异色瓢虫对白毛蚜捕食作用的研究

试验研究了异色瓢虫Leis axyridis(Pallas)各龄幼虫和戌虫对白毛蚜Chaitophorus po-pulialbae无翅成蚜的捕食功能反应及其成虫的寻找效应。功能反应均属Holling II型。异色瓢虫成虫寻找效应和自身密度之间的关系用Hasell & arley(1969)模型E=QP-m 和Beddington(1975)模型E=aT/［1+btm(P-1)]进行了模拟,Beddington模型更好地反映寻找效应和瓢虫密度之间的 关系。寻找效应与瓢虫成虫自身密度和蚜虫密度之间的关系用Bcddington(1995)模型E＝aT/[1+aT_mN十bt_m(P-1)]进行描述,表明寻找效应(E)随瓢虫密度(P)和猎物蚜虫密度(N)的增大而下降     

多粘菌素B对类囊体膜上M_g~(2+)-ATPase功能的影响及其作用部位

多粘菌素B抑制类囊体膜上的Mg~(2+)-ATP酶活力,且其部分抑制作用受控于高能态。如将酶反应速度和[Mg~(2+)ATP]的浓度作双倒数图,则可观察到多粘菌素B和[Mg~(2+)ATP]浓度之间存在着类似竞争的关系。再经用多粘菌素B抑制游离的β亚单位的活力。证明多粘菌素B在偶联因子上的作用部位是在β亚单位上。     

基于分位数回归的长白落叶松人工林最大密度线

基于东北地区378块固定样地和415块临时样地的调查数据和Reineke方程,利用线性分位数回归技术建立了不同分位点(τ=0.90、0.95、0.99)下的长白落叶松人工林最大林分密度与林木平均胸径的关系模型,选出拟合长白落叶松人工林最大密度线的最优模型. 利用人为选取最大的拟合数据,采用最小二乘(OLS)和最大似然(ML)回归同时建立最大密度线模型. 采用极值统计理论的广义Pareto模型推算现实林分特定径阶的极限最大株数,进一步建立极限密度线模型. 将线性分位数回归模型与其他方法进行对比.结果表明: 在全部径阶范围内选取5个最大数据点拟合的方法能够得到现实林分的最大密度线,选取的样点过多会使模拟结果偏离最大密度线,且ML法要优于OLS法. 分位点为0.99的线性分位数回归模型能够取得与ML接近的拟合结果,但分位数回归模型参数的估计结果更稳定. 人为选取拟合数据具有一定的人为性,最终选取分位点为0.99的分位数回归模型为拟合最大密度线的最优模型,参数估计结果为k=11.790、β=-1.586,极限密度线模型的参数估计结果为k=11.820、β=-1.594. 所确定的极限密度线位置略高于最大密度线,但二者差异不明显. 由固定样地数据的验证结果可知,所建立的最大林分密度线及极限密度线能够对现实林分的最大密度及极限密度进行预测,为长白落叶松人工林的合理经营提供依据.     

龟纹瓢虫对豆蚜的捕食功能反应及寻找效应研究

龟纹瓢虫雌虫和雄虫对豆蚜的功能反应符台Holling Ⅱ型模型,其模型为：Na=0．9233N／(1 0．0171N)(雌虫)和Na=0．8641N／(1 0．0164N)(雄虫),瓢虫捕食豆蚜的数量随豆蚜密度增加而增加．但寻找效应随豆蚜密度增加而降低。日最大捕食量和最佳寻找密度分别为37.42(雌)、34．11头(雄)和17．25（雌)、15．8头(雄)。龟纹瓢虫寻找效应随自身密度的增加而降低,其数学模型为：E=0．3032·P^-15634(雌)和E=0．3048·P^-1.1697(雄)。干扰反应的教学模型为：E=0．8104·P^-2.1721(雌),E=0．7125·P^-2.2660,E=0．5963·P^-2.1751(雌雄混台种群)。     

两种瓢虫对刺槐蚜的捕食作用

在实验室条件下研究了龟纹瓢虫成虫和异色瓢虫成虫对不同密度刺槐蚜的捕食功能反应,符合HollingⅡ 型功能反应模型,其模型分别为:Na=0.4050/1+0.0073N和Na=0.4227N/1+0.0046N,x2值均小于X20. 05=9.49,最大捕食量分别为55.6头和90.9头.圆盘方程理论值与实测值相符.随着瓢虫密度的增加,单个瓢虫捕食率下降,龟纹瓢虫和异色瓢虫自身密度的干扰效应模型分别为:E=0.208P-0.235,E=0.236P-0.324.     

改进的IWAO M—M模型

按照Iwao,倘若?_b/m_b是常数,?=α+βm是线性的。但在自然界,?-m。往往不是线性的,β也不是常数,因此,Iwao的模型有明显的局限性。 我们将β做为m的函数:β=β′+γm。这样,改进模型就是: ,?=α′+β′m+γm~2其中; α′:每个基本成分中个体数的分布的平均拥挤度。 β′:在低密度下基本成分分布的相对聚集度。 γ:基本成分的分布的相对聚集度随种群密度而变化的速率。 本文以温室白粉虱及棉铃虫种群做了例证研究。 结论是: (1)改进的Iwao模型克服了Iwao方法的局限性。既可用于?—m呈线性关系时,也可以应用于?—m呈非线性关系时。因此,改进模型能更准确地描述?和m之间的关系。(2)某种群属随机分布若近似于随机分布时(α′→0,β′→1,γ→0),改进模型可以被原Iwao模型所代替或近似。若在某些种群中,种群密度对基本成分的相对聚集度没有影响(即γ=0),则改进模型就是原Iwao模型。由此可见,Iwao模型是改进模型的一个特例。(3)改进模型的3个参数α′、β′、γ均有其特定的生物学含义,可用于探讨和分析种群的空间格局。此方法不但能提供有关分布的基本成分,基本成分的分布的情况,而且能提供有关基本成分的分布随密度而变化的信息。     

蝇蛹金小蜂对桔小实蝇蛹的寄生功能反应

在温度25±1℃、相对湿度70±5%、光照周期（L∶D）14 h∶10 h条件下,研究了蝇蛹金小蜂对桔小实蝇蛹的寄生功能反应及干扰效应。结果表明,寄主密度、寄主日龄均影响寄生蜂的寄生效能。蝇蛹金小蜂对桔小实蝇2日龄（N=2）、4日龄（N=4）蛹的寄生功能反应均符合HollingⅡ模型,其方程分别为Na= 0.4494N2/ (1+ 0.0294N2)、Na= 0.5586N4/ (1+ 0.0253N4)。24h内单头雌成蜂最多可寄生2日龄、4日龄蝇蛹数量分别为15.29、22.08头。自身密度对蝇蛹金小蜂寄生产生一定的干扰效应,其干扰效应符合Hassell－Varley模型（a= 0.0719P－0.2526）,表明蝇蛹金小蜂雌蜂的发现域随着自身密度的增加而逐渐变小,雌蜂个体间干扰效应降低了寄生效能。     

I-69杨竞争密度效果分析

用竞争密度效果的倒数式分析了I－69杨（Populus deltoids）的生长过程。随着时间的推移,C－D线在双对数图上向上移动。生物时间τ（τ被定义为逻辑斯蒂生长曲线中生长系数λ（t）的积分）与物理时间t的关系可以用双曲线方程表示。C－D效果倒数式（即1／w＝Aρ＋B,式中w和ρ分别代表平均单株材积和密度）中的系数A和B被求出。随着生物时间τ的增加,系数A急剧增另到最大值后逐渐下降。而系数B呈指数下降,倾向于接近零。随着林分的生长,生长系数λ（t）倾向于下降。     

中华通草蛉幼虫对麦蚜捕食作用的初步研究

室内试验研究了中华通草蛉Chrysoperla sinica(Tjeder)(Neuroptera:Chrysopidae)1～3三龄幼虫对麦蚜Phopalosiphum padi(Linnaeus)的功能反应、二龄幼虫自身密度干扰作用和种内干扰效应.研究结果表明,幼虫的功能反应均属HollingⅡ型,日最大捕食蚜虫量1～3龄分别为331头、470头和767头,功能反应的参数表明中华通草蛉幼虫对麦蚜具有很大的捕食潜能.二龄幼虫自身密度干扰作用分别用Hassel&Varley的模型E=QP-m和Beddington的模型E=at/(1+btw(P-1))进行模拟,模拟模型分别为E=0.555P-0.765和E=0.515/(1+0.551(P-1)),结果表明:随着二龄幼虫密度的增大,其捕食作用率随之减少.二龄幼虫的种内干扰效应试验表明,在捕食过程中捕食者密度的增大和蚜虫数成倍增加的时候,其捕食作用率仍然显著下降.     

知母皂苷元对痴呆模型大鼠脑内M受体密度分布的影响

目的：观察知母皂苷元对痴呆大鼠模型脑内M受体密度分布的影响。方法：单侧基底核内联合注射β-淀粉样肽25-35片段(Aβ25-35)和兴奋性氨基酸建立大鼠痴呆模型．然后将模型动物分为假手术组、模型组和ZMS组,采用放射配基结合分析法测定皮层、海马和纹状体中的M受体密度。结果：脑内联合注射Aβ和Ibotenicacid(IBO)后,模型大鼠脑内有明显的Aβ斑块沉积．同时上述的三个区域中的M受体密度明显比假手术组减少,而模型大鼠喂服知母皂苷元60天后,能有效地增加模型大鼠脑内不同区域中的M受体密度。结论：知母皂苷元能使痴呆动物脑内M受体密度增加。说明它对老年性痴呆的胆碱系统功能渐进性退化有一定的预防和治疗作用。     

The significance of the asymmetric effect of crowding for coexistence in a mixed temperate forest

Abstract. The coexistence of coniferous (mostly Abies homolepis) and broad-leaved tree species (mostly Fagus crenata) in a mixed temperate old-growth forest in Japan was simulated by a size-structure dynamics model incorporating the asymmetrical (one-sided) effect of shading between these two life-form guilds. The model assumes that the crowding effect due to one-sided competition for light on a tree of a given size regulates the rate of size growth and recruitment. The cumulative basal area of trees larger than a given tree in the forest is employed to express the intensity of one-sided competition on that tree. Cumulative basal areas of both guilds negatively affected the growth rate of any tree. The shading effect by conifers on the growth rate of either guild was stronger than that by broad-leaved species. Two types of model were tested for recruitment; an additive and a reciprocal model. A reciprocal model, where basal area density of conifers and broad-leaved species has a negative effect on the recruitment of its own guild but has a positive effect on that of the other guild, fit the observed data better than an additive model where total basal area of the two guilds suppresses recruitment rates. Simulations using these models showed that, within a particular range of the set of recruitment rates, the two guilds could coexist. The tendency for reciprocal replacement, incorporated in the reciprocal model, substantially widened the range of coexistence and shortened the time required for convergence.     

Theoretical considerations on the C-D effect in self-thinning plant populations

A model for describing the competition–density (C-D) effect in self-thinning populations was developed on the basis of the following three basic assumptions: (1) the growth of mean phytomass follows a general logistic equation; (2) final yield is independent of initial population density; and (3) there exists a functional relationship between actual and initial population densities at any given time. The resultant equation takes the same reciprocal form as the reciprocal equation of the C-D effect derived from Shinozaki–Kira's theory (i.e., the logistic theory of the C-D effect), which deals with the density effect in nonself-thinning populations. However, one of the two time-dependent coefficients is quite different in mathematical interpretation between the two reciprocal equations. The reciprocal equation for self-thinning populations is essentially the same as the reciprocal equation assumed in the derivation of the functional relationship between actual and initial population densities. The establishment of the reciprocal equation is supported by the empirical facts that the reciprocal relationship between mean phytomass and population density is discernible in not only nonself-thinning populations but also in self-thinning populations. The present model is expected to systematically interpret underlying mechanisms between the C-D effect, which is observed at a time constant among populations with various initial densities, and self-thinning, which is observed along a time continuum in a given population. Received: August 5, 1998 / Accepted: January 7, 1999     

Density-dependence and co-existence of conifer and broad-leaved trees in a Japanese northern mixed forest

Abstract. The growth and survival of coniferous trees (particularly Abies sachalinensis) and broad-leaved trees (particularly Quercus crispula) were followed over a 15-yr period in a 15.5-ha area in a northern mixed forest in Japan, and the coexistence of the two groups was simulated by a density-dependent projection matrix model. The density-dependent model assumes that the density effect of mother trees due to one-sided competition for light on smaller-sized tree regulates the demographic functions. The mother tree densities of conifers and broad-leaved trees have stronger negative effects on the recruitment and survival of seedlings of their own group than of the other group. These results support the idea of reciprocal replacement for conifer and broad-leaved trees. Simulations using the density-dependent model showed that the two groups will co-exist within a particular range of recruitment rates. However, the density of both groups did not affect the growth rate of any tree, and equilibrium DBH-distributions from density-dependent matrices were quite different from present distributions both for conifers and broad-leaved trees. On the other hand, equilibrium DBH-distributions of conifer and broad-leaved trees from density-independent matrices were quite distinct from each other, reflecting different survivorship curves of the two dominants. These results suggest that density-dependent processes are not so important for shaping population structures in this northern mixed forest.     

The crowding effect in an artificially mixed population of three species

Three species of root vegetables and leaf vegetables were grown in mixed stands at various densities and mixing ratios in tow experiments. The reciprocal equation of the crowding effect for two-species mixtures was utilized for the three-species mixtures. Interactions between species in two- and three-species mixtures were compared using a density conversion factor which converts the density of one species to the density of the other species on the basis of its effect on the growth of the species. The mean plant weights in a three-species mixture could be estimated by putting the density conversion factors obtained from two-species mixtures into the reciprocal equations for a three-species mixture.     

山杨林林分密度效应动态模拟

 本文用林窗模型研究了小兴安岭南坡山杨林林分密度动态过程,在给定林分初始条件后,模拟了林分密度、断面积、生物量、叶面积指数和生产力150年的变化。用林分密度效应的3/2法则和产量恒定法则检验模拟林分,结果表明模拟林分密度发展与理论预测相符合。通过本文的研究既检验了林窗动态模型又印证了林分密度效应理论。     

基于线性分位数混合效应的辽东山区红松冠幅模型

冠幅是反映单木生长状态及构建林木生长收获模型的重要变量。本研究以辽东山区大边沟林场10～55年生红松人工林为对象,基于66块固定样地的2763株红松的每木检尺数据,选取冠幅基础模型,采用再参数化的方法引入单木竞争指标(R_d),利用哑变量的方法引入了林分密度、林层变量,构建不同分位点(0.50、0.90、0.93、0.95、0.96、0.99)的冠幅分位数回归模型,并与传统方法进行比较,选取模拟林分最大冠幅的最优分位点。为反映林分中单木冠幅在林木个体之间的差异,建立了基于样地水平的最优分位点的线性混合效应分位数回归冠幅模型,分析各变量对单木冠幅的影响。结果表明: 基于F统计检验,不同林分密度和林层的冠幅模型具有显著差异,在基础模型中引入林层、林分密度和竞争后,模型R_a²提高0.0104,均方根误差降低0.0115,均方误差降低为7.4%;与最小二乘法比较,分位数回归模型能够较好地模拟林分状态下的单木最大冠幅,并选出0.96分位点和0.93分位点作为上林层和下林层的分位数回归模型的最优分位点。引入混合效应的线性分位数回归模型的赤池信息准则、贝叶斯信息准则、HQ信息准则等评价指标优于传统分位数回归,参数标准误显著降低,混合效应的引入很好地解释了样地之间的差异。就上林层和下林层而言,林分密度越大,最大冠幅越小;相对直径越大,最大冠幅越大,其中林分密度对下林层的冠幅影响大于上林层,当林分密度足够大时,冠幅随着胸径的增大先增大后降低。本研究构建的基于混合效应的分位数回归模型能有效提高模型的拟合优度,今后可通过调控林分密度、适度抚育间伐等措施,实现对辽东山区红松人工林的科学营建和可持续发展。     

北京地区侧柏人工林密度效应

密度是影响森林尤其是人工林生长的重要因素,林冠层是森林生态系统与其他系统进行能量和物质交换的重要场所,树木及树冠生长对林分密度的响应关系可以看作是生物对环境变化产生的适应性现象。林分密度效应是生态学和森林培育学的重要研究内容之一。以23块8种不同密度梯度的北京山区侧柏人工幼龄林林分为研究对象分析其树木生长及树冠生长对密度的响应关系,其中树冠指标使用了参照了美国林务局(USDA)的树冠调查指标。研究结果表明:(1)林分平均胸径、平均树高和平均冠幅生长均随密度增大而减小,林分密度大于3000株/hm2时各指标减小的趋势变缓,使用异速生长模型可以很好地拟合这种变化关系;(2)随密度增加,树冠水平方向和垂直方向生长均到显著地抑制作用,树冠外形表现出由饱满冠型向狭长冠型变化的适应性现象;(3)使用树冠二维、三维指标与密度进行相关性分析可知树冠长度、树冠率等指标与林分密度呈负相关关系,树冠圆满度及树冠生产效率与密度表现出极显著正相关关系;(4)采用枝解析的方法研究了树枝长度、材积的平均生长量、连年生长量与密度的关系,结果表明幼龄期各生长量差异不大;(5)在建立冠幅模型时考虑了自变量间的多重共线性问题,所建的胸径单自变量二次方模型能够很好地预测侧柏人工幼龄林冠幅生长过程,模型相关系数R2为0.961。     

Simulating Stationary Size Distribution of Trees in Rain Forests

A simple dynamic model of the distribution of tree size (trunkdiameter) in natural rain forests is presented. Based on dataof permanent plot measurements in a tropical rain forest anda warm-temperate rain forest, the cumulative basal area densityof trees larger than a given tree, at any particular time, isused to express the effect of suppression, or one-sided competition,on the growth rate of that tree. It also shows that increasingthe basal area density of all trees in the stand depresses therate of recruitment from the pool of seedlings. Mortality istreated as independent of the cumulative basal area. Simulationwith the model, applying the one-dimensional drift-diffusionequation, reproduces the observed course of reforestation afterclear-felling and leads to convergence to a unique stationarysize distribution by 200 years. This concuts with the size distributionobserved in primary forest stands. The present model representsan extension of density-dependent population growth models tosize-structured tree populations. Competition, cumulative basal area, density dependence, equilibrium, population, simulation, size distribution, tropical rain forest, warm—temperate rain forest     

桤柏混交林密度变化规律的人工神经网络模型研究

本文应用人工神经网络方法建立了桤柏混交林密度变化的神经网络模型,并与传统模型进行了比较,仿真结果表明,人工神经网络模型可适用于桤柏混交林密度变化规律描述,且优于传统模型,从而丰富和发展了森林稀疏规律理论。     

杉木竞争密度效果分析

用竞争密度(CD)效果的倒数式分析了杉木的生长过程.随着时间的推移,CD曲线在双对数图上向上移动.随着物理时间t的增加,生物时间τ(τ被定义为逻辑斯蒂生长曲线中生长系数λ(t)的积分)倾向于增加到最大值.CD效果倒数式中的系数A和B被求出.随着生物时间τ的增加,系数A急剧增加到最大值后下降,倾向于稳定在一个常数,而系数B呈指数下降,倾向于接近零.随着林分的生长,生长系数λ(t)倾向于下降.