黑龙江省红松人工林枝条分布数量模拟

基于黑龙江省佳木斯市孟家岗林场的12块样地65株人工红松解析木的955个枝解析数据,以Poisson回归模型和负二项回归模型作为备选模型,构建了人工红松二级枝条数量分布模型,并采用AIC、Pseudo-R²、均方根误差(RMSE)和Vuong检验对模型的拟合优度进行比较.结果表明: 每轮一级枝条分布数量集中在3~5个,均值为4个,一级枝条分布数量与人工红松自身的枝条属性相关.一级标准枝上二级枝条分布的离散程度较大,利用全部子回归技术构建二级枝条分布数量模型,最终选择以负二项回归模型为基础的E(Y)=exp(β₀+β₁lnRDINC+β₂RDINC²+β₃HT/DBH+β₄CL+β₅DBH)作为二级枝条分布数量最优预测模型(β为参数;RDINC为相对着枝深度;HT为树高;DBH为胸径;CL为冠长).最优模型的Pseudo-R²为0.79,平均偏差接近于0,平均绝对偏差<7.对于所建立的模型,lnRDINC、CL和DBH的参数为正值,RDINC²和HT/DBH的为负值,随着RDINC增大,在树冠内二级枝条分布数量存在最大值.总的来说,所建立的人工红松二级枝条分布数量模型的预测精度为96.4%,可以很好地预估该研究区域人工红松二级枝条分布数量,为以后枝条的光合作用和生物量的研究提供了理论基础.     

大兴安岭塔河地区林火发生的优势预测模型选择

选取在经济学和社会科学领域广泛应用的零膨胀模型(zero-inflated models)和栅栏模型(Hurdle models)对大兴安岭地区林火发生进行模拟,应用赤池准则(AIC)、似然比检验(LR)和模型残差平方和(SSR)对两类共4个回归模型——零膨胀泊松模型(ZIP)、零膨胀负二项模型(ZINB)、栅栏泊松模型(PH)、栅栏负二项模型(NBH)进行拟合分析,最终选取适合此林火发生特性的预测模型.模型的AIC和SSR值表明,ZINB模型对当地林火数据的拟合度最高.运用LR检验对嵌套模型(ZINB与ZIP,NBH与PH)进行检验,结果显示: ZINB和NBH均优于各自的嵌入模型,说明负二项(NB)模型对数据结构中的过度离散现象可以很好地模拟和解释.根据研究区林火实际发生规律和两类不同模型的应用假设条件判断,零膨胀模型更适合塔河地区的林火特性.     

Plant-parasitic Nematode Distributions in an Alfalfa Field

A 7-ha alfalfa field (Medicago saliva L. cv Mesa Sirsa) was sampled systematically on a 6 x 6-m grid by removing individual cores (2.54 cm diam) to a depth of 45 cm from each of the 1,936 grid intersections. The soil was mainly coarse-textured with a fine-textured streak running centrally, north to south. Nematodes were extracted by a semiautomatic elutriator and sugar flotation-sieving technique. Five plant-parasitic species were consistently present: Meloidogyne arenaria, Pratylenchus minyus, Merlinius brevidens, Helicotylenchus digonicus, and Paratrichodorus minor. All species had a highly skewed nonnormal frequency distribution that departed significantly from randontness. Goodness-of-fit tests on the distribution of five populations in the entire field showed that three (Meloidogyne, Merlinius, and Helicotylenchus) were described by a negative binomial. When the samples were categorized by soil texture (coarse vs. fine-textured), all populations in the fine-textured areas, and three populations (Meloidogyne, Pratylenchus, and Merlinius) in the coarse areas, fitted a negative binomial distribution. Nearly all populations titted a negative binomial when the frequency distributions from randomly located one-meter-square areas were examined for each species.     

On a Model for Estimating the Parameter of the Human Reproductive Process

Attempt has been made in this paper to estimate certain parameters (data pertaining to which are either not available or easily reportable) of the human reproductive process as the period of postpartum ammenorrhoea (P.P.A.), number of foetal wastages in between live births etc., using a truncated negative binomial probability model. In view of the hypothesis that the probability of foetal wastages varies from mother to mother, the truncated negative binomial distribution has been compounded by weighing with the best prior Beta distribution of the parameter. Estimation has been made by successive approximation using the method of moments.     

基于线性混合模型的红松人工林一级枝条大小预测模拟

基于黑龙江省孟家岗林场60株人工红松955个标准枝数据,采用线性混合效应模型理论和方法,考虑树木效应,利用SAS软件中的MIXED模块拟合红松人工林一级枝条各因子(基径、枝长、着枝角度)的预测模型.结果表明： 通过选择合适的随机参数和方差协方差结构能够提高模型的拟合精度;把相关性结构包括复合对称结构CS、一阶自回归结构AR(1)及一阶自回归与滑动平均结构ARMA(1,1)加入到一级枝条大小最优混合模型中,AR(1)可显著提高枝条基径和角度混合模型的拟合精度,但3种结构均不能提高枝条角度混合模型的精度.为了描述混合模型构建过程中产生的异方差现象,把CF₁和CF₂函数加入到枝条混合模型中,CF₁函数显著提高了枝条角度混合模型的拟合效果,CF₂函数显著提高了枝条基径和长度混合模型拟合效果.模型检验结果表明：对于红松人工林一级枝条大小预测模型,混合效应模型的估计精度比传统回归模型估计精度明显提高.
     

Distribution of foundress group size in Ropalidia fasciata and R. plebeiana (Hymenoptera: Vespidae): an analysis using zero-truncated distribution models

Distribution patterns of the number of foundresses per newly established nest (foundress group size, FGS) of two primitively eusocial, independent-founding wasps, Ropalidia fasciata and R. plebeiana, were studied using zero-truncated distribution models. The distribution pattern of the FGS of R. fasciata is significantly different from a zero-truncated Poisson distribution but fits the zero-truncated negative binomial distribution well, indicating a strongly contagious distribution. R. plebeiana sometimes establishes new colonies by reusing old nests. In this case, distributions are strongly contagious. Competition among foundresses may be one reason for the contagious distribution of FGS in R. fasciata and in cases of old-nest reuse by R. plebeiana, but further studies, especially on the behaviour of foundresses in relation to FGS, are necessary. Electronic Publication     

基于负二项和零膨胀负二项回归模型的大兴安岭地区雷击火与气象因素的关系

雷击火的发生与气象因子之间存在着密切的关系。该文选用符合大兴安岭地区林火发生数据结构的负二项(negative binomial,NB)和零膨胀负二项(zero-inflated negative binomial,ZINB)两种模型对大兴安岭林区1980–2005年间雷击火的发生与气象因素间的关系进行建模分析,并与以往研究中所使用的最小二乘(OLS)回归方法相对比。使用SAS和R-Project统计软件进行模型拟合运算,计算得出模型各参数。结果表明,NB和ZINB模型对数据拟合较好,模型内各气象因子显著性水平较高,对雷击火发生次数均具有较好的预测能力。运用AIC和Vuong等检验方法,进一步比较了NB和ZINB模型对数据的拟合水平以及模型预测水平,结果表明ZINB模型无论在数据拟合还是模型预测上都要优于NB模型。提出了大兴安岭地区林火发生与气象因子关系的最优模型。     

How does variance in fertility change over the demographic transition?

Most work on the human fertility transition has focused on declines in mean fertility. However, understanding changes in the variance of reproductive outcomes can be equally important for evolutionary questions about the heritability of fertility, individual determinants of fertility and changing patterns of reproductive skew. Here, we document how variance in completed fertility among women (45–49 years) differs across 200 surveys in 72 low- to middle-income countries where fertility transitions are currently in progress at various stages. Nearly all (91%) of samples exhibit variance consistent with a Poisson process of fertility, which places systematic, and often severe, theoretical upper bounds on the proportion of variance that can be attributed to individual differences. In contrast to the pattern of total variance, these upper bounds increase from high- to mid-fertility samples, then decline again as samples move from mid to low fertility. Notably, the lowest fertility samples often deviate from a Poisson process. This suggests that as populations move to low fertility their reproduction shifts from a rate-based process to a focus on an ideal number of children. We discuss the implications of these findings for predicting completed fertility from individual-level variables.     

高效液相色谱法快速分析红松,云杉针叶中的维生素C

高效液相色谱法快速分析红松、云杉针叶中的维生素Ｃ刘海玲,杜英君,杨志勇（中国科学院沈阳应用生态研究,沈阳１１００１５）ＨｉｇｈｅｆｆｅｃｔｉｖｅｌｉｑｕｉｄｃｈｒｏｍａｔｏｇｒａｐｈｉｃａｎａｌｙｓｉｓｏｆｖｉｔａｍｉｎＣｉｎＰｉｎｕｓｋｏｒａｉｅｎ...     

红松营养枝和生殖枝不同叶龄针叶形态解剖结构和光合特性

本研究以全光下6、7和8月处于结实状态的40年生红松母树生殖枝和营养枝上的当年生和一年生针叶为研究对象,比较针叶形态解剖结构和光合性能指标的差异,分析不同枝型和叶龄针叶各指标间的相关性。结果表明: 除了气孔密度、叶宽和中柱面积外,当年生针叶其他形态指标、解剖结构指标和含水率在不同月份间差异显著,而一年生针叶在不同月份间差异不明显。当年生针叶在7和8月叶长分别比6月显著提高91.0%～110.1%和122.2%～131.5%,比叶面积分别显著减小32.8%～40.9%和44.8%～52.5%,木质部面积分别显著增大47.3%～70.8%和75.9%～105.7%,韧皮部面积分别显著增大29.2%～30.0%和64.3%～73.2%。当年生和一年生针叶净光合速率(P_n)在不同月份间的变化趋势相反,表现出当年生针叶在7月和8月的P_n比6月分别增高 17.1%～39.8%和40.3%～51.5%,而一年生针叶在7月和8月的P_n比6月分别降低40.1%～56.9%和45.2%～46.1%。生殖枝和营养枝之间的针叶叶长和P_n差异显著,表现在生殖枝6和7月当年生针叶叶长分别比营养枝显著减小16.4%和28.1%,生殖枝当年生和一年生针叶P_n分别比营养枝显著减小23.1%和20.4%。生殖枝和营养枝当年生针叶的PSⅡ反应中心激发能捕获效率(F_v′/F_m′)和P_n以及营养枝当年生针叶胞间CO₂浓度与除了气孔密度之外的其他形态解剖结构指标紧密相关,而一年生针叶相关不紧密。叶龄是导致针叶形态解剖结构和光合性能指标产生差异的主要因素,枝条类型仅对叶长和P_n有显著影响。     

基于线性混合效应的红松人工林枝条生物量模型

基于黑龙江省孟家岗林场60株红松解析木3643个枝条生物量的实测数据,利用全部子回归技术建立了枝条生物量模型(枝、叶和枝总生物量模型),最终选择lnw=k₁+k₂lnL_b+k₃lnD_b为枝条生物量最优基础模型.利用SAS 9.3统计软件的PROC MIXED模块建立枝条生物量混合模型,并采用AIC、BIC、对数似然值和似然比等统计指标评价不同模型的拟合效果.结果表明: 红松解析木的叶和枝总生物量混合模型以k₁、k₂、k₃作为随机效应参数的拟合效果最好,而枝生物量混合模型以k₁、k₂作为随机效应参数的拟合效果最好.最后将枝条生物量最优基础模型与最优混合模型进行模型检验.混合模型各项指标优于基础模型,能有效地提高模型的预估精度,并且通过方差协方差结构校正随机参数来反映树木之间的差异.     

Bivariate Modified Power Series Distribution Some Properties,Estimation and Applications

The class of bivariate modified power series probability distribution (BMPSD) has been defined by P(X = x, Y=y) =a(x, y) (g(?₁ ?₂))^x (h(?₁, ?₂))^xwhere a(x,y) is a sub-set of the Cartesian product of the set of non-negative integers and g(?₁, ?₂), h(?₁ ?₂) and f(?₁, (?₁, ?₂) are positive finite and successively differentiable functions of ?₁and ?₂. It includes a very large number of well known probability distributions. The recurrence relations for central moments and factorial moments have been determined. Also, the M.L. estimators for ?₁ and ?₂ and their asymptotic biases and variances are obtained. Some important properties are discussed. The results of an BMPSD have been applied to derive the corresponding results for the bivariate generalized negative bino-mial distribution and the bivariate Lagrangian Poisson distribution.