Search Results (113)

Pinus yunnanensis, a native tree species in southwest China, is shading-tolerant and ecologically significant. Light has a critical impact on plant physiology, and decapitation improves canopy light penetration and utilization efficiency. The study of allometric relationships is well-known in forestry, forest ecology, and related fields. Under control (full daylight exposure, 0% shading), L1 (partial shading, 25% shading), L2 (medium shading, 50% shading), and L3 (serious shading, 75% shading) levels, this study used the decapitation method. The results confirmed the effectiveness of decapitation in annual P. yunnanensis and showed that the main stem maintained isometric growth in all shading treatments, accounting for 26.8% of the individual plant biomass, and exhibited dominance in biomass allocation and high shading sensitivity. These results also showed that lateral roots exhibited a substantial biomass proportion of 12.8% and maintained more than 0.5 of higher plasticity indices across most treatments. Moreover, the lateral root exhibited both the lowest slope in 0.5817 and the highest significance (p = 0.023), transitioning from isometric to allometric growth under L1 shading treatment. Importantly, there was a positive correlation between the biomass allocation of an individual plant and that of all components of annual P. yunnanensis. In addition, the synchronized allocation between main roots and lateral branches, as well as between main stems and lateral roots, suggested functional integration between corresponding belowground and aboveground structures to maintain balanced resource acquisition and architectural stability. At the same time, it has been proved that the growth of lateral roots can be accelerated through decapitation. Important scientific implications for annual P. yunnanensis management were derived from these shading experiments on allometric growth. Full article

Forests are a key terrestrial carbon sink, storing carbon in biomass, the forest floor, and the mineral soil (SOC). Since Pinus radiata D. Don is the most widely planted forest species in Chile, it is important to understand how environmental and soil factors influence these carbon pools. Our objective was to evaluate the effects of climate and site variables on carbon stocks in adult radiata pine plantations across contrasting water and nutrient conditions. Three 1000 m² plots were installed at 20 sites with sandy, granitic, recent ash, and metamorphic soils, which were selected along a productivity gradient. Biomass carbon stocks were estimated using allometric equations, and carbon stocks in the forest floor and mineral soil (up to 1 m deep) were assessed. SOC varied significantly, from 139.9 Mg ha⁻¹ in sandy soils to 382.4 Mg ha⁻¹ in metamorphic soils. Total carbon stocks (TCS) per site ranged from 331.0 Mg ha⁻¹ in sandy soils to 552.9 Mg ha⁻¹ in metamorphic soils. Across all soil types, the forest floor held the lowest carbon stock. Correlation analyses and linear models revealed that variables related to soil water availability, nitrogen content, precipitation, and stand productivity positively increased SOC and TCS stocks. In contrast, temperature, evapotranspiration, and sand content had a negative effect. The developed models will allow more accurate estimation estimates of C stocks at SOC and in the total stand. Full article

The biology literature addresses two puzzles: (i) the increase in specific metabolic rate of organs (SOrMR, W/kg of organ) with a decrease in body mass (M_B) of biological species (BS), and (ii) how the organs recognize they are in a smaller or larger body and adjust metabolic rates of the body (${\dot{q}}_B$) accordingly. These puzzles were answered in the author’s earlier work by linking the field of oxygen-deficient combustion (ODC) of fuel particle clouds (FC) in engineering to the field of oxygen-deficient metabolism (ODM) of cell clouds (CC) in biology. The current work extends the ODM hypothesis to predict the whole-body metabolic rates of 114 BS and demonstrates Kleiber’s power law {${\dot{q}}_B = a {M_B}^b$}. The methodology is based on the postulate of Lindstedt and Schaeffer that “150 ton blue whale. and the 2 g Etruscan shrew.. share the same.. biochemical pathways” and involve the following steps: (i) extension of the effectiveness factor relation, expressed in terms of the dimensionless group number G (=Thiele Modulus²), from engineering to the organs of BS, (ii) modification of G as G_OD for the biology literature as a measure of oxygen deficiency (OD), (iii) collection of data on organ and body masses of 116 species and prediction of SOrMR_k of organ k of 114 BS (from 0.0076 kg Shrew to 6650 kg elephant) using only the SOrMR_k and organ masses of two reference species (Shrew, 0.0076 kg: RS-1; Rat Wistar, 0.390 kg: RS-2), (iv) estimation of ${\dot{q}}_B$ for 114 species versus M_B and demonstration of Kleiber’s law with a = 2.962, b = 0.747, and (v) extension of ODM to predict the allometric law for maximal metabolic rate (under exercise, {${\dot{q}}_{B,MMR} = a_{MMR} {M_B}^{b_{MMR}}$}) and validate the approach for MMR by comparing b_MMR with the literature data. A method of detecting hypoxic condition of an organ as a precursor to cancer is suggested for use by medical personnel Full article

The complexity of forest ecosystems leads to differences in the distribution patterns of different vegetation types along elevation gradients. This study aimed to explore the characteristics of AGB variations along elevation gradients for different forest types and tree species components in the Qinling–Daba Mountains. Based on 329 field vegetation survey plots, including four sampling transects and four representative mountains, individual tree AGB was calculated using allometric biomass equations. Further, generalized additive models (GAMs) were used to investigate the relationships between AGB and elevation for four forest types (broadleaf forests, coniferous forests, mixed coniferousbroadleaf forests, and shrublands) and three AGB components (total AGB (tAGB), broadleaf species AGB (bAGB), and coniferous species AGB (cAGB)) across eight vegetation survey regions. The results showed that the AGB of different forest types is significantly related to elevation (p < 0.05), with broadleaf forest AGB showing a unimodal pattern with elevation, coniferous forest and mixed forest AGB increasing with elevation, and shrubland AGB exhibiting a noticeable rise at higher elevations. The AGB components across different vegetation survey regions also showed significant relationships with elevation (p < 0.05), with broadleaf species AGB displaying a monotonically increasing trend in regions with a small elevation range and exhibiting a unimodal or bimodal distribution in regions with a large elevation range, while coniferous species AGB generally increased with elevation. Although elevation significantly influenced forest AGB, the variation in R² values indicated that elevation is not the sole determinant of AGB variation. This study improves the understanding of spatial patterns of forest biomass along elevation gradients. Full article

Young forest stands from natural regeneration are characterized by high competitive pressure and dynamic changes over time, especially in the initial growth stages. Despite their increasing area in the temperate zone, they have received significantly less scientific attention than old forest stands. Therefore, our research was conducted on young, over-dense European beech (Fagus sylvatica L.) forest originating from natural regeneration, grown in central Slovakia, Western Carpathians. Repeated measurements of tree height and stem diameter measured on the base within a beech stand revealed significant temporal changes in their relationship. Over 16 years, height increased more than stem diameter. Both Lorey’s height and mean diameter d₀ showed continuous growth, with Lorey’s height increasing 3.5-fold and mean diameter increasing 2.8-fold. The height-to-diameter ratio increased until stand age 15, then briefly declined before rising again. Stand density decreased over time, with the sharpest decline occurring between ages 15 and 16 (dropping from 843 to 599 trees per 100 m²). Mortality rates peaked at age 16, with an average annual rate of 9.4% over the entire observation period (2008–2023). Specific leaf area (SLA) was negatively related to tree size, and its value was smaller in 10- than in 20-year-old stands. The increase in SLA was driven by greater leaf area relative to leaf weight. Additionally, allometric relationships showed that branch and leaf contributions to aboveground biomass decreased with tree size within the stand but were greater in the older stand than in the younger growth stage. Estimated aboveground biomass was 667 ± 175 kg per 100 m² in the 10-year-old stand and 1574 ± 382 kg per 100 m² in the 20-year-old stand, with stems contributing the majority of biomass. Leaf Area Index (LAI) remained similar across both stand ages, while the Leaf Area Ratio (LAR) was nearly twice as high in the younger stand. These findings highlight dynamic shifts in beech stand structure, biomass allocation, and leaf traits over time, reflecting growth patterns and competition effects. The outputs indicate that competition in young forest stands is a dominant force in tree mortality. Understanding key interactions in young stands is crucial for sustainable forest management, as these interactions influence long-term stand stability and ecosystem functions. Full article

In this study, we present a methodology for predicting timber board foot volume using a forest landscape model, incorporating allometric equations and forest inventory data. The research focuses on the Ozark Plateau, a 48,000-square-mile region characterized by productive soils and varied precipitation. To simulate timber volume, we used the LANDIS PRO forest landscape model, initialized with forest composition data derived from the USDA Forest Service’s Forest Inventory and Analysis (FIA) plots. The model accounted for species-specific growth rates and was run from the year 2000 to 2100 at five-year intervals. Timber volume estimates were calculated using both quadratic mean diameter (QMD) and tree diameter in the Hahn and Hansen board foot volume equation. These estimates were compared across different forest types—deciduous, coniferous, and mixed stands—and verified against FIA plot data using a paired permutation test. Results showed high correlations between QMD and tree diameter methods, with a slightly lower volume estimate from the QMD approach. Projections indicate significant increases in board foot volume for key species groups such as red oak and white oak while showing declines toward the end of the model period in groups like shortleaf pine due to age-related mortality and regeneration challenges. The model’s estimates closely align with state-level FIA data, underscoring the effectiveness of the integrated approach. The study highlights the utility of integrating landscape models and forest inventory data to predict timber volume over time, offering valuable insights for forest management and policy planning. Full article

In order to examine the seasonal variations in the morphological characteristics and diet of Mactra veneriformis in the Northern Yellow River Delta’s intertidal zone and provide a scientific basis for its resource conservation and population restoration, tested clams were collected in four consecutive seasons from summer of 2022 to spring of 2023. Morphological traits were measured, and the DNA of the stomach contents was analyzed using high-throughput sequencing. The tidal differences and seasonal variations in the northern habitat of the Yellow River Estuary significantly affect the morphological characteristics and growth of M. veneriformis. Among the four seasons, significant differences in the morphological characteristics of M. veneriformis were observed between the middle-tide and low-tide zones (p < 0.05). In both middle-tide and low-tide zones, the morphological characteristics and body wet weight of M. veneriformis in winter were significantly higher than those in other seasons (p < 0.05). Moreover, the morphological characteristics of M. veneriformis were extremely significantly influenced by the interaction between tide and season (two-way interaction, p < 0.001). In all seasons, M. veneriformis in the middle- and low-tide zones exhibited positive allometric growth. While there was no significant difference in the stomach content between the spring and summer samples in the same tidal zone (p > 0.05), there was a significant difference between the middle- and low-tide samples in winter (p < 0.05). This suggests that seasonal variations, rather than tidal differences, had a larger impact on the diet of M. veneriformis in the northern Yellow River estuary and that feeding differences may be related to changes in environmental factors, such as temperature. The findings of this study provide initial insights into the feeding ecology of M. veneriformis and offer a scientific foundation for the conservation and management of its resources. Full article

Dendrocalamus brandisii (Munro) Kurz is a high-quality bamboo species for shoots, known for its sweet, tender, and crisp bamboo shoots, making it highly valuable for development. The biomass of bamboo forests is closely related to bamboo shoot yield, and studying biomass accumulation helps maintain the stability of artificial forest ecosystems. Biomass estimation facilitates the monitoring of stand dynamics and promotes the scientific management and sustainable development of D. brandisii plantations. This study collected biological data from 181 D. brandisii individuals in Changning County, Yunnan Province, to construct mathematical models for estimating single-plant biomass using the least squares method. The models were iteratively optimized using the quasi-Newton method. Based on performance indicators and residual analysis, six models were identified as suitable for estimating the biomass of D. brandisii, including multiple linear regression (MLR), linear, allometric growth, and cubic models. These models provide valuable references for biomass estimation and the management of D. brandisii plantations. Full article

Rhyssoplax olivacea is the most common Mediterranean polyplacophoran species; however, no information exists regarding the functionality of its skeleton. The present study describes allometric trends related to its valves and radula and examines their chemical composition using specimens from the Aegean Sea, eastern Mediterranean Sea. Differences in valve width and thickness were found among all three valves; in particular, the intermediate valve had a significantly shorter length compared to the two terminal ones. The intermediate valve exhibited different trends for valve length to valve width and valve length to valve thickness compared to the terminal valves. However, all valve morphometrics to body length appeared to adhere to a shared trend. The radula to body length exhibited positive allometry. Regarding the elemental composition, all three valves appeared to have similar elemental compositions; however, the element concentrations in the radula differed with the tooth type. Iron was always the dominant element, with the highest values reported for the major lateral tooth (83% wt%). This study provides valuable insights into the different aspects of the skeleton of R. olivacea, enabling future research to focus on the skeletal functionality from evolutionary and ecological perspectives. Full article

Otoliths are important structures for balance and hearing of fish and constitute a useful tool in fisheries science. This study provides, for the first time in the Mediterranean, information on the otolith morphometrics of Dentex maroccanus, collected from the South Aegean Sea, and enriches the existing information on its age and growth by sex. The otolith shape variables examined showed a more circular to square otolith shape, related to the body size. Significant differences between sexes were detected for the otolith Area, Diameter, Perimeter, and Radius. Exponential regressions were used to examine the relationship of the otolith variables with total body length, from which five showed a strong correlation (Diameter, Width, Radius, Area, and Perimeter). The eviscerated weight–length relationship exhibited an isometric growth for both sexes, whereas when total weight was applied, a positive allometric growth was found for females. Sagittal otolith readings revealed four age groups for females and five for males. A Bhattacharya method was used for age validation. Von Bertalanffy growth parameters were as follows: L∞ = 23.08, k = 0.27, t₀ = −1.93 for females and L∞ = 24.07, k = 0.24, t₀ = −2.26 for males. This research offers valuable biological information for Dentex maroccanus useful in fisheries science. Full article

The present study aimed to describe the skull and mandibles of the brown bear (U. arctos) from the Dancing Bear Belitsa Park using advanced 3D morpho-geometric techniques. The objective was to explore how sexual dimorphism and size influence cranial structures using advanced 3D geometric morphometric methods. Three-dimensional models of the skulls and mandibles of 12 brown bears were used. Differences in skull morphology between male and female brown bears were observed in this study. The male brown bear skull, larger than the female, exhibited a more pronounced extension of the upper part of the nuchal region towards the posterior. Additionally, the posterior part of the frontal region appeared notably thinner in male brown bears compared to females. Analysis of the mandible revealed that the masseteric fossa was more developed in males than females. These shape differences between males and females were found to be influenced by body size. Statistical analyses indicated a significant allometric effect of body size on skull PC1 values, suggesting that giant bears tend to have more elongated skulls. This implies a relationship in which larger individuals exhibit greater cranial elongation. In contrast, mandible PC1 values showed no size-related variation, indicating that mandibular shape is less influenced by overall body size. However, PC2 values in the mandible increased significantly with larger specimens, indicating a larger masseteric fossa in larger bears. This morphological adaptation potentially enhances feeding efficiency and bite strength in larger individuals, reflecting functional adaptations in brown-bear mandibular morphology. These findings contribute to our understanding of sexual dimorphism and size-related morphological adaptations in brown bears, providing insights into their adaptation biology and ecological roles within their habitats. Full article

Carbon stocks provide information that is essential for analyzing the role of forests in global climate mitigation, yet they are highly vulnerable to wildfires in Mediterranean ecosystems. These carbon stocks’ exposure to fire is usually estimated from specific allometric equations relating tree height and diameter to the overall amount of aboveground carbon storage. Assessments of vulnerability to fire additionally allow for specific fire resistance (bark thickness, crown basal height) and post-fire recovery traits (cone mass for regeneration, and fine branches or leaves mass for flammability) to be accounted for. These traits are usually considered as static, and their temporal dynamic is rarely assessed, thus preventing a full assessment of carbon stocks’ vulnerability and subsequent cascading effects. This study aimed to measure the pools of carbon stocks of individual trees varying between 30 and 96 years old in the Djbel Mansour Aleppo pine (Pinus halepensis) forest in semi-arid central Tunisia in the southern range of its distribution to fit a sigmoid equation of the carbon pools and traits recovery according to age as a vulnerability framework. Allometric equations were then developed to establish the relationships between fire vulnerability traits and dendrometric independent variables (diameter at breast height, height, and live crown length) for further use in regional vulnerability assessments. The total carbon stocks in trees varied from 29.05 Mg C ha⁻¹ to 92.47 Mg C ha⁻¹. The soil organic carbon stock (SOC) at a maximum soil depth of 0–40 cm varied from 31.67 Mg C ha⁻¹ to 115.67 Mg C ha⁻¹ at a soil depth of 0–70 cm. We could identify an increasing resistance related to increasing bark thickness and basal crown height with age, and enhanced regeneration capacity after 25 years of age with increasing cone biomass, converging toward increasing vulnerability and potential cascading effects under shorter interval fires. These results should be considered for rigorous forest carbon sequestration assessment under increasing fire hazards due to climate and social changes in the region. Full article

Allometry reflects the quantitative relationship between the allocation of resources among different organs. Understanding patterns of forest biomass allocation is critical to comprehending global climate change and the response of terrestrial vegetation to climate change. By collecting and reorganizing the existing allometric models of tree species in China, we established a database containing over 3000 empirical allometric models. Based on this database, we analyzed the model parameters and the effect of climate on forest biomass allocation under the context of ‘optimal allocation theory’. We showed that (1) the average and median exponent of power functions for above-ground biomass were 2.344 and 2.385, respectively, which significantly deviated from the theoretical prediction of 2.667 by metabolic theory (p < 0.01). (2) The parameters of the allometric model were not constant, and not significantly correlated with temperature, precipitation, latitude, and elevation (p > 0.05), but were more closely related to individual size (p < 0.01). (3) Among different types of forests, the proportion of above-ground biomass in tropical rainforests and subtropical evergreen rainforests was significantly higher than that in temperate forests and boreal forests (p < 0.05). The proportion of trunk and branch biomass allocated to tropical rainforest was significantly higher than that of boreal forest (p < 0.05), while the proportion of root and leaf biomass allocated to tropical rainforest was significantly lower than that of boreal forest (p < 0.05). (4) The abiotic environment plays a crucial role in determining the allocation of plant biomass. The ratio of below-ground/above-ground biomass is significantly and negatively correlated with both temperature and rainfall (p < 0.01), and significantly and positively correlated with altitude and latitude (p < 0.01). This means that as temperature and rainfall increase, there is a decrease in the amount of biomass allocated to below-ground structures such as roots. On the other hand, as altitude and latitude increase, there is an increase in below-ground biomass allocation. These findings highlight the importance of considering the influence of abiotic factors on plant growth and development. Full article

Knowledge of tree biomass allocation is fundamental for estimating forest acclimation and carbon stock for global changes in the future. Optimal partitioning theory (OPT) and allometric partitioning theory (APT) are two major patterns of biomass allocation, and occurrences have been tested on taxonomical, ontogenetic, geographic and environmental scales, showing conflicting results and unclear ecophysiological mechanisms. Here, we examine the biomass allocation patterns of two young poplar (Populus) clones varying greatly in drought resistance under different soil water and nitrogen availabilities and the major physiological processes involved in biomass partitioning. We found that Biyu, a drought-sensitive hybrid poplar clone, had significant relations among biomass of leaf, stem and root, showing allometric partitioning. Xiaoye, a drought-tolerant poplar clone native to semi-arid areas, on the contrary, showed tightly regulated biomass allocation following optimal partitioning theory. Biyu had higher nitrate reductase activity in the fine roots, while Xiaoye had higher nitrate reductase activity in the leaves. Biochemical analyses and measurements of fluorescence and gas exchange showed that Xiaoye maintained more stable chloroplast membranes and photosystem electron flow, showing higher water use efficiency and a higher resistance to drought. A nitrogen addition could improve leaf photosynthesis and growth both in Biyu and Xiaoye seedlings under drought conditions. We concluded that the two poplar clones showed different biomass allocation patterns and suggest that the site of nitrate assimilation may play a role in biomass partitioning under varying water and nitrogen availabilities. Full article

Understanding the demographic structure is vital for wildlife research and conservation. For crocodylians, accurately estimating total length and demographic class usually necessitates close observation or capture, often of partially immersed individuals, leading to potential imprecision and risk. Drone technology offers a bias-free, safer alternative for classification. We evaluated the effectiveness of drone photos combined with head length allometric relationships to estimate total length, and propose a standardized method for drone-based crocodylian demographic classification. We evaluated error sources related to drone flight parameters using standardized targets. An allometric framework correlating head to total length for 17 crocodylian species was developed, incorporating confidence intervals to account for imprecision sources (e.g., allometric accuracy, head inclination, observer bias, terrain variability). This method was applied to wild crocodylians through drone photography. Target measurements from drone imagery, across various resolutions and sizes, were consistent with their actual dimensions. Terrain effects were less impactful than Ground-Sample Distance (GSD) errors from photogrammetric software. The allometric framework predicted lengths within ≃11–18% accuracy across species, with natural allometric variation among individuals explaining much of this range. Compared to traditional methods that can be subjective and risky, our drone-based approach is objective, efficient, fast, cheap, non-invasive, and safe. Nonetheless, further refinements are needed to extend survey times and better include smaller size classes. Full article