Trade-off between height growth and stem diameter growth for an evergreen Oak, Quercus glauca, in a mixed hardwood forest

1. Patterns of stem growth of a mid-successional evergreen Oak species ( Quercus glauca ) in a mixed hardwood forest were examined to explore the trade-off relationship between stem-diameter growth and height growth.
2. The mean cross-sectional area (and the corresponding mean diameter) of a stem at a point in time was defined as the stem volume divided by tree height. Based on this definition, a simple equation representing the trade-off relationship between the height growth and mean diameter growth was formulated.
3. In the long term, allocation to height growth was encouraged at the seedling stage and it gradually declined with time, with the decline in the suppressed seedlings being more pronounced than in the dominant trees.
4. However, both the suppressed and the dominant trees showed acceleration of height growth at various ages. Such a fluctuation in the allocation of biomass to height growth is likely to have been caused by chronological changes in light conditions, and meandered the trajectory of allometry between the height and mean diameter.
5. The observed stem growth patterns of the individual trees could explain the chronological changes in the diameter–height relationship of the population.     

Changes of Leaf Morphological, Anatomical Structure and Carbon Isotope Ratio with the Height of the Wangtian Tree （Parashorea chinensis） in Xishuangbanna, China

Leaf morphological and anatomical structure and carbon isotope ratio （δ^13C） change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf mass （ratio of leaf mass to leaf area [LMA]）, thickness of the total leaf, cuticle, epidermis, palisade and sponge mesophyll, stomata traits and δ^13C at different heights of Parashorea chinensis with methods of light and scanning electron microscopy （SEM） and isotope-ratio mass spectrometry. The correlation and stepwise regression between tree height and leaf structure traits were carried out with SPSS software. The results showed that leaf structures and δ^13C differed significantly along the tree height gradient. The leaf area, thickness of sponge mesophyll and size of stomata decreased with increasing height, whereas the thickness of lamina, palisade mesophyll, epidermis, and cuticle, ratios of palisade to spongy thickness, density of stomata and vascular bundles, LMA and δ^13C increased with tree height. Tree height showed a significant relationship with all leaf indices and the most significant relationship was with epidermis thickness, leaf area, cuticle thickness, δ^13C. The δ^13C value showed a significantly positive relationship with LMA （R = 0.934）. Our results supported the hypothesis that the leaf structures exhibited more xeromorphic characteristics with the increasing gradient of tree height.     

Boom, bust, and the human body: Further evidence on the relationship between height and business cycles

Historical time series for average human height exhibit short- and medium-term cycles that can be associated with business cycles in the 19th and 20th century. Using spectral analysis, we calculate the proportion of cyclical fluctuations in height series attributable to economic cycles. We also analyze the extent to which these cyclical phenomena change over time. In the U.S., the association between height cycles and business cycles was weaker among richer segments of the society, and weaker among men than among women. Additionally, the relationship diminished over time, probably with the rich preceding the population at large.     

Allometry of axis length, diameter, and taper in the devil's walking stick (Aralia spinosa; Araliaceae)

The allometry of axis length, diameter, and taper is described for the trunk, rachis, and rachilla of nonbranching ramets of Aralia spinosa. Significant log-linear relationships were found between length and diameter for all axis categories, and in all cases, scaling was negatively allometric. Linear models best described the relationship between length and diameter for the rachis and rachilla, while a quadratic model best described this relationship for the trunk. During the trunk-building stage, the safety factors for trunk height were size dependent, with larger trunks exceeding their predicted critical buckling height. Taper was described by a linear relationship between diameter and position along the axis for all axis categories. All rachises and rachillas sampled exhibited taper along the length of the axis, however, only 51% of the trunks showed continuous taper. The trunk was less tapered than the rachis, but no differences in taper were found between the trunk and the rachilla, or the rachis and the rachilla. In unbranched ramets the large bipinnately compound leaves occupy the space normally occupied by lateral branches. We suggest that the rachis and rachilla are functionally equivalent to branches, that is, acting as axes of exploration and exploitation of the environment.     

Height, health, and income in the US, 1984–2005

Height has been associated with better physical health when outcomes such as diabetes, heart disease, and obesity are considered, yet stature is rarely used in predicting comorbidities or as a proxy for physical health when analyzing outcomes such as income. Since height is a more exogenous measure than variables likely to be affected by lifestyle changes, such as obesity, observing labor market outcomes based on height may be revealing. In addition, gender and racial differences must be taken into account when analyzing the effects of height on physical health and labor market outcomes. This study utilizes the 1984--2005 samples of the Behavioral Risk Factor Surveillance System in estimating trends in height over time by gender and race, and in analyzing the relationship between height and physical health and labor market outcomes in the United States. Trends show that height has not changed substantially at a time when physical health, as indicated by the incidence of obesity, Type II diabetes, and cholesterol, has deteriorated, and earnings disparities across racial gaps persist. Results at mean values for males indicate that being 10cm taller is associated with a 14-47% increase in obesity, an 8-13% reduction in cholesterol prevalence, and a $1874-2306 income premium. For females, results indicate that being 10cm taller is associated with an 8-18% reduction in cholesterol, a 14% reduction in diabetes for white females, and an $891-2243 earnings premium.     

广东省福寿螺形态性状变异及其与体质量的关系

【背景】福寿螺是危害极其严重的入侵我国的水生生物,目前利用相关分析、通径分析对福寿螺形态性状变异的研究较少。【方法】随机采集7个地区的福寿螺(雌雄比例差别很大),测量其壳高、壳宽、口宽、层高4个形态性状和体质量,采用相关分析、通径分析方法计算福寿螺的各形态指标变异系数、相关系数和通径系数,剔除对体质量影响不显著的指标,确定每个地区与体质量最相关的指标。【结果】除惠州之外,其余地区福寿螺的壳高和壳宽与体质量的相关性较高,且口宽与壳高共同作用对体质量的直接影响很大。【结论与意义】此结果为研究不同生境、不同温度下福寿螺的形态性状变异程度奠定了基础,同时为福寿螺形态鉴定、分类及其灾害预测预报提供了基础数据。     

Teenage births and final adult height of mothers in India, 1998-1999

This paper investigates the statistical association between teenage births and the physical growth path of these mothers. It draws on data on the height of ever-married women aged 15-49 and their birth histories collected in India's National Family Health Survey in 1998-99, and shows that there was a negative relationship between final adult height of women and the number of births they had as teenagers. Using multiple regression analysis, it is shown that this negative relationship is robust to confounding factors such as standard of living, urban-rural residence, state of origin in India and age of the women.     

Inequality in Japan (1892–1941): Physical stature, income, and health

This paper investigates the relationship between physical stature, per capita income, health, and regional inequality in Japan at the prefecture-level for the period 1892-1941. The analysis shows that inequality in income and access to health services explains differences in average height of the population across the 47 Japanese prefectures during this period and that variation in income contributed to changes in height during the 1930s. Annual regional time series of height indicate that Japan experienced a regional convergence in biological welfare before 1914, and that a divergence occurred during the interwar period; personal inequality followed a similar pattern.     

锡林浩特草原小叶锦鸡儿灌丛的阻雪能力及其对积雪形态的影响

通过对典型草原区小叶锦鸡儿灌丛积雪体的调查,研究了灌丛特征(灌丛高度、灌丛迎风侧宽度、灌丛顺风侧长度)对积雪形态(积雪高度、积雪宽度、雪辫长度)的影响.结果表明:小叶锦鸡儿灌丛高度与积雪形态参数呈显著二次多项式函数关系,灌丛迎风侧宽度、灌丛顺风侧长度与积雪形态参数呈显著幂函数关系(指数<1).灌丛积雪形态和发育特征是灌丛特征参数共同影响和作用的结果,其中,灌丛高度对积雪高度影响最大,灌丛迎风侧宽度对积雪宽度和雪辫长度影响最大.灌丛较小时积雪形态发育较快,随后逐渐趋于稳定.灌丛二维滞雪范围模型直接反映灌丛对风力的干扰范围和积雪的潜在范围,间接反映灌丛的滞雪能力;灌丛三维阻雪体积模型直接反映一定雪源、风况条件下灌丛的阻雪能力.本文建立的灌丛滞雪范围和灌丛阻雪体积模型可为典型草原风吹雪区积雪资源估算和雪害防治提供理论依据.     

What causes the vegetation types on Mount Bloomfield,a coastal tropical mountain of the western Philippines?

Mount Bloomfield has been shown to have several vegetation types, including medium stature forest on greywacke, small stature forest on serpentinized peridotite, and scrub and Gymnostoma woodland on dunite. The causes of the large physiognomic and floristic differences among these vegetation types have been investigated by soil chemical analyses, soil physical studies, and by a phytometer experiment involving the crop plant Zea mays. There was no relationship between maximum tree height and the soil chemical factors analysed (P, K, Ca, Mg, Ni) but there was a directly proportional relationship between maximum tree height and soil water retention. The phytometer experiment supported the idea that there is no acute soil toxicity in spite of the high soil Ni and Mg/Ca quotients recorded in this study. It is concluded that soil water retention, perhaps in combination with fire, is the major cause of stature differences among the vegetation types and together with soil chemistry is an important determinant of floristic composition.     

Ramet size equalisation in a clonal plant,Phragmites australis

The influence of shading from older generations of dead culms (standing litter) on density, growth rate and development of size structure at the ramet level was investigated in a pure stand of Phragmites australis by experimental neutral shading of plots after removal of standing litter. Initial differences in height distribution between autumn and spring cohorts disappeared in the course of shoot growth. The Gini coefficients of shoot heights and estimated shoot weights indicated that the size structure of the shoots became more equal with increasing mean size in both shaded and unshaded plots. Relative growth rate for height (RHGR) and weight of individual shoots was negatively related to shoot size during the early and presumably storage-dependent growth period, suggesting a strong support for growth of smaller shoots. No etiolation was indicated by mean or maximum height in shaded and unshaded plots, or by the relationship between shoot height and weight. Mean shoot density was significantly lower in shaded than in unshaded plots in one of two shade treatment years. A regression model indicated a small but significant effect of shoot density on the approximately linear relationship between RHGR and the logarithm of height. The growth rate of small shoots was slightly larger at low than at high shoot density. Therefore, it is suggested that the shade from standing litter in P. australis stands can decrease shoot natality in the spring cohort, and thereby increase the support to fewer small shoots.     

What is driving the relationship between height and cognition? Evidence from the Twins Early Development Study

Taller children tend to have better cognitive ability, and the relationship between height and cognition has been proposed as an explanation for the height-wage labor market premium. Height-cognition associations may arise due to social factors that favor taller individuals or be driven by “common factors” that are correlated with height and cognition. Indeed, there is now evidence of a genetic correlation between height and cognition that provides specific evidence for this concern. We examine whether genetic factors explain the relationship by estimating associations between childhood height and cognition in the Twins Early Development Study. We find that height is associated with better cognition even after controlling for genetic and environmental factors shared by twins. The association between height and cognition within fraternal twin pairs is also robust to controlling for individual genetic predictors of height and cognition. These results suggest that genetic factors are not solely responsible for driving the relationship between height and cognition.     

A comparison of 12 tree species of Amazonian caatinga using growth rates in gaps and understorey, and allometric relationships

1. The relative growth rate of saplings of 12 species from an oligotrophic lowland rain forest were measured in treefall gaps and understorey. Mean relative height growth ( R _H) within treefall gaps was found to be slowest for tall-tree species with branched saplings, intermediate for subcanopy trees and fastest for tall-tree species with unbranched saplings. Most species had similar R _H within the understorey. R _H values were not related to leaf mass per unit area (LMA) or foliar N concentrations.
2. Allometric relationships between the total leaf area (TLA) and height were dependent upon light conditions; in general saplings of a given height had a greater TLA in treefall gaps than in understorey. The species with the largest estimated TLA values in gaps tended to have the greatest R _H values in gaps; no such trend emerged in the understorey. The values of the allometric coefficients were not related to foliar properties.
3. The relationship between stem diameter and height was only weakly dependent on light conditions and the relationship between the growth rates in these dimensions was also weak. The lack of plasticity may reflect the fact that the height–diameter relationship has little bearing on a sapling's tolerance of shade.
4. One way of accommodating the dependence of allometry upon irradiance is to add R _H as a covariate. We derive a relationship between growth rates from this resource-dependent allometric equation and show that it reasonably describes measurements taken in the caatinga forest.     

Influence of ethnicity, geography and climate on the variation of stature among Indian populations

This paper analyzes the variation in the mean stature of adult males of a variety of population groups in India and examines the influence of geographical, climatic and ethnic factors on it. A considerable variation in mean stature has been found with respect to these three attributes. Variation "between" ethnic groups compared with "within" ethnic groups was found to be much more than that of geographical and climatic zones. Scheduled Castes (SC) and Scheduled Tribes (ST) populations have much low average height than that of General Castes (GC). Climatically dry and semiarid zones have a tendency to have higher stature than in the Monsoon areas. The mean height has been found to be the highest in north India. It is closely followed by west India. An interesting feature is that as one goes towards east and south the mean height gradually decreases. It is the lowest in islands. The mean heights have been regressed on geographical, climatic and ethnic factors, after converting these factors into binary variables. The regression analysis has strengthened the findings, that there is a highly significant relationship between height and geographical, climatic and ethnic factors.     

Vertical stratification of ithomiine butterfly (Nymphalidae: Ithomiinae) mimicry complexes: the relationship between adult flight height and larval host-plant height

Data are presented which confirm previous findings that sympatric mimicry complexes dominated by unpalatable Neotropical ithomiine butterflies (Nymphalidae: Ithomiinae) are vertically stratified by height of flight. Flight height of ithomiine species is positively correlated with the height of their larval host-plants. Thus members of a mimicry complex utilize host-plants of similar heights. Non-mimetic British woodland butterflies also show a positive relationship between flight height and host-plant height, which suggests that the relationship is independent of mimicry. I propose that female butterflies fly at heights which maximize the probability of encountering their larval host-plants, and that males fly at similar heights to females in order to maximize the probability of encountering potential mates. Female butterflies probably encounter plants of similar heights to their larval hosts more frequently than they encounter plants of other heights. I suggest that butterfly species may therefore be more likely to make host shifts to plant species of a similar height to their current host-plants. Finally, I discuss how the relationship between flight height and height of larval host-plants, coupled with microhabitat-dependent selection on colour pattern, could lead to the evolution in sympatry of vertically stratified mimicry complexes.     

Geometric mean shape of the shell in lacustrine and riverine limpets, Ancylus fluviatilis Müller

SUMMARY. Geometric mean (GM) shell shape in populations of limpets from three rivers was compared with that of populations from two lakes in England. The GM ratio of width on length was 0.78 in both river and lake limpets, but they respectively had GM ratios of 0.55 and 0.47 for height on width. The difference was compared statistically by prediction of mean values for height and width using linear logarithmic regressions. Shell height was significantly different ( P 0.05) in river limpets, which were about 20% taller than lake limpets at shell widths of 5.0–6.0 mm. The relationship between shell height and width or length was allometric in limpets from two rivers and isometric in a lake population. Similar results and conclusions were obtained using the GM regression (Teissier, 1948; Ricker, 1973) and the ordinary predictive regression.     

Weight-height relationships and body mass index: some observations from the Diverse Populations Collaboration

Body mass index (BMI, weight (kg)/height (m)(2)) is the most widely used weight-height index worldwide. This universal use of BMI assumes that the rationale for its use is universally applicable. We examine two possible rationales for using BMI as a universal measure. The first rationale is that BMI is strongly correlated with weight, but is independent of height. The second rationale is that BMI correctly captures the relationship between weight and height, which implies that the slope of log weight regressed on log height is 2. We examined the weight-height relationship in 25 diverse population samples of men and women from the US, Europe, and Asia. The analysis included 72 subgroups with a total of 385,232 adults aged 25 years and older. Although BMI was highly correlated with weight in all studies, a significant, negative correlation between BMI and height was found in 31 out of 40 subgroups of men (r=-0.004 to -0.133) and 32 of 32 groups of women (r=-0.016 to -0.205). When log weight was regressed on log height, the 95% confidence intervals (CI) of the slopes did not include 2 in 25 out of 40 male subgroups. The summary estimate of the slopes across studies of men was 1.92 (95% CI, 1.87-1.97). For women, slopes were lower than 2 in 28 of 32 subgroups with a summary estimate of 1.45 (95% CI, 1.39-1.51). In most of the populations, BMI is not independent of height; weight does not universally vary with the square of height; and the relationship between weight and height differs significantly between males and females. The use of a single BMI standard for both men and women cannot be justified on the basis of weight-height relationships.     

Estimating the Biases Associated with Self-Perceived,Self-Reported,and Measured BMI on Mental Health

Purpose

The purpose of the study is to explore the relationship between individuals'' perceptions of their weight-status, self-reported height and weight, and measured weight status.

Methods

A national survey of 9,248 adolescents (47% male) between the ages of 11 and 27 is analyzed to determine whether inaccuracies in reporting are caused by misperception or conscious intent, and whether there tends to be a systematic bias in how individuals self-report. Self-esteem was used as an example of an important outcome variable in order to illustrate the magnitudes of the biases that may arise when using different measures of body size.

Results

Our results indicate that measured obesity status is associated with the reduction in Rosenberg Self-Esteem (RSE) of 0.30 points (p-value 0.005) among adolescents and 0.20 points (p-value 0.002) among young adults; in addition, using self-reported height and weight as opposed to measured height and weight does not result in a statistically detectable difference in the estimates.

Conclusions

Individuals'' self-reports of height and weight are not as unreliable as we might have expected. Although estimates from measured height and weight are preferred, in the absence of such measures, self-reported measures would likely be a reliable alternative. The differences in self-perception of weight status, however, imply that it is not comparable to measured weight categories.