秦岭太白红杉群落特征及其物种多样性的研究

选择太白红杉群落分布集中的太白山、长安光头山、玉皇山和冰晶顶等4个地段,设计18个样地,用样方法进行调查,共作样方280个。分析了太白红杉群落的种类组成、区系特点、群落外貌、垂直结构和水平结构等群落学特征,并对该群落的环境概况进行分析,计划了不同地段上群落的频、盖度指标和不同层次上的Shannon-Wiener指数,Simpson指数、Pielou指数和种间相遇指数。结果表是,太白红杉主要分布于秦岭海拔2800－3500m的高海拔山地,群落组成种类约85种,北温带分布属占优势,地面芽植物种类多,数量大,是该群落的优质层片。乔木层为太白红杉单优组成,平均高度约8．6m,多样性指数0．207－0．420,灌木层H值为1．779－2．363,草本层H值最高,为2．122－3．025。本研究为太白红杉可持续利用和保护提供了有益的参考。     

秦岭太白红杉群落种间关系的数量分析

应用2×2列联表的Fisher精确检验,研究了太白红杉群落中44种植物 共946个种对 的种间关系.结果有33个种对正关联,12个种对负关联 P<0.05或P<0.01 .另外,用Pearson积矩相关系数和Spearman秩相关系数检验刻划了种对间的数量变化关系.Pearson相关系数显示有31个种对呈显著正协变,5个种对呈显著负协变;Spearman秩相关系数显示有30个种对呈显著正协变,5个种对呈显著负协变,并分别计算出了其相关系数.研究结果表明,太白红杉群落种间关系较为简单,但草本层物种间连接相对较为复杂,灌木层次之.乔木层中,太白红杉和巴山冷杉呈显著的负协变效应.     

滇西北海拔上限大果红杉径向生长对气候变化的响应

基于树轮年代学方法,利用玉龙雪山、哈巴雪山和普达措国家公园海拔上限大果红杉树轮宽度资料,分别建立3个样点大果红杉的差值年表(RES),研究其径向生长对气候响应的异同,探讨影响滇西北大果红杉生长的关键气候因子.结果表明: 生长季初期(5月和6月)温度是影响滇西北大果红杉生长的主要因子,与3个样点的径向生长表现出显著正相关关系,同时普达措国家公园大果红杉还受生长季以前温度的影响,分别与上年7月和11月温度呈显著负相关和显著正相关;3个样点大果红杉生长对降水的响应存在差异,随着纬度升高主要由负相关转为正相关,大果红杉径向生长与降水的关系在玉龙雪山(纬度梯度最南)主要表现为与生长季初期降水量呈显著负相关,在哈巴雪山(纬度梯度中部)表现为与9月降水量呈显著负相关,在普达措国家公园(纬度梯度最北)表现为与3月降水量呈显著正相关.另外,7月降水的增多有利于玉龙雪山大果红杉的生长.基于气候模型预测,综合大果红杉对温度和降水响应模式与响应程度分析,未来气候变化有利于滇西北高原大果红杉的径向生长.     

中国植物区系地理学研究的回顾和展望

植物区系地理学是研究世界或某一地区植物种类的组成、现代和过去的分布以及它们的起源和演化历史的科学。植物区系地理学的研究内容包括广义植物地理学中的植物科属地理学、植物分布学和植物历史地理学３个部分。植物区系地理学是生物地理学的一个分支,是植物学和地理学...     

生物地理学（一）

一、引言 生物地理学研究生物的地理分布。探险家冯·洪堡(Von Humboldt, A, 1769—1859)是最早使用生物地理学(biogeography)一词的学者之一。他根据环境的温度、海拔和纬度等物理因子解释动、植物的分布。生物地理学以前只是描述和解释自然界和生物界之间的关系,在地理学和生物学之间占据一个不明确的领域。对生物地理学感兴趣的主要是生物学家,生物学家有时用地球物理学的理论来解释动植物为什么生活在某个地方。     

(0──1)变量与定量、定性变量间的相关分析

本文介绍了经验Logistic回归及列联表检验的基本思想,探讨了用经验Logistic回归及列联表检验研究（0-1）变量与定量、定性变量相关的方法,并举例作了说明。     

水杉属和红杉属化石叶表皮鉴定参照系的特殊性

杉科植物的许多属种在小枝的形态和叶片排列上相似,而杉科植物的化石标本多保存为枝叶形式。表皮的特征作为压型化石枝叶标本细胞信息的重要来源,甚至是惟一来源。一直作为杉科植物化石分类鉴定的主要依据。水杉和北美红杉分别是水杉属和红杉属植物化石的惟一现存最近亲缘种,以往关于北美红杉的气孔分布和排列等方面的报道存在分歧,根据作者的研究,北美红杉的表皮特征变异幅度非常广。水杉的气孔分布也与以往报道有差异。利用表皮的特征鉴定杉科植物化石时;不同的处理方法和处理时间,角质层的完整程度和观察数量等均可以影响植物表皮特征的正确获取。     

昆虫种群动态预测的加权列联表分析法

<正> 昆虫种群动态的预测预报是昆虫种群数理生态学研究的重要方面之一。近些年来,不少数学分析方法和预报模型相继提出,列联表分析就是其中之一,如朱伯承提出的由列联表直接分析各因子与预报量的“单相关”,从而建立预报方程(下简称“综合相关法”)以及李火苟提出的用条件频率法简化《综合相关法》(下简称“条件频率法”)等。 本文将在上述工作的基础上,给出一种能充分、客观利用信息,试报满意,算法简便的以表征各因子相关程度的随机列联系数为权重,定义因子和预报量的条件频率之和的列联参数为预报依据的加权列联表因素分析方法,并举例说明之。     

荒漠内陆河岸胡杨和多枝柽柳幼苗种群空间分布格局及种间关联性

运用方差均值比率法、负二项参数、丛生指标、平均拥挤度、聚块性指数和扩散系数等7个指标以及双项轨迹方差法,研究了塔里木河中下游荒漠河岸植被建群种胡杨(Populus euphratica)和多枝柽柳(Tamarix ramosissima)幼苗种群的空间分布格局和种间关联性.结果表明,胡杨和多枝柽柳幼苗的空间分布呈显著的聚集分布,聚集规模大小为16 m2.利用2×2列联表χ2统计量、联结系数和共同出现百分率等测度方法,综合分析了2个种对联结性质和程度.结果表明,胡杨和多枝柽柳2个幼苗种群表现出强的正关联,这2种植物种群现处于稳定分布格局,种间共存,占有共同的生态位.     

折迭三维列联表的临床应用

在医学研究中,我们会遇到多指标的问题,就是多变量的问题。如果这些变量是定量的,可用多元分析方法。如果这些变量是定性的,那么就需要采用多维列联表,然而分析多维列联表的工作是相当繁重的,许多研究工作者设法从多维表导出一系列二维列联表,用对它们进行分析来代替对多维表的分析。我们把合并除了指定的两个变量外的所有变量的各种取值来导出二维列联表的方法称为就某些变量来折迭多维列联表。问题是在什么条件下将多维表折迭为二维表能保持不破坏它的结构。     

Brazilian Páramos IV. Phytogeography of the campos de altitude

Aim This contribution treats the phytogeography of the contemporary campos de altitude flora, with a focus on patterns at the level of genus. Comparative analysis using data from 17 other sites in Latin America is used to describe phytogeographical patterns at the continental scale. Results are combined with those of previous publications to shed light on the biogeographical origins of contemporary floristic patterns in the high mountains of south‐east Brazil. Location The campos de altitude are a series of cool‐humid, mountaintop grass‐ and shrublands found above elevations of 1800–2000 m in south‐east Brazil, within the biome of the Atlantic Forest. Methods Vascular floras are compiled for the three best‐known campos de altitude sites, and for 17 other highland and lowland locations in Latin America. Floras are binned into phytogeographical groups based on centres of diversity/origin. Floristic and geographical distances are calculated for all location‐pairs; Mantel tests are used to test for relationships between patterns in geographical distance, and floristic and climatic similarity. Multivariate statistics are carried out on the similarity matrices for all genera, and for each phytogeographical group. Predominant life‐forms, pollination and dispersal syndromes are determined for each genus in the campos de altitude flora, and proportional comparisons are made between phytogeographical groups. Supporting evidence from previously published literature is used to interpret analytical results. Results Two‐thirds of the genera in the campos de altitude are of tropical ancestry; the remainder are of temperate‐zone or cosmopolitan ancestry. Most campos de altitude genera are phanerophytes and hemicryptophytes, insect pollinated, and wind or gravity dispersed, but there are significant differences in the distribution of these traits among phytogeographical groups. The campos de altitude show stronger floristic similarities with other Brazilian mountain sites and distant Andean sites than with nearby low‐ and middle‐elevation sites; these similarities are best explained by climatic similarities. Floristic similarities among sites for temperate genera are better explained by ‘sinuous’ distance (e.g. measured along the spines of mountain ranges) than by direct distance; similarities in tropical genera are more related to direct distance. Different phytogeographical groups appear to be responding to different climatic signals. Main conclusions Many taxa currently living at the summits of the south‐east Brazilian Highlands trace their ancestry to temperate latitudes. Patterns of endemism and diversity in the south‐east Brazilian mountains point to climatically driven allopatry as a principal mechanism for speciation. The tropical component of the campos de altitude flora is primarily derived from drier, highland environments of the Brazilian interior; the temperate component rises in importance with elevation, but never reaches the levels seen in the tropical Andes. Most temperate taxa in the campos de altitude appear to have arrived via migration through favourable habitat rather than by recent, long‐distance dispersal. At least 11% of the plant species in the campos de altitude study sites are directly shared with the Andes. Palynofloras show that the campos de altitude have significantly contracted over the past 10,000 years, as regional temperatures have warmed and become more humid.     

An exact test for all-way interaction in a 2M contingency table: application to interval capture-recapture estimation of population size

An exact conditional test for an M-way log-linear interaction in a fully observed 2M contingency table is formulated. From this is derived a procedure for interval estimation of the total count N in a 2M contingency table, one of whose entries is unobserved. This procedure has an immediate application to interval estimation of the size of a closed population from incomplete, overlapping lists of records, as in capture-recapture analysis of epidemiological data. Data on the prevalence of spina bifida in live births in upstate New York in 1969-1974 illustrate this application.     

Large-scale spatial patterns in the distribution of Collembola (Hexapoda) species in Antarctic terrestrial ecosystems

Aim  We tested whether the distribution of three common springtail species ( Gressittacantha terranova , Gomphiocephalus hodgsoni and Friesea grisea ) in Victoria Land (Antarctica) could be modelled as a function of latitude, longitude, altitude and distance from the sea.
Location  Victoria Land, Ross Dependency, Antarctica.
Methods  Generalized linear models were constructed using species presence/absence data relative to geographical features (latitude, longitude, altitude, distance from sea) across the species' entire ranges. Model results were then integrated with the known phylogeography of each species and hypotheses were generated on the role of climate as a major driver of Antarctic springtail distribution.
Results  Based on model selection using Akaike's information criterion, the species' distributions were: hump-shaped relative to longitude and monotonic with altitude for Gressittacantha terranova ; hump-shaped relative to latitude and monotonic with altitude for Gomphiocephalus hodgsoni ; and hump-shaped relative to longitude and monotonic with latitude, altitude and distance from the sea for Friesea grisea .
Main conclusions  No single distributional pattern was shared by the three species. While distributions were partially a response to climatic spatial clines, the patterns observed strongly suggest that past geological events have influenced the observed distributions. Accordingly, present-day spatial patterns are likely to have arisen from the interaction of historical and environmental drivers. Future studies will need to integrate a range of spatial and temporal scales to further quantify their respective roles.     

Considering of certain relevant information in the analysis of contingency tables. A three-step procedure

A heuristic three-step procedure for analysing multidimensional contingency tables is given to meet the requirements of a mixed analysis from both hypotheses-ruled and data-ruled type. The first-step provides the structure of relationships among the attributes by fitting an appropriate unsaturated log-linear model to the data of the given contingency table. Restriction to elementary hierarchical models allows to get them by combining pairs of conditional independence. The result of the first step may be regarded as a certain validisation of real model ideas. In the second step the significant pairs of conditional dependence are analysed in regard to the levels of the condition complex. Only such significant pairs are to be considered, in general, where the condition complex does not include the response variable. The third-step may test special subtests in that significant two-dimensional tables found in step two or may extend the general statements by partitioning, the corresponding test statistics in additive components. Application examples demonstrate the general line of action.     

The Power Function of the Test for ‘No Three Factor Interaction’ in 2×2×2 Contingency Tables

Three approximations to the power function of the chi-square test for the hypotheses of ‘no three factor interaction’ in a 2 × 2 × 2 contingency table are introduced and compared. The first method is based on the sampling distribution of the logarithm of the odds ratio, the second-on the non-central X² distribution and the third—on the conditional distribution of a cell entry. The last method is found to provide the closest approximation under various alternative hypotheses and sample sizes.     

Analysis of contingency table data on torus mandibularis using a log linear model

The hypothesized sexual difference in the incidence of torus mandibularis in Eskimoid groups, as well as age and group differences, was studied in two Northwest Territories Eskimo groups and in an Aleut group (examined by Moorrees). The data were analyzed using statistical methods new to the field of anthropology. The method analyzes data sampled from a multinomial distribution. A hierarchy of log linear models are fitted to the cell counts of a contingency table. An iterative proportional fitting procedure is used to obtain expected cell counts under each log linear model. The “goodness of fit” of each model is tested by the log likelihood ratio. This statistic can be partitioned into additive components such that differences between models can be tested. In this way a “best” model, from the hierarchy of models, is chosen. Among these three groups of Eskimos, the incidence of torus mandibularis was not affected by sex but was affected by age and was different between the three groups.     

Latitudinal gradients in onset date, onset temperature and duration of spawning of roach

Onset date, onset temperature and duration of spawning of roach Rutilus rutilus were related to latitude (40–66° N) and altitude (−1–825 m) based on data from the literature over the whole geographic distribution of roach. Onset date was positively and duration was negatively correlated with latitude, while no correlation was found between onset temperature and latitude. No significant correlations were found between any of the analysed variables of spawning and altitude, probably because most of the analysed populations were below 300 m altitude.     

Large‐scale patterns in genetic variation,gene flow and differentiation in five species of European Coenagrionid damselfly provide mixed support for the central‐marginal hypothesis

Recently, an increased effort has been directed towards understanding the distribution of genetic variation within and between populations, particularly at central and marginal areas of a species’ distribution. Much of this research is centred on the central‐marginal hypothesis, which posits that populations at range margins are sparse, small and genetically diminished compared to those at the centre of a species’ distribution range. We tested predictions derived from the central‐marginal hypothesis for the distribution of genetic variation and population differentiation in five European Coenagrionid damselfly species. We screened genetic variation (microsatellites) in populations sampled in the centre and margins of the species’ latitudinal ranges, assessed genetic diversity (H_S) in the populations and the distribution of this genetic diversity between populations (F_ST). We further assessed genetic substructure and migration with Bayesian assignment methods, and tested for significant associations between genetic substructure and bioclimatic and spatial (altitude and latitude) variables, using general linearized models. We found no general adherence to the central‐marginal hypothesis; instead we found that other factors such as historical or current ecological factors often better explain the patterns uncovered. This was illustrated in Coenagrion mercuriale whose colonisation history and behaviour most likely led to the observation of a high genetic diversity in the south and lower genetic diversity with increasing latitude, and in C. armatum and C. pulchellum whose patterns of low genetic diversity coupled with the weakest genetic differentiation at one of their range margins suggested, respectively, possible range shifts and recent, strong selection pressure.     

Geographic variation in breeding parameters of the Pied Flycatcher Ficedula hypoleuca

Variation in laying date, clutch-size and number of fledglings of the Pied Flycatcher Ficedula hypoleuca was studied in relation to altitude, habitat and latitude, using data from 99 breeding areas from 35̀ N to 70̀ N. Laying date significantly increased with altitude and showed a significant quadratic relationship with latitude, with the earliest values at about 50̀ N. This quadratic relationship shows the same pattern as the relationship between arrival time of adults on the breeding areas and latitude. Clutch-size variation was significantly related to altitude and habitat, small clutches being laid at high altitude and in coniferous forests. Number of fledglings was significantly affected by habitat type, with lower values in the coniferous than in the deciduous forest. Mean clutch-size and mean number of fledglings showed the same quadratic relationship with latitude. In contrast to some earlier studies, an increased clutch-size with latitude was found, mainly because of new data from areas in the southern part of the species' distribution.