Standardized Major Axis Research Articles

Canopy Position Influences the Degree of Light Suppression of Leaf Respiration in Abundant Tree Genera in the Amazon Forest

Leaf respiration in the dark (Rdark) and light (Rday) is poorly characterized in diverse tropical ecosystems, and little to no information exists on the degree of light suppression in common tree species within the Amazon basin, and their dependences upon plant functional traits and position within the canopy. We quantified Rdark and apparent Rday using the Kok method and measured key leaf traits in 26 tree individuals of different species distributed in three different canopy positions: canopy, lower canopy, and understory. To explore the relationships between the leaf traits we used the standardized major axis (SMA). We found that canopy trees had significantly higher rates of Rdark and Rday than trees in the understory. The difference between Rdark and Rday (the light suppression of respiration) was greatest in the understory (68 ± 9%, 95% CI) and lower canopy (49 ± 9%, 95% CI) when compared to the canopy (37 ± 10%, 95% CI). We also found that Rday was significantly and strongly correlated with Rdark (p < 0.001) for all the canopy positions. Also, leaf mass per area (LMA) and leaf Phosphorus concentration (P) had a significant relationship with Rdark (p < 0.001; p = 0.003), respectively. In addition, a significant relationship was found for LMA in the canopy and lower canopy positions (p = 0.009; p = 0.048) while P was only significant in the canopy (p = 0.044). Finally, no significant relationship was found between Rdark and nitrogen, sugars, and starch. Our results highlight the importance of including representation of the light suppression of leaf respiration in terrestrial biosphere models and also of accounting for vertical gradients within forest canopies and connections with functional traits.

Roots of Apium graveolens and Petroselinum crispum—Insight into Phenolic Status against Toxicity Level of Trace Elements

Celery (Appium graveolens L.) and parsley (Petroselinum crispum (Mill.) Fuss) are herbs utilized in the everyday diet as spices and culinary flavorings, often used in the chemical and medicinal industries. Despite the knowing benefits of different plants from the Apiaceae family, their chemical composition is closely associated with various extrinsic factors. Environmental loading with trace elements (TEs) can modify a plant’s metabolic pathways, change bioactive compounds production, cause plant pollution, and consequently provoke human health issues. Therefore, we established this research aiming to unravel the linkage between TEs accumulation and phenolic status in celery and parsley. Higher As, Cd, and Ni levels were observed in celery, which was followed by greater DPPH∙ radical scavenging activity and higher coumarins content. Contrary, parsley accumulated chromium to a greater extent, was richer in flavonoids, apigenin, and its glucosides. No significant difference between species was found in total phenolic contents, where ferulic and chlorogenic acid dominated in both species. A direct relationship between TEs and selected secondary metabolites was proven by the standardized major axis model. Besides abundant bioactive compounds, analyzed plant species showed a moderate hazard index in the children population, since the hazard index was higher than 1. Therefore, future perspectives should be turned towards the production of genotypes with a lower potential for toxic elements accumulation, so the health benefits of plant food will be more prominent.

Twig biomass allocation of Betula platyphylla in different habitats in Wudalianchi Volcano, northeast China.

Understanding the response of biomass allocation in current-year twigs is crucial for elucidating the plant life-history strategies under heterogeneous volcanic habitats. We aimed to test whether twig biomass allocation, within-leaf biomass allocation, and the size-number trade-off of Betula platyphylla would be influenced. We measured twig traits of B. platyphylla in Wudalianchi volcanic kipuka, the lava platform, and Shankou lake in northeastern China using standardized major axis analyses. The results showed that the leaf number, total lamina mass (TLAM), stem mass (SM), and twig mass (TM) were significantly different between the three habitats and were greatest in kipuka with abundant soil nutrients. TLAM and SM scaled allometrically with respect to TM, while the normalization constants of the lava platform differ significantly between kipuka and Shankou lake, which showed that under certain TM, leaves gain more biomass in the lava platform. However, within the leaf, individual lamina mass (ILM) scaled isometrically with respect to individual petiole mass (IPM) in kipuka and the lava platform, but ILM scaled allometrically to IPM in Shankou lake. Our results indicated that inhabitats influenced the twig traits and biomass allocation and within-leaf biomass allocation are strategies for plants to adapt to volcanic heterogeneous habitats.

Differing Trade-Off Patterns of Tree Vegetative Organs in a Tropical Cloud Forest.

Functional trait ecology demonstrates the significance of the leaf economics spectrum in understanding plants’ trade-off between acquisitive and conservative resource utilization. However, whether trait variations of different vegetative organs are coordinated and whether the plant economics spectrum is characterized by more than one vegetative organ remain controversial. To gain insights into these questions, within a tropical cloud forest in Hainan Island, a total of 13 functional traits of 84 tree species were analyzed here, including leaf, stem and root traits. By using standardized major axis (SMA) regression and principal components analysis, we examined the trait variations and correlations for deciphering plants’ trade-off pattern. We found decreases of leaf phosphorus content, leaf nitrogen content and specific leaf area and increases of leaf mass per unit area (LMA), wood density and leaf thickness along the first principal component, while there were decreases of specific root length and specific root area and increases of root tissue density along the second principal component. Root phosphorus and nitrogen contents were significantly positively associated with the phosphorus and nitrogen contents of both stem and leaf. Wood density was significantly positively associated with LMA and leaf thickness, but negatively associated with leaf thickness and specific leaf area. Our results indicate that, in the tropical cloud forest, there is a “fast–slow” economic spectrum characterized by leaf and stem. Changes of nutrient trait are coordinated, whereas the relationships of morphological traits varied independently between plant above- and below-ground parts, while root nutrient traits are decoupled from root morphological traits. Our findings can provide an insight into the species coexistence and community assembly in high-altitude tropical forests.

Effects of succession stages and altitudinal gradient on leaf surface area and biomass allocation of typical plants in the subalpine of Eastern Tibetan Plateau

Leaves are the main organs of plants for photosynthesis. The scaling relationship between leaf mass (LM) and leaf area (LA) can reflect the capabilities of plants to capture light energy, obtain net carbon benefits, and adapt to environmental changes. The LA-LM relationship is intimately associated with the water and carbon economics of plants. The scaling relationship between LA and LM is important to reveal the strategies of plant biomass allocation with changes of environmental stresses. Previous studies primarily focused on relatively close plants within the same taxon (e.g., a family or a genus), different plants in different altitude gratient, or special groups such as epiphytes. However, it is still unknown about whether and how the scaling relationship between LM and LA varies across succession stages and altitudinal gratient. We measured LA, leaf fresh weight (LFW) and leaf dry weight (LDW) of 201 plant species with 603 individuals in nine plots in Zhouqu County of China to study the strategy of allometry relationships of LA and LM among different plant life forms, succession stages and altitudinal gratient. We found that the quotient of LDW and LFW for woody plants was significantly higher than that for herbaceous plants. In the process of adapting to changes of life forms, succession stages and altitudes, the scaling exponent of LFW vs. LA was more sensitive than that of LDW vs. LA. Most scaling relationships of LFW vs. LA conformed to the law of diminishing returns, but the scaling relationship between LDW and LA appeared more complicated. The scaling relationships between LDW and LFW mainly exhibited an increasing returns. Increasing returns were more obvious in life forms, middle altitude and mid-succession. In addition, no matter at which level, the coefficient of determination (i.e. R2) of LA vs. LFW was greater than that of LA vs. LDW. It might be more convincing to predict the relationship between LA and LM by using the data of LA vs. LFW. Most of (17 of 24, 70.83%) the R2 of PGLS (Phylogenetic Generalized Least Squares) regression were higher than those of SMA (Standardized Major Axis) regression, which showed that the influence of phylogeny should not be ignored in the study of multi-species traits relationships. In general, the trade off or allometry between LA and LM varied among plants life forms or environmental changes including succession stages and elevation variability. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains.

Effects of ontogenetic stage and leaf age on leaf functional traits and the relationships between traits in Pinus koraiensis

Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth. However, few studies have been conducted to show how traits and trait-trait relationships change across a range of ontogenetic stage and leaf age for evergreen coniferous species. We divided 67 Pinus koraiensis Sieb. et Zucc. of various sizes (0.3–100 cm diameter at breast height, DBH) into four ontogenetic stages, i.e., young trees, middle-aged trees, mature trees and over-mature trees, and measured the leaf mass per area (LMA), leaf dry matter content (LDMC), and mass-based leaf nitrogen content (N) and phosphorus content (P) of each leaf age group for each sampled tree. One-way analysis of variance (ANOVA) was used to describe the variation in leaf traits by ontogenetic stage and leaf age. The standardized major axis method was used to explore the effects of ontogenetic stage and leaf age on trait-trait relationships. We found that LMA and LDMC increased significantly and N and P decreased significantly with increases in the ontogenetic stage and leaf age. Most trait-trait relationships were consistent with the leaf economic spectrum (LES) at a global scale. Among them, leaf N content and LDMC showed a significant negative correlation, leaf N and P contents showed a significant positive correlation, and the absolute value of the slopes of the trait-trait relationships showed a gradually increasing trend with an increasing ontogenetic stage. LMA and LDMC showed a significant positive correlation, and the slopes of the trait-trait relationships showed a gradually decreasing trend with leaf age. Additionally, there were no significant relationships between leaf N content and LMA in most groups, which is contrary to the expectation of the LES. Overall, in the early ontogenetic stages and leaf ages, the leaf traits tend to be related to a "low investment-quick returns" resource strategy. In contrast, in the late ontogenetic stages and leaf ages, they tend to be related to a "high investment-slow returns" resource strategy. Our results reflect the optimal allocation of resources in Pinus koraiensis according to its functional needs during tree and leaf ontogeny.

Intraspecific allometries reveal hyper‐slender stems in forest gaps and the impact on tree growth from insect herbivores

AbstractConspicuously absent from plant allometric models are insect herbivores, despite their ubiquity in pantropical forests as well as the importance of gauging their impact on plant growth for understanding tree regeneration dynamics. Conceivably, the scaling relationships of plant populations with and without exposure to insects could be compared to gain insight, but this has yet to be tried. Here, I examined the size allometry of three canopy‐statured species (Fabaceae) by fitting standard major axis regressions of stem height, number of leaves, and maximum area per leaf against stem diameter (root collar) of their juveniles (seedlings/saplings) in 41 canopy gaps after ca. 2 years of herbivore exclusion (using mesh cages with mesh‐rooftop controls), in a central African forest. Herbivores did not change the slope or intercept, nor shift the location of Tetraberlinia bifoliolata and T. korupensis populations, whose seedlings tolerate shade well. In stark contrast, all three size allometries were altered in the faster‐growing Microberlinia bisulcata, whose seedlings cannot tolerate shade indefinitely. More pronounced than either an altered slope (scaling exponent) or intercept was the strong rightward shift in location (to larger sizes) of protected M. bisulcata, whereas its normal (control) population was left stunted, with fewer and smaller leaves. Nevertheless, all species had higher than theoretically predicted scaling exponents, even in the absence of herbivores, suggesting a convergent response early in tree ontogeny across the shade‐tolerance spectrum prioritizing height gain over mechanical stability in forest gaps. But insect herbivores were able to significantly strengthen this deviation in M. bisulcata, and perhaps in T. korupensis. These results demonstrate an allometric approach may prove useful for revealing how insects differentially impact trees' growth and form (slenderness) when they are most vulnerable to herbivory.

Trade-off relationship and internal mechanism of plant leaf size and number in Hulunbuir grassland, China.

The trade-off between leaf size and number is the basis for plant growth strategies. It is of great significance to study the underlying mechanism of leaf size and number trade-offs for well understanding plant growth strategies. In this study, leaf size was expressed by the dry mass of single leaf, while leafing intensity was expressed by the number of leaves per unit stem volume. We used standardized major axis regression analysis method to examine the trade-off relationship between leaf size and number in Hulunbuir grassland. There was a significant negative isometric-growth trade-off between leaf size and number in Chenqicuogang (typical steppe) and Chenqibayi (meadow steppe). There was a significant negative allometric-growth trade-off between leaf size and number in Xeltala (meadow steppe). The underlying mechanism of the relationship between leaf size and number depended on the leaf and stem biomass allocation mechanism and the changes of the stem tissue density.

金塔绿洲不同林龄多枝柽柳根系分叉数与分支角度的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 金塔绿洲不同林龄多枝柽柳根系分叉数与分支角度的关系 DOI: 10.5846/stxb201907261581 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41861009，41461013） Relationship between root forks and branch angle of Tamarix ramosissima at different stand ages in oasis of Jinta County Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根系构型影响根系空间分布和营养吸收效率，反映了植物适应环境胁迫的生存策略。采用标准化主轴估计（Standardized major axis estimation，SMA）的方法，分析了甘肃金塔北海子国家湿地公园3年生和6年生多枝柽柳（Tamarix ramosissima）根系分叉数与分支角度的异速生长关系。结果表明：随着林龄的增长，湿地群落盖度、高度逐渐增加，多枝柽柳种群的盖度、密度、高度和地上生物量以及根系深度、分叉数、比根长、比表面积、各级根系直径随之增加，根系分支角度和根冠比逐渐减小；多枝柽柳根系分叉数与分支角度回归方程的标准主轴斜率逐渐增大（P<0.05），随着林龄的增长，多枝柽柳根系分叉数的增加速度逐渐大于根系分支角度的生长速度，二者在林龄间呈现出差异化的异速生长关系。随着林龄的增长，多枝柽柳根系构型模式由"扩散型"转变为"紧缩型"，体现了种群应对生境胁迫和竞争的生态适应机制。 Abstract:The root architecture influences root spatial distribution and resorptiton efficiency of nutrients, which may reflect the plant growth strategies to adapt to the environmental stresses. This paper studied the relationship between root forks and branch angle of Tamarix ramosissim at three-year and six-year. The study site was located in Jinta Beihaizi Wetland Park of Gansu Province with the method of standardized major axis estimation (SMA). The height, density and above-ground biomass of the wetland communities were recorded from 5 m×5 m grids at two plots with six replicates. Seventy-two plants of Tamarix ramosissim were selected; the above-ground parts of those plants were cut while the roots were collected by excavating the whole root system, and both were taken back to the lab. In the laboratory, the roots were scanned with Win-RHIZO to measure the root forks and root length. The individual roots was dissected according to the branching order, starting from the distal end of the root system that was numbered as the first order and then increasing sequentially with each branch from the first order to the third order roots. The biomasses of different plots were put in an oven and dried (at 80℃ for 12 h), and then measured. Similarly, the soil moisture content was also measured by oven-drying (at 105 ℃for 24 h). The results showed that with the increasing stand ages, the density, cover, height of the plant community increased, while the root-shoot ratio, root branch angle decreased, the specific cover, density, height, above biomass, root depth, root forks, specific root length and specific root surface area increased, and diameter of different root orders increased. In addition, with the increasing stand ages, the standardized major axis slope of regression equation in the scaling relationships between root forks and branch angle increased (P<0.05). Additionally, the increase speed of the root forks was greater than the growth speed of the root branch angle, and the allometric relationship between root forks and branch angle of Tamarix ramosissima was distinguished at different stand ages. With the increasing stand ages, the root architecture model of Tamarix ramosissima form diffusion to gathering, reflected the mechanism of ecological adaptation under conditions of environmental stresses and competition of the population. 参考文献 相似文献 引证文献

Trade-off relationship between light interception and leaf water shedding at different canopy positions of 73 broad-leaved trees of Yangji Mountain in Jiangxi Province, China

<p indent=0mm>As light interception and leaf water shedding may require different leaf traits, trade-offs may exist between the leaves’ abilities in light interception and leaf water shedding. Moreover, such trade-offs may vary with the vertical canopy position as leaf traits vary with tree height. We studied the variations in leaf traits at different canopy positions to study how canopy positions would affect the trade-off between the traits related to light interception and leaf water shedding in subtropical broad-leaved trees. We used the standardized major axis regression method to analyze the relationships among leaf morphological traits (leaf thickness and leaf length/width ratio), configuration traits (leaf angle and leaf drip tip length), and physiological traits (photosynthesis-light saturation point and photosynthesis-light compensation point) between sun and shade leaves. The results are as follows: (i) There was no significant difference in the leaf thickness and leaf length/width ratio at different canopy positions (<italic>P</italic>>0.05). The leaf angle (34.92°±1.15°), light saturation point ((954.89±27.86) µmol/(m²·s)), and light compensation point ((29.45±1.02) µmol/(m²·s)) at the upper canopy were significantly higher than those at the lower canopy (leaf angle: 16.66°±0.50°, light saturation point: (520.74±15.47) µmol/(m²·s), and light compensation point: (12.54±0.38) µmol/(m²·s); <italic>P<</italic>0.05). However, the leaf drip tip length was significantly shorter at the upper canopy position ((4.26±0.15) mm) than at the lower canopy position ((7.18±0.22) mm; <italic>P</italic><0.05). (ii) There were significant correlations among leaf angle, leaf drip tip length, light saturation point, and light compensation point at different canopy positions (<italic>P</italic><0.05), but the leaf drip tip length and leaf length/width ratio were only weakly correlated at the upper canopy leaves (<italic>P</italic><0.05). (iii) Common slope (<italic>P</italic>>0.05) and isometric scaling existed among the leaf angle, light saturation point, and light compensation point at different canopy positions, but there was no common constant (<italic>P</italic><0.05). These results indicated that the canopy position does not alter the trade-off strategy between light interception and leaf water shedding. The leaf drip tip length and inclination were mainly affected by the light saturation point and light compensation point.

Multiple‐scale negative impacts of warming on ecosystem carbon use efficiency across the Tibetan Plateau grasslands

AbstractAimEcosystem carbon use efficiency (CUEe) is a core parameter of ecosystem process models, but its relationships with climate are still uncertain, especially for ecosystems with harsh environments. Large inconsistencies in climate impacts on the CUEe have been reported among various spatial scales. The goal of this study was to examine whether warming promotes or restricts the CUEe and whether the CUEe responds to a warming gradient in a linear or nonlinear manner.LocationTibetan Plateau.Time period2000–2018.Major taxa studiedAlpine grassland ecosystem.MethodsWe integrated multiple‐source data of carbon fluxes and CUEe, including warming experiments at a site scale, eddy covariance observations at a landscape scale and synthesized warming experiments and ecosystem process models at a regional scale. Next, we deployed a statistical model to examine the warming impacts on the CUEe across scales; the effects of biotic and abiotic factors on the CUEe and its components were summarized based on the results of standardized major axis tests and routines, structural equation modelling and nonlinear models.ResultsThis study reported a suppressive warming impact on the CUEe, which followed a nonlinear curve with severe inhibition in the high‐level warming treatment. With a warming threshold of 1.5–2.0°C, CUEe response patterns transitioned from no change to a significant decrease. The restriction effects can be ascribed to the joint adverse and asymmetric effects of warming on CUEe components under multiple‐level warming. Warming‐modified relationships among CUEe components and the nonlinear effects of biotic and abiotic factors led to the nonlinear responses of CUEe to warming.Main conclusionsThis study revealed suppressive and nonlinear effects of warming on the CUEe, including especially dramatic CUEe decreases with high‐level warming. These findings are critical for optimizing model parameters and improving predictions of the carbon sequestration capacity of alpine grasslands.

The relationships among structure variables of larch forests in China

BackgroundLarch (Larix Mill.) forests are widely distributed in the upper parts of mountainous areas in China, playing vital roles in constructing mountain landscapes and maintaining mountain environments. Despite their importance, our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear. In this paper, we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch forests.ResultsThe structure characteristics were significantly different among larch forest types. For different larch forest types, the power function fits the relationships between tree height and diameter at breast height (DBH), average DBH and stem density, and taper and stem density well, but with different exponents among larch forest types. The power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93 (mean = 0.86) by standard major axis regression (SMA), and from 0.51 to 0.78 (mean = 0.56) by ordinary least square regression (OLS). The 50%, 75% and 95% quantile regression (QR) and OLS indicated that the average DBH and taper of the L. gmelinii forests, L. gmelinii var. principis-rupprechtii forests, and L. sibirica forests were significantly correlated with stem density.ConclusionsThe relationship between tree height and DBH showed a power function relationship for all larch forest types in China, but with different exponents. Overall, stem density was negatively correlated with average DBH and taper. The Sect. Larix forests exhibited stand density effect. Our findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.

Application of leaf size and leafing intensity scaling across subtropical trees.

Understanding the scaling between leaf size and leafing intensity (leaf number per stem size) is crucial for comprehending theories about the leaf costs and benefits in the leaf size–twig size spectrum. However, the scaling scope of leaf size versus leafing intensity changes along the twig leaf size variation in different leaf habit species remains elusive. Here, we hypothesize that the numerical value of scaling exponent for leaf mass versus leafing intensity in twig is governed by the minimum leaf mass versus maximum leaf mass (M min versus M max) and constrained to be ≤−1.0. We tested this hypothesis by analyzing the twigs of 123 species datasets compiled in the subtropical mountain forest. The standardized major axis regression (SMA) analyses showed the M min scaled as the 1.19 power of M max and the ‐α (−1.19) were not statistically different from the exponents of M min versus leafing intensity in whole data. Across leaf habit groups, the M max scaled negatively and isometrically with respect to leafing intensity. The pooled data's scaling exponents ranged from −1.14 to −0.96 for M min and M max versus the leafing intensity based on stem volume (LIV). In the case of M min and M max versus the leafing intensity based on stem mass (LIM), the scaling exponents ranged from −1.24 to −1.04. Our hypothesis successfully predicts that the scaling relationship between leaf mass and leafing intensity is constrained to be ≤−1.0. More importantly, the lower limit to scaling of leaf mass and leafing intensity may be closely correlated with M min versus M max. Besides, constrained by the maximum leaf mass expansion, the broad scope range between leaf size and number may be insensitive to leaf habit groups in subtropical mountain forest.

Altitudinal pattern of shrub biomass allocation in Southwest China.

Shrubs play an important role in the global carbon cycle and are particularly sensitive to climate change. However, the altitudinal pattern of biomass allocation in mountainous shrubs and its responses to climate change are still unclear. In this study, biomass accumulation and allocation of the shrub community and their relationships with climatic factors were investigated in 331 sampling sites along an extensive altitudinal gradient (311–4911 m) in Southwest China. The results showed that the above-ground biomass (AGB) and the total biomass (TB) of the shrub community decreased quadratically (R2 = 0.107) and linearly (R2 = 0.024) from 9.86 to 0.15 kg·m-2 and 15.61 to 0.26 kg·m-2 with increasing altitude, respectively. However, the below-ground biomass (BGB) and TB of the herb layer increased quadratically with increasing altitudes (R2 = 0.136 and 0.122, respectively. P<0.001). The root/shoot ratio (R/S) of the community and its component synusiae increased gradually with increasing altitudes (P<0.001). The standardized major axis (SMA) indicated an isometric relationship between AGB and BGB for the whole shrub community, but allometric relationships were found for the shrub and herb layer. Redundancy analysis and Pearson correlation analysis showed that the biomass and R/S were significantly correlated with mean annual temperature (MAT), mean annual precipitation (MAP) and reconnaissance drought index (RDI). These findings indicate that shrub biomass allocation is strongly affected by the altitude, MAT and MAP and support the isometric relationship of AGB and BGB partitioning at the community level on mountainous shrub biomes.

Soil temperature drives elevational patterns of reproductive allometry in a biodiversity hotspot

Understanding the geographic patterns of reproductive allocation helps in clarifying the selective forces that shape the reproductive strategies of plants. However, studies on the elevational patterns of reproductive allocation remain limited. Moreover, although soil attributes have long been suspected to drive elevational patterns of reproductive allocation, few studies have explored this relationship. Delaying reproduction and allocating a high proportion of biomass to vegetative organs may be risky for plants living under high-elevation habitats, as these two processes can potentially lead to plant reproductive failure due to the low temperatures and short growing seasons at high elevations. Thus, we hypothesize that reproductive effort will increase with elevation and the elevational pattern of reproductive allocation will be largely driven by soil attributes, given their covariation with elevation. To test these hypotheses, we determined the vegetative and reproductive biomass of individual Impatiens arguta (Balsaminaceae) plants across 12 populations in the Gaoligong Mountains (China), and collected data on soil temperature, nutrients, moisture, and pH for each population. Based on standard major axis regression and linear regression models, we found that (1) both vegetative and reproductive biomass decreased with elevation; (2) all populations demonstrated significant allometric slopes (i.e., linear coefficients of log[reproductive biomass] − log[vegetative biomass] regressions) > 1; (3) allometric slopes decreased with elevation; and (4) soil temperature was a better predictor of the allometric slope than elevation, i.e., the allometric slope decreased with soil temperature. These results suggest that plant species growing at high elevation invest proportionately more resources to reproduction as an adaptation to low-temperature environments, and reproductive output is heavily dependent on vegetative growth. This study provides the first evidence of soil temperature driving reproductive allocation patterns, which suggests that plant species will favor allocation to growth under increasing soil temperatures with climate warming.

Frond size, shape and fertility of Thelypteris confluens (Thunb.) C. V. Morton in wetlands disturbed by human activities in Hokkaido, northern Japan

Thelypteris confluens (Thunb.) C. V. Morton exhibits dimorphism between sterile and fertile fronds when fully matured. To assess the frond fertility patterns in this species, the frond size and the shape and degree of fertile fronds were measured in individuals growing in disturbed wetlands in Hokkaido, northern Japan, between late summer and early autumn in 2017 and 2018. This species often establishes on human-disturbed wetlands in boreal regions. The measured parameters were frond fertility, number of veins (NV), dry weight (DW), frond length (FL), blade length (BL), blade width (BW), frond area and blade perimeter. The Dissection Index, aspect ratio and specific frond area were calculated. The data were analyzed by generalized linear models (GLMs) and standardized major axis tests to investigate the determinants of frond fertility and the differences between the sterile and fertile fronds. All the GLMs for predicting frond fertility contained NV, FL and BL, suggesting that NV had a specific role in fertility. Compared with the use of destructive measurements, the use of nondestructive measurements in the GLMs led to slightly lower prediction accuracies. The frond sizes and shapes in relation to fertility were not strongly related to the disturbance rank scores, while the populations in highly disturbed sites showed low numbers of fertile fronds. These findings strongly suggested that the shape- and size-related variables and NV affected frond fertility differently. NV provides more precise measurements of frond maturity and population dynamics for nondestructive long-term monitoring.

Frog somatic indices: Importance of considering allometric scaling, relation with body condition and seasonal variation in the frog Leptodactylus latrans

• Scaled somatic indices should be employed in Leptodactylus latrans. • Scaled liver index best correlated with body condition. • Scaled fat index and scaled gonad present opposite variations. • Carcass-related energy reserves are of importance for body condition. • No single somatic index can solely illustrate body condition. Snout-vent length (SVL) and liver, gonad, fat bodies and carcass weight data from 661 individual Leptodactylus latrans frogs collected over ten years in the Pampa Region of Argentina were analyzed to evaluate the best approach for expressing the corresponding somatic indices. The seasonal variation of these indices and their respective correlation with body condition was also examined. Results obtained demonstrated that the weight of all examined tissues and organs vary in an allometric manner in function of SVL, which implies that scaled somatic indices should be employed in this species. The study also highlights the fact that size-independent somatic indices are more easily obtained if the scaling exponent is defined through a non-linear regression of mass on length rather than by performing a standardized major axis regression of lnweight on lnlength. In the case of liver, fat and carcass, the non-linear regression curves were not statistically different amongst sexes and so a single relationship was described for both males and females L. latrans . Logically, the relationships between SVL and male and female gonad weight varied on distinct scale, and so it was necessary to analyze ovaries and testis separately. Scaling factors equal to 5.03, 3.11 and 2.75 were calculated to respectively estimate fat (SFI), liver (SLI) and carcass (SCI) scaled indices of L. latrans. In the case of the scaled gonadal index (SGI), scaling factors equal to 3.81 and 6.49 were used to calculate male and female indices. In both sexes, the seasonal variation in SFI and SGI was perfectly opposite, SGI being at its maximum in the spring when SFI was near zero, and reaching its lowest values in February-March when SFI increased. The amplitude of these changes was, nevertheless greater in females, representing a 4–5 times order of variation, in contrast to a 2–3 times order of change in males. In both sexes, SLI exhibited a 30% drop from October to December, although this loss was completely recovered in the second half of the summer (December to March). SLI was the somatic index that best correlated with the 14–18% natural variation in body condition that was observed over the spring-summer season. Nevertheless, carcass-related energy reserves were also of significant importance for frog metabolism as SCI varied very closely with body condition, explaining 75–80% of is variation. Results obtained illustrate the fact that no single somatic index can solely illustrate body condition because of the intricate relationship existing between SGI and SFI, and the importance of carcass-related energy reserves. In view of all the above, body condition comes out as the ideal monitoring endpoint for acquiring information on frog energy status.

Convergent nitrogen-phosphorus scaling relationships in different plant organs along an elevational gradient.

A general relationship between the nitrogen (N) and phosphorus (P) content of all plant organs (e.g. leaf, stem, and root) is hypothesized to exist according to whole-plant economics spectrum (PES) theory, but the evidence supporting these expected patterns remains scarce. We measured the N and P content of the leaves, twigs and fine roots of 64 species in three different forest communities along an elevational gradient (evergreen broad-leaved forest, 1319 m a.s.l., coniferous and broad-leaved mixed forest, 1697 m a.s.l., and deciduous forest, 1818 m a.s.l.) in the Wuyishan National Nature Reserve, southeastern China. The scaling relationship between the N and P content and the linear regression relationship between the N:P ratio and N and P content were analysed. The leaf N and P content was significantly higher at the high-elevation site than at the low- or middle-elevation sites (P < 0.001). The N and P content followed a power-law relationship with similar scaling slopes between organs. The N (common slope, 1.13) and P (common slope, 1.03) content isometrically covaried among leaves, twigs and roots. The scaling exponents of the N–P relationship were not significantly different from 1.0 in all organs, with a common slope of 1.08. The scaling constants of N–P decreased significantly (P < 0.05) from the highest value in fine roots (β = 1.25), followed by leaves (β = 1.17), to the lowest value in twigs (β = 0.88). Standardized major axis (SMA) analyses and comparisons of 95 % confidence intervals also showed that the numerical values of the scaling slopes and the scaling constants did not differ regardless of elevation. The N content, but not the P content, accounted for a large proportion of the variation in the N:P ratio in leaves (N:P and N: r2 = 0.31, F = 33.36, P < 0.001) and fine roots (N:P and N: r2 = 0.15, F = 10.65, P < 0.05). In contrast, the N:P ratio was significantly related to both the N and P content in the twigs (N:P and N: r2 = 0.20, F = 17.86, P < 0.001; N:P and P: r2 = 0.34, F = 35.03, P < 0.001, respectively). Our results indicate that different organs of subtropical woody plants share a similar isometric scaling relationship between their N and P content, providing partial support for the PES hypothesis. Moreover, the effects of the N and P content on the N:P ratio differ between metabolic organs (leaves and fine roots) and structural organs (twigs), elucidating the stoichiometric regulatory mechanism of different organs.

Frog body condition: Basic assumptions, comparison of methods and characterization of natural variability with field data from Leptodactylus latrans

Body weight and snout-vent length (SVL) data of 3006 individual Leptodactylus latrans frogs collected over ten years in the Pampa Region of Argentina were analyzed to evaluate the best approach for expressing body condition and to characterize the natural variability of this parameter. Two different methods for expressing body condition were compared: the scaled mass index (SMI) and the residuals methods. Body weight of L. latrans was related to SVL through an allometric relationship described by the power function: Y = 0.00006 X3.11. The shape of the weight-length relationship was not affected by neither the sex of the animal nor its date or site of capture. A truly size-independent SMI value was more easily obtained when defining the scaling exponent through a non-linear regression of mass on length rather than when performing a standardized major axis regression of lnweight on lnlength. Overall, it was proved optimal to use a single scaling factor equal to 3.11 to compute SMI of all L. Latrans from the Pampa Region, irrespective of their gender and month or site of capture. Altogether, obtained results showed that SMI is a more performant indicator of body condition than residuals because it is less variable and it allows a better detection of effects. SMI and residuals condition factors deviated from each other in the extremities of L. latrans size range because scaling is not considered when calculating residuals. Body condition of females, males and juveniles was significantly lower in December/January compared to October/November and February/March. Moreover, juveniles consistently exhibited a lower body condition compared to both males and females. Based on the natural inter- and intra-annual variability observed for L. latrans SMI values, it should be possible to detect a 10% difference in SMI in an intra-annual study by sampling 14 to 17 frogs per group, whereas a 15% difference in SMI could be detected in an inter-annual study by sampling 23–29 animals per site. These numbers show that alterations of body condition should be straightforwardly identifiable in field studies with L. latrans when using SMI. The determination of SMI body condition factor during amphibian monitoring programs could be of great value, as it would provide information on amphibian health together with population abundance numbers.

Functional adaptation rather than ecogeographical rules determine body-size metrics along a thermal cline with elevation in the Chinese pygmy dormouse (Typhlomys cinereus)

Phenotypic plasticity is crucial for how organisms respond to variation in their environment, affecting their diversity and distribution, especially in the light of rapid environmental change. Ecogeographical rules predict an association between specific adaptive morphological and physiological traits with cooler conditions due to higher latitude, elevation, or climate change. Such ecogeographical effects are often most evident in ancient species due to continuous selective adaptation occurring over long periods of time. Here, we use the suitably ancient Chinese pygmy dormouse (Typhlomys cinereus) to test whether body-size, appendage length and heart size vary in accordance with Bergmann's, Allen's and Hesse's rule, respectively. Based on a sample of 67 adult individuals (female, n=29; male n=38) trapped at 37 sites transcending an elevational range from 414 to 1757m, we tested for trait concordance with Bergmann's rule (body mass, length and SMI), Allen's rule (length of tail, foot, ear, snout), and Hesse's rule (wet and dry heart mass). Effects of elevation (and thus temperature lapse rate; calculated as 0.61°C per 100m) on body size, appendage length and heart size, were tested by fitting Standardized Major Axis (SMA) models. We observed substantial heterogeneity in morphometric traits allowing for the detection of ecogeographical clines. However, none conformed with Bergmann's, Allen's (except ear size), or Hesse's rule. However, our results indicate some support for Geist's rule of net primary productivity. We conclude that pervasive functional life-history adaptations in this blind, arboreal, echolocating ancient species exceeded selection for morphological energy efficiency constraints, with the notable exception of reduced ear pinnae size at colder, elevated sites. This is an important consideration for predicting how species, and populations in general, may adapt to human induced rapid environmental change, contrary to expectations of warming driving selection for smaller body-size.