排列法检测围隔生态实验中加磷对浮游植物结构的影响

分析了1997和1998年3次围隔实验中的浮游生物结构和环境因子，检验加P及赤潮前后的变化和对它们的影响。采用因子分析（EA）和关联分析（CA），得出浮游植物种类集合的序列，根据因子分析和关 联分析的前两个轴建立平面坐标，并用方差分析（ANOVA）检验其差异，探讨加P及赤潮相关的群落结构模式。建立种类序列坐标轴，为确定种对结构分散的重要程度评估提供 客观方法，并用方差检验差异确立加P发生赤潮和 分浮游植物的体积进行了测量，并用经验公式计算了单个细胞的碳含量。     

保护植物野生大豆群落不同物种间的生态关系分析

野生大豆(Glycine soja)为我国二级濒危保护植物.通过野外调查和室内实验,利用TWINSPAN分类、DCA间接排序和CCA直接排序的数量分析方法,定量研究了野生大豆群落分布与环境之间的关系.结果表明,TWINSPAN分类将106个样方分为4个群丛组,分别代表水库撂荒地、湿河床、较湿石质河床和较干土质河床4种不同的生境类型,不同的群从组在DCA排序轴上的位置基本反映出其分布与环境梯度的关系;进一步的DCA间接排序和CCA直接排序分析显示,土壤含水量和土壤养分是决定各个不同野生大豆群丛组分布的关键因子;最后通过建立野生大豆3个种群特征与DCA排序第一轴的回归关系分析,确定了盖度和重要值在反映野生大豆种群优势度上要优于高度.图4表1参19     

长江口邻近水域浮游植物群落动态变化及其环境因子的研究

根据1998-2003年长江口邻近水域(30°-32°N,121°27′-122°30′E),丰水期和枯水期10个航次、20个点位的海洋监测结果,对浮游植物动态变化及其环境影响因子进行了研究。6年内共检出浮游植物238种,其中大部分为硅藻。研究结果表明,深水航道附近水域中,浮游植物种类、丰度和生物多样性均呈下降趋势。相反,航道内浮游植物总丰度呈直线上升(R=0.81,P<0.05)。对航道内12个环境因子做主成分分析,盐度、溶解氧、硅酸盐和浊度为主要环境主要因子。其中浊度和硅酸盐与浮游植物群落变化关系密切,是影响浮游植物群落动态变化的关键因子,并受深水航道工程影响。     

Matching species traits to environmental variables: a new three-table ordination method

This paper addresses the question of studying the joint structure of three data tablesR,L andQ. In our motivating ecological example, the central tableL is a sites-by-species table that contains the number of organisms of a set of species that occurs at a set of sites. At the margins ofL are the sites-by-environment data tableR and the species-by-trait data table Q. For relating the biological traits of organisms to the characteristics of the environment in which they live, we propose a statistical technique calledRLQ analysis (R-mode linked toQ-mode), which consists in the general singular value decomposition of the triplet (R ^t D _I LD _J Q,D _q ,D _p ) whereD _I ,D _J ,D _q ,D _p are diagonal weight matrices, which are chosen in relation to the type of data that is being analyzed (quantitative, qualitative, etc.). In the special case where the central table is analysed by correspondence analysis,RLQ maximizes the covariance between linear combinations of columns ofR andQ. An example in bird ecology illustrates the potential of this method for community ecologists.     

On the Assessment of the Structural Organization of Phytoplankton (Lake Bol'shoe Miassovo,the Southern Urals)

Ordination methods were applied to the identification of structural units in the phytoplankton community. The groups of phytoplanktonic species identified by the time gradient and the method of cluster analysis of species lists were compared. The structural complexity of the phytoplankton community was evaluated using the index of cenotic significance (ICS) and derivative calculation coefficients. A high degree of similarity in the structure of dominance between the zooplanktonic and phytoplanktonic communities of the water body was revealed.     

赣江流域浮游硅藻功能群多样性及其水期演替的驱动特征

为了摸清我国南方丰水型河流流域重要的环境指示类群——浮游硅藻的功能多样性及其环境驱动要素,以赣江流域为例,采用国际上普遍认可的雷氏(Reynolds)、博氏(Borics)和帕氏(Padisák)分类体系进行浮游硅藻类群的系统研究. 结果表明:赣江流域共发现11个浮游硅藻功能类群(包含122种硅藻),并以MP、P、D和L_O类群物种最丰富,全年以MP、P、C和D类群占优势,不同水文期浮游硅藻优势功能类群存在明显分异,表现为丰水期以MP类群占绝对优势,枯水期以C和MP类群占共优势,平水期以则以C类群占绝对优势. 多元逐步回归分析发现,与丰水期占优势的MP、P、C和D类群密度呈显著相关的主要环境因子为纬度、ρ(Hg)、ρ(Zn)、pH和ρ(S2-),与枯水期占优势的C、MP、P和D类群密度呈显著相关的主要环境因子为ρ(Pb)、ρ(Cr6+)、纬度、ρ(BOD₅)、ρ(N)、ρ(P)和ρ(CN-),与平水期占优势的C、P和MP类群密度呈显著相关的主要环境因子为ρ(BOD₅)、ρ(Pb)、ρ(Hg)、ρ(Cd)和ρ(NH₄+-N)等.除趋势对应分析(DCA)和冗余分析结果显示,影响赣江流域浮游硅藻功能多样性的主要环境因子包括流域的经纬度、ρ(FC)(FC为粪大肠杆菌)、重金属含量〔ρ(Cu)、ρ(Pb)和ρ(Cr6+)〕、水位等(解释度达77.0%~90.4%). 研究显示,赣江流域浮游硅藻功能类群多样性及结构呈明显的季节性演替特征,南-中亚热带流域的纬度差异、气温的时空差异以及水位的水期波动、污染物年内排放节律等的共同作用会引起河流流域水体物理和化学生境的改变,这是促使浮游硅藻功能类群不同水期演替的重要原因.      

Shrub communities as inhibitors of plant succession in southern Quebec

The purpose of our research was to identify shrub species growing in southern Quebec that inhibit ecological succession in power-line corridors. Results are presented in three parts. First, clonal characteristics that allowed the establishment of stable communities were identified. Second, successional vector analysis identified those species that have the potential to inhibit succession. In poorly drained sites those species wereCornus stolonifera, C. obliqua, Salix petiolaris, andSpiraea alba. In well-drained sites, those species wereZanthoxylum americanum, Rubus idaeus, Spiraea alba, Rhus typhina, andThuja occidentalis. Third, analysis of variance showed that there is a significantly larger number of tree seedlings found in adjacent herbaceous communities than found under the dense cover ofCornus stolonifera, C. obliqua, Salix petiolaris, Spiraea alba, Rhus typhina, Rubus idaeus, Thuya occidentalis, andZanthoxylum americanum. These results indicate that the planting of selected shrub species could, through biological control, delay reforestation.     

The dynamics of shifting cultivation captured in an extended Constrained Cellular Automata land use model

This paper presents an extension to the Constrained Cellular Automata (CCA) land use model of White et al. [White, R., Engelen, G., Uljee, I., 1997. The use of constrained cellular automata for high-resolution modelling of urban land-use dynamics. Environment and Planning B: Planning and Design 24(3), 323–343] to make it better suited for modelling the dynamics of shifting cultivation. In the extended model the time passed since the last land use transition of a location is a factor of its land use potential. The model can now account for the gradual decrease in soil fertility after an area of forest has been cleared for cultivation and also capture the process of regeneration once the plot is fallowed. The model is applied for the Ruhunupura area of Sri Lanka where chena, a particular practice of shifting cultivation, is a common land use that dominates the landscape dynamics. The model is calibrated for the period 1985–2001 and the results are assessed in terms of location to location overlap as well as structural similarity at multiple scales. These results give confidence in the representation of land use dynamics for the main land use classes. On the basis of a long term scenario run for the period 2001–2030, it is verified that the model captures stylized facts related to chena dynamics, in particular shortening fallow periods and increasingly long cultivation periods of chena, as a result of increasing land use pressure.     

Convexity in projection matrices: Projection to a calibration problem

Convexity, as a fundamental property of sets and functions defined on convex sets, plays an important role in many mathematical and applied disciplines, including extremal and optimal-control problems. We prove the set of all feasible projection matrices in a general class of matrix models for stage-structured population dynamics to be convex and the dominant eigenvalue (λ₁) of any projection 2 × 2 matrix to be either a convex, or a concave function on a simplex of the matrix first-row entries (i.e., stage-specific reproduction rates). The latter is also conjectured for the general n × n case. Though looking far from practical needs of matrix population models, this mathematical result has appeared to be quite useful in solving a practical problem to calibrate the projection matrix, i.e., to estimate all the stage-specific vital rates, from empirical data. The data from monitoring of individual life histories of marked plants on permanent sample plots during successive years enable direct calculation of the stage-specific survival and ontogenetic transition rates, but the rates of reproduction do remain uncertain as far as the parent plants can hardly be determined for the (not yet marked!) recruitment.