松嫩平原碱化草甸天然翅碱蓬种群的密度制约模型

翅碱蓬是一年生藜科植物,耐碱性极强。本文根据在单—种群落随机取样的调查数据,从种群水平分析了松嫩平原碱化草甸天然翅碱蓬种群的密度制约特征。结果表明,翅碱蓬种群在不同生长期及不同数量性状的密度制约模型均可由多种函数形式同时较好地表达出来。但本文仅以相关性最好的拟合方程作为种群某一性状密度制约特征的模型。孕蕾期的平均植株重和单位面积籽实重的密度制约表现为变形双曲线函数y=a+b/x形式;籽实成熟期的平均植株重、平均植株籽实重、平均植株种子数和单位面积种子数均表现为幂函数y=ax-b形式;地上生物量在孕蕾期为变形双曲线函数y=1/(a+bx)形式,在籽实成熟期为对数函数y=a-blnx形式。     

松嫩平原碱化草甸天然碱地肤种群的密度制约规律

 本文以两个生长季的调查测定为基础,分析了松嫩平原碱化草甸天然碱地肤种群不同数量性状的密度制约规律及其数量调节机制。两个生长季取样合并拟合的幂函数模型,是碱地肤种群平均植株重、平均植株籽实重、单位面积籽实重、籽实重比率以及在籽实成熟期的地上生物量等性状密度制约的最好描述模型。综合分析的结果表明,环境容纳量随环境条件而变化,在环境容纳量和密度制约上,两个生长季均表现为籽实成熟期比开花期大。密度制约作用是一个连锁反应过程,碱地肤种群最终是以增减对生殖生长能量分配的生殖对策来实现其种群的数量调节。     

Competitive regulation of plant allometry and a generalized model for the plant self-thinning process

Taking into account the individual growth form (allometry) in a plant population and the effects of intraspecific competition on allometry under the population self-thinning condition, and adopting Ogawa's allometric equation 1/y = 1/axb + 1/c as the expression of complex allometry, the generalized model describing the change mode of r (the self-thinning exponential in the self-thinning equation, log M = K + log N, where M is mean plant mass, K is constant, and N is population density) was constructed. Meanwhile, with reference to the changing process of population density to survival curve type B, the exponential, r, was calculated using the software MATHEMATICA 4.0. The results of the numerical simulation show that (1) the value of the self-thinning exponential, r, is mainly determined by allometric parameters; it is most sensitive to change of b of the three allometric parameters, and a and c take second place; (2) the exponential, r, changes continuously from about -3 to the asymptote -1; the slope of -3/2 is a transient value in the population self-thinning process; (3) it is not a 'law' that the slope of the self-thinning trajectory equals or approaches -3/2, and the long-running dispute in ecological research over whether or not the exponential, r, equals -3/2 is meaningless. So future studies on the plant self-thinning process should focus on investigating how plant neighbor competition affects the phenotypic plasticity of plant individuals, what the relationship between the allometry mode and the self-thinning trajectory of plant population is and, in the light of evolution, how plants have adapted to competition pressure by plastic individual growth.     

The 'ghost of settlement past' determines mortality and fecundity in the barnacle, Semibalanus balanoides

Intraspecific competition is common in many organisms. For many sessile marine invertebrates high settlement densities can lead to competition with conspecifics that can affect the probability of mortality, morphology, and reproductive output. This work aims to determine the affect of recruit density on shell morphology and fecundity and the temporal nature of intraspecific competition for the acorn barnacle, Semibalanus balanoides . Two tile arrays were used; experiment 1 was deployed at the start of the settlement season (43,264 recruits, 4.1% survivorship to adult), experiment 2 was deployed in the middle of the season (5,454 recruits, 42.8% survivorship). Experiment 2 displayed density dependent mortality between recruits and juveniles and adults, whereas no relationship was found for exp. 1. Experiment 2 had higher egg production per individual, but also higher egg production per area of tile compared to exp. 1. A negative relationship was found between recruit density and egg production, however during the summer period, this relationship switched to a positive relationship between juvenile density and egg production, due to high mortality on tiles with high recruit density. Cumulative population density (CPD) was calculated as the cumulative mean density of barnacles per cm^-2 of tile and was used as an index of intraspecific competition. There was a linear negative relationship between mass of eggs per individual and CPD. However, CPD over the summer period more fully explained egg production per individual. A time window was identified when cumulative intraspecific competitive effects were shown to have a strong negative effect on egg production and an increase in mortality, causing a flip from density independent fecundity to density dependent fecundity. These results suggest that recruit density is an important driver of subsequent population processes.     

Food limitation of population density in the orb-wed spider,Nephila clavata

Field studies were conducted to clarify whether variation in food availability among habitats influences population density, and whether population density has a negative effect on foraging success in the orb-web spider, Nephila clavata. Lifetime food consumption per individual (i.e., foraging success) strongly correlated with mean body size of adult females and mean fecundity in populations. Also, there was a positive correlation between foraging success and population density. Since foraging success reflected potential prey availability in the habitat, food resource appeared to be a limiting factor for populations in this spider. Mean fecundity per individual correlated with population density of the following year, suggesting that decreased reproduction is a major component of food limitation on population density. Consistent defferences in mean body size between particular sites were observed over years, while such difference was less obvious in density. Thus, ranking of food abundance among habitats seems to be predictable between years. A field experiment revealed that an artificial increase in population density had no negative effect on the feeding rate of individuals, suggesting that intraspecific competition for food is not important in this species.     

笼养褐马鸡冬季的社群等级

本文用BBS方法（Batchelder-Bershad-Simpson Scaling Method)对笼养褐马鸡的社群等级进行了排序,发现其等级制度为近单线式。成鸟的等级明显高于亚成体,成年雄鸟的等级明显高于成年雌鸟,成年个体的等级与体重呈显著正相关,与面部红斑大小及耳簇羽长呈极显著正相关,全体14只鸟的体重与体长及耳簇羽长呈显著正相关,与面部红斑大小呈极显著正相关。体重可以认为是直接与个体的争斗实力相关的参数,而面部红斑大小,耳簇羽长则可能是个体争斗实力的外在信号,在体重相近的雌性个体中,面部红斑和耳簇羽对社群等级有很大的影响。褐马鸡的争斗炫耀可能是以面部为中心的。     

Effects of simulated herbivory on tillering and reproduction in an annual ryegrass,Lolium remotum

This study examined the overall impact of simulated herbivory on tillering and reproductive performance of an annual ryegrass,Lolium remotum. The interaction between herbivore damage and intraspecific competition and the effect of the timing of damage were also studied. The experimental plants were sown at two densities and were randomly assigned to eight different damage treatments consisting of artificial leaf area removal by clipping with scissors or removal of one-third of the ripening seeds. The treatments were executed at two flowering stages. The pattern of tiller development differed significantly among treatments and between densities. At the lower density, earlier treatments delayed tiller development more than the same treatments executed later. At the higher density, all treatments delayed tiller development. The density effect was significant for all reproductive traits measured. The reproductive output of plants grown at the higher density was lower and the negative treatment effects were stronger than at the lower density. The treatment effect was significant for seed dry weight per plant and individual seed weight but not for number of seeds per plant. There were no statistically significant interaction effects between the damage treatments and density, suggesting that the plants responded to the damage similarly, irrespective of the density. The plants did not totally compensate for losses due to damage at either density, even though they slightly increased their resource allocation to sexual reproduction at the higher density.     

海南岛南湾半岛猕猴(Macaca mulatta)种群数量动态及分布

自1981年以来,对海南岛南湾半岛猕猴进行了连续5年的调查研究。归纳1965年到1984年底的材料,该种群从100只发展到930只,其间种群的年均增长率为13％,种群增长率受着种群密度的制约,密度与增长率间存在着关系式y=-0.0003x~2+0.0857x+0.3534。该种群生长曲线可表示为指数函数式y=0.1253e~(0.1046x)或为Logistic曲线N=1850/1+e~(11.28-0.13x)。该半岛猕猴最大容纳量为1850只。各猴群的弹性核域受猴群密度和植被质量的影响,绘出了它们之间的关系图。     

丘陵红粘土旱地冬小麦根系生长规律的研究

 对豫西丘陵红粘土旱地小麦根系生长规律进行的研究结果表明：初生根、次生根长度和根条数均随生育期后延而增加,根系最大入土深度可达340cm,根系生物量(Y,kg·hm-2的增长为5次曲线方程：Y＝495.195-40.980X+1.3530X2-0.014985X3+0.0000699X4+0.000000116X5,表现出越冬前和冬后至抽穗期两个增长高峰,各生育期根条数和根系生物量在土体中的分布均符合Y=ae-bx的由上到下的负指数递减方程;土壤含水量与根系生长的关系表现为,当土壤含水量低于16％时,根系和地上部分均不能正常生长,根系入土深度(Y,cm)和根尖处土壤含水量(X,％)的函数关系为：Y＝2.009e0.2204X;次生根的发生与主茎叶片数没有明显的对应关系,而与分蘖的发生相对应,根系干物质积累与地上部分干物质积累存在着正向协同关系;初生根条数增加可显著增加成穗数,次生根条数增加则主要对穗粒数和千粒重有促进作用;用叶面宝、磷酸二氢钾等微肥、激素浸种可有效增加根的数量和根系入土深度,促进根系干物质和地上部分干物质的积累,增加成穗数和穗粒数,显著提高小麦产量。     

THE NATURAL CONTROL OF POPULATIONS OF BUTTERFLIES AND MOTHS

1. Life-table data for 14 species of Lepidoptera are analysed by the k -factor technique of Varley & Gradwell (1960). Two factors are shown to be of particular importance in determining fluctuations in abundance from one generation to the next. These key factors are predators and the failure of females to lay their full complement of eggs.
2. Data from 24 studies are reviewed to identify any density-dependent factors that would be capable of regulating the populations about an equilibrium density. In eight studies no density-dependent relationships could be identified, and in a further 13 the only density dependence demonstrated was due to intraspecific competition for resources. It is argued that competition is incapable of regulating populations at low density. In the other three studies, natural enemies are thought to be acting in a density-dependent manner, but their ability to regulate the populations is questioned.
3. The frequency of over-population and of extinction is reviewed and both appear to occur frequently in Lepidoptera. This, coupled with the failure of most studies to demonstrate the existence of density-dependent processes capable of regulating populations, leads the author to reject the model of regulation about an equilibrium density in favour of a model of population limitation by a ceiling set by resources.
4. Fluctuations in resource availability may be important in determining variations in the abundance of many Lepidoptera, but at present too few ecologists have quantified the carrying capacity of habitats occupied by the species they study to generalize about this.