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Nature‐based solutions, through conservation or (re)creation of vegetated shorelines, are recognized to mitigate the impact of waves and erosion risks on shorelines. Wave attenuation is known to be dependent on plant traits, resulting in increasing wave attenuation rates with increasing shoot density, shoot thickness, height, and stiffness. However, following the allometric scaling theory, we hypothesize that increasing shoot density (a canopy‐scale trait) may be associated with decreasing shoot thickness and stiffness (a shoot‐scale trait), with potential opposing effects on overall wave attenuation. This study investigates (1) the presence of such allometric relations across intertidal shore plant species via existing literature and (2) the trade‐off effects on the overall wave attenuation capacity of shore vegetation through a flume experiment. Our results reveal for the first time the presence of allometric relationships between shoot‐scale and canopy‐scale plant properties in perennial intertidal plant species. Across different species, increasing shoot densities are indeed associated with decreasing shoot thickness and shoot stiffness. Next, we performed a wave flume experiment with plant mimics, showing that wave attenuation rate follows a logarithmic increase with increasing shoot density, even though the increasing shoot density was associated with thinner and more flexible individual shoots. Synthesis and applications. We conclude that wave attenuation is predominantly governed by canopy‐scale properties, but a trade‐off with shoot‐scale properties mediates the overall wave attenuation capacity of the vegetated shore. Our findings imply that nature‐based projects (re‐)creating vegetated shorelines should account for potential trade‐off effects of species‐specific plant traits at the canopy scale and individual shoot scale. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Summary Forests worldwide face significant challenges due to climate change, impacting their health and productivity. In this study, we examined how European beech and Scots pine influence each other's phenology and growth in mixed forests. Our findings indicate that mixing these complementary tree species can increase resource efficiency within forest ecosystems. By leveraging informed species selection, this research highlights the potential for developing knowledge‐based, resource‐efficient forests. These insights are invaluable for policymakers and forest managers in designing forests that are not only productive but also sustainable and adaptable to evolving environmental conditions. We investigated the effects of interspecific neighbors on crown morphology and growth efficiency in European temperate forests, specifically focusing on European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.). Our goal was to determine whether the previously reported overyielding in this mixture is primarily due to improved space‐use efficiency and packing density or enhanced resource‐use efficiency. Our methodology involved a detailed analysis of 128 individual felled trees. We assessed the effect of intraspecific and interspecific neighbors on stem volume growth, the allometric relationships of tree crowns and their components, and the allocation of branch and leaf biomass along the trees' vertical structure. Our findings demonstrate that interspecific neighbors significantly influence the allometric relationships of tree crowns, especially altering the vertical biomass distribution in European beech. Additionally, we found that interspecific neighbors can significantly enhance the growth efficiency of European beech but not for Scots pine. This research provides valuable insights for enhancing forest growth models and guiding forest management practices. By understanding the critical role of crown biomass allocation and growth efficiency in mixed‐species stands, policymakers and forest managers can design forests that are both productive and adaptable to changing environmental conditions. This study emphasizes the importance of species interactions in forest dynamics and bridges theoretical concepts with practical applications. [ABSTRACT FROM AUTHOR]

Given the complexity of integrating and forecasting the interconnected effects of body size, population dynamics, and energy availability, theoretical approaches that link ecological and computational knowledge are required. Individual attributes, such as body size, exert influence and are, in turn, influenced by community structure. Distinguishing between the processes that generate population patterns and making predictions poses a challenge in theoretical ecology, drawing on concepts ranging from traditional natural philosophy to contemporary physical sciences. To address this challenge, our research proposes a computational model for conducting theoretical-exploratory simulations of a biological community, incorporating body size, density, and population dynamics based on the Metabolic Theory of Ecology principles. This community includes reproductive and non-reproductive individuals transitioning between feeding and reproductive areas. Accounting for seasonal limits and finite energy, we delineate the dynamic relationship between body size and population abundance. Additionally, we present a temporal simulation of allometric exponents describing the density pattern. The findings highlight the importance of considering energetic limitations to maintain the relationship between body size and population density and present the possibility of temporally modeling the allometric exponent of this demographic pattern.

Volume is an important attribute used in many forest management decisions. Data from 83 fixed-area plots located in central New Brunswick, Canada, are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer’s (1967) volume equation. When density was included in the models (Volume=f(Diameter,Height,Density)) choice of diameter measure was more important than choice of height measure. When density was not included (Volume=f(Diameter,Height)), the opposite was true. For models with density included, moment-based estimators of stand diameter and height performed better than all other measures. For models without density, largest tree estimators of stand diameter and height performed better than other measures. The overall best equation used quadratic mean diameter, Lorey’s height, and density (root mean square error ​= ​5.26 ​m3⋅ha−1; 1.9 % relative error). The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha (root mean square error ​= ​32.08 ​m3⋅ha−1; 11.8 % relative error). The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.

Allometric biomass allocation theory and optimal partitioning theory are the most important theoretical frameworks for explaining and predicting plant biomass allocation patterns. But their focus on equilibrium conditions does not advance our understanding of transient allocation patterns. To address this limitation, we develop a heuristic approach with a quantitative metric to theoretically analyze transient patterns of plant allocation of photosynthetic products to different plant organs. The approach is also used to ask how various factors can drive transient patterns. A case study is analyzed, showing how periodic perturbations of transient patterns of plant leaf and stem biomass can decrease or increase in response to plant height, crown diameter, and projected crown area. The predictions are consistent with global data on forest plants. The approach here addresses the limitations of optimal partitioning theory by revealing the variation in plant photosynthetic partitioning over short time scales. Given the central role of plant biomass allocation patterns for both empirical and theoretical studies, there is a large scope for applying this approach to improve estimations of carbon stock, and stabilized yields in forest management.

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco 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.)

Whole genome duplication (WGD) or polyploidization can occur at the cellular, tissue, and organismal levels. At the cellular level, tetraploidization has been proposed as a driver of aneuploidy and genome instability and correlates strongly with cancer progression, metastasis, and the development of drug resistance. WGD is also a key developmental strategy for regulating cell size, metabolism, and cellular function. In specific tissues, WGD is involved in normal development (e.g., organogenesis), tissue homeostasis, wound healing, and regeneration. At the organismal level, WGD propels evolutionary processes such as adaptation, speciation, and crop domestication. An essential strategy to further our understanding of the mechanisms promoting WGD and its effects is to compare isogenic strains that differ only in their ploidy. Caenorhabditis elegans (C. elegans) is emerging as an animal model for these comparisons, in part because relatively stable and fertile tetraploid strains can be produced rapidly from nearly any diploid strain. Here, we review the use of Caenorhabditis polyploids as tools to understand important developmental processes (e.g., sex determination, dosage compensation, and allometric relationships) and cellular processes (e.g., cell cycle regulation and chromosome dynamics during meiosis). We also discuss how the unique characteristics of the C. elegans WGD model will enable significant advances in our understanding of the mechanisms of polyploidization and its role in development and disease. [ABSTRACT FROM AUTHOR]

The ability to estimate the space volume that a tree occupies, in various heights, is a crucial factor in designing the street trees schedule in pavements of new urban infrastructures. The dimensions of Acer negundo tree crown in various heights can be the basis for a better space management in the pavements of cities. In this study, the height and the crown width of the A. negundo street trees in the Greek cities of Orestiada and Alexandroupoli and the allometric relations that can be found between them, were investigated. Data from 117 street trees growing in semi-permeable pavements of the two cities were used. In each selected tree, the total height (H), and the maximum and minimum crown diameter (CW) were measured. The selected model (CW-H) for Alexandroupoli exhibits a coefficient of determination (R2) of 0.81. The R2 of the model selected for Orestiada is lower (R2 = 0.66). The R2 of the model selected using the complete dataset is 0.77. A. negundo appears to have greater crown width in Alexandroupoli compared to that of Orestiada. In Orestiada the conditions of growth were variable since in many cases the measured trees were under side shade, while this not the case in the corresponding trees in Alexandroupoli. The better fit of the selected model in Alexandroupoli compared to that of Orestiada is probably due to the more variable growth conditions of Orestiada.

The objective of this study was to evaluate height-diameter, volumetric, and taper models to estimate tree height and volume to describe the bole profiles of a eucalypts clone established in three agrosilvopastoral spatial arrangements (18 × 2.5; 5 × 2 + 40; 3 (3 × 2) + 30) in Coronel Xavier Chaves, Minas Gerais state, Brazil. The diameter at breast height, total height, and diameter outside bark along the stems of the sample trees were collected. Height-diameter, volume, and taper models were fit to the observed data for each spatial arrangement and were compared to select the best alternative. The mean annual increment for single, double, and triple lines at 48, 60, and 72 months of age, respectively, ranged from 26.0 to 34.6 m3 ha−1 year−1, as well as individual volume ranged from 0.41 to 0.53 m3 tree−1. The height-diameter curves showed a distinct tendency for each spatial arrangement and can be represented by different equations. The equations to estimate volume and taper fit well to the data, and the Spurr and Garay models were selected as the best fitting, respectively. In addition, Graybill's F-test (Theory and application of the linear model. Duxbury Press, Massachussetts, 1976) showed that a single equation could fit the Spurr and Garay models for all spatial arrangements. [ABSTRACT FROM AUTHOR]

Keywords: allometric relationships; biodiversity; extinction debt; fragmentation; habitat destruction; IUCN Red List; population persistence; biodiversidad; destrucción del hábitat; deuda de extinción; fragmentación; Lista Roja de la UICN; persistencia poblacional; relaciones alométricas; ; ; ; ; ; ; EN allometric relationships biodiversity extinction debt fragmentation habitat destruction IUCN Red List population persistence biodiversidad destrucción del hábitat deuda de extinción fragmentación Lista Roja de la UICN persistencia poblacional relaciones alométricas 1 12 12 10/04/22 20221001 NES 221001 INTRODUCTION Habitat destruction is currently one of the greatest threats to biodiversity (IPBES, 2019; Maxwell et al., 2016; Munstermann et al., 2021). Red-list classification Eight species (5%), including 6 forest specialist species, were categorized in a higher red-list category when we used their habitat area hosting viable populations as the AOO, instead of the total initial habitat area (Figure 4). Red List classification To evaluate the importance of time-lagged effects of habitat fragmentation in terms of species' threat status, we determined the red-list category for each species according to criterion B2. We defined forest specialists (124 species) as species occurring exclusively in forest habitat types and considered the remaining species (33) habitat generalists. [Extracted from the article]

Optimizing stand structure can enhance plantation forest ecosystem service functions by regulating litterfall patterns; however, the effects of close-to-nature management on litterfall production remain unclear. Here, we selected three cypress (Cupressus funebris) plantations, including one using the practice of strip filling (SF), one using the practice of ecological thinning (ET), and one pure cypress plantation without any artificial interference. The production of total litterfall and its components (leaf, twig, reproductive organ and miscellaneous litterfall) were investigated monthly over one year from September 2019 to August 2020. Compared with that of the pure plantation, the total annual litterfall production of the SF and ET plantations decreased significantly by 10.8% and 36.44%, respectively. The annual production of leaf and reproductive organ litter was similar to that of total litterfall, but that of twig and miscellaneous litter was higher in the SF and ET plantations than in the pure plantation. Moreover, total, leaf and reproductive organ litterfall production displayed unimodal dynamics regardless of plantation, although the peaks of reproductive organ litter production occurred in different months. In contrast, the production of twig litter showed bimodal dynamics in the pure plantation, while unimodal and irregular dynamics were observed in the plantations with ET and SF, respectively. Additionally, insignificant differences in the isometric growth index of leaf litter and total litterfall were observed. The allometric indices of twig litterfall versus total litterfall, reproductive organ litterfall versus total litterfall, and leaf litterfall versus twig litterfall were higher in the plantations with SF and ET than in the pure plantation. Redundancy analysis (RDA) revealed that diameter at breast height and air temperature were the most important factors shaping the annual and monthly production of litterfall, respectively. These results provide efficient data to support the rectification of the material circulation of cypress plantations and their future management. [ABSTRACT FROM AUTHOR]

Copyright of Ciência Florestal (01039954) is the property of Ciencia Florestal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The edible water frog Pelophylax epeiroticus, distributed mainly in Northwest Greece and utilized commercially as food, was investigated in lake Pamvotida (Ioannina). The objective was to assess aspects of population structure (sex ratio, morphometric characteristics, allometric relationships) and proximate composition of the Epirus water frog (Pelophylax epeiroticus). Commercial samples (31 females and 54 males) were obtained and sex ratio, morphometric characteristics, allometric relationships and proximate composition were assessed. A significantly lower abundance of females was indicated (31 females and 54 males). Body length range was higher in females (females 3.4 mm, males 2.6 mm), whereas total weight range was higher in males (females 45.08 gr, males 48.35 gr). Differences in allometric relationships were indicated between sexes. The high protein (15.93 ± 3.32) and low lipid (0.25 ± 0.13) contents indicated that P. epeiroticus is an excellent food source of high nutritional value. A tree classification algorithm indicated that the principal contributing component for sex classification was dry matter, followed by a proportion of edible flesh and protein content. A predicted future increase in demand for wild-caught individuals requires the use of a suitable management plan, coupled with the development of farming practices aiming to assure the sustainable exploitation of this important resource and alleviate the pressure on its populations. [ABSTRACT FROM AUTHOR]

Context: Allometric equations describing the relationships between tree height (H) and breast height diameter (D) should be both statistically efficient and biologically relevant. Aims: To determine whether selected allometric equations can meet established criteria for both efficiency and relevance. Methods: Nine equations were compared to define the H – D relationships of 1122 individuals and 18 species from an Australian subtropical rainforest. Key results: Three-parameter asymptotic equations described initial slope (a), curvature (b), and asymptotic height (H a). Each equation was evaluated for precision (root mean square error, RMSE) and bias in H estimates, and ease of interpretation of function parameters. For both individual species and all stems, a non-rectangular hyperbola (NRH) provided almost equally high precision and low bias as did the statistically most parsimonious generalised Michaelis–Menten function, plus linear parameter values easily relatable to tree structural and functional attributes. The value of NRH a increased linearly with wood density for canopy species, but not for understorey and subdominant species, whereas the value of NRH b decreased as H a increased from understorey to canopy species. Conclusions: Species within understorey, subdominant, and canopy structural groups shared similar ranges of parameter values within groups that reflect both intrinsic architectural and developmental patterns, and environmental limitations to H a. Implications: The NRH can be used to visualise both early and later tree development stages and differences among the growth patterns of species occupying different positions within a forest. Process rate equations (generalised Michaelis–Menten, GMM, and non-rectangular hyperbola, NRH) described rainforest tree height–diameter relationships more precisely than did biophysical or growth rate equations. The GMM was the most efficient for modelling but the NRH best visualised interactions between stem structure and tree architecture from saplings to maturity for understorey to upper-canopy species. [ABSTRACT FROM AUTHOR]

Generalized height-diameter at breast height (D) models are essential for the estimation of the timber stocks of a forest stand, as well as in the generation of base information to develop forest growth models, and as basic inputs in the development of forest management plans. Generalized models were developed to estimate total height (TH) based on the D and stand variables, of five Pinus species in forests under forest management of Ixtlán de Juárez, Oaxaca, Mexico. The data used come from a timber forest inventory, where n = 1041 sampling plots of 1000 m2 each were established based on a stratified-systematic sampling design. The species selected according to their relative abundance were: Pinus patula, Pinus oaxacana, Pinus ayacahuite, Pinus teocote and Pinus leiophylla. Five nonlinear equations were fitted using regression techniques to predict the TH of the trees under several silviculture regimes and forest management conditions. The statistical criteria of goodness of fit used were: adjusted coefficient of determination (R2adj), root mean square error (RMSE) and absolute average bias in the prediction (Ē). Likewise, the graphic analysis of the predictive capacity of the equations was considered. The D and the stand variables (quadratic mean diameter, dominant diameter and dominant height) for these species explained between 75 and 83% of the variability of the TH data. The predicting variables to apply the developed generalized models to estimate tree's total height require less sampling effort and are derived from conventional forest inventory data, which allows to reduce costs and time in field work.

Invasive bivalves continue to spread and negatively impact freshwater ecosystems worldwide. As different metrics for body size and biomass are frequently used within the literature to standardise bivalve‐related ecological impacts (e.g. respiration and filtration rates), the lack of broadly applicable conversion equations currently hinders reliable comparison across bivalve populations. To facilitate improved comparative assessment among studies originating from disparate geographical locations, we report body size and biomass conversion equations for six invasive freshwater bivalves (or species complex members) worldwide: Corbicula fluminea, C. largillierti, Dreissena bugensis, D. polymorpha, Limnoperna fortunei and Sinanodonta woodiana, and tested the reliability (i.e. precision and accuracy) of these equations.Body size (length, width and height) and biomass metrics of living‐weight (LW), wet‐weight (WW), dry‐weight (DW), dry shell‐weight (SW), shell free dry‐weight (SFDW) and ash‐free dry‐weight (AFDW) were collected from a total of 44 bivalve populations located in Asia, the Americas and Europe. Relationships between body size and individual biomass metrics, as well as proportional weight‐to‐weight conversion factors, were determined.For most species, although inherent variation existed between sampled populations, body size directional measurements were found to be good predictors of all biomass metrics (e.g. length to LW, WW, SW or DW: R2 = 0.82–0.96), with moderate to high accuracy for mean absolute error (MAE): ±9.14%–24.19%. Similarly, narrow 95% confidence limits and low MAE were observed for most proportional biomass relationships, indicating high reliability for the calculated conversion factors (e.g. LW to AFDW; CI range: 0.7–2.0, MAE: ±0.7%–2.0%).Synthesis and applications. Our derived biomass prediction equations can be used to rapidly estimate the biologically active biomass of the assessed species, based on simpler biomass or body size measurements for a wide range of situations globally. This allows for the calculation of approximate average indicators that, when combined with density data, can be used to estimate biomass per geographical unit‐area and contribute to quantification of population‐level effects. These general equations will support meta‐analyses, and allow for comparative assessment of historic and contemporary data. Overall, these equations will enable conservation managers to better understand and predict ecological impacts of these bivalves. [ABSTRACT FROM AUTHOR]

Biological and ecological aspects of organisms are important to understand the role of species in aquatic ecosystems. Measuring growth rate is useful to analyse these aspects through the estimation of instar and biomass in aquatic insects like shredder trichopterans. We aimed to produce allometric relationships based on larval body parts and case dimensions to estimate larval instars and biomass for Phylloicus cressae Prather, 2003. Here, we showed that classification tree analysis and power and exponential models proved that dorsal and ventral length of cases were good predictors of larval instars and biomass for P. cressae. We also found that allometric relationships involving the length of the prothoracic mid-dorsal ecdysial suture were suited for assessing larval instars but performing these measurements on cased trichopterans is difficult without damaging them. So, allometric models like ours, based on case dimensions, are invaluable when dealing with live individuals. [ABSTRACT FROM AUTHOR]

Optimizing stand structure can enhance plantation forest ecosystem service functions by regulating litterfall patterns; however, the effects of close-to-nature management on litterfall production remain unclear. Here, we selected three cypress (Cupressus funebris) plantations, including one using the practice of strip filling (SF), one using the practice of ecological thinning (ET), and one pure cypress plantation without any artificial interference. The production of total litterfall and its components (leaf, twig, reproductive organ and miscellaneous litterfall) were investigated monthly over one year from September 2019 to August 2020. Compared with that of the pure plantation, the total annual litterfall production of the SF and ET plantations decreased significantly by 10.8% and 36.44%, respectively. The annual production of leaf and reproductive organ litter was similar to that of total litterfall, but that of twig and miscellaneous litter was higher in the SF and ET plantations than in the pure plantation. Moreover, total, leaf and reproductive organ litterfall production displayed unimodal dynamics regardless of plantation, although the peaks of reproductive organ litter production occurred in different months. In contrast, the production of twig litter showed bimodal dynamics in the pure plantation, while unimodal and irregular dynamics were observed in the plantations with ET and SF, respectively. Additionally, insignificant differences in the isometric growth index of leaf litter and total litterfall were observed. The allometric indices of twig litterfall versus total litterfall, reproductive organ litterfall versus total litterfall, and leaf litterfall versus twig litterfall were higher in the plantations with SF and ET than in the pure plantation. Redundancy analysis (RDA) revealed that diameter at breast height and air temperature were the most important factors shaping the annual and monthly production of litterfall, respectively. These results provide efficient data to support the rectification of the material circulation of cypress plantations and their future management.

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield.

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield. [ABSTRACT FROM AUTHOR]

Introduction Since the leaves are the main source of production of photosynthetic substances in plants, dry matter production and crop yield potential is largely depend on the leaf surface, and many environmental changes affect growth and yield through changes in leaf area. Hence, green leaf area per plant and leaf area index measure in almost all studies of crop physiology to understand the mechanism of yield alteration. However, measurement of leaf area compared with other traits such as plant height and total plant dry weight is very difficult, precise instruments and spend more time and cost. Therefore, according to the allometric relationships in plants, extensive studies were done to find the relationship between leaf area and other plant traits that their measurement is easier, faster and cheaper, and does not require expensive equipment. Allometric relationships in plants reveal changes in the growth of an organ of plant than to all or another part or organ of plant. The leaf area in plant as main source of photosynthetic substances closely associated with the growth and yield. Thus, it is usually measured for justifying variations of the growth and yield. Due to the difficulty, time‌consuming and requires devices to measure leaf area, an alternative approach for measuring the leaf area is the use of allometric relationships between leaf area and traits that their measuring is easy and quick and requires no expensive equipment. This study aimed to obtain the allometric relationships between green leaf area and a number of vegetative attributes such as number of leaves per main stem, green leaf dry weight, total dry weight of vegetative parts of plant. Allometric equations was used successfully to calculate leaf area in various crops such as cotton, wheat, chickpea, faba bean, peanuts, soybean and sweet sorghum. The effects of three factors cultivar, inter‌ and intra‌row spacing on the allometric relationships were examined. Materials & Methods This experiment was conducted using two cultivars of faba bean (a conventional, Barecat and a new cultivar, French), three inter‌row spacing (25, 50 and 75 cm) and two intra‌row spacing (8 and 15 inches) in a randomized complete block design with 4 replications in the farm of Gorgan University of Agricultural Sciences and Natural Resources during 2010‌2011 growing season. Sampling to measure the green leaf area and leaf dry weight and other vegetative traits during the growing season was carried out with intervals of 7 to 15 days (depending on the temperature and rate of plant growth). Different mathematical functions were fitted to the data to obtain allometric relationships. To compare the accuracy of the equations, coefficient of determination (R2) and root mean square error (RMSE) were used. Higher coefficient of determination, and lower coefficient of variation and root mean square error reflects the higher accuracy of the equation to describe allometric relationships. Results & Discussion According to the results of this experiment, the relationship between leaf area and leaf dry weight and total plant dry weight in faba bean was not affected by cultivar, inter‌ and intra‌row spacing, statistically. Thus, an equation was fitted to leaf area data against leaf dry weight or total plant dry weight in all treatment (both cultivars and all inter‌ and intra‌row spacing). Also, results of this study showed that the relationship between green leaf area and leaf dry weight as well as number of nodes per main stem has higher coefficient of determination (0.98 for green leaf dry weight, and 0.98 and 0.95 for node number per main stem in 8 and 15 cm intra‌row spacing, respectively) and lower the root mean square (1.05 for green leaf dry weight, and 1.08 and 1.064 for node number per main stem in 8 and 15 cm intra‌row spacing, respectively) than other traits. Conclusion Since the relationship between green leaf area and green leaf dry weight per plant had a higher coefficient of determination (0.98) as well as smaller root mean square (1.05) than other traits including leaf number per main stem, as well as the ease of measuring the green leaf dry weight, it is suggested that the relationship between leaf area and leaf dry weight (a segmented relationship) is used to estimate green leaf area during the growing season in faba bean. Also, this relationship can be used to predict faba bean leaf area with sufficient accuracy in the simulation models.

Aims: The improvement of nitrogen use efficiency (NUE) of crops allows crop nitrogen (N) demands to be met while reducing N supply, and so reducing excess N which has potential negative environmental implications. NUE is often determined destructively at the end of crop growth-cycles without considering temporal variability. Here we present a methodological study which optimises the determination of NUE throughout the sugarcane growth-cycle using minimally destructive methods, and suggest the use of these methods for non-destructive NUE determination over the growth-cycle of other giant C4 crops. Methods and results: The determination of the NUE relied on the optimisation of three methods: the estimation of aboveground biomass, N content and N derived from fertiliser (NdfF). First, the ability of different allometric relationships to estimate sugarcane biomass was investigated by selecting a relationship based on height and diameter to estimate aboveground biomass along the crop growth-cycle. Secondly, we assessed the minimum number of harvested sugarcane required to construct a dilution curve to predict N content from biomass and found that a sampling of 5 sugarcane at 3 dates was sufficient to represent aboveground N content over the growth-cycle. Finally, the ability of 15N content of individual leaves to represent the NdfF in 15N-fertilised cane was tested. The first and second leaf below the top visible dewlap were the most representative. Based on a variance analysis, we assessed the level of influence of each method on the NUE calculation. Crop age accounted for 54% of the variance of NUE, the choice of 15N leaf 13%, with the choice of model to estimate biomass and the number of plants harvested for the N dilution curve, each accounting for less than 2% over the four sampling dates. Conclusions: This study highlighted the importance of evaluating NUE not only at the point of harvest. We propose, therefore, a set of methods to study NUE throughout the sugarcane growth-cycle by using minimally destructive sampling. [ABSTRACT FROM AUTHOR]

A central goal of benthic ecology is to describe the pathways and quantities of energy and material flow in seafloor communities over different spatial and temporal scales. We examined the relative macrobenthic contribution to the seafloor metabolism by estimating respiration and secondary production based on seasonal measurements of macrofauna biomass across key coastal habitats of the Baltic Sea archipelago. Then, we compared the macrofauna estimates with estimates of overall seafloor gross primary production and respiration obtained from the same habitats using the aquatic eddy covariance technique. Estimates of macrobenthic respiration rates suggest habitat-specific macrofauna contribution (%) to the overall seafloor respiration ranked as follows: blue mussel reef (44.5) > seagrass meadow (25.6) > mixed meadow (24.1) > bare sand (17.8) > Fucus-bed (11.1). In terms of secondary production (g C m−2 y−1), our estimates suggest ranking of habitat value as follows: blue mussel reef (493.4) > seagrass meadow (278.5) > Fucus-bed (102.2) > mixed meadow (94.2) > bare sand (52.1). Our results suggest that approximately 12 and 10% of the overall soft-sediment metabolism translated into macrofauna respiration and secondary production, respectively. The hard-bottoms exemplified two end-points of the coastal metabolism, with the Fucus-bed as a high producer and active exporter of organic C (that is, net autotrophy), and the mussel reef as a high consumer and active recycler of organic C (that is, net heterotrophy). Using a combination of metrics of ecosystem functioning, such as respiration rates and secondary production, in combination with direct habitat-scale measurements of O2 fluxes, our study provides a quantitative assessment of the role of macrofauna for ecosystem functioning across heterogeneous coastal seascapes. [ABSTRACT FROM AUTHOR]

Plant quality and survival prediction tools are useful when applied in the field in different agricultural sectors. The objectives of this study were to conduct a review and bibliometric analysis of the Dickson Quality Index (DQI) as a key plant quality indicator and with respect to its scientific applications. A third objective was to identify the main morphological and physiological parameters used in plant production research. The methodology and findings of 289 scientific articles were analysed based on the morphological, physiological, and mathematical parameters used as plant quality indicators in research on forest, medicinal, horticultural, aromatic, and ornamental species. During the last 10 years, the number of publications that have used the DQI as a plant quality parameter has increased by 150%, and Brazilian researchers stand out as the most frequent users. Forestry is the discipline where quality parameters and their biometric relationships are most often used to facilitate intensive plant production. Use of the DQI increases the certainty of prediction, selection, and productivity in the plant production chain. The DQI is a robust tool with scientific application and great potential for use in the preselection of plants with high quality standards among a wide range of plant species.

Studies of invasive Australian Acacia have shown that many seeds are still produced and accumulate in soil stored seed banks regardless of the presence of seed-targeting biological control agents. This is despite claims of biological control success, although there is generally a lack of data on the seed production of invasive Australian Acacia before and after the release of the respective agents. We aimed to quantify seed production and seed survival of invasive Australian Acacia currently under biological control. The seed production and survival (proportion of aborted, predated and surviving seeds) of A. longifolia, A. pycnantha and A. saligna were each studied at four to five sites in the Western Cape of South Africa. The relationships between seed production and stand characteristics were determined and the relative effects of seed predation and abortion on seed survival were established. The investigated invasive Australian Acacia produced many seeds that survived the pre-dispersal stage despite long-term presence of released biological control agents. It was shown that seed crop size is the only significant factor influencing seed survival of the studied Australian Acacia species. Furthermore, the seeds surviving per tree and per square meter were related to tree size. No quantitative evidence was found to suggest that seed-reducing biological control agents are having an impact on the population dynamics of their Australian Acacia hosts. This study illustrates the importance of studying the seed ecology of invasive plants before biological control agents are selected and released.

Foredunes are defined as the first shore-parallel dune ridges adjacent to stable and prograding beaches, formed on the backshore by aeolian sand deposition influenced by vegetation. Foredunes have the important functions for mitigating impacts caused by extreme events, providing sediment to the beaches during storm and accumulating sediment again under fair weather wave conditions. Mainly for this reason, there is currently great interest in preserving, building or recovering foredunes. On a long-term timescale (decades), foredunes are recognized as exhibiting possible equilibrium conditions. The identification of this condition is of interest to projects involving the recovery and creation of foredune/beach systems. Therefore, the main objective of this work is to identify the morphometric characteristics of equilibrium foredunes and the interrelations between the morphometric parameters of height, width, volume and maximum slope (allometric relationships). To reach this objective, 193 foredune/subaerial beach profiles from along the northern coast of Spain that have characteristics close to equilibrium conditions were evaluated. The results indicate that foredune size can vary significantly; however, strong correlations between morphometric parameters have been verified and allometric relationships between foredune volume, height, width and maximum slope are proposed. • Foredunes along the northern Spain coast exhibit important variability in size. • Foredunes represent approximately 50% of the volume and width of the entire backshore. • Strong correlations between foredune morphometric parameters were verified. [ABSTRACT FROM AUTHOR]

Crop models simulate growth and development and they are often used for climate change applications. However, they have a variable skill in the simulation of crop responses to extreme climatic events. Here, we present a new dynamic crop modelling method for simulating the impact of abiotic stresses. The Simultaneous Equation Modelling for Annual Crops (SEMAC) uses simultaneous solution of the model equations to ensure internal model consistency within daily time steps; something that is not always guaranteed in the usual sequential method. The SEMAC approach is implemented in GLAM, resulting in a new model version (GLAM-Parti). The new model shows a clear improvement in skill under water stress conditions and it successfully simulates the acceleration of leaf senescence in response to drought. We conclude that SEMAC is a promising crop modelling technique that might be applied to a range of models. • A new simultaneous equation crop modelling technique (SEMAC) is presented. • SEMAC provides higher internal model consistency than step-wise modelling approaches. • Incorporation of SEMAC into GLAM improves model performance under water stress. • SEMAC can be applied to other crop models. [ABSTRACT FROM AUTHOR]

In invasive dreissenid communities, the zebra mussel usually appears earlier and then is displaced by the quagga mussel. We analysed length-weight allometric relationships, attachment strength (2 days, 1 week and 1 month of exposure), shell crushing resistance and glycogen content across the entire size range of both species in large shallow European lakes where this displacement has recently occurred. In Lake Balaton (Hungary) and Ijsselmeer (The Netherlands), the soft tissue dry weight increment of zebra mussels per unit length decreased after the quagga mussel invasion and became lower than that of quagga mussels. In Lake Markermeer (the Netherlands), having relatively worse environmental conditions, dry weight increment per unit length was always higher in quagga mussels than in zebra mussels, but no negative change in dry weight increment occurred in zebra mussels during the quagga mussel invasion. Small zebra mussels had more resistant shells and stronger attachment than quagga mussels. These differences were reduced (shell hardness) or reversed (long-term attachment) in larger individuals. Zebra mussels had lower glycogen content than quagga mussels across the entire size range. Thus, the quagga mussel advantage over zebra mussel likely consists in the faster dry weight increment per unit length and higher storage product contents of the former, due to its lower investments in attachment strength and shell crushing resistance. [ABSTRACT FROM AUTHOR]

Highlights • E. erythropappus had high trait variability in forest-savanna transitions. • Forest trees had tall and slender stems, packed crowns, and acquisitive leaves. • Trees in the transition zone had displaced crowns to intercepted light. • Savanna trees had short mechanical-stable stems and conservative leaves. • Light competition plays a vital role in forests and stress tolerance in savannas. Abstract Intraspecific trait variability is pivotal for plants to overcome environmental filters, shaping the species distribution and abundance in heterogeneous landscapes such as ecotonal zones. In this study, we aimed to understand the role of intraspecific trait variation on species occupation in a sharp ecotone. For this, we used, as a model, a dominant tree species of forest-savanna transitions in Brazil's Southwest and focused on stem architecture and allometries and leaf functional traits. Our results showed that trait variability improves plant performance along the ecotonal gradient. In fact, trees in forest optimize the light-interception and -use by the production of tall and slender stems and more acquisitive, smaller, and thinner leaves. On the other hand, trees in savannas had the opposite morpho-functional pattern, enhancing their resistance to wind, drought, continuous light incidence, and nutrient-poor soils. Surprisingly, trees right at the forest-savanna transition resembled forest tress regarding shoot morphology and savanna trees regarding leaf functional traits. However, displaced crowns were a singularity of transition trees. Taken together, our study shows that intraspecific variability is crucial for a dominant plant to successfully occupy contrasting habitats along the forest-savanna transition. Our study thus highlights the importance to investigate the role of intraspecific trait variation to better understand species dominance and community assembly in ecotonal zones. [ABSTRACT FROM AUTHOR]

Studies of invasive Australian Acacia have shown that many seeds are still produced and accumulate in soil stored seed banks regardless of the presence of seed-targeting biological control agents. This is despite claims of biological control success, although there is generally a lack of data on the seed production of invasive Australian Acacia before and after the release of the respective agents. We aimed to quantify seed production and seed survival of invasive Australian Acacia currently under biological control. The seed production and survival (proportion of aborted, predated and surviving seeds) of A. longifolia, A. pycnantha and A. saligna were each studied at four to five sites in the Western Cape of South Africa. The relationships between seed production and stand characteristics were determined and the relative effects of seed predation and abortion on seed survival were established. The investigated invasive Australian Acacia produced many seeds that survived the pre-dispersal stage despite long-term presence of released biological control agents. It was shown that seed crop size is the only significant factor influencing seed survival of the studied Australian Acacia species. Furthermore, the seeds surviving per tree and per square meter were related to tree size. No quantitative evidence was found to suggest that seed-reducing biological control agents are having an impact on the population dynamics of their Australian Acacia hosts. This study illustrates the importance of studying the seed ecology of invasive plants before biological control agents are selected and released. [ABSTRACT FROM AUTHOR]

Abstract In order to find plant growth characteristic relationships with leaf area index in Pumpkin (Cucurbita pepo L.), an experiment was conducted based on randomized complete block design with three replications. Three planting dates (Apr. 20, May 21 and Jun. 21) performed at the research field of Abooreihan Campus, the University of Tehran, Pakdasht, Tehran, Iran, in 2009–2010 cropping season. Sampling was performed during the whole growing season and leaf area (LA), leaf no. per plant, leaf dry weight (LDW), leaf fresh weight (LFW), node no. per main stem and plant height, were measured. The aim of this study was to collect and evaluate nonlinear regression models in the plant growth characteristic studies (exponential, Gaussian, linear, quadratic, symmetric, sigmoid). Root Mean Square Error (RMSE), the standard error of the estimate (SE) and coefficient of determination (R 2) were used to find the appropriate model(s). The result showed that, the linear model predicted significant relationships between LAI and LA (R 2 = 90), LAI and leaf no. per plant (R 2 = 90), LAI and node no. per main stem (R 2 = 90), LAI and LDW (R 2 = 98) and LAI and LFW (R 2 = 98). These result showed that the linear model can be used for estimation of LAI Pumpkin, especially where there is no LAI-meter available. [ABSTRACT FROM AUTHOR]

Highlights • Notable variation in the size of main-branch shoots of Luma apiculata is evidenced. • The number of leaf primordia preformed in winter buds is low and little variable. • Organ addition to the autumn preformation implies shoot structure re-adjustment. • The relevance of preformation on shoot structure reveals different growth strategies. Abstract A close examination of axis differentiation is key to the understanding of plant architecture and its ecological consequences. The present study was aimed at evaluating the relationship between shoot size/structure and shoot growth dynamics in Luma apiculata (Myrtaceae), a widely distributed and cultivated but little investigated Andean-Patagonian woody species. We assessed (a) organ preformation in apical buds, (b) shoot growth through repeated observations of labeled axes, (c) axillary production, leaf area, stem volume, dry mass of leaves, stem and reproductive structures, and allometric relationships for annual shoots of different sizes. The number of preformed organs in apical buds of L. apiculata averages seven nodes and exhibits little variability, in contrast with the highly variable growth period (from few weeks up to more than six months) and the size reached by annual shoots. The leaf area/stem volume ratio increased more sharply during shoot extension in short than in long shoots. Stem thickness was proportionally higher than other shoot-size measures in short shoots and long shoots as compared to intermediate-size shoots. Both the presence and the position of branches along shoots varied notably with shoot size. Proportional mass and meristem allocation to fruit production decreased with shoot size. Unlike many other broadleaved temperate and temperate-cold tree species so far studied, the size reached by L. apiculata shoots developed in the same year varies notably among axes in the same topological position, and seems to depend largely on the expansion of non-preformed organs. A low dependency of shoot growth on organ preformation may increase plasticity in axis structure, at the cost of a less hierarchical (more shrubby) architecture. Simultaneous organ differentiation and expansion may allow plants to fine-tune shoot structure to the prevailing conditions during the growing season, and represent an advantage whenever conditions favourable for growth exhibit high between-year variations. [ABSTRACT FROM AUTHOR]

Research Highlights: Studies on tree canopy dwelling species often require simple proxies of tree canopy volume estimated at a stand level. These include allometrically related tree crown parameters such as crown area and basal area, and canopy cover. Background and Objectives: In monoculture Scot’s pine and mixed pine/Norway spruce forest, we aimed to test the relationships between tree diameter at breast height (DBH) and tree crown volume at a tree level and between densitometer canopy closure estimates and tree crown volume at a stand level. Materials and Methods: The study was carried out in eastern Latvia (hemiboreal zone) in monoculture pine and mixed coniferous stands. On a subset of trees in 22 forest stands (88 100 m2 plots), we determined the best regression model that described the relationship between tree DBH and crown volume for spruce and pine. Tree crown volume at a stand level was determined from the individual tree volume estimates calculated from these regression models. On a stand level, we also calculated regression models for densitometer closure estimates versus total crown volume for pine and mixed stands. Results: Linear mixed effects models showed significant relationships between DBH and crown volume for pine (R2 = 0.63) and spruce (R2 = 0.40), indicating that basal area could be used as a predictor of crown volume at a stand level. Variance explained by a regression model of canopy closure versus tree crown volume at a stand level was R2 = 0.52. Conclusions: Tree basal area and crown closure can be used as proxies of tree crown volume at a stand scale in monoculture stands. In mixed stands estimates of crown volume based on basal area need to be calculated separately for each tree species, while canopy closure will provide an estimate of total crown volume.

Limpets are pivotal for structuring and regulating the ecological balance of littoral communities and are widely collected for human consumption and as fishing bait. Limpets of the species Patella caerulea were collected between April 2016 and April 2017 from two sites, and two samplings per each site with varying degree of exposure to wave action and anthropogenic pressure, in Eastern Mediterranean (Pagasitikos Gulf, Central Greece). This study addresses a knowledge gap on population characteristics of P. caerulea populations in Eastern Mediterranean, assesses population structure, allometric relationships, and reproductive status. Morphometric characteristics exhibited spatio-temporal variation. Population density was significantly higher at the exposed site. Spatial relationship between members of the population exhibited clumped pattern of dispersion during spring. Broadcast spawning of the population occurred during summer. Seven dominant age groups were identified, with the dominant cohort in the third-year class. Significant negative allometric relationships were exhibited between morphometric characteristics. Differences in growth patterns among populations were indicated.

Large trees play several vital roles in the Angkor monuments landscape. They protect biodiversity, enhance the tourism experience, and provide various ecosystem services to local residents. A clear understanding of forest composition and distribution of individual species, as well as timely monitoring of changes, is necessary for conservation of these trees. using traditional field work, obtaining this sort of data is time-consuming and labour-intensive. This research investigates classification of very high resolution remote sensing data as a tool for efficient analyses. QuickBird satellite imagery was used to clarify the tree species community in and around Preah Khan temple, to elucidate differences in ecological traits among the three dominant species (Dipterocarpus alatus, Lagerstroemia calyculata and Tetrameles nudiflora), and to identify crowns of the dominant species.

Fine roots are of major importance for belowground processes in mangrove ecosystems. Little is known about individual mangrove root systems, particularly the fine root component. We measured fine root biomass distribution of solitary standing Rhizophora mangle L. individuals with the dual aim of (a) deepening our understanding of the belowground ecology and allometric relations of this species; and (b) gaining further information about its climatic relevance. Twelve trees of variable height (45-240 cm) were measured on three reforested sites in south-east Florida, USA. Soil cores were collected from individual trees at transects by means of auger sampling. Fine roots were extracted, sorted, dried and weighed. Mean fine root biomass varied between 20.56-253.12 g/m2. Two separate mixed-effects models led to statistically sound predictions of spatial fine root biomass distribution. The first model was based on distance function and tree height (Model 1, R2=0.77, p value ≤ 0.001), and the second on prop root density (Model 2, R2=0.56, p value ≤ 0.001). Besides the aforementioned fixed effects, the results of both models indicated random, site-specific variation with regards to fine root biomass distribution. Nevertheless, we were able to explain individual fine root biomass distribution with reference to aboveground characteristics alone. These findings may help to improve the modelling of belowground plant interaction and carbon storage in mangroves, both of which are intrinsically linked to fine roots. [ABSTRACT FROM AUTHOR]

The coffee tree is an important economic plant for several developing countries. Stem and leaf dry biomass, which are key traits of plant production, are used in functional-structural plant models to simulate plant growth and predict yield. These values are difficult to obtain since they classically rely on time-consuming protocols and require destructive measurements. Measuring stem and leaf dimensions (length and width) to estimate them provides a non-destructive and rapid approach for use in the field. In this study we sought the best allometric relationships existing between stem and leaf dimensions and their corresponding dry mass in order to avoid destructive measurements which are also time-consuming. This was investigated in three coffee species: Coffea canephora, Coffea liberica var. liberica and Coffea liberica var. dewevrei in Ivory Coast. For each species, the internodes and leaves of three axis categories (stem, branch and branchlet) comprising the main compartments were sampled. Two different equations were found to estimate the stem and leaf dry mass whatever the species and the axis categories: (1) a linear equation for the relation between the stem volume (V) and its corresponding dry mass (IWe), IWe = 0.70 × V and (2) a power law for the relation between the leaf area [as the product of length (LL) and width (Wi)] and its dry mass (LWe), LWe = 0.007 (LL × LWi)1.02. Finally, stem and leaf dry mass could be easily obtained without destructive measurements. This method could be applied to estimate the plant total leaf area and the total stem and leaf biomass of a plant in an agroforestry system. [ABSTRACT FROM AUTHOR]

We proposed two hypotheses to explain why food chains are longer in pelagic than terrestrial ecosystems: greater trophic efficiency of pelagic animal taxa at lower trophic levels and a higher pelagic biomass production rate at lower trophic levels because of smaller pelagic body masses. Giacomini favored the former, invoking in support the energetic equivalence hypothesis. We reply that the energetic equivalence hypothesis does not describe populations at differing trophic levels and so does not refute a significant role for body-mass dependence in explaining faster trophic transfer in pelagic ecosystems. Metabolic scaling as body mass to the exponent 1/4, widely accepted, remains important for trophic dynamic models. We suggest a likelihood method to compare the two hypotheses on the basis of models of whole-ecosystem energetics. [ABSTRACT FROM AUTHOR]

Estimation of vegetation water content (VWC) by optical remote sensing improves soil moisture retrievals from passive microwave radiometry. For a variety of vegetation types, the largest unknown for predicting VWC is stem water content, which is assumed to be allometrically related to the water content of the plant canopy. For maize and soybean, measured stem water contents were highly correlated to canopy water contents, so VWC was calculated directly from the normalized difference infrared index (NDII), which contrasts scattering at near-infrared wavelengths with absorption of shortwave infrared wavelengths by liquid water. Woodland tree height is linearly related to woody stem volume, and hence to stem water content. We hypothesized that tree height is positively correlated with canopy water content, and thus with NDII. Airborne color-infrared imagery was acquired at two study areas in a mixed agricultural and woodland landscape, and photogrammetric structure-from-motion point clouds were derived to estimate tree heights. However, estimated tree heights were only weakly correlated with measured data acquired for validation. NDII was calculated from Landsat 8 Operational Line Imager (30-m pixel) and WorldView-3 (7.5 m pixel); but contrary to the hypothesis, NDII was not correlated with woodland tree height. Lastly, the interaction of woodland and crops stem water contents on total VWC in a mixed landscape were simulated for 2 days, one in the early summer and one in the late summer. VWC for the region varied from 2.5 to 3.0 kg m-2, which was just under a threshold for accuracy for soil moisture retrievals using Coriolis WindSat. Woodland tree height should be included as an ancillary data set along with land cover classification for soil moisture retrieval algorithms. [ABSTRACT FROM AUTHOR]

خشکی یکی از مهمترین تنش های محیطی است که تولید محصولات زراعی در ایران را تحت تاثیر قرار می دهد. سیب زمینی اغلب به عنوان محصولی حساس به خشکی در نظر گرفته شده که مواجهه با تنش آب حتی در دوره های کوتاه مدت از جوانه زنی تا رشد غده، می تواند باعث کاهش معنی­دار عملکرد آن گردد. به منظور بررسی اثر تنش آب در مرحله رشد رویشی بر خصوصیات ریشه و روابط آلومتریک میان آن­ها و اندام­های هوایی در ارقام دیررس و زودرس سیب زمینی، این مطالعه با استفاده از طرح کرت­های خرد شده در قالب بلوک­های کامل تصادفی در سال 1390 در گلخانه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد اجرا شد. تیمارهای آزمایشی شامل آبیاری با دو سطح تنش خشکی و عدم تنش به عنوان عامل اصلی و 20 رقم سیب زمینی در دو گروه دیررس و زودرس به عنوان عامل فرعی بودند. در تیمار تنش، آبیاری بر اساس 60 درصد آب مورد نیاز جهت رسیدن به ظرفیت زراعی انجام شد. درتیمار عدم تنش آبیاری کامل گلدان­ها به اندازه نیاز آبی بر مبنای میزان تخلیه از ظرفیت زراعی انجام شد. صفات مورد بررسی شامل عمق ریشه، وزن خشک ریشه، مجموع طول ریشه­ها، سطح ریشه، قطر ریشه، نسبت وزن ریشه به اندام­های هوایی، نسبت وزن ریشه به وزن برگ و نسبت سطح ریشه به سطح برگ بودند. نتایج نشان داد که تمامی صفات مورد بررسی تحت تاثیر تیمار تنش آب قرار گرفتند. همچنین پاسخ ارقام مختلف در گروه­های رسیدگی دیررس و زودرس به صفات فوق متفاوت بود. تنش آب سبب افزایش انتقال مواد فتوسنتزی به ریشه ها شد که خود باعث افزایش صفات ریشه نظیر وزن خشک ریشه، عمق ریشه، سطح و مجموع طول ریشه گردید.

We aimed to answer the following questions related to the architecture of individuals 0.5-3.0 m in height belonging to understory or canopy/emergent layer tree species: "Is there a difference between individuals belonging to different strata developing in environments with the same light intensity, in terms of their architecture?"; and "Given the same light intensity, do understory species exhibit less crown plasticity than do canopy/emergent layer species?" Thirteen architectural variables were evaluated in 80 individuals per species. We found that understory species showed greater increases in stem thickness and leaf number, as well as wider, deeper crowns, longer branches, greater self-shading and less crown plasticity. Stems and crowns were more slender in the canopy species than in the understory species. These differences might be due to the trade-off between vertical and lateral growth. Our results indicate that, regardless of the group to which they belong, species are best able to take advantage of light conditions in the understory of the forest. However, because they demand more light, canopy species showed a growth form that resulted in an architecture that is likely to enable better light capture in the understory.

Allometric relationships (defined as correlation coefficients between plant mass - stem diameter, plant mass - stem height and stem diameter - stem height) in plants of Tagetes patula L. (Brassicaceae) var. "Tangerine" were analyzed. Competing and non-competing plants were compared in a glasshouse experiment. Competing plants were grown in broad range of densities, from 200 to 6000 individuals • m-2. For non-competing plants no allometric relationships were observed, while for competing plants they were strong, irrespective of density treatment used. Gradual changes of plant morphology (plant mass, stem diameter, stem height and height/mass ratio) with the increase of competition intensity were also analyzed.The present study clearly showed, that the intraspecific competition influenced allometric relationships between height, mass and stem diameter of Tagetes patula.