestations of Colorado Plateau ponderosa pine using repeatedly-measured field plots

Decades of research have brought increasing focus to the biotic and abiotic factors associated with bark beetle infestation of North American conifers. Information is lacking, however, regarding beetle-caused mortality for ponderosa pine of the Colorado Plateau. From 1995 to 2019, we installed and periodically remeasured permanent plots in this forest type with a goal of identifying factors related to infestation probability including tree and stand characters, and abiotic factors such as temperature and precipitation. Forty-eight sites were distributed throughout the Colorado Plateau, each with two transects of 10 contiguous ∼ 0.04 ha circular plots. Stand and tree conditions were measured or interpolated for each year from plot establishment in 1995 until the final measurements in 2019. Temperature, precipitation, and other abiotic conditions were estimated from Daymet interpolations. We used a generalized linear mixed model to identify significant explanatory variables resulting in the best accuracy of predicting stem-level bark beetle-caused pine mortality. Tree and stand conditions were found related to the probability of infestation. Pines >15.2 cm dbh were more likely to become infested compared to pines below that threshold; no relationship was found above that breakpoint. Similarly, stems 80–180 years old had elevated probability of infestation compared to stems < 80 years; stems > 180 years were intermediate. Pines with poor crown vigor (low crown volume, suppressed or intermediate canopy position) were more likely to become infested compared to pines with good crown vigor (high crown volume, dominant or open grown canopy position). Pine basal area (BA), a surrogate for intra-species competition, was positively related to probability of infestation. Pine BA infested the previous year, a surrogate for beetle population size, was also positively related to probability of infestation. Several drought- and precipitation-related variables resulted in similar model accuracy. Best model fit among these, by a slight margin, was contemporaneous climate water deficit (CWD), a measure of plant water stress, summed from April-August. Increasing CWD was associated with increased probability of infestation. Finally, counts of days above 16 °C the previous year were negatively related to infestation probability. That is, relatively warm weather during the previous year was associated with reduced beetle success, possibly because it can result in fractional beetle life cycles that disrupt synchronized attacks on new hosts or leave overwintering brood in less cold hardy life stages.

Investigation of some factors affecting habitat selection and nest size of Formica rufa

The study aimed to assess the habitat preferences and nest volumes of Formica rufa in coniferous stands, taking into account various stand, topographic, and climatic variables. The variables that impact the habitat of F. rufa in the Western Black Sea region were identified through the utilization of climate data, stand map, DEM data, and field data. Ten different variables were analyzed separately for F. rufa nests using the Geographic Information System (GIS). Based on the stand variables, it can be inferred that F. rufa were predominantly preferred as over-mature, full canopy cover, medium and poor site class, and productive stands. Based on the analysis of topographical variables, the ants exhibit a preference for areas that have low slopes, high elevations, and shady aspects. Additionally, the investigation of climatic variables revealed a higher incidence of ants in regions with an average temperature below 12 °C, and low levels of precipitation. It was determined that nest volumes are larger in high site index, productive stands, young stands, low crown closure stands and high elevation. Based on the findings, it is crucial to monitor the habitat preferences of F. rufa over extended periods and large geographical areas. The protection and enhancement of their habitats are imperative for the sustainability and health of the ecosystem.

Impact of Crown Closure on Cone Production and Effective Number of Parents in Natural Stands of Taurus Cedar (Cedrus libani A. Rich.)

This study was carried out to estimate the effect of crown closure classes (degraded forest, low crown coverage, medium crown coverage, and full crown coverage) and growth characteristics (three heights, diameter at base, diameter at breast height, and crown diameter) on cone production and to estimate fertility variation and its allied parameters in 130-year-old natural populations of Taurus cedar, also called cedar of Lebanon (Cedrus libani A. Rich.). The effect of biotic (e.g., growth characteristics, crown closure) and abiotic (e.g., light penetration, temperature, humidity, and soil characteristics) factors on cone production, fertility variation, and gene diversity was evaluated in two consecutive years of Taurus cedar. The factors, viz., altitude, temperature, aspect, and rainfall, varied, while some of them could be managed by cultural operations such as management of the crown and stand density. The impact of crown closure on cone production, fertility variation, and related parameters were observed in Taurus cedar’s natural populations sampled from southern Turkey. Maximum cone productions of 29 and 40/tree were recorded with full crown closure in two consecutive years, due to significant differences among individuals within crown closure class. For instance, cone productions were between 10 and 67 in the full crown closure of the first year. The sibling coefficient, which is a measure of the fertility variation in a stand, was the highest (1.16) for the full crown closure in the first (meaning 86% fertile trees) and the second years (1.55, 65%), while it was the lowest for the medium crown closure (1.09, 92%) in both years. Gene diversity decreased from a degraded patch (0.987) to that with full crown closure (0.984). Results of variance analysis showed a significant (p ≤ 0.05) difference between crown closure classes for cone production within the second year and between years. Significant positive (p ≤ 0.05) correlations were noted between years for cone production (r = 0.22) and between cone production and crown closure in the first and second years (r = 0.29). However, growth characteristics had no effect on cone productions in individual crown closure classes, while there were significant (p ≤ 0.05) correlations between the diameter at breast height and cone production for both years (r = 0.15 and 0.17) in pooled populations.

Simulation based analysis to study the effect of compression ring crown height in ring liner assembly on the performance of four stroke petrol engine

Among different piston rings of an Internal Combustion Engine (IC), the top compression ring-liner assembly shared a momentous amount of the total frictional losses, particularly at the Top Dead Center (TDC) and Bottom Dead Center (BDC) where boundary lubrication subsists. In the present study, the lubrication mechanism in piston ring cylinder liner conjunction for top compression ring using one dimensional Reynolds equation assuming axisymmetric contact was studied. The hydrodynamic and mixed lubrication regimes were taken during the study. Gumbel boundary conditions were used for Reynolds equation solution. For boundary pressure calculation, first, combustion chamber pressure variation was determined, then, interring pressure was calculated assuming orifice volume method by solving mass flow rate through crevice volumes using Runge-Kutta 4th order method. The Reynolds equation was solved using finite difference method. Whole solution process was repeated for different engine speed and crown height of top compression ring to study the effect of them in wear and power loss. First, the solution was found for 3000, 5000 and 7500 RPM keeping constant crown height of 10 µm. Average power loss was found to be increased with the increasing engine speed. There was increased in oil film thickness around mid-stroke with the increased engine speed, but there was no significant change in film thickness with the engine speed at the TDC and BDC positions. Then, the solution was again repeated for different RPM varying the crown height. The compression ring with lower crown height showed the better wear performance by increasing the minimum film thickness in critical zones of engine cycle for all RPM. The crown height of 5,7 and 9 µm gave the minimum power loss (77.89, 163.47 and 297.33 W) for 3000, 5000 and 7500 rpm. Moreover, the power loss in the range of 5-9 µm had no significant differences.

Unique dentition of rhynchosaurs and their two‐phase success as herbivores in the Triassic

AbstractRhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically, and much of their success may relate to their dentition. They show the unique ankylothecodont mode of tooth implantation, with deep roots embedded in the bone of the jaw and low crowns that were rapidly worn down in use. During growth, the main area of oral food processing, located in the middle and posterior portions of the occlusal surfaces of the jaws, moved posteriorly relative to the anterior tips of the jaws, which curved up. As the maxilla and dentary grew by addition of new bone posteriorly, the dental lamina fed in new teeth at the back of the tooth rows. CT scanning of the holotype skull of Bentonyx sidensis from the Middle Triassic of England reveals previously concealed details of the dentition. Together with new dentary material from the same location, this has enabled us to examine the tooth replacement process and elucidate ontogenetic changes in dentition and jaw morphology as the animals aged. There were major changes in rhynchosaur anatomy and function through their evolutionary history, with the early forms of the Middle Triassic dying out before or during the Carnian Pluvial Episode (233–232 Ma), and the subclade Hyperodapedontinae, with broad skulls and adaptations to chop tough vegetation, subsequently diversifying worldwide in a successful ecological expansion until their global extinction 227–225 Ma.

Comparative analysis of clinical and functional parameters of the gingival margin of patients with low crown height against the background of various methods of preparation for prosthetics

Currently, one of the most common types of prosthetics are restorative crowns or bridges, which cannot provide high-quality retention and long-term fixation with a low crown of supporting teeth. For an orthopedic dentist, the question arises of choosing a method of preparation before prosthetics. In this work, a comprehensive examination and treatment of 95 patients with a low crown of supporting teeth was carried out, who were randomized into 3 groups according to the methods of preparation for orthopedic treatment gingivoretraction, gingivectomy and gingiviplasty. The change in the state of the dentoalveolar complex was carried out clinically and functionally. The hygienic index API, papillary bleeding index PBI, the index of need for periodontal treatment CPITN, gum recession and depth of probing were determined. Laser Doppler flowmetry was used to assess the state of local blood flow and vasomotor activity of vessels. The studied parameters were evaluated before the start of preparation for orthopedic treatment and after 14 days. During the study, complications and side effects were not revealed, however, clinical and functional indicators indicate that preference should be given to gingivoplasty as one of the qualitative methods of preparing the dentoalveolar complex in patients with a low crown of supporting teeth.

Mapping individual tree and plot-level biomass using airborne and mobile lidar in piñon-juniper woodlands

Piñon-juniper (PJ) woodlands are a widespread dryland ecosystem in the US containing an immense but poorly-constrained amount of aboveground biomass (AGB). Found at the dry end of the climatic range within which trees can persist, PJ faces an uncertain future in a changing climate, giving unique importance to mapping its AGB, past, present, and future. Lidar remote sensing offers great potential towards that end with research in a range of tree-dominant ecosystems demonstrating a strong capacity for mapping AGB. However, studies applying lidar to the task of mapping AGB in PJ are few. Given the unique structural characteristics of PJ trees, which tend to be short in stature (<10 m), possess multiple stems often obscured by low crown base heights, and irregularly-shaped canopies, there remains a high degree of uncertainty surrounding tree- and stand-level structural mapping in these woodlands. To resolve our limited understanding of how to best quantify AGB in PJ using lidar, we conducted a field-validated analysis comparing lidar platform (airborne laser scanner, ALS vs. mobile laser scanner, MLS) and analytical framework (area-based modeling vs. individual tree-based modeling). We used a random forest machine learning approach to predicting tree- and stand-level structure with leave-one-out cross-validation to assess model performance. In an area-based context, MLS only marginally outperformed ALS, with both able to explain approximately 80 % of variance in AGB. However, in an individual tree-based context, MLS significantly outperforms ALS at several tasks, including: (1) delineating tree crowns (MLS delineated 100 % of trees; ALS delineated 69 %); (2) directly characterizing tree structural parameters including height (R2ALS = 0.52 vs. R2MLS = 0.74) and crown area (R2ALS = 0.26 vs. R2MLS = 0.68); and (3) modeling AGB (R2ALS = 0.38 vs. R2MLS = 0.62). We attribute this difference in performance to the vastly greater structural detail contained within the MLS point cloud data as compared to ALS, with the former possessing an average of approximately 30,000 pts/m2 and the latter 14 pts/m2. Based on our results, we make the following recommendation: if individual tree structure is needed, MLS is the far superior option; however, given the wider availability, ALS data are a suitable substitute when mapping PJ AGB, particularly under an area-based modeling analytical framework. This study represents the first time MLS data have been applied to tree structure mapping in PJ, and provides strong quantitative evidence towards best structural and AGB mapping practices in this unique, widespread, and important ecosystem. It serves as a solid foundation upon which future studies aiming to map AGB in PJ and other similar dryland woodland ecosystems can be built.

Tooth discoloration induced by endodontic sealers and cervical limit: 1-year in vitro evaluation.

This laboratory study aimed to evaluate the influence of endodontic sealer and cervical limit of root filling on the discoloration of root canal treated teeth. Bovine incisors were randomly distributed into six experimental groups and control (n=21/group), according to the endodontic sealer used [AH Plus (AP); MTA Fillapex (MF) and Sealer Plus BC (SPB)] and the cervical limit of root filling [dental cervix (DC) or 2 mm in apical direction (2mm-AD)]. Tooth discoloration (ΔE) was evaluated by a digital spectrophotometer using the CIED2000 method. Color assessments were performed immediately before (baseline), 1 week, 1, 3, 6 months, and 1 year after obturation. Data were analyzed by ANOVA and Tukey's post-hoc tests (α=5%). Teeth filled with the three sealers showed perceptible tooth discoloration (ΔE≥2.7) in 1 week, maintaining similar values over time. There was a significant difference between MF and SPB sealers in the 2mm-AD groups. In addition, 2mm-AD groups promoted significantly lower discoloration than DC groups for AH (3 months) and SPB (1 and 3 months) sealer,s. Teeth filled with AP, MF, and SPB sealers displayed discoloration from 1 week to one year, with differences between MF and SPB sealers. A cervical limit of filling material at 2 mm from the dental cervix seems more advisable, promoting lower crown discoloration.

Microclimatic gradients cause phenological variations within temperate tree canopies in autumn but not in spring

Tree crowns experience strong vertical microclimatic gradients, particularly in light availability. Surprisingly, little is known about whether these gradients cause within-crown variation in leaf phenology and whether such variations represent different light-use strategies of sun- and shade leaves.In a temperate mixed forest at the Swiss Canopy Crane II site in Switzerland, we measured over three years the annual leaf phenology in the upper and lower crowns of mature trees from six broadleaved and three conifer species. We further recorded the microclimate (temperature, humidity, light) continuously in various positions within the canopy.We found microclimatic canopy gradients to be strongest during summer, but negligible in winter and spring, indicating that any phenological gradients in autumn, but not in spring, might be driven by microclimatic differences. Budbreak timing did not differ within the crowns of any of the broadleaved trees. However, in the three species with deeper crowns, leaf unfolding was up to 10 days faster in the lower crown but showed no difference in the more shallow-crowned species. Surprisingly, only the evergreen conifers Abies alba and Picea abies showed earlier bud break in the lower crowns. In autumn, senescence in all broadleaved species progressed from the upper crown downwards, resulting in up to two weeks longer vegetation seasons in the lower crown.With this first broad assessment of within-tree phenology, we show how microclimatic gradients and different light-use strategies lead to a considerable variability of within-crown phenological gradients. We interpret the faster leaf unfolding in the lower crown of three broadleaved species as a shade avoidance strategy, allowing shade branches to improve their C balance early in the season. In contrast, longer retention of lower leaves in autumn is unlikely to significantly improve the C balance, and more likely caused by higher summer temperature and irradiance in the upper leaves.