Maximum Crown Diameter Research Articles

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.

Terrestrial Laser Scanning in Assessing the Effect of Different Thinning Treatments on the Competition of Scots Pine (Pinus sylvestris L.) Forests

Thinning is a forest management activity that regulates the competition between the trees within a forest. However, the effect of different thinning treatments on competition is largely unexplored, especially because of the difficulty in measuring crown characteristics. This study aimed to investigate how different type and intensity thinning treatments affect the stem- and crown-based competition of trees based on terrestrial laser scanning (TLS) point clouds. The research was conducted in three study sites in southern Finland where the Scots pine (Pinus sylvestris L.) is the dominant tree species. Nine rectangular sample plots of varying sizes (1000 m2 to 1200 m2) were established within each study site, resulting in 27 sample plots in total. The experimental design of each study site included two levels of thinning intensities and three thinning types, resulting in six different thinning treatments. To assess the competition between the trees, six distance-dependent competition indices were computed for each tree. The indices were based on diameter at breast height (DBH) (CIDBH), height (CIH), maximum crown diameter (CIMCD), crown projection area (CICA), crown volume (CICV), and crown surface area (CICS). The results showed that for both moderate and intensive intensities, the competition decrease was 45.5–82.5% for thinning from below, 15.6–73.6% for thinning from above, and 12.8–66.8% for systematic thinning when compared with control plots. In most cases, the crown- and stem-based metrics were affected by thinning treatments significantly when compared with control plots at a 95% confidence interval. Moreover, moderate from-below and from-above thinning showed no statistical difference with each other in both crown- and stem-based competition indices except for CIDBH (p-value ≤ 0.05). Our results confirm the great potential of TLS point clouds in quantifying stem- and crown-based competition between trees, which could be beneficial for enhancing ecological knowledge on how trees grow in response to competition.

Effects of Stem Density on Crown Architecture of Scots Pine Trees.

Trees adapt to their growing conditions by regulating the sizes of their parts and their relationships. For example, removal or death of adjacent trees increases the growing space and the amount of light received by the remaining trees enabling their crowns to expand. Knowledge about the effects of silvicultural practices on crown size and shape and also about the quality of branches affecting the shape of a crown is, however, still limited. Thus, the aim was to study the crown structure of individual Scots pine trees in forest stands with varying stem densities due to past forest management practices. Furthermore, we wanted to understand how crown and stem attributes and also tree growth affect stem area at the height of maximum crown diameter (SAHMC), which could be used as a proxy for tree growth potential. We used terrestrial laser scanning (TLS) to generate attributes characterizing crown size and shape. The results showed that increasing stem density decreased Scots pine crown size. TLS provided more detailed attributes for crown characterization compared with traditional field measurements. Furthermore, decreasing stem density increased SAHMC, and strong relationships (Spearman’s correlations > 0.5) were found between SAHMC and crown and stem size and also stem growth. Thus, this study provided quantitative and more comprehensive characterization of Scots pine crowns and their growth potential. The combination of a traditional growth and yield study design and 3D characterization of crown architecture and growth potential can open up new research possibilities.

Integrating National Ecological Observatory Network (NEON) Airborne Remote Sensing and In-Situ Data for Optimal Tree Species Classification

Accurately mapping tree species composition and diversity is a critical step towards spatially explicit and species-specific ecological understanding. The National Ecological Observatory Network (NEON) is a valuable source of open ecological data across the United States. Freely available NEON data include in-situ measurements of individual trees, including stem locations, species, and crown diameter, along with the NEON Airborne Observation Platform (AOP) airborne remote sensing imagery, including hyperspectral, multispectral, and light detection and ranging (LiDAR) data products. An important aspect of predicting species using remote sensing data is creating high-quality training sets for optimal classification purposes. Ultimately, manually creating training data is an expensive and time-consuming task that relies on human analyst decisions and may require external data sets or information. We combine in-situ and airborne remote sensing NEON data to evaluate the impact of automated training set preparation and a novel data preprocessing workflow on classifying the four dominant subalpine coniferous tree species at the Niwot Ridge Mountain Research Station forested NEON site in Colorado, USA. We trained pixel-based Random Forest (RF) machine learning models using a series of training data sets along with remote sensing raster data as descriptive features. The highest classification accuracies, 69% and 60% based on internal RF error assessment and an independent validation set, respectively, were obtained using circular tree crown polygons created with half the maximum crown diameter per tree. LiDAR-derived data products were the most important features for species classification, followed by vegetation indices. This work contributes to the open development of well-labeled training data sets for forest composition mapping using openly available NEON data without requiring external data collection, manual delineation steps, or site-specific parameters.

Microhabitat utilization by fork-marked dwarf lemurs (Phaner spp.) and needle-clawed galagos (Euoticus spp.) in primary and secondary forests.

Needle-clawed galagos (Euoticus spp.) and fork-marked dwarf lemurs (Phaner spp.) are specialist gummivores inhabiting the forests of Cameroon and Madagascar, respectively. They share a suite of adaptations related to their foraging behavior, but are distantly related. I compared structural characteristics of the natural vegetation in which these strepsirrhines occurred using 10 m × 10 m (100 m2 ) quadrats established in forest areas selected on the grounds of observations of animals during nocturnal surveys. I established a total of 27 quadrats (13 in Madagascar and 14 in Cameroon). In each quadrat, trees potentially used by the animals (i.e., with a circumference at breast height ≥10 cm) were assessed for diameter at breast height (DBH), total height, and maximum crown diameter (MCD) as well as tree density. The nature of the bark, and presence of exudates and flowers were also assessed, together with habitat characteristics such as percentage canopy cover and herbaceous cover. Primary and secondary forest types studied in Madagascar showed significant differences in DBH, MCD, and tree density, whereas only tree density was significantly different for the two forest types in Cameroon. Most of the trees in the quadrats had rough bark, but few had either exudates or flowers. Both Phaner and Euoticus show some degree of plasticity in their use of both primary and secondary forests, although they specialize in habitats with tall, large diameter trees. They can adjust to using trees in human modified habitats. Both taxa can survive in areas where a reasonably continuous canopy is not lacking.

Impact of benzyladenine and gibberellic acid on quality and economics of runner production in Chandler strawberry (Fragaria × ananassa) under subtropical climate

An experiment was conducted to study the impact of plant bioregulators on quality and economics of runner production in Chandler strawberry (Fragaria × ananassa Duch.) cultivar under subtropical climatic conditions. The experiment was carried out in a randomized block design with 16 treatments and each treatment replicated thrice. The results revealed that the application of plant growth regulators enhanced the runner production in strawberry. Among all the treatments, the treatment GA3 100 ppm recorded maximum plant height per runner (10.88 cm), petiole length (10.70 cm) and root length (5.90 cm). The treatment of GA3 at 300 ppm + BA at 150 ppm was found superior than other treatments for producing maximum runners/mother plant (13.53), number of train/mother plant (4.10), number of runner/train (3.30), plant spread/runner (10.83cm), and number of leaves/runner plants (7.29). This treatment also gave highest cost benefit ratio (1:2.85) as compared to other treatments. However, control plants recorded maximum crown diameter (6.92 mm), crown weight (0.66 g) and leaf area (16.57).

Post-harvest chemical manipulation in strawberry regeneration under Jammu sub-tropics

The present investigation on postharvest chemical manipulation in strawberry (Fragaria × ananassa Duch.) regeneration under Jammu sub-tropics was carried out to standardize the dose and time of application of chemicals for optimising the runner production. Application of plant growth regulators enhanced the runner production in strawberry cultivar Chandler under Jammu sub-tropics. The maximum number of runners/mother plant (13.53), number of trains/mother plant (4.10), number of runners/train (3.30), plant spread per mother plant (34.02 cm), plant spread per runner plant (10.83 cm), number of leaves per mother plant (22) and number of leaves per runner plants (7.29) of strawberry cv. Chandler was recorded with the application of 300 ppm GA3 + 150 ppm BA. The maximum plant height per mother plant (23.29 cm), plant height per runner (10.88 cm), petiole length per mother plant (19.1 cm), petiole length per runner plant (10.70 cm) and root length per runner plant (5.90 cm) were recorded under application of GA3 100 ppm. Whereas, control treatment recorded the maximum crown diameter (6.92 mm), crown weight (0.66 g) and leaf area (16.57). The findings indicated that the application of GA3 (300 ppm) + BA (150 ppm) enhanced the regeneration capacity of strawberry runners under Jammu sub-tropics.

Assessing the importance of seed immigration on coexistence of plant functional types in a species-rich ecosystem

Modelling and empirical studies have shown that input from the regional seed pool is essential to maintain local species diversity. However, most of these studies have concentrated on simplified, if not neutral, model systems, and focus on a limited subset of species or on aggregated measures of diversity only (e.g., species richness or Shannon diversity). Thus they ignore more complex species interactions and important differences between species. To gain a better understanding of how seed immigration affects community structure at the local scale in real communities we conducted computer simulation experiments based on plant functional types (PFTs) for a species-rich, fire-prone Mediterranean-type shrubland in Western Australia. We developed a spatially explicit simulation model to explore the community dynamics of 38 PFTs, defined by seven traits – regeneration mode, seed production, seed size, maximum crown diameter, drought tolerance, dispersal mode and seed bank type – representing 78 woody species. Model parameterisation is based on published and unpublished data on the population dynamics of shrub species collected over 18 years. Simulation experiments are based on two contrasting seed immigration scenarios: (1) the ‘equal seed input number’ scenario, where the number of immigrant seeds is the same for all PFTs, and (2) the ‘equal seed input mass’ scenario, where the cumulative mass of migrating seeds is the same for all PFTs. Both scenarios were systematically tested and compared for different overall seed input values. Without immigration the local community drifts towards a state with only 13 coexisting PFTs. With increasing immigration rates in terms of overall mass of seeds the simulated number of coexisting PFTs and Shannon diversity quickly approaches values observed in the field. The equal seed mass scenario resulted in a more diverse community than did the seed number scenario. The model successfully approximates the frequency distributions (relative densities) of all individual plant traits except seed size for scenarios associated with equal seed input mass and high immigration rate. However, no scenario satisfactorily approximated the frequency distribution for all traits in combination. Our results show that regional seed input can explain the more aggregated measures of local community structure, and some, but not all, aspects of community composition. This points to the possible importance of other (untested) processes and traits (e.g., dispersal vectors) operating at the local scale. Our modelling framework can readily allow new factors to be systematically investigated, which is a major advantage compared to previous simulation studies, as it allows us to find structurally realistic models, which can address questions pertinent to ecological theory and to conservation management.

Investigating laser pulse penetration through a conifer canopy by integrating airborne and terrestrial lidar

This study examines the distribution of laser pulse returns obtained from coincident airborne and terrestrial lidar surveys of a closed-canopy red pine (Pinus resinosa) plantation. The purpose of this study is to improve our understanding of laser pulse sampling within closed canopies so that estimates of forest structural variables (e.g., biomass, needle-leaf area, and base-of-live-crown) can be improved at the individual tree and stand levels using lidar. The results of this study indicate the following: (1) There is a statistically significant difference between field measurements of tree height and estimates derived from the maximum laser pulse return from airborne and terrestrial lidar. In both cases, maximum laser pulse returns underestimate tree height by 1 m, on average. (2) Both terrestrial and airborne lidar are unable to discern the base of the measured live crown. Laser pulse returns from airborne lidar are biased towards the top of the tree crown, i.e., lowest laser pulse returns occur 1.4 m on average higher in the canopy than the measured base-of-live-crown. On the other hand, terrestrial lidar captures dieback at the base of the live crown, thereby lowering the base-of-live-crown estimate by 6.6 m, on average. (3) Median airborne laser pulse returns within the canopy (20.4 m), believed to be associated with needle leaf area, occur below the maximum frequency of laser pulse returns (20.8 m) but higher in the canopy than the height of maximum crown diameter obtained from terrestrial lidar (18.0 m). The bias of airborne laser pulse reflections towards the top of the canopy with less penetration to a depth where the maximum crown diameter occurs may result in an underestimation of the needle leaf area. The results of this research suggest that future research should focus on improving our understanding of how laser pulse returns are "triggered" within vegetated environments and how canopy properties or data acquisition parameters may influence the location of this "trigger" event.

Associations between Carabelli trait and cusp areas in human permanent maxillary first molars

Few dental anthropological studies have investigated the associations between tooth crown size and crown traits in humans using quantitative methods. We tested several hypotheses about overall crown size, individual cusp areas, and expression of Carabelli cusps in human permanent first molars by obtaining data from standardized occlusal photographs of 308 Australians of European descent (171 males and 137 females). Specifically, we aimed to calculate the areas of the four main molar cusps, and also Carabelli cusp, and to compare the relative variability of cusp areas in relation to timing of development. We also aimed to compare cusp areas between males and females and to describe how Carabelli cusp interacted with other molar cusps. Measurements included maximum crown diameters (mesiodistal and buccolingual crown diameters), the areas of the four main cusps, and the area of Carabelli cusp. The pattern of relative variability in absolute areas of molar cusps corresponded with their order of formation, the first-forming paracone displaying the least variation, and the last-forming Carabelli cusp showing the greatest. Overall crown size and areas of individual cusps all showed sexual dimorphism, with values in males exceeding those in females. Sexual dimorphism was smallest for paracone area and greatest for Carabelli cusp area. Overall crown size and cusp areas were larger in individuals displaying a Carabelli cusp, especially the hypocone area. Although the combined area of the protocone and a Carabelli cusp was greater in cuspal forms than noncuspal forms, protocone area alone was significantly smaller in the former. Our findings lead us to propose that, in individuals with the genotype for Carabelli trait expression, larger molar crowns are more likely to display Carabelli cusps, whereas molars with smaller crowns are more likely to display reduced forms of expression of the trait. We suggest that the pattern of folding of the internal enamel epithelium in developing molar crowns, particularly in the protocone region, can be modified by a developing Carabelli cusp.

Functions for estimating stem diameter and tree age using tree height, crown width and existing stand database information

The aim was to investigate the relations between diameter at breast height and maximum crown diameter, tree height and other possible independent variables available in stand databases. Altogether 76 models for estimating stem diameter at breast height and 60 models for tree age were formulated using height and maximum crown diameter as independent variables. These types of models can be utilized in modern remote sensing applications where tree crown dimensions and tree height are measured automatically. Data from Finnish national forest inventory sample plots located throughout the country were used to develop the models, and a separate test site was used to evaluate them. The RMSEs of the diameter models for the entire country varied between 7.3% and 14.9% from the mean diameter depending on the combination of independent variables and species. The RMSEs of the age models for entire country ranged from 9.2% to 12.8% from the mean age. The regional models were formulated from a data set in which the country was divided into four geographical areas. These regional models reduced local error and gave better results than the general models. The standard deviation of the dbh estimate for the separate test site was almost 5 cm when maximum crown width alone was the independent variable. The deviation was smallest for birch. When tree height was the only independent variable, the standard deviation was about 3 cm, and when both height and maximum crown width were included it was under 3 cm. In the latter case, the deviation was equally small (11%) for birch and Norway spruce and greatest (13%) for Scots pine.

Molar intercuspal dimensions: genetic input to phenotypic variation.

Molecular studies indicate that epigenetic events are important in determining how the internal enamel epithelium folds during odontogenesis. Since this process of folding leads to the subsequent arrangement of cusps on molar teeth, we hypothesized that intercuspal distances of human molar teeth would display greater phenotypic variation but lower heritabilities than overall crown diameters. Intercuspal distances and maximum crown diameters were recorded from digitized images of dental casts in 100 monozygotic and 74 dizygotic twin pairs. Intercuspal distances displayed less sexual dimorphism in mean values but greater relative variability and fluctuating asymmetry than overall crown measures. Correlations between intercuspal distances and overall crown measures were low. Models incorporating only environmental effects accounted for observed variation in several intercuspal measures. For those intercuspal variables displaying significant additive genetic variance, estimates of heritability ranged from 43 to 79%, whereas those for overall crown size were higher generally, ranging from 60 to 82%. Our finding of high phenotypic variation in intercuspal distances with only moderate genetic contribution is consistent with substantial epigenetic influence on the progressive folding of the internal enamel epithelium, following formation of the primary and secondary enamel knots.

Patterns of Architectural Variation in Thuja occidentalis L. (Eastern White Cedar) from Upland and Lowland Sites

The distribution of Thuja occidentalis L. (eastern white cedar) within its range in northeastern North America is bimodal, as it occurs both on cliffs (dry uplands) and in swamps (wet lowlands). A comparison of the gross architecture of individual trees was made in situ, in order to characterize the architecture of this species and to examine the pattern of architectural variation among sites of the same habitat type and between habitat types. Architectural measurements were made on randomly selected trees growing in three cliff and three swamp sites in southern Ontario. Height, maximum crown diameter, basal stem diameter, angle of initial stem orientation, angle of present growth, number of reiterated axes, number of points of contact with the substrate, and age were determined for each tree. Architectural variation was small among sites of the same habitat type and between cliff and swamp habitats as well. These results confirm other findings that the trees studied were part of a larger rather homogeneo...

Dimensional weights and forage of Barclay willow and sweetgale on moose ranges in the wetlands of the Copper River Delta, Alaska

Above-ground shoots of Barclay willow ( Salix barclayi) and sweetgale ( Myrica gale var. tomentosa) from shrub-swamp on the wetlands of the Copper River Delta, Alaska, were harvested at the early-growth, full-growth, and early-dormancy stages of growth. Seven dimensional measurements (vertical height, basal stem diameter, upper stem diameter, basal stem length, crown depth, maximum crown diameter, second crown diameter) were made on each above-ground shoot before harvest. The cross-sectional area of the crown was calculated from crown diameters and also used as a non-destructive measurement. Each shoot was sorted into four individual (basal stem, branch, terminal twig, leaf) and two combined (crown wood, total above-ground) dimensional weight categories and the oven-dry weights of each category determined. Measurements were used as independent variables in forward, stepwise multiple regression to develop a ‘best model’ estimator of mean dimensional weight at each growth stage. The ability of the regression models to accurately predict mean dimensional weight at each growth stage was tested on an independent sample of above-ground shoots of both shrubs. The early-dormancy regression model predicted mean weights of basal stem, twig and total above-ground dimensional weights of Barclay willow within 1% of actual weights. The full-growth regression model gave the most accurate predictions of the mean dimensional weights of crown wood, branch and leaf of Barclay willow. The early-dormancy regression model provided the closest estimates of the mean weights of basal stem and crown wood of sweetgale. Total above-ground shoot and branch mean weights were best estimated by the regression model for the full-growth period. Neither regression model gave accurate estimates of the mean weights of sweetgale twigs and leaves. Digestibility, nutrient status and energy content of the material in each dimensional category were determined at each growth period.