华东地区青冈种群的等位酶变异

华东地区６个青岗种群等位酶变异的检测结果表明,青冈种群的遗传变异较大,每位点含有的等位基因较多,平均为２．３个,种水平的平均每位点等位基因数目为２．４。种群水平有效等位基因数目为１．４４６,种水平为１．４６７。Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡检验表明,青冈种群中不少位点偏离该平衡,其原因是种群内含有较多的纯合子,表现为多数位点的固定指数大于０,其中有９个位点的固定指数与０的偏差达到显著水平。     

格氏栲种群调节模型的研究

在前人对植物种群自然稀疏过程的研究基础上,结合自适应通用增长模型,推导出一种能描述密度变化全过程的理论模型,ｌｎＮ＝ａｌｎ＾２Ｓ＋ｂｌｎＳ＋ｃ,其中Ｎ和Ｓ分别为种群密度和单株基面积,ａ、ｂ、ｃ为参数。     

黄山钓桥青冈种群的交配系统与近交衰退

采用垂直板型不连续聚丙烯酰胺凝胶电泳检测了黄山钓桥青冈种群的遗传变异、交配系统及近交衰退程度。黄山钓桥青冈群维持有中等程度的遗传变异,多态位点百分比和期望杂合度分别为５０％和０．１８１４。采用ＰＯＤ－２、ＥＳＴ－１和ＥＳＴ－２等３个多态位点,利用ＭＬＴ程序估计的花粉库和母株基因频率之间存在一些差异,可能是由于成熟个体花粉产量不同和种群内个体非随机分布造成的。单位点杂交率平均为０．３９２,略高于多位     

黄山西坡青冈种群结构与分布格局研究

黄山西坡青冈种群结构与分布格局研究陈小勇,张庆费,吴化前,宋永昌（华东师范大学环境科学系,上海,２０００６２）ＡＳＴＵＤＹＯＮＴＨＥＳＴＲＵＣＴＵＲＥＡＮＤＳＰＡＴＩＡＬＰＡＴＴＥＲＮＳＯＦＣＹＣＬＯＢＡＬＡＮＯＰＳＩＳＧＬＡＵＣＡＰＯＰＵＬＡＴＩＯ...     

密度因素在布氏田鼠种群调节中的作用

对布氏田鼠栖息密度不同的种群同时进行取样,研究密度因素对布氏田鼠种群发展的调节作用。结果表明,在高密度区布氏田鼠种群繁殖强度受到抑制,雌鼠怀孕率、雄鼠睾丸下降率、贮精囊肥大率和睾丸长度都小于低密度种群。高密度种群繁殖季节结束时间早于低密度种群,幼鼠肥满度较小,性成熟速度较慢,种群年龄结构中,幼年鼠所占比例小于低密度种群。这些都是导致高密度种群增长速度减慢的因素。     

中国东部亚热带青冈种群叶片的生态解剖

运用生态解剖学的方法对我国亚热带东部分布的１０个青冈种群叶片的解剖特征进行了比较分析,结果如下：①青冈叶片结构在种群间存在着广泛的差异,这种差异是青冈适应不同环境条件的结构基础。青冈叶片各部分结构特征在种群间的变化不晃同步的,变异系数（ＣＶ）在６．０％～２０．５％之间;变异幅度最大的是栅栏组织和上角质膜厚度,最小的是下表皮厚度。②相关分析表明,温度和降雨是影响青冈叶片地理变异的主导因子,其中温度、     

昆明西山滇青冈林内滇青冈种子库动态的研究

通过对昆明西山滇青冈林内滇青冈种子库的跟踪取样调查和种子埋藏试验,对滇青冈种子库的动态进行了研究。昆虫在种子成熟前侵入种子,经种子雨进入种子库时已有71.8%的种子失去萌发能力。种子雨输入种子库的绝大部分种子停留在表面种子库,其中48.55%的种子被虫害,25.36%被某些非生物或生物搬运,17.39%的腐烂,8.7%的被动物当场取食,没有种子萌发,影响种子库动态的各种因子的作用大小在时间上是变化。被搬运的种子中,有4.9%的由表面种子库转移到埋藏种子库。土层是滇青冈种子的安全生境,土壤种子库的存在时间超过250天。埋入土壤的试验种子一直处于静止状态,到6月雨季后有80%种子萌发,20%的腐烂。萌发种子数是当年产种子的0.26%。滇青冈林内的滇青冈种子库是季节性的,种子库对种群个体的补充作用是有限的。     

洪水干扰对青冈群更新的影响

本文在安徽黄山选择位于溪谷,受洪水干扰程度不同的３个样地,调查青冈种群的更新特征,结论如下：１．从幼苗数量来看,受洪水影响最轻的样地３个最多,密度为０．５８２５株ｍ＾－２,洪水影响最严重的样地１数量最少,密度仅为０．１１５０株ｍ＾－１,从幼苗性质来看,样地１萌生苗比率最高,３个样地中,随着高度级别增加,萌生苗的比例也增加。２．萌生苗高度的分布接近于对称的低峰分面     

青冈种群克隆多样性及其与环境因子的关系

 采用等位酶分析测定了6个青冈种群的克隆多样性。种群和种水平上每基因型含有的个体(克隆分株)数分别为1.270和1.508。青冈种群中克隆多样性较高,Simpson’s指数平均为0.9882,均匀度平均为0.7921。81.3％的基因型为局部分布,仅有1种(0.5％)基因型分布于75％以上的种群中。相关分析表明Simpson’s指数与总氮含量呈显著的负相关(P<0.05),与其他环境因子的相关性不显著。     

The demise of the population regulation controversy?

For many decades a controversy in population dynamics theory has been raging concerning whether or not populations are regulated by density dependent factors, without reaching a satisfactory conclusion. It is suggested that this failure to solve the problem is due to asking the wrong question and it is suggested that this controversy should be buried and forgotten.     

古田山青冈林优势种群生态位特征

利用样方法进行野外调查,每个样地大小20 m×20 m。采用生态位宽度、生态位相似比例和生态位重叠值公式统计分析了古田山自然保护区青冈林优势种群生态位特征。结果表明,古田山青冈林中青冈、马银花、木荷、甜槠、麂角杜鹃等具有较大的生态位宽度,其Bi、Ba分别为0.7974、0.6435、0.6272、0.5908、0.5783和0.7770、0.4012、0.4745、0.4171、0.4303;而光叶石楠和栲树的生态位宽度较小,Bi、Ba仅为0.3966、0.2716和0.1441、0.0825。生态位宽度大的种群间生态位相似比例较高,如青冈与马银花、麂角杜鹃的生态位相似比分别为0.6134、0.6056;反之则低,如光叶石楠和栲树生态位相似比为0.1039。生态位重叠与生态位宽度有一定的联系,高生态位宽度种群间的生态位重叠通常较大,反之则低。     

桂林岩溶石山青冈栎群落的数量分析

应用双向指示种分析(TWINSPAN)和除趋势对应分析(DCA)方法对桂林岩溶石山青冈栎群落进行数量分类与排序。通过TWINSPAN分类,将青冈栎群落60个样方划分为8个群丛类型,探讨了各群丛类型的基本特征。结果表明:DCA排序与TWINSPAN分类结果较一致,DCA排序较好地体现了各群丛类型与环境因子的相互关系,DCA第一排序轴主要反映了坡度的变化梯度;DCA排序图的对角线基本体现了坡向的变化梯度。坡度的变化是影响岩溶石山青冈栎群落物种组成与分布的重要生态因子。     

桂东北山地五列木种群结构与动态的初步研究

根据四个代表性样地的典型取样资料,运用数学分析方法,研究桂东北山地五列木种群的结构与分布格局及其动态。结果表明,五列木的重要值远高于群落中其它种类,优势度十分突出,为优势种群;分布格局呈聚集分布,其成因主要是由环境因子的影响所决定的;幼树数量大,种群的年龄结构呈发展型。     

Density-dependent population dynamics in clonal organisms: a modelling approach

1. Density dependence may act at several stages in an organisms life-cycle (e.g. on mortality, fecundity, etc.), but not all density-dependent processes necessarily regulate population size. In this paper I use a density manipulation experiment to determine the effects of density on the transition rates between different size classes of the clonal zoanthid Palythoa caesia Dana 1846. I then formulate a density-dependent matrix model of population dynamics of Palythoa , and perform a series of sensitivity analyses on the model to determine at what stage in the life-cycle regulation acts.
2. Seven of the 16 transition probabilities decreased with density, most of them being shrinkage (due to loss of tissue or fission) and stasis (the self–self transition) of medium and large colonies. The only probability to increase was for the stasis of large colonies. Recruitment was quadratically dependent on density, peaking at intermediate densities.
3. Equilibrium cover in the model was 84% and was reached in ≈40 years. To determine which density-dependent transitions were involved in population regulation, the strength of density dependence was varied in each independently. This sensitivity analysis showed that only changes in the probabilities of large colonies remaining large and producing medium colonies, were regulating.
4. These results suggest that regulation is primarily acting on fission of large colonies to produce intermediate-sized colonies, in combination with size specific growth rates. Fission rates decrease greatly with density, resulting in a greater proportion of large colonies at high densities and large colonies grow more slowly than small. Overall, this behaviour is very similar to that of clonal plants which have a phalanx type life history.     

青冈种群的能量积累

１引言青冈（Ｃｙｃｌｏｂａｌａｎｏｐｓｉｓｇｌａｕｃａ）种群的能量积累,是能量代谢的主要部分。能量积累过程是通过植物的三大生理代谢活动之一光合作用而实现的。在研究了青冈林能量环境的基础上,对植物的光合作用进行了测试和分析,从而阐明了能量积累的规律。青...     

Influence of termites on the soil seed bank in an African savannah

In savannah ecosystems, termites drive key ecosystem processes, such as primary production through creation of patchiness in soil nutrients availability around their nests. In this study, we evaluated the role of termites in altering the soil seed bank size, an important ecosystem component that has often been overlooked in previous work. Data on above ground vegetation and soil seed bank samples were collected from four microhabitats, that is, the wooded mound, unwooded mound, tree sub‐canopy and the open grassland matrix in a protected game reserve in south‐central Zimbabwe. The seedling emergence method was then used to identify species present in the soil samples. One‐way analysis of variance followed by Tukey's multiple comparison tests was executed to test for significant differences in plant species richness among the four microhabitats. The results indicate that plant species richness was high on wooded termite mound but did not differ between the unwooded and the sub‐canopy microhabitats. The open grassland microhabitat had the lowest plant species richness. The influence of termites on the soil seed bank composition was also life form specific. The herb and woody life forms had significantly (α = 0.05) higher species richness in the soil seed bank at wooded and unwooded termite mounds when compared to the other two microhabitats. Overall, these results imply that termites alter the soil seed bank and the findings enhance our understanding of the significant role termites play in regulating processes in savannah ecosystem.     

夏块菌与青刚栎形成外生菌根形态变化的研究

夏块菌（Tuber aestivum）是一种具有较高经济价值的菌根食用菌。对夏块菌与青刚栎（Cycloba-lanopsis glauca）在形成菌根过程中不同阶段的菌根形态变化进行了研究,结果显示：用夏块菌孢子液接种青刚栎苗后,第14天起开始形成淡乳色的外生菌根,外延菌丝刚毛状;第一至第二个月可形成黄褐色、褐色外生菌根,外延菌丝刚毛或羊毛状。外生菌根为单根,长1～4mm,直径150～250μm。菌套厚12～20μm,平坦或自菌根延伸出刚毛状菌丝,外延菌丝束黄绿色;哈替氏网菌丝直径1～1.5μm。菌根老化后变暗褐或萎缩。外延菌丝束呈黄绿色是夏块菌菌根区别于其它块菌菌根最重要的形态特征。     

黄土塬区不同品种玉米间作群体生长特征的动态变化

不同玉米品种间作,品种间的竞争对群体结构和产量可能有促进作用.为了明确不同密度下品种间作对不同生育期群体生长特征的影响,以及在不同生育期的变化规律,选用郑单958和沈单16两个不同株型的玉米品种在中、高两种密度条件下进行隔行间作田间试验.研究结果表明:不同密度间作群体叶面积指数(Leaf Area Index,LAI)显著增加,同密度不同品种间作LAI在生育后期显著增加,有利于形成合理的冠层结构以获得更多的光照;中等密度下品种间作单株叶面积较单作显著增加,而高密度间作显著降低了单株叶面积;中等密度下,品种间作地上部干物质积累量显著增加,郑单958尤为突出,但高密度间作时的增加幅度较小,这与高密度下株高、茎粗相对减小有关.品种株高、茎粗随间作密度的增加而有所增加,对间作竞争的响应与品种特性密切相关;在不同生育期,郑单958和沈单16号表现不同的生长规律,前者在整个营养生长过程中对间作竞争的响应明显、持续和稳定,而进入生殖期后,间作的生长优势逐渐消失;后者在营养生长期干物质积累量大,但持续时间较短,表现出较弱的竞争性.品种间作可有效改善群体冠层结构,增加群体物质生产力,更好的为增产鉴定基础.