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Accurate measurement of tree architecture is vital for understanding forest dynamics and supporting effective forest management. This study evaluates close-range photogrammetry (CRP) using TreeQSM (v2.4.1) software, reconstructing 3D tree structures in both deciduous and coniferous species and comparing its performance to the Fastrak 3D digitizing method. CRP proved less labor-intensive and effective for estimating parameters like tree height, stem diameter, and volume of thicker branches in small trees. However, it struggled with capturing intricate structures, overestimating volumetric values and underestimating branch lengths and counts. Mean relative root mean square errors for height, diameter at 0.3 m height, volume, and branch count were 34.19%, 69.9%, 107.87%, and 142.03%, respectively. These discrepancies stem from challenges in reconstructing moving objects and filtering non-woody elements. While CRP shows potential as a complementary method, further advancements are necessary to improve 3D tree model reconstruction, emphasizing the need for ongoing research in this domain. [ABSTRACT FROM AUTHOR]

Mixed stands of tree species with complementary traits can modulate stand growth and timber quality. At the Fengshushan Forest Farm, mixtures of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) with Liquidambar formosana Hance, Schima superba Gardner & Champ., Elaeocarpus sylvestris (Lour.) Poir., Cinnamomum camphora (L.) Presl, and Chinese fir monoculture were established. Differences in stand growth and timber quality among these mixtures were assessed and a test was conducted to evaluate the factors influencing the mixture effects. The average diameter at breast height, tree height, stand volume, and individual tree annual increment of mixtures generally exceeded those of Chinese fir monocultures but not necessarily those of broad-leaved monocultures. When the net interaction between species was complementary, overyielding in mixtures occurred (RPfir,bl > 0), which was influenced significantly by stand density, soil properties, and timber quality. The timber quality and wood production of Chinese fir were enhanced by mixture with some broad-leaved species, with reduced slenderness and knottiness in mixtures, and notable increases in medium- (average outturn rates of 56.13%) and large-diameter (11.71%) timber in C. lanceolata/C. camphora mixture. The growth and timber quality of Chinese fir are largely promoted when grown mixed with broad-leaved species. Overyielding at the stand level occurs where Chinese fir compensates for the underperformance of broad-leaved trees. [ABSTRACT FROM AUTHOR]

A newly found leaf arrangement to reduce self-shading was observed in a Japanese warm-temperate forest. For monoaxial trees that deploy leaves directly on a single stem, leaf arrangements involving progressive elongation of the petiole and progressive increase in deflection angle (the angle between stem and petiole) from the uppermost to the lowermost leaves act to reduce self-shading. However, the progressive reduction in petiole length and deflection angle from the uppermost to the lowermost leaves should also result in the reduction of self-shading. Nevertheless, the latter leaf arrangement has not been reported previously for any tree species. Four Araliaceae species, namely, Gamblea innovans, Chengiopanax sciadophylloides, Dendropanax trifidus and Fatsia japonica, which are typical monoaxial tree species in Japan, were studied. We examined the crown structure of saplings growing in the light-limited understorey in a Japanese warm-temperate forest. Two evergreen species, Dendropanax trifidus and F. japonica showed progressive petiole elongation and progressive increase in the deflection angle from the uppermost to the lowermost leaves. In contrast, saplings of deciduous species, G. innovans and C. sciadophylloides had a leaf arrangement involving progressive reduction in petiole length and deflection angle from the uppermost to the lowermost leaves. The leaf arrangement has diversified among members of the same family, but all four studied species develop a crown with little self-shading that is adapted for growth in the light-limited understorey. Although trees are likely to be under the same selective pressure to reduce self-shading, this study revealed that there is flexibility in its morphological realisation, which has been poorly appreciated previously. [ABSTRACT FROM AUTHOR]

• Diurnal LST variations across different landscape types were compared. • Trees exhibit lower LST than low vegetation during the daytime and transition time. • 3D landscapes exhibited a greater impact on diurnal LST than 2D landscapes. • Nonlinear relationships between key factors and diurnal LST were revealed. The diverse urban features considerably influence land surface temperature (LST). Numerous studies have extensively investigated the impacts of 2D/3D urban features on LST. However, the diurnal impacts have not been comprehensively understood. Therefore, taking 1, 510 blocks within the 4th ring road of Beijing as samples, this study examined the influence of urban features (2D: low vegetation, water, and impervious surface; 3D: buildings and trees) on diurnal LST at the block scale based on ECOSTRESS LST using boosted regression tree (BRT) algorithm. The results showed that trees exhibit better cooling effects than low vegetation except at 3:09. The 3D features exhibited a greater impact on diurnal LST compared with 2D features, and it contributed strongly to daytime LST, which was 27.8 % on average higher than the 2D features. Building and tree densities had the greatest influence on daytime LST, while building height influenced nighttime LST the most. The impacts of key metrics on diurnal LST were nonlinear, and the relationship had diurnal variations. Taller buildings and trees were negatively correlated with LST during the daytime and transition time, but positively correlated with nighttime LST. The findings provide insights into landscape optimization strategies to improve block thermal comfort. [ABSTRACT FROM AUTHOR]

State-of-the-art approaches to forest fire spread are based on either 2D numerical simulations of trees on GIS or rough 3D visualization. In this paper, we approximate the tree form by dynamically changing sets of tree-shape modules according to the morphological structure and wind fields. Guided by finite state machine, we define the states of equilibrium, heating, pyrolysis, cooling and destruction of tree-shape modules. Interactions between tree-shape modules drive the state transfer to achieve forest fire spread. Additionally, Loose Quadtrees are adopted to the spatial distribution of trees, which allows us to maintain the visual fidelity of the representation while rendering the forest fire spreads in real-time. Our method allows us to construct the Jiufeng forest example about 10km x 10km extent at interactive rates. The capabilities of tree-shape modules and forest fire spread visualization are demonstrated by numerous examples. [Display omitted] • Use FSM to define the state and transition rules of the tree-shape module, and adopt the state to drive the temperature, moisture, and mass of the tree to simulate the pyrolysis. • Use Loose Quadtree to generate tree-shape modules in real time, and tree-shape modules can be deformed by the joint action of wind field and terrain slope to control the spread of forest fire. • Calculate the barycentric coordinates of a triangle in a tree surface mesh as the position of preset flame and store in the Priority Queue to orderly generate flames on trees. [ABSTRACT FROM AUTHOR]

Recently, there has been considerable interest in establishing tree-rearing methods for breeding nursery trees, which are similar to the methods employed in plant factories to produce vegetables. Studies have shown that the efficiency of tree cultivation can be improved by changing the wavelength of the lighting that is used to raise young plants and that light emitting diodes (LEDs) are effective for this purpose. In this study, the effect of blue (450 nm), red (660 nm), and white (combination of blue and yellow (525 nm) LED lights was investigated for rearing Cryptomeria japonica saplings. 7 saplings with each LED were prepared and reared for 52 weeks in a constant environment chamber (Temperature: 23 ± 2 ºC, relative humidity 50% ± 10%), and their growth rates and root system morphology were compared. After 52 weeks of breeding, red light induced slightly more stem growth than white light. Blue light was nearly three times more effective in stem growth than white light. Furthermore, the wavelength of light affected the root system morphology. Many root branches were observed in saplings reared under red light, while marked taproot growth was observed in saplings reared under blue light. There was a possibility that saplings could be produced more efficiently by using LED. [ABSTRACT FROM AUTHOR]

Background and Aims Crown shyness describes the phenomenon whereby tree crowns avoid growing into each other, producing a puzzle-like pattern of complementary tree crowns in the canopy. Previous studies found that tree slenderness plays a role in the development of crown shyness. Attempts to quantify crown shyness have largely been confined to 2-D approaches. This study aimed to expand the current set of metrics for crown shyness by quantifying the characteristic of 3-D surface complementarity between trees displaying crown shyness, using LiDAR-derived tree point clouds. Subsequently, the relationship between crown surface complementarity and slenderness of trees was assessed. Methods Fourteen trees were scanned using a laser scanning device. Individual tree points clouds were extracted semi-automatically and manually corrected where needed. A metric that quantifies the surface complementarity (S c) of a pair of protein molecules is applied to point clouds of pairs of adjacent trees. Then 3-D tree crown surfaces were generated from point clouds by computing their α shapes. Key Results Tree pairs that were visually determined to have overlapping crowns scored significantly lower S c values than pairs that did not overlap (n = 14, P < 0.01). Furthermore, average slenderness of pairs of trees correlated positively with their S c score (R 2 = 0.484, P < 0.01), showing agreement with previous studies on crown shyness. Conclusions The characteristic of crown surface complementarity present in trees displaying crown shyness was succesfully quantified using a 3-D surface complementarity metric adopted from molecular biology. Crown surface complementarity showed a positive relationship to tree slenderness, similar to other metrics used for measuring crown shyness. The 3-D metric developed in this study revealed how trees adapt the shape of their crowns to those of adjacent trees and how this is linked to the slenderness of the trees. [ABSTRACT FROM AUTHOR]

Global acreage of forested lands has increased in some countries. At least some of this increase is due to the natural conversion of abandoned agricultural lands into forests. However, little is known about how these new stands develop on abandoned agricultural lands in comparison with natural regeneration of existing forests. Specifically, knowledge of how black pine (Pinus nigra Arnold) naturally establishes and develops on abandoned agricultural lands is limited. In this study, we examined the density and growth of black pine saplings as well as some morphological and anatomical characteristics on an abandoned agricultural land (AAS). These data were compared with those observed in a naturally regenerated stand (NRS), and in a forest opening (FOS). The greatest sapling density was observed in the NRS site, while sapling growth and stem biomass were higher in AAS followed by NRS and FOS. Moreover, each study site exhibited site-specific morphological and anatomical traits in their saplings. Our findings showed that site treatments and overstory openness would both play crucial role for establishment and development of black pine. [ABSTRACT FROM AUTHOR]

Inclusion of stemflow and throughfall processes in rainfall-runoff modelling requires reliable models for their estimation. In the present paper, stemflow and throughfall generation processes were investigated in relation to rainfall, and morphological properties of four major fruit species grown in hot and sub-humid climatic region. Two types of models, rainfall-based and morphology-based, were developed and validated using observed data. Morphology-based models included relative roughness of branch (RR), leaf area index (LAI), canopy length (CL), tree height (TH) and diameter at breast height (DBH) as input variables. Rainfall-based stemflow prediction models, namely, Weibull, Logistic, Allometric and Exponential (R2 = 0.74 to 0.82) and throughfall prediction models, namely, Weibull, Allometric, Linear and Linear (R2 = 0.94 to 0.99) provided the best goodness-of-fit statistics for mango, litchi, guava and jackfruit, respectively. The parameters RR and LAI affected stemflow irrespective of rainfall depth. However, different sets of variables, namely, CL-LAI, CL-LAI-TH, CL-LAI-TH and DBH-CL-LAI affected throughfall in rainfall ranges 20 mm, respectively. The higher range of interception loss (6.5% for guava to 21.3% for jackfruit) indicated that interception loss from fruit trees needs to be considered in the water balance modelling of watersheds having larger areas under orchards.

Species-specific morphological characteristics play a decisive role in determining stemflow. However, in tropical forests, as a result of high biodiversity, the results can be conflicting. The objective of this study was to analyse the influence of tree morphology on water running down tree trunks in a forest-savanna transition area in the Brazillian Amazon. A total of 46 trees were installed samplers for stemflow monitoring. Rainfall events with a volume of > 10 mm were recorded. Dendometric variables and morphological characteristics of the trees were related to the stemflow volume. Circumference at breast height, basal area and canopy projection area were determinants for the formation of distinct tree groups, whereas these variables were not significantly correlated with stemflow volume. When the trees were grouped according to their morphological characteristics, significant correlations were identified for basal area and circumference at breast height for stemflow from trees with an upright trunk and rough bark. Mean stemflow volume from trees with a smooth bark was higher than the other trees. However, when the variable trunk inclination was inserted, the mean stemflow from upright trunks was lowest and that from inclined trunks was highest, showing the relevance of this variable for stemflow production. [ABSTRACT FROM AUTHOR]

Tree saplings are exposed to a competitive growth environment in which resources are limited and the ability to adapt determines general vitality and specific growth performance. In this study we analyzed the aboveground spatial neighborhood of oak [Quercus petraea (Matt.) Liebl.] and beech (Fagus sylvatica L.) saplings growing in Germany, by using hemispherical photography and terrestrial laser scanning as proxy for the competitive pressure saplings were exposed to. The hemispherical images were used to analyze the light availability and the three-dimensional (3D) point clouds from the laser scanning were used to assess the space and forest structure around the saplings. The aim was to increase the precision with which the biomass allocation, growth, and morphology of the saplings could be predicted by including more detailed information of their environment. The predictive strength of the models was especially increased through direct neighborhood variables (e.g., relative space filling), next to the light availability being the most important predictor variable. The biomass allocation patterns within the more light demanding oak were strongly driven by the space availability around the saplings. Diameter and height growth variables of both species reacted significantly to changes in light availability, and partly also to the neighborhood variables. The leaf morphology [as leaf-area ratio (LAR)] was also driven by light availability and decreased with increasing light availability. However, the branch morphology (as mean branch weight) could not be explained for oak and the model outcome for beech was hard to interpret. The results could show that individuals of the same species perform differently under constant light conditions but differing neighborhoods. Assessing the neighborhood of trees with highly precise measurement devices, like terrestrial laser scanners, proved to be useful. However, the primary response to a dense neighborhood seemed to be coping with a reduction of the lateral light availability aboveground, rather than responding to an increase of competition belowground. The results suggest continuing efforts to increase the precision with which plant environments can be described through innovative and efficient methods, like terrestrial laser scanning.

Inclusion of stemflow and throughfall processes in rainfall-runoff modelling requires reliable models for their estimation. In the present paper, stemflow and throughfall generation processes were investigated in relation to rainfall, and morphological properties of four major fruit species grown in hot and sub-humid climatic region. Two types of models, rainfall-based and morphology-based, were developed and validated using observed data. Morphology-based models included relative roughness of branch (RR), leaf area index (LAI), canopy length (CL), tree height (TH) and diameter at breast height (DBH) as input variables. Rainfall-based stemflow prediction models, namely, Weibull, Logistic, Allometric and Exponential (R² 0.74 to 0.82) and throughfall prediction models, namely, Weibull, Allometric, Linear and Linear (R² = 0.94 to 0.99) provided the best goodness-of-fit statistics for mango, litchi, guava and jackfruit, respectively. The parameters RR and LAI affected stemflow irrespective of rainfall depth. However, different sets of variables, namely, CL-LAI, CL-LAI-TH, CL-LAI-TH and DBH-CL-LAI affected throughfall in rainfall ranges <5, 5-10, 10-20 and >20 mm, respectively. The higher range of interception loss (6.5% for guava to 21.3% for jackfruit) indicated that interception loss from fruit trees needs to be considered in the water balance modelling of watersheds having larger areas under orchards. [ABSTRACT FROM AUTHOR]

Water and potassium are limiting factors for tree growth. Their influence on morphology and anatomy are well known, but their combined effects on tree growth remain to be clarified. A single clone of Eucalyptus grandis was analyzed under different treatments of rainfall exclusion and fertilization. Eight trees per treatment were sampled to investigate the influence of these treatments on the morphological, mechanical, and anatomical traits. The results showed that the fertilization mainly influenced the morphological and anatomical characteristics. Considering the difference between the fertilized and non-fertilized trees, the function of mechanical support was provided through increasing the diameter and the stiffness. Considering the fertilized trees, two different mechanisms occurred inducing a high stiffness: the wood density was higher for trees with rainfall exclusion; the specific modulus was higher for trees with a normal water supply. [ABSTRACT FROM AUTHOR]

Tree saplings are exposed to a competitive growth environment in which resources are limited and the ability to adapt determines general vitality and specific growth performance. In this study we analyzed the aboveground spatial neighborhood of oak [ Quercus petraea (Matt.) Liebl.] and beech (Fagus sylvatica L.) saplings growing in Germany, by using hemispherical photography and terrestrial laser scanning as proxy for the competitive pressure saplings were exposed to. The hemispherical images were used to analyze the light availability and the three-dimensional (3D) point clouds from the laser scanning were used to assess the space and forest structure around the saplings. The aim was to increase the precision with which the biomass allocation, growth, and morphology of the saplings could be predicted by including more detailed information of their environment. The predictive strength of the models was especially increased through direct neighborhood variables (e.g., relative space filling), next to the light availability being the most important predictor variable. The biomass allocation patterns within the more light demanding oak were strongly driven by the space availability around the saplings. Diameter and height growth variables of both species reacted significantly to changes in light availability, and partly also to the neighborhood variables. The leaf morphology [as leaf-area ratio (LAR)] was also driven by light availability and decreased with increasing light availability. However, the branch morphology (as mean branch weight) could not be explained for oak and the model outcome for beech was hard to interpret. The results could show that individuals of the same species perform differently under constant light conditions but differing neighborhoods. Assessing the neighborhood of trees with highly precise measurement devices, like terrestrial laser scanners, proved to be useful. However, the primary response to a dense neighborhood seemed to be coping with a reduction of the lateral light availability aboveground, rather than responding to an increase of competition belowground. The results suggest continuing efforts to increase the precision with which plant environments can be described through innovative and efficient methods, like terrestrial laser scanning. [ABSTRACT FROM AUTHOR]

The paper aims to contribute to the determination of reasons causing the irregular growth of young pedunculate oaks occurring at the margins of naturally and artificially regenerated plots neighbouring with adult stands on alluvial sites. It presents analyses of aboveground biometric parameters, mortality, root system architecture of young trees, root density in the soil profile, global solar radiation and soil moisture content in dependence on the location of oaks at the northern, southern, eastern or western margins of the regenerated area and on the distance from the stand margin. The highest impact of the neighbouring adult stand is always recorded on the margin of the regenerated plot while its effect is weakening towards the plot centre, and fading away ca. 7 m behind the crown projection of adult trees. Regardless of the oak location (northern, southern, eastern or western margin), the cause is a high root density of marginal trees of the adult stand, which induces the critical lack of water under their crown projections.

Premise of the Study: Thinning is a frequent disturbance in managed forests, especially to increase radial growth. Due to buckling and bending risk associated with height and mass growth, tree verticality is strongly constrained in slender trees growing in dense forests and poor light conditions. Tree verticality is controlled by uprighting movements implemented from local curvatures induced by wood maturation stresses and/or eccentric radial growth. This study presents the first attempt to compare the real uprighting movements in mature trees using a theoretical model of posture control. Methods: Stem lean and curvature were measured by Terrestrial LiDAR Scanner (TLS) technology before and 6 years after thinning and compared to unthinned control poles. Measures for several tree and wood traits were pooled together to implement a widely used biomechanical model of tree posture control. Changes in observed stem lean were then compared with the model predictions, and discrepancies were reviewed. Key Results: Even under a highly constrained environment, most control poles were able to counterbalance gravitational curvature and avoid sagging. Thinning stimulated uprighting movements. The theoretical uprighting curvature rate increased just after thinning, then slowed after 2 years, likely due to the stem diameter increase. The biomechanical model overestimated the magnitude of uprighting. Conclusions: Most suppressed beech poles maintain a constant lean angle, and uprighting movements occur after thinning, indicating that stem lean is plastic in response to light conditions. Acclimation of posture control to other changes in growth condition should be investigated, and lean angles should be measured in forest inventories as an indicator of future wood quality. [ABSTRACT FROM AUTHOR]

Abstract Quantitative measurements of structure and morphology of urban trees are hardly exhausted so far, especially in regard to variations caused by altering urban environments. However, structure and functions of trees are heavily interwoven. In fact, knowledge about structural attributes is essential for a better understanding of urban ecosystem functions and services. In order to scrutinize spatially explicit and detailed structural attributes under varying urban environments, we acquired terrestrial laser scans and applied the according methodological approaches to the common urban tree species black locust (Robinia pseudoacacia L.) and small-leaved lime (Tilia cordata Mill.). We analyzed 52 small-leaved limes and 41 black locust trees within the city of Munich (Germany). Species as well as growing location had a significant effect on the height-diameter relation. We also found greater crown volumes for small-leaved lime. Black locust however, displayed more crown projection area and likely more shade efficient crown shapes at similar volumes. Stem inclination of black locust was found to be higher in parks than in street canyons with town squares lying in between. Furthermore, black locust displayed strong crown asymmetry in park areas, likely caused by competition with neighbors. The angles of main branches did not differ significantly between both species nor between the growing location. Branch angles, branch bending, the length of the branches as well as species and growing location had a significant effect on vertical crown center position, i.e. general crown shape. Surface complexity of lime is lower than of black locust, with its lowest manifestation in parks. Fractal-like crown surface structures, increasing surface roughness and complexity, were found to be more pronounced for black locust than for small-leaved lime. Thereby, black locust featured the highest crown surface complexity in parks, the lowest in street canyons. The results suggest that studies on spatially explicit tree structures may contribute to more target oriented tree plantings and thus, more effective exploitation of ecosystem services and benefits. [ABSTRACT FROM AUTHOR]

A major goal of managers in fire-prone forests is restoring historical structure and composition to promote resilience to future drought and disturbance. To accomplish this goal, managers require information about reference conditions in different forest types, as well as tools to determine which individual trees to retain or remove to approximate those reference conditions. We used dendroecological reconstructions and General Land Office records to quantify historical forest structure and composition within a 13,600 ha study area in eastern Oregon where the USDA Forest Service is planning restoration treatments. Our analysis demonstrates that all forest types present in the study area, ranging from dry ponderosa pine-dominated forests to moist mixed conifer forests, are considerably denser (273–316% increase) and have much higher basal area (60–176% increase) today than at the end of the 19th century. Historically, both dry pine and mixed conifer forest types were dominated by shade-intolerant species. Today, shadetolerant tree cover has increased in dry pine stands, while mixed conifer stands are now dominated by shade-tolerant species. Federal managers in eastern Oregon are currently required to retain all live trees >53 cm diameter at breast height in the course of forest management activities because this size class is assumed to be under-represented on the landscape relative to historical conditions. However, we found the same or greater number of live trees >53 cm today than in the late 19th century. Restoring historical conditions usually involves removing shade-tolerant trees that established since Euro-American management significantly altered natural disturbance regimes. We evaluated a wide range of tree morphological and environmental variables that could potentially predict the age of grand fir and Douglas-fir, the most abundant shade-tolerant species found within the study area. We describe several morphological characteristics that are diagnostic of tree age and developed decision trees that predict the approximate age of trees using morphological characteristics that are easy to measure in the field such as height to live foliage or height to dead branches. Information about structural and compositional change over time combined with tree-age prediction tools provides a flexible framework for restoring historical conditions and meeting other resource management objectives. [ABSTRACT FROM AUTHOR]

ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) was first described as a protein involved in salicylic acid (SA)-, ethylene-, and reactive oxygen species (ROS)-dependent defense and acclimation responses. It is a molecular regulator of biotic and abiotic stress-induced programmed cell death. Its role is relatively well known in annual plants, such as Arabidopsis thaliana or Nicotiana benthamiana. However, little is known about its functions in woody plants. Therefore, in this study, we aimed to characterize the function of EDS1 in the Populus tremula L.  ×   P. tremuloides hybrid grown for several seasons in the natural environment. We used two transgenic lines, eds1–7 and eds1–12 , with decreased EDS1 expression levels in this study. The observed changes in physiological and biochemical parameters corresponded with the EDS1 silencing level. Both transgenic lines produced more lateral shoots in comparison to the wild-type (WT) plants, which resulted in the modification of tree morphology. Photosynthetic parameters, such as quantum yield of photosystem II (ϕPSII), photochemical and non-photochemical quenching (qP and NPQ, respectively), as well as chlorophyll content were found to be increased in both transgenic lines, which resulted in changes in photosynthetic efficiency. Our data also revealed lower foliar concentrations of SA and ROS, the latter resulting most probably from more efficient antioxidant system in both transgenic lines. In addition, our data indicated significantly decreased rate of leaf senescence during several autumn seasons. Transcriptomic analysis revealed deregulation of 2215 and 376 genes in eds1-12 and eds1-7 , respectively, and also revealed 207 genes that were commonly deregulated in both transgenic lines. The deregulation was primarily observed in the genes involved in photosynthesis, signaling, hormonal metabolism, and development, which was found to agree with the results of biochemical and physiological tests. In general, our data proved that poplar EDS1 affects tree morphology, photosynthetic efficiency, ROS and SA metabolism, as well as leaf senescence. [ABSTRACT FROM AUTHOR]

In tropical rain forests, shade-tolerant tree species exhibit the typical wide-crown architectural type characteristic of low-light environments. In recent studies, though, some shade-tolerant species have been found not to show this typical architectural type. In the present study, the stem and crown architectural type of three shade-tolerant tree species was analyzed, two from the forest understorey and one from the mid-canopy. Twelve architectural variables were measured in 254 saplings between 50 cm and 300 cm tall in Los Tuxtlas, México. The allometric analysis showed that the three species are not similar in architecture. Instead, they present architectural differences related to their adult canopyposition. Both sub-canopy species presented thicker stems and flatter crowns, while the mid-canopyspecies was taller, presenting a slenderer stem and crown, and a less vertical crown shading. It is con- cluded that within the group of shade-tolerant tree species there is certainly more than a single archi- tectural crown type depending on the adult canopy position of the particular species. The previous single wide-crown architectural type is not the only or typical architectural type for shade-tolerant species.

The crown architecture of three shade-tolerant tree species (two subcanopy and one mid-canopy) was analyzed in relation to the light regime of the forest understorey. The aim was to examine to which extent shade-tolerant species variate in their crown architecture. Tree saplings (265) between 50 and 300 cm height, and distributed from understorey to variously-sized canopy gaps, were measured for 13 architectural traits in the lowland rain forest of Los Tuxtlas, México. The analysis showed that the three species changed their architecture as light increased but in a different way. No species conformed to the typical wide-crown type expected for shade-tolerant species, and in contrast they presented some traits of light demanding species. The two sub-canopy species tended to adopt a crown form between a narrow- and wide-crown type, and the mid-canopy species showed more traits of a narrow-crown type. The horizontal crown area appeared as the more related trait to the light and sapling height. It is concluded that despite being shade-tolerant, the studied species make use of better-lit environments in the forest understorey. The crown architecture of shade-tolerant species is not as rigid as originally conceived.Se analizó la arquitectura de la copa de tres especies tolerantes a la sombra (dos del sotobosque y una del dosel medio) en relación con el ambiente lumínico del sotobosque de la selva. El objetivo fue examinar el grado de variación que presenta la arquitectura de la copa de especies tolerantes a la sombra. Para esto, se midieron 13 variables arquitecturales en 265 árboles juveniles (50-300 cm de altura) distribuidos desde sitios de selva madura hasta claros de diversos tamaños, en la selva húmeda tropical de Los Tuxtlas, México. El análisis mostró que las tres especies cambian la arquitectura de su copa a medida que aumenta la disponibilidad de luz, pero de diferente forma. Ninguna especie presentó el típico modelo de copa plana esperado para las especies tolerantes a la sombra. Las dos especies del sotobosque tendieron a adoptar una copa intermedia entre plana y alargada, mientras que la especie del dosel medio, tendió hacia una copa alargada. El área horizontal de la copa se mostró como la variable más relacionada con la luz y altura del árbol. Se concluye que a pesar de ser especies tolerantes a la sombra, aprovechan los ambientes más luminosos para su desarrollo. La arquitectura de copa de las especies tolerantes a la sombra no es tan rígida como se creía en un principio.

Geographic differences in tree morphology and climate and growth responses of longleaf pine have been documented, yet how these differences vary at a larger scale has not. In this study, we documented changes in tree morphology and climate and radial growth responses of six longleaf pine (Pinus palustrisMill.) stands in three physiographic regions in North Carolina. We sampled from more than fifteen trees per stand and compared site- and regional-level total and latewood ring width values to temperature, precipitation, and drought. All morphological characteristics expressed a strong west–east gradient. Climate and radial growth response was strongest for the Sandhills region and then Piedmont and Coastal Plain regions. The distinct morphological characteristic gradient did not covary with climate and radial growth response, suggesting that additional environmental influences affect needle length, trunk diameter, and height. [ABSTRACT FROM PUBLISHER]

• Distribution of costs and benefits of adding height change congruently with crowding. • Marginal height cost increases with the square of initial height. • Marginal height cost increased with changes in foliage and foliage distribution. • Height is a major factor of production rate due to coordinated tree form. Height growth in trees is expensive in terms of the amount of stem tissue required to maintain productive tissue in sunlight. However, shifting allocation from stem support to leader growth and foliage production may allow trees to minimize shading effects on photosynthesis, especially for shorter trees within the population. This hypothesis was evaluated with data collected in competition studies for red alder (Alnus rubra Bong.), Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco), and red pine (Pinus resinosa Ait.). Stem allocation per unit height growth was defined as a marginal height cost, and foliage added per unit height growth was defined as marginal height benefit. A symmetry index was calculated as a simple function of the cumulative relative costs and benefits of the shorter half of trees within plots. Analyses of variance indicated that marginal height costs and benefits significantly increased with age at rates unique to the different levels of competition. It also indicated that marginal height costs were related to the square of initial height at levels also unique to the competition treatments. The effects of competition on the symmetry indexes for marginal height costs and marginal height benefits significantly interacted with age for red alder and Douglas-fir, but not for red pine; for red pine, the indexes only varied with age. The slope between the two indexes was nearly one for all three species, indicating that marginal height costs and benefits change congruently with competition. The results did not support the hypothesis that shorter trees in competing populations change stem allocation to favor foliage growth. The correspondence between the symmetry indexes for marginal height cost and marginal height benefit was apparently due to coordinated development where population effects on how much and where leaf area is added with height growth determine how much stems need to grow to counter the changes in mechanical forces created by the change in crown dimensions. The results provide additional evidence that tree form is the result of coordinated development, not allometry between trees foliage and structural components. [ABSTRACT FROM AUTHOR]

The relationship between functional traits and environmental factors contribute to understanding community structure and predicting which species will be able to elude environmental filters in different habitats. We selected 10 functional traits related to morphology, demography and regeneration niche in 54 subtropical premontane tree species to describe their main axes of functional differentiation. We derived species traits, environmental variables and species abundance data from 20 1-ha permanent plots established in a seasonal subtropical premontane forest in northwestern Argentina. We analyzed the relationship between species functional traits and environmental factors through RLQ and fourth-corner analyzes. We found an axis of structural differentiation that segregates understory from canopy species, and an axis of functional differentiation that segregates species that maximize resource acquisition from those that promote resource conservation. Environmental and forest use gradients operate hierarchically over subtropical premontane tree species influencing the distribution of demographic and morphological traits. The interaction between climatic and topographic factors influences the distribution of species functional traits at the regional scale. In addition, the history of forest use seems to operate at the landscape scale and explains the distribution of species traits reflecting a trade-off between resource acquisition and resource conservation strategies in secondary forests across different successional stages. Our results support the idea that functional traits may be used to analyze community structure and dynamics through niche differentiation and environmental filtering processes. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effects of soil treatments (ST) [fertilized sand (control) vs. added amendments of 78 Mg ha −1 compost (1×), 156 Mg −1 compost (2×), 15 cm of topsoil (TS), and 1 × compost + TS]; and restored microtopography (MT; level, pit and mound) on young bald cypress [ Taxodium distichum (L.) Rich] tree growth in a created tidal freshwater wetland in southeastern Virginia. The crown class and position of each tree was classified according to the Kraft system ten years after establishment along with morphometrics of height (HT), trunk diameter at 10 cm above the soil surface (DIA 10), tree diameter at breast height (DBH at 1.3 m), and basal trunk swelling factor (D diff = DIA 10 − DBH). Additionally, competition effects of all planted and successional woody vegetation on the planted bald cypress were evaluated. There were no effects of soil treatments on the measured parameters, but there were strong overall experiment-wide effects of MT. Diameter at 10 cm (DIA 10) and basal swelling (D diff) were significantly ( P < 0.05) greater in pits while overall height ( p = 0.006) and DBH ( p = 0.033) showed an even stronger response. Differentiation of individual tree crown classes and position was readily observable by year 10 and trees growing in pits were more likely to be in dominant and co-dominant positions (Kraft classes 1 and 2). The lack initial soil treatment effects (topsoil and compost additions) was surprising, but indicates that the overall quality of the site hydrology and initial soil substrate was high and therefore, microtopographic influences were dominant over the 10-year period studied. The results indicate that bald cypress plantings in created wetlands in this region would benefit from installed microtopography and that soil amendments per se may be less important. [ABSTRACT FROM AUTHOR]

Populus euphratica (Euphrates poplar) is the dominant tree species of the riparian (“tugai”) forests of Central Asia, which provide important ecosystem services to a rapidly growing population. However, overuse of the forests by wood harvest (pollarding) contributes markedly to their destabilisation. At the upper reaches of the Tarim River (Xinjiang, NW China), we investigated the effects of past pollarding (in the 1970s and 1980s) on the stand structure, tree morphology, stem diameter increment and intrinsic water use efficiency (iWUE) of poplars with different pollarding intensities in the past (‘No Use’, ‘Moderate’, ‘Intense’) growing on three adjacent plots with the same distance to the groundwater level. Compared to the non-used trees, the pollarded poplars (in particular, the intensely used trees) exhibited smaller figures of the following morphological variables: ratio of tree height to diameter at breast height, vertical crown extension, crown projection area, crown volume, and tree-ring width as well as basal area increment (BAI) during the past 24 years; but a higher number of secondary shoots, a higher percentage of hollow stems and a higher degree of hollowness of the stems. The pollarded trees were capable of regenerating to a certain extent, which was obvious from the formation of secondary shoots and, in the intensely pollarded trees, from a lower iWUE (inferred by more negative δ 13 C isotopic ratios of the tree rings; most probably due to higher rates of gas exchange) as well as from their capability of re-establishing a crown efficiency similar to non-pollarded trees. However, the BAI of the main trunk and the secondary branches of the pollarded trees decreased continuously during the last 24 years of investigation. Whilst moderate intensities of pollarding seem to be sustainable for the riparian P. euphratica forests, intense pollarding reduces the growth increment of the trees and, even more importantly, results in a distinct increase in the percentage of hollow stems, which can render the trees less stable and more susceptible to secondary damaging factors. The significant correlations between BAI and morphological variables of crown projection area and crown volume are promising for developing approaches to assess the productivity of P. euphratica stands on a landscape level using methods of remote sensing. [ABSTRACT FROM AUTHOR]

The leaf area-to-sapwood area ratio ( LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species., We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5-15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate., Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology. [ABSTRACT FROM AUTHOR]

Urban dwellers often breathe air that does not meet the European and WHO standards. Next to legislative initiatives to lower atmospheric pollutants, much research has been conducted on the potential of urban trees as mitigation tool for atmospheric particles. While leaf-deposited dust has shown to vary significantly throughout single tree crowns, this study evaluated the influence of micro-scale tree crown morphology (leaf density) on the amount of leaf-deposited dust. Using a ground-based LiDAR approach, the three-dimensional tree crown morphology was obtained and compared to gravimetric measurements of leaf-deposited dust within three different size fractions (>10, 3–10 and 0.2–3 μm). To our knowledge, this is the first application of ground-based LiDAR for comparison with gravimetric results of leaf-deposited particulate matter. Overall, an increasing leaf density appears to reduce leaf-deposition of atmospheric particles. This might be explained by a reduced wind velocity, suppressing turbulent deposition of atmospheric particles through impaction. Nevertheless, the effect of tree crown morphology on particulate deposition appears almost negligible (7% AIC decrease) compared to the influence of physical factors like height, azimuth and tree position. [ABSTRACT FROM AUTHOR]

The steep and complex topography in high-elevation mountains usually generates heterogeneous habitats, where reproductive isolation in spatially discrete populations, such as unsynchronized flowering, likely occurs. Therefore, genetically differentiated populations in some cases can be expected. Patterns of genetic variation and directions of gene flow among discrete populations could hold crucial information for a better understanding of population genetic structures in heterogeneous habitats. In this study, we examined the local-scale genetic structure and gene flow patterns among Abies mariesii populations in a heterogeneously snowy subalpine ecosystem. We found that A. mariesii populations, though spatially discrete and undergoing strong habitat heterogeneity, are less likely to be genetically differentiated. Gene flow was biased toward the moorlands, and compared to the forest populations, the genetic diversity in the moorland populations was found to be significantly higher, suggesting that the moorlands could serve as sinks of genetic diversity for A. mariesii. Finally, we quantified the morphological variation of A. mariesii and discovered that being able to adjust tree morphology in contrasting eco-habitats may strengthen the competitiveness of A. mariesii. This may also make a tangible contribution to the maintenance of populations in contrasting habitats. [ABSTRACT FROM AUTHOR]

Why do fires occur more frequently in Pinus densiflora forests in Korea, and why is the related damage more severe on such sites? We assumed that the reasons stem from characteristics of the tree species, including their combustibility, morphology and stand structure. Investigating both P. densiflora forests and the less vulnerable Quercus variabilis forests along the Korean eastern coast, we determined that, in spring, when fires are most frequent, the extremely flammable moisture content of fine fuels (6%) is not significantly different between the two types and the fine fuel load is much greater in the Q. variabilis forests. The P. densiflora forests retain more ladder fuel due to the greater coverage and density of their shrub layers in addition to their dead branches from lower on their boles and thinner barks, which enable fires to spread vertically with greater tree withering. Thus, when one considers all of these factors in combination, the following conclusions become apparent. First, in the initial ignition phase of fire, P. densiflora forests are more vulnerable due to their combustion characteristics. Second, those forests might allow flames to move vertically because of tree morphology and a stand structure that retains abundant ladder fuel. Finally, P. densiflora forests might be vulnerable to massive blazes because of their vast contiguous nature, especially in that region of Korea. [ABSTRACT FROM AUTHOR]

Red deer are increasing and spreading in Scandinavia. The species is capable of causing severe damage to Norway spruce through bark-stripping. We studied occurrence of bark-stripping on 18,000 trees in six study areas within two different regions in Sweden. The susceptibility for damage was related to morphological characters of the trees (bark thickness, branchiness, stem diameter) and whether the trees had old damage or not. In southernmost Sweden, 83, 89 and 92% of the stems were damaged in the three study areas, whereas 2, 8 and 46% was damaged in the three study areas in the region further north. Gnawing was the most common type of damage. Peeling was rare in the northern region but more frequent in the southern region. Bark-stripped trees had on average fewer branches, thinner bark and smaller diameter compared to undamaged trees. Furthermore, the risk of fresh damage was higher for already damaged trees in the northern region whereas the opposite pattern was evident in the southern region. Silvicultural measures may indirectly affect the risk of damage since it may affect branchiness, diameter and number of damaged trees left after thinning. [ABSTRACT FROM AUTHOR]

Longevity of trees is known to be associated with growth rates, but also with tree morphology and spatial influences. However, very little quantitative information is available on the effects of these biotic and abiotic influences on maximum ages of trees. The objectives of this study were to investigate the trade-off between longevity and growth rates of Norway spruce ( Picea abies) and to quantify the effects of tree morphology and abiotic site conditions on longevity of this species. Data were collected along different topographical and climatic gradients in a 20 × 25 km study area in the northern part of the Swiss Alps (Glarus). The ages of the more than 100 sampled dead Norway spruces ranged between 50 and 367 years. Longevity of these trees was negatively related to tree growth, i.e. slow-growing trees tended to grow older than fast-growing trees. Tree height was positively associated with longevity for both upper and lower storey trees. Longevity of lower storey trees was increased with large crown diameter, but decreased with long crown length. Upper storey trees growing at higher altitude tended to get older than at lower altitude. We conclude that the combined effects of growth rates, variability in site conditions and different traits of tree morphology determine tree longevity of Norway spruce in the Swiss Alps. Because longevity is tightly linked to mortality rates of tree populations, our study may improve our understanding of long-term processes of forest dynamics under current and future climate. [ABSTRACT FROM AUTHOR]

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Abstract: Singleleaf pinyon pine (Pinus monophylla) is a long-lived tree species that dominates montane plant communities over large areas of the arid and semi-arid Intermountain West, USA. Although old-growth forests are widely valued by society, old trees in pinyon-dominated woodlands may be threatened by active management against woodland expansion on rangelands, particularly in the absence of knowledge concerning old tree morphology and crown architecture. This study, which took place within a 15-km2 area in central Nevada, used detailed field observations of tree morphology and dendrochronological measurements of tree age, in combination with principal components analysis and multiple linear regression, to identify the distinctive attributes of old P. monophylla trees that require long time periods to develop. P. monophylla tree age was most parsimoniously quantified using three linear combinations of field-measured variables, representing overall tree size, crown diminishment with age, and “stubbiness” (i.e. the combination of short stature and wide girth). These composite variables were derived from just five types of tree measurements: stem diameter, height, diameter of lowest branch, crown area, and an index of bark texture. The three composite variables have intuitive meaning and do not require precise quantification to aid researchers and natural resource managers in developing more accurate visual estimations of approximate tree ages in P. monophylla or other cembroid pines characteristic of arid lands. Old tree attributes identified in this study are likely characteristic of long-lived conifers growing in arid and semi-arid regions, and are expected to provide important elements of habitat structure and complexity for diverse taxa. [Copyright &y& Elsevier]

The author presents several upper elementary science activities involving tree limbs that were collected after severe weather conditions. The activities involved 3rd-grade students arranging tree limb pieces in the correct order from the trunk to the tip of the limb, measuring the pieces, determining the age of a tree limb by its rings, identifying factors that affect the number and size of the rings, and drawing specific parts of tree limbs as an assessment. [ABSTRACT FROM AUTHOR]

1. The shade-tolerant conifer Abies alba Mill. (European silver fir) is a favoured browse species of several large herbivores. We performed an experiment to investigate how sun or shade conditions influence the recovery of A. alba saplings following simulated browsing. The browsing treatment involved clipping the leader and/or lateral shoots. For two growing seasons after applying the treatment, we recorded various measures of plant growth including bud development and the origin of new leaders. We then harvested the trees to determine patterns of above-ground biomass allocation. In the discussion, we consider the physiological basis for the observed responses to damage and evaluate the hypothesis that they represent an evolved defensive strategy against herbivory. 2. After 2 years, most saplings in the sun had compensated for lost height due to leader clipping, whereas saplings in the shade lagged 1 year behind. The degree of height recovery was influenced less by the length of the new leader than by its mode of origin; thus, there was overcompensation if the new leader developed from a side-shoot turning upwards (‘flagging’), while there was undercompensation if it was produced from an interwhorl or a secondary whorl bud. Leader origin, in turn, proved to be light-dependent, with flagging occurring twice as often in sun as in shade. Some trees, mostly in the shade, produced no leader in the first year but several leaders from secondary whorl buds in the second year (i.e. multiple stemming). Clipping of the leader also induced local bud development and led to greater allocation of resources to new leaders than in unclipped trees. Clipping of lateral shoots had no effect on either height increment or growth of lateral branches. 3. We conclude that, by influencing how the new leader is produced, light availability also affects the degree to which A. alba can compensate for loss in height from browsing. A possible interpretation of the overcompensation under high-light is as a defensive reaction to escape future browsing. However, an alternative explanation is that overcompensation and other morphological reactions, for example, multiple leaders, are merely contrasting physiological responses to release from apical dominance under different environmental conditions. [ABSTRACT FROM AUTHOR]

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

Palms build tall trees entirely by primary growth in a way that limits their growth habit, but not their capacity for continued stem development. They achieve massive primary stature because of distinctive features of leaf development, stem vasculature and anatomical properties. They exhibit several record features of leaf and seed, and inflorescence size and leaves of great complexity. A marked ability to generate new roots allows them to be transplanted easily. As climbing plants they develop the longest unrooted stems in which there are, paradoxically, anomalous features of vascular construction compared with tree palms. It is here claimed that they are the world’s longest lived trees because stem cells of several kinds remain active in differentiated tissues throughout the life of the palm. Absence of physiological dormancy may be related to this property, together with inability to withstand freezing temperatures that would cause irreversible cavitation of tracheary elements. This largely restricts them to the tropics, for which they are emblematic organisms. In these biological features palms are indeed unique organisms. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 151, 5–14. [ABSTRACT FROM AUTHOR]

In temperate trees, the extension growth history of stems and branches is easily inferred from the positions of the rings of over-wintering bud-scale scars, allowing one to assess environmental responses from surveys of saplings (Beaudet & Messier 1998, Canham 1988, King 2001). But tropical trees rarely show such distinct demarcations of growth flushes. Furthermore, the frequency of flushing may vary with tree size and environment, and a number of tropical species, often light demanding, show continuous leaf production and extension growth throughout the year (Coley 1983). [ABSTRACT FROM PUBLISHER]

Wildfires may be started naturally by lightning or artificially by humans. In the savanna regions of southern Africa, lightning fires tend to occur at the start of the wet season, during October and November, while anthropogenic fires are usually started during the dry season, between July and August. A long-term field manipulation experiment initiated in the Kruger National Park in 1952 was used to explore whether this seasonal divergence affects tree abundance, spatial pattern, size and architecture. After 44 years of prescribed burning treatments that simulated the seasonal incidence of lightning and anthropogenic fires, mean densities of the locally-dominant shrub, Colophospermum mopane, were 638 and 500 trees ha-1 respectively. Trees in burnt plots had aggregated distributions while trees in unburnt plots had random distributions. Significant differences (p < 0.001) were recorded in a range of morphological parameters including tree height, canopy diameter, mean stem circumference and number of stems. The incidence of resprouting also differed significantly between treatments, with burnt trees containing a high proportion of coppiced stems. The differences in tree size and architecture between the mid-dry season and early-wet season burning plots suggest that anthropogenic fires applied during July and August cannot substitute for a natural lightning fire regime. Anthropogenic fire yields a landscape that is shorter, more scrubby and populated by numerous coppiced shrubs than the landscape generated by natural lightning fire conditions. [ABSTRACT FROM AUTHOR]