辽东次生林区主要阔叶林型叶面积指数季节动态

蒙古栎（Quercus mongolica）、花曲柳（Fraxinus rhynchophulla）和胡桃楸（Juglans mandshurica）林是我国东北天然次生林区具有代表性的主要林型。本研究以该3种林型为对象,利用数码相机外带鱼眼镜头获得3种林型的半球面影像,再利用专用软件Gap Light Analyzer处理分析获得了叶面积指数、林冠孔隙度和林下光照因子等参数。结果表明,3种林型的叶面积指数变化总体趋势是一致的,均呈先上升再下降的单峰曲线,蒙古栎林和胡桃楸林都是在7月中旬或8月中旬达到最大峰值,花曲柳林是在8月中旬或9月中旬达到最大峰值;3种林型冠层孔隙度的变化总体趋势也是一致的,呈先下降再上升的单峰曲线,不同样地峰值出现的时间也不同,最低峰值在6、7、8、9月中旬均有出现;通过对不同月份的叶面积指数、林下散射光、林下直射光的变异系数分析表明,7—9月叶面积指数的空间格局是影响林下散射光空间分布的主要因素。叶面积指数与林冠孔隙度呈指数相关。     

两个典型荒漠化地区景观多样性变化的比较——景观基质的影响

利用青海沙珠玉沙区英德尔乡和陕西榆林沙区可可盖乡两个典型荒漠化地区两个时期的土地利用和荒漠化数据,分析了多样性、优势度和均匀度等景观多样性指标在两个地区的变化规律及其指示的景观生态学意义。研究结果表明,这些指标在两个地区都能够较好地评价荒漠化土地的动态变化规律,对分析荒漠化土地的发展趋势具有较好的指示意义。但由于景观基质的影响,上述指标在两个地区存在着完全不同的变化趋势,即随着荒漠化土地的增加,在沙珠玉沙区表现为多样性指数增加、优势度指数减小和均匀度指数增大;在榆林沙区则表现为多样性指数减小、优势度指数增加和均匀度指数减小。     

不同斑块类型的景观指数粒度效应响应——以无锡市为例

斑块类型与景观格局粒度效应响应关系密切。以无锡市为研究区域,针对地区社会经济活动频繁、人为干扰强烈和生态脆弱等特性,以土地利用类型、热力等级和生态贡献为斑块类型划分依据,构建出对应的3种不同景观格局。在相同粒度变化情况下,选用了19个景观水平指数和Moran's I指数,分析了不同景观格局粒度效应的响应情况。结果表明,随粒度变粗:1)土地利用类型、热力等级和生态贡献斑块的部分景观指数响应曲线变化剧烈程度依次减弱;2)3类斑块的Moran's I指数均存在尺度效应。其中,土地利用类型和生态贡献斑块的Moran's I指数存在负相关,热力等级斑块没有。生态贡献斑块响应曲线在正相关区域内变化相对平缓,土地利用类型与热力等级斑块响应曲线变化趋势相反;3)指数反映的第一临界粒度基本一致,但景观指数响应曲线的临界现象更为明显。总体上,不同类型斑块在同一研究区构成的景观格局、指数响应曲线变化趋势和第一临界粒度都较为相似;斑块类型对景观指数粒度效应响应存在影响,但还有待深入探讨。     

半个世纪来南京市儿童体型的长期变化

本文报告了半世纪来南京市儿童体型发展的长期变化,１９３６年至１９８５年,南京市儿童身高、体重、坐高均有显著增加,对１９３６、１９５６、１９７５、１９８５四个年代７－１７岁儿童的坐高指数,克托莱指数,考甫指数,劳累尔指数,利比指数,培利迪西指数六个指数作对比分析,结果表明,半个世纪来,南京市儿童以体重和身高关系所表现的体型趋向瘦长,１９７５、１９８５年资料表明成熟期躯干与下肢比例关系无明显变化。     

昆虫发育进度的非正态描述──分段指数曲线

提出了分段连续指数曲线转化为多元线性回归方程的方法。利用取剩余平方和最小的方法确定未知折点。给出了在描述昆虫发育进度的模拟模型。     

瓶尔小草是观察厚囊蕨类孢子囊发育的好材料

瓶尔小草是观察厚囊蕨类孢子囊发育的一种好材料。以瓶尔小草为材料观察孢子囊发育具有如下优点:便于确定和获得孢子囊发育的各个时期;易制作半薄切片和观察;可代表较原始的蕨类植物孢子囊发育的特点(厚囊型)等;为丰富《植物学实验》的教学材料提供参考。     

包含哑变量的黑龙江省落叶松人工林碳储量预测模型系统

利用2005—2010年两期黑龙江省落叶松人工林固定监测样地数据,分析黑龙江省落叶松人工林各林分变量因子之间的关系,建立地位级指数曲线模型和林分密度指数模型,采用两步最小二乘的方法建立预测包含林分平均断面积和林分碳储量的联立方程组,将以上所构建的模型统称为黑龙江省落叶松人工林碳储量预测模型系统.同时将龄组和区域作为哑变量加入到预测模型中.结果表明: 模型系统中除地位级指数曲线模型之外,剩余模型的确定系数(R²)均大于0.98,均方根误差均小于4,而加入哑变量的模型R²有所增加,均方根误差均小于3,说明模型稳定性较好,预估参数较为精确.各模型的平均相对误差均小于2%,大部分模型平均相对误差绝对值小于15%,模型精度均在95%以上,研究结果可以对黑龙江省不同区域和龄组的落叶松人工林林分平均树高进行精确拟合.根据地位级指数曲线模型和联立方程组的拟合参数进行分析,当调查样地在同一区域时,林分年龄越大,林分平均树高、林分平均断面积和林分碳储量越大,符合实际生长规律;而在林分年龄相同、区域不同时,不同区域林分平均树高由大到小的排列顺序为: 平原地区、小兴安岭南坡地区、张广才岭东坡地区、完达山地区、张广才岭西坡地区、小兴安岭北坡地区.不同区域林分断面积和林分碳储量由多到少的排列顺序为: 张广才岭东坡地区、小兴安岭北坡地区、张广才岭西坡地区、小兴安岭南坡地区、完达山地区、平原地区.     

昆虫发育过程中的速率累加效应对其日均发育率的影响

昆虫发育速率V与温度T之间呈S型曲线关系。在确定适合昆虫发育的变温范围的基础上,利用萝卜蚜的试验数据,通过计算机模拟,探讨了“速率累加”过程通过V与T之间的曲线关系在各种变温条件下对昆虫日均发育速率所产生的影响。结果表明,在排除温度波动本身可改变瞬时发育速率的前提下,这种速率累加效应导致在低温区内变温下的发育比在恒温下快,在高温区内则相反,且温度变幅越广差异就越大。文中指出,由于日均发育速率会依温度的变化方式和幅度不同而发生改变,而依据恒温速率曲线可计算出各种变温下的发育进度,故对于预测昆虫在适温区发育进度而言,恒温试验结果比变温试验结果具有更广泛的适用性。     

油菜地上部干物质分配与产量形成模拟模型

利用油菜器官生长与发育进程及环境因子之间的定量关系,构建了基于分配指数的油菜地上部器官干物质分配动态模拟模型.各器官干物质分配指数随着生理发育时间而变化,基因型、播期、氮素及水分水平影响各器官干物质在地上部分配的大小.其中,氮素营养水平对绿色叶片干物质分配影响最大,氮素营养水平越高,绿色叶片分配指数越大;播期影响角果分配指数,晚播的角果分配指数高于早播.模型引入氮素营养指数、水分及播期影响因子来定量油菜各器官在实际生产条件下的分配强度,同时考虑了品种遗传特性的影响.通过不同品种氮肥处理试验建立模型,利用不同品种播期试验资料对模型进行了初步检验,表明模型具有较好的预测性和适用性.     

不同发育时期小麦种子活力的变化及其对环境温度的响应

以济麦22和山农23号为试验材料,利用标准发芽试验法对不同年份小麦种子发育过程中的种子活力变化进行研究,分析环境温度对不同发育时期小麦种子活力变化的影响,为早期小麦种子的利用及高活力种子的生产提供参考依据.结果表明: 伴随着小麦种子发育,鲜种子在花后26 d左右出现发芽能力,之后其发芽率整体呈上升趋势;干种子发芽势、发芽率和发芽指数在花后5～8 d迅速升高,之后保持相对稳定,活力指数主要受到幼苗单株干质量的影响而持续升高,一般在完熟前4～6 d达到最大值;不同发育时期小麦干种子的田间种植及其后代种子的活力测定表明,济麦22花后17 d以后的干种子田间出苗较好,并可成穗结实,其后代种子的发芽率和活力指数在不同样品间无显著差异.环境温度对不同发育时期小麦种子活力变化的影响显著,小麦花后日平均温度均值、日最高气温均值以及日最低气温均值均高,且花后日温差均值大的年份,种子发育时间短、百粒重及种子活力达到最大值的时间较早;反之,发育时间较长、百粒重及种子活力达到最大值的时间较晚,但完熟期积温高,种子活力较高.     

Pelvic Morphology,Body Posture and Standing Balance Characteristics of Adolescent Able-Bodied and Idiopathic Scoliosis Girls

The purpose of this study was to determine how pelvic morphology, body posture, and standing balance variables of scoliotic girls differ from those of able-bodied girls, and to classify neuro-biomechanical variables in terms of a lower number of unobserved variables. Twenty-eight scoliotic and twenty-five non-scoliotic able-bodied girls participated in this study. 3D coordinates of ten anatomic body landmarks were used to describe pelvic morphology and trunk posture using a Flock of Birds system. Standing balance was measured using a force plate to identify the center of pressure (COP), and its anteroposterior (AP) and mediolateral (ML) displacements. A multivariate analysis of variance (MANOVA) was performed to determine differences between the two groups. A factor analysis was used to identify factors that best describe both groups. Statistical differences were identified between the groups for each of the parameter types. While spatial orientation of the pelvis was similar in both groups, five of the eight trunk postural variables of the scoliotic group were significantly different that the able-bodied group. Also, five out of the seven standing balance variables were higher in the scoliotic girls. Approximately 60% of the variation is supported by 4 factors that can be associated with a set of variables; standing balance variables (factor 1), body posture variables (factor 2), and pelvic morphology variables (factors 3 and 4). Pelvic distortion, body posture asymmetry, and standing imbalance are more pronounced in scoliotic girls, when compared to able-bodied girls. These findings may be beneficial when addressing balance and ankle proprioception exercises for the scoliotic population.     

MRI-derived body segment parameters of children differ from age-based estimates derived using photogrammetry

Body segment parameters are required when researching joint kinetics using inverse dynamics models. However, the only regression equations for estimating pediatric body segment parameters across a wide age range were developed, using photogrammetry, based on 12 boys and have not been validated to date (Jensen, R.K., 1986. Body segment mass, radius and radius of gyration proportions of children. Journal of Biomechanics 19, 359–368). To assess whether these equations could validly be applied to girls, we asked whether body segment parameters estimated by the equations differ from parameters measured using a validated magnetic resonance imaging (MRI) method. If so, do the differences cause significant differences in joint kinetics during normal gait? Body segment parameters were estimated from axial MRIs of the left thigh and shank of 10 healthy girls (9.6±0.9 years) and compared to those from Jensen's equations. Kinematics and kinetics were collected for 10 walking trials. Extrema in hip and knee moments and powers were compared between the two sets of body segment parameters. With the exception of the shank mass center and radius of gyration, body segment parameters measured using MRI were significantly different from those estimated using regression equations. These systematic differences in body segment parameters resulted in significant differences in sagittal-plane joint moments and powers during gait. Nevertheless, it is doubtful that even the greatest differences in kinetics are practically meaningful (0.3%BW×HT and 0.7%BW×HT/s for moments and power at the hip, respectively). Therefore, body segment parameters estimated using Jensen's regression equations are a suitable substitute for more detailed anatomical imaging of 8–10-year-old girls when quantifying joint kinetics during gait.     

Age dynamics of sex differences according to integral indices of habitus in 7 to 17-year-old children

Using analysis of major components with varimax-rotation, factor analysis of 26 anthropometric parameters has been performed in 1,100 children of both sex at the age of 7-17 years. Three orthogonal components are distinguished, embracing 76.6% of total variance. The first factor--the component of general size; the second and the third factors characterize variability connected with differentional processes. After calculation of individual values of the factors, the main statistical parameters of the body integral indices are defined for all age-sex groups. Convergence of the component values of the total size is observed, when comparing cohorts of boys and girls at the conclusive stages of ontogenesis studied. As for the two other integral parameters, the boys differ from the girls nearly in all age groups; the second factor demonstrates more differences in younger, and the third factor--in older age.     

Body build classes as a method for systematization of age-related anthropometric changes in girls aged 7-8 and 17-18 years

A total of 462 schoolgirls aged 7-8 and 17-18 years were examined anthropometrically (45 body measurements and 10 skinfolds) in a cross-sectional study. The data were processed in two age groups: 7-8-year-olds (n = 205) and 17-18-year-olds (n = 257). Relying on average height and weight in the groups, both groups were divided into five body build classes: small, medium, large, pyknomorphous and leptomorphous. In these classes, the differences in all other body measurements were compared, and in both age groups, analogous systematic differences were found in length, width and depth measurements and circumferences. This enabled us to compare proportional changes in body measurements during ten years, using for this ratios of averages of basic measurements and measurement groups in the same body build classes. Statistical analysis by the sign test revealed statistically significant differences between various body build classes in the growth of averages. Girls belonging to the small class differed from the girls of the large class by an essentially greater increase in their measurements. Our results suggest that the growth rate of body measurements of girls with different body build can be studied by the help of body build classification.     

Sexual dimorphism in growth from 8 to 18 years

A mixed longitudinal study of growth and development has been conducted, centering on an analysis of differences based on sex between the ages of 8 and 18 years for a series of 12 anthropometric indicators. The sample consisted of 50 girls and 63 boys. Proceeding from the specific differences, the variables can be divided into four groups with identical structures of differences. The first group comprises measurements of body height, body mass, shoulder width and pelvic span, all of which have higher values in boys between 8 and 10 and between 14 and 18. Between the ages of 11 and 13 girls are taller, heavier, with broader shoulders and pelvises. The second group covers measurements of subcutaneous fat. which are higher for girls throughout the period under review. The third group of indicators comprises the diameters of the joints of the extremities, i.e. of elbows and knees. Throughout the period under observation, these measurements are higher in boys, with the absolute differences between the sexes being the same at the age of 8 and ten years later. The fourth group consists of circumferences measurements of the extremities. It was found that calf circumferences manifested a specific inversion of the curves between 14 and 15, with girls showing a larger calf circumference up to the age of 14, and boys from the age of 15. The effect of earlier onset of puberty in girls was found to be reflected only on the inversion of the curve flow of the variables from the first group.     

Are there sex differences in the prevalence of overweight and adiposity in elementary school children in Austria

Based on the data of 203 male and 179 female schoolchildren from Eastern Austria (Burgenland), aged between 6 and 10 years, sex typical differences in body composition (absolute and relative body fat, lean body mass) and weight status were analyzed. Body composition analyses were carried out by means of BIA method, weight status was estimated using BMI percentiles (BMI > 90th percentile defined overweight, BMI > 97th percentile defined obesity). Statistically significant sex differences were found for all body composition parameters, girls exhibited a significantly higher amount of absolute and relative body fat, whereas their male counterparts exhibited a significantly higher amount of lean body mass. Regarding weight status, no statistically significant sex differences were observable, however, a higher amount of girls could be classified as overweight or obese. Evolutionary and sociocultural explanations for these observations are discussed.     

Childhood Growth Trajectories According to Combinations of Pregestational Weight Status and Maternal Smoking during Pregnancy: A Multilevel Analysis

Pregestational weight status and maternal smoking during pregnancy are significantly associated with fetal and childhood growth. However, few studies have examined associations between childhood growth and combinations of these factors using multilevel analysis. This study aimed to describe differences in childhood growth trajectories according to these combinations, using data from a prospective cohort study in Japan. The study participants were 1,973 women and their singletons, who were born between April 1, 1991 and March 31, 2003. Children were categorized according to whether they were born to normal-weight, nonsmoking mothers (NN); normal-weight, smoking mothers (NS); underweight, nonsmoking mothers (UN); underweight, smoking mothers (US); overweight, nonsmoking mothers (ON); or overweight, smoking mothers (OS). Birth weight and anthropometric data were collected from 1,965 children at birth (99.6%), 1,655 aged 3 (83.9%), 1,527 aged 5 (77.4%), 1,497 aged 7–8 (75.9%), and 1,501 aged 9–10 (76.1%). Multilevel analysis examining both individual and age as different level variables according to sex was used to describe the trajectories of body mass index z scores for statistical analyses. Although children of the OS group were the leanest at birth, their body mass indices had increased rapidly by 3 years of age. Moreover, body mass index was also likely to increase in boys in the NS and ON groups. A different trend was observed in girls. Body mass index decreased from 5 years of age in girls in the US group. There were no remarkable differences in body mass index trajectories between children in the other groups. In conclusion, childhood growth trajectories differed according to combinations of pregestational weight status and maternal smoking during pregnancy. Further, there were sex-related differences in the associations between childhood growth and factor combinations.     

Reference norms for a fat-free mass index and fat mass index in the Japanese child population

The aims of this study were to determine reference norms for a fat-free mass index (FFMI) and fat mass index (FMI) in a large population of healthy children in Japan, to observe differences in these values in three age groups between ages three and eleven, and to develop percentile distributions for these parameters. Five hundred twenty-two boys and six hundred forty-nine girls with a wide spectrum of stature, body mass, and body composition underwent bioelectrical impedance analysis (BIA) for the determination of fat-free mass (FFM) and fat mass (FM). Both FFM and FM were divided by stature(2) to give FFMI and FMI, as described previously. Normal FFMI and FMI were defined within the range of the 25th to 75th percentile of age- and gender-specific data in this study. The reference norms for FFMI (3-11 yrs) were 12.7-13.4 kg/m(2) in boys and 12.0-13.0 kg/m(2) in girls. A modest increase in boys was observed with an age increase; otherwise, there were no marked age differences in FFMI for the children as a whole. The reference norms for FMI were 2.8-3.6 kg/m(2) in boys and 3.2-3.8 kg/m(2) in girls. For each 3-year category (i.e., ages 3-5, 6-8 and 9-11 yrs.), FMI progressively increased by an average of 28.6% in boys and 18.8% in girls, compared to an increase in BMI of 11.0 and 11.3% respectively. FFMI and FMI are appropriate for many purposes, and have the advantage of expressing both aspects of body composition in common units. In conclusion, the data presented as percentiles can serve as reference in comparing a child's body composition to that of healthy children of the same age and gender. The reference standards should be appropriate for almost all children in the Japan for whom stature, body mass, and body composition can be measured satisfactorily. However, a more sophisticated approach is ultimately required for evaluating body composition. This article is a preliminary attempt to promote future research in the area of childhood body composition.     

27个少数民族女青少年生长发育状况的分析

利用主成分分析与聚类分析相结合,从分析7项生长发育指标的相似与相异点入手,对我国27个少数民族的32个女青少年样本进行分类比较。所聚成的7个类,在生长发育状况上存在着显著差异。这些差异的产生除受社会-经济状况影响外,与各民族所居住地区的地理生态、城乡差异和生活习惯等因素也有关。作者就聚类分析所展示的各民族女青少年生长发育的特点和趋势进行了讨论,并就如何改善某些民族在生长发育方面的落后状态提出建议。