杭州石荠苧不同地方种群分化及空间利用策略研究

从杭州石荠苧(Mosla hangchowensis)5个不同地方种群采集种子,在实验室萌发,幼苗移植到实验地。在营养生长末期时,研究了株高、冠幅、主茎长、最大分枝长、基茎粗、叶面积、一级分枝数、平均二级分枝数、主茎叶对数、根长和根幅等11个空间结构参数,分析不同种群的空间利用策略和分化程度。结果发现：基本无基因交流的各地方种群产生了不同的适应方式,并在表型上有可见的差异。其中惠安种群以扩大冠幅占领较大的横向空间,种群分化程度最大;杭州种群以增加高度占领较大的纵向空间,分化程度次之;临海、天台和普陀种群分化程度较小。临海和天台种群水选下层种子萌发生长的植株个体比水选上层种子形成植株个体大,但个体对空间的利用策略仍一致。     

杭州石荠种子萌发的生理生态学研究

本文研究了我国特有的、分布区极狭窄的１年生草本植物——杭州石荠（Ｍｏｓｌａｈａｎｇｃｈｏｗｅｎ－ｓｉｓ）种子萌发的生理生态学特性。结果表明：杭州石荠种子冬天休眠,早春开始萌发;萌发的温度范围是１０～３５℃,２０℃时萌发率最高,因此其萌发的季节仅限于春季;变温处理的萌发率不高于恒温处理;全日照和黑暗条件使萌发率比最适条件的萌发率降低３６％;水选上层种子的萌发率仅为７％,水选下层种子萌发率可达６０％,但水选下层种子在全部种子中仅占３２．６％,说明种子质量差可能是其萌发率低的重要原因。萌发率与千粒重、气介容重及电导率有显著相关;与母株生境也有一定关系,４０％日照下母株所产种子的平均萌发率为２４．６％,４０％日照以下母株所产种子的萌发率降低;不同地区种群种子萌发率均低于３５％。种子萌发率低是杭州石荠各个种群存在的共同问题。     

北京东灵山地区辽东栎林种群空间分布分形分析

通过植物个体的坐标点与模拟冠幅的分形维数的分析,对辽东栎林内不同种群沿海拔梯度变化的空间分布格局和种群动态进行了比较和讨论。结果表明:模拟冠幅分形分析方法更适于分析具有大小不等、复杂多样的冠幅的植物个体空间分布格局。随着海拔的升高,不同种群的空间占据能力也随之变化。辽东栎种群的空间分布占绝对优势地位,分形维数可达1.9811;五角枫种群则逐步下降,分形维数最低为0.1170。低海拔山坡六道木种群空间占据能力较强,高海拔山坡照山白种群有较大的空间占据能力。在一定的环境条件下,不同的种群可能具有相近的空间占据能力,但对乔木层与灌木层来说,相同的分形维数的内涵是不同的。冠幅的分形维数作为表征植物种群空间占据能力的工具,是种群动态分析和种群分布格局研究的的重要指标之一。     

鄂尔多斯高原特有种四合木生长和繁殖的种群间变异与濒危机制

四合木为中国特有种,其分布区局限于鄂尔多斯高原的西部。为了认识四合木濒危的机制并为其保护提供理论依据。对四合木生活史的关键阶段－－繁殖进行了野外研究,由于分布区内存在较大的生境异质性,并受到了不同强度的人类干扰,所以不同生境条件下的6个群进行了取样,通过对四合木的营养生长和繁殖的比较分析。得出如下结论：（1）四合木植要朱的基径和冠幅和高度与年龄显著相关,但是与其茎和冠幅相关性更大,冠幅可作为个体大小的测度估计种群的大小结构;（2）冠幅大小呈负偏斜分布,通过不同种群冠幅与年龄的相关分析,得出冠幅的增长速率随种群的衰老耐减缓;（3）四合木的冠幅与其果实量和种子量相关关系显著,随着冠幅的增大,四合木植株的果实产量和种子产量也相应增加,但是这种关系存在种群间差异;（4）四合木的大部分群都处于衰老期,种群内个体的大小变异性很小,对于种群的生存有不利影响;（5）由于空间上四合木的大小结构以及反映四合木繁殖状况的植株果实产量,种子产量等参数在不同种群之间存在显著差异（P＜0．001）,因此应对不同的种群采取相应的管理措施以促进种群的更新和续存。     

山西濒危植物翅果油树植冠的构型分析

应用分形理论及方法,从分枝格局和冠幅扩展2个方面对山西翼城和乡宁的35株翅果油树(Elaeagnus mollis Diels)个体的植冠构型进行统计分析。结果表明,幼树和成树的总体分枝率和逐步分枝率有显著变化;一级枝的平均枝长和枝径有显著差异,但枝和叶的方位角及叶倾角差异不明显。不同发育阶段个体的冠幅变化较大,幼树冠幅的分形维数(2.0026)小于成树(2.2694)。翅果油树在不同生长发育阶段对生境变化有不同的构型策略。     

福建山樱花形态多样性分化的研究

以闽、赣、粤、台4省13个种群292份福建山樱花种质为分析材料,对16个形态性状进行聚类分析和主成分分析。结果表明:福建山樱花不同个体间各性状均有明显差异,变异系数较大,优株选择潜力很大。系统聚类分析可将292份参试材料划分为2个表征群4个亚表征群,除重瓣型福建山樱花外,单瓣型福建山樱花的形态特征在种群间总体上无明显的分化规律,不同种群的个体交叉聚在同一个表征群内,但在同一亚表征群内,同一种群的多数个体常能聚在一起,表明种群之间在形态上发生了一定程度的分化,只是这种分化还不能清楚地区分不同的种群。主成分分析结果表明叶形、叶尖、叶缘、分枝能力、60 d苗高、花色和花形是造成福建山樱花形态分化的主要因素。     

北京东灵山地区辽东栎林种群空间分布分形分析

通过植物个体的坐标点与模拟冠幅的分形维数的分析,对辽东栎林内不同种群沿海拔梯度变化的空间分布格局和种群动态进行了比较和讨论。结果表明：模拟冠幅分形分析方法更适于分析具有大小不等、复杂多样的冠幅的植物个体空间分布格局。随着海拔的升高,不同种群的空间占据能力也随之变化。辽东栎种群的空间分布占绝对优势地位,分形维数可达１．９８１１;五角枫种群则逐步下降,分形维数最低为０．１１７０。低海拔山坡六道木种群实     

杭州石荠苎生态学特性的研究

杭州石荠苎的种子完全靠风传播,但由于种子大,传播距离不远,种子在冬季休眠,春天（２月末３月初）萌发,种子萌发率很低,尤其是水选上层种子,主要原因是质量差,杭州石荠苎的营养期从３月初到８月上旬,株高在８月中旬以前基本为匀速增加,早期生长极为缓慢,形态和生殖力的环境可塑性极强,自然生长的植株冠幅变动在４￣５６１６ｃｍ＾２之间。杭州石荠苎在自然生境中有时形成单优群落,通常与其它植物伴生。由于早期生长慢,     

东阿拉善珍稀濒危植物绵刺种群结构与点格局分析

绵刺(Potaniniamongolica)是古老的单种属残遗种,在中国分布于西北荒漠区,为国家二级重点保护植物。为了揭示不同类型绵刺种群的结构、种内或种间的相互作用以及对环境的适应策略,该研究选择集中分布区的绵刺种群(阿拉善种群,在砾石地大面积分布)和分布区东缘的种群(鄂尔多斯种群,在沙地呈斑块分布),采用大小结构分析法将绵刺植株分为3个等级(I级:d≤10 cm; II级:10 cm 30 cm, d为株高×冠幅长×冠幅宽的立方根),运用空间点格局分析的Ripley’sK函数对2个绵刺种群的年龄结构、空间分布格局以及各大小级间空间关联性进行分析。结果表明:1)阿拉善绵刺种群以II级植株为主,占69%,I级植株虽仅占5%,但由于无性生殖的存在,种群仍呈稳定状态;而鄂尔多斯种群II级与III级植株占比相近,无I级植株,以种子进行更新受限。2)阿拉善种群总体呈随机分布,其中I、II级植株在中小尺度以聚集分布为主,在大尺度呈随机分布;鄂尔多斯种群不论是总体还是各大小级均以聚集分布为主,与种间竞争有着较大的关系。3)阿拉善种群III级个体与I级...     

不同密度下凤仙花重要形态性状与花朵数的关系

对30cm×30cm和50cm×50cm种植密度下的凤仙花(Impatiens balsamina L.)的地径、株高、冠幅、叶面积、花期、花径、一级分枝数、二级分枝数、一级分枝部位高和二级分枝部位高10个重要形态性状与花朵数的关系差异进行了相关性及通径分析,为凤仙花栽培与性状选择提供科学基础。结果表明:30cm×30cm种植的凤仙花的一级分枝数、二级分枝部位高都与花朵数呈显著正相关,地径、冠幅、二级分枝数与花朵数呈极显著正相关,对花朵数的直接效应大小顺序为:二级分枝数>一级分枝数>花径>花期;50cm×50cm种植的凤仙花,其地径、冠幅和二级分枝数都与花产量呈显著正相关,对花朵数的直接效应大小顺序为:二级分枝数>冠幅。二级分枝数对两种密度栽培的凤仙花花产量都起着重要作用。不同种植间距下凤仙花采用了不同的适应方式以获得最大花朵数目,进而获得最大数量的种子,获得较多的繁殖机会。在30cm×30cm下,是通过获得较多一级分枝数;在50cm×50cm下,是通过增加冠幅来产生较大花产量,而且与前者相比,植株茎秆粗壮,对霜霉病的抗性也强,因此,在栽培中,应以适合的低密度栽培比较好。     

杭州石荠苧生态学特性研究

 杭州石荠苧(Mosla hangchowensis)的种子完全靠风传播,但由于种子大,传播距离不远;种子在冬季休眠,春天(2月末3月初)萌发,种子萌发率很低,尤其是水选上层种子,主要原因是质量差。杭州石荠苧的营养期从3月初到8月上旬,株高在8月中旬以前基本为匀速增加,早期生长极为缓慢。形态和生殖力的环境可塑性极强,自然生长的植株冠幅变动在4～5616cm2之间。杭州石荠苧在自然生境中有时形成单优群落,通常与其它植物伴生。由于早期生长慢,限制了其在群落中的竞争能力,在土壤条件好的地方绝大部分被排挤掉,只是由于其极强的耐旱能力才在高温、干旱、土少的生境中得以存活。 将同属不濒危的华荠苧与之比较,其种子小于杭州石荠苧,但萌发率却高于杭州石荠苧。华荠苧的植株较矮,花色不如杭州石荠苧鲜艳,同在路边生长,不像杭州石荠苧那样容易被人采摘;华荠苧的根较杭州石荠苧的根深,抗雨水冲刷能力较强。华荠苧在自然生境中植株投入生殖的比例大于杭州石荠苧。     

凤丹栽培群体的表型变异研究

从我国6个凤丹(Paeonia ostii T.Hong et J.X.Zhang)中心产区,选取15个群体共398个单株,对20个表型性状进行调查和分析。结果显示,枝条数、地径、株高、茎长、冠幅长、冠幅宽、成花枝、芽位数、叶长和叶宽等10个表型性状受植株株龄的影响显著,随着株龄增加,除叶长和叶宽的平均值呈递减趋势外,其他8个性状的平均值都呈现递增趋势。凤丹群体间的表型分化系数为0~50.14%,平均值为27.62%,变化幅度最大的是二年生枝长,最小的为心皮数和二年生枝径。对当年生枝长、芽位高、当年生枝径、顶生小叶长、二年生枝径、顶生小叶宽、复叶数、心皮数、二年生枝长和叶柄长等不受株龄影响的10个表型性状进行主成分分析,结果显示前6个性状是影响表型差异的主要性状。各表型性状间存在一定的相关性,聚类分析结果将受株龄影响的10个性状划分为4组。研究结果表明凤丹表型性状在群体间和群体内的变异非常丰富,可为遗传改良和品种选育储备丰富的植物材料。     

Competitive strategies in adult beech and spruce: space-related foliar carbon investment versus carbon gain

In Central Europe, Fagus sylvatica and Picea abies represent contrasting extremes in foliage type, crown structure and length of growing season. In order to examine the competitive strategies of these two co-occurring species, we tested the following hypotheses: (1) the space occupied by the foliage of sun branches is characterized by greater foliar mass investment compared to shade branches, (2) the carbon (C) gain per unit of occupied space is greater in sun than in shade branches, and (3) annual C and water costs of the foliage for sustaining the occupied space are low, wherever C gain per unit of occupied space is low. These were investigated in a mature forest in Southern Germany. The examination was based on the annual assessment of space-related resource investments and gains of the foliage. The foliated space around branches was regarded as the relevant volume with respect to aboveground resource availability. Occupied crown space per standing foliage mass was higher in shade compared to sun branches of beech, whereas no difference existed in crown volume per foliage mass between sun and shade branches of spruce (hypothesis 1 accepted for beech but rejected for spruce). However, beech occupied more space per foliage mass than spruce. The C gain per occupied crown volume was greater in sun than in shade branches (hypothesis 2 accepted) but did not differ between species. The amount of occupied space per respiratory and transpiratory costs did not differ between species or between sun and shade branches. In beech and spruce, the proportion of foliage investment in the annual C balance of sun and shade branches remained rather stable, whereas respiratory costs distinctly increased in shade foliage. Hence, shade branches were costly structures to occupy space, achieving only low and even negative C balances (rejection of hypothesis 3), which conflicts with the claimed C autonomy of branches. Our findings suggest that competitiveness is determined by the standing foliage mass and the annual branch volume increment rather than annual investments in foliage. Expressing competitiveness in terms of space-related resource investments versus returns, as demonstrated here, has the potential of promoting mechanistic understanding of plant–plant interactions.     

航天诱变凤仙花SP2代形态变异的研究

对经“神舟4号”卫星搭载后的SP2代凤仙花的形态变异进行了研究。结果表明:子叶数目除有了两片的外,尚有三片和四片的。子叶形态上出现连生子叶、杯状子叶和大小不等子叶。真叶的形态上出现线状披针形,其小孢子母细胞减数分裂不正常,小孢子不育。花的结构上出现花瓣增多和花的叶化现象。茎的分枝上,有的不分枝,仅具主茎,有的分枝多达40枝以上。这些变化对研究和认识航天诱变育种有一定的理论和实际的意义。     

EFFECT OF SEED DIMORPHISM ON THE DENSITY-DEPENDENT DYNAMICS OF EXPERIMENTAL POPULATIONS OF ATRIPLEX TRIANGULARIS (CHENOPODIACEAE)

The importance of seed size and density in determining individual plant performance and plant population dynamics in experimental populations of the halophyte Atriplex triangularis was studied. Two distinct seed morphs—large, light seeds and small, dark seeds—are produced by individual A. triangularis plants. Experimental populations consisting of seed size monocultures (large or small seeds) and seed size mixtures were established at three different densities, and the time of germination, plant size, plant survivorship, and plant fecundity were monitored. Marked variation in time of germination was observed among treatments and between seed sizes, but germination within any given treatment occurred over a five- to ten-day period. Large seeds produced larger plants than small seeds did, and this dichotomy was maintained over the course of the entire experiment. Germination date and seed size interacted such that larger plants grew from seeds which germinated earlier than those which germinated later, regardless of seed size. Germination date had a more pronounced effect than seed size did on plant mortality in high density populations. At high density, large seed monocultures experienced greater mortality than small seed monocultures did, but in seed size mixtures, the mortality was evenly distributed between plants from the two seed sizes. Regardless of density conditions and parentage, large and small seeds were produced in equal proportion by the plants. Total seed production, however, was dramatically affected by plant density, and to a lesser degree by germination date. Although seed size effects alone did not appear to affect directly final plant biomass and fecundity, effects of seed size early in ontogeny may have contributed to differences in fecundity.     

Effects of cold storage of germinated vegetable seeds prior to fluid drilling on emergence and yield of field crops

Germinated seeds of five vegetable crops were stored at 1 °C in aerated water or humid air for periods of up to 15 days and then fluid drilled in the field. Viability of germinated seed was maintained in carrot and parsnip for a minimum of 15 days, salad onion for 9 days, lettuce for 6 days and cabbage for 3 days. When salad onion, lettuce and cabbage seeds were stored for longer than these times there was a reduction in the number of seedlings emerging. In species where storing seeds for up to 15 days caused a reduction in emergence an adjustment to the seed rate related to the length of storage can be made to achieve the desired population and still retain the advantages of fluid drilling pre-germinated seeds. This is possible because with one exception (an increase in the variation of salad onion stem diameters) the performance of plants from all stored germinated seeds after emergence was similar to plants from freshly germinated seeds.     

Genetic structure of experimental populations and reproductive fitness in a heterocarpic plant Atriplex tatarica (Chenopodiaceae)

Atriplex tatarica is a heterocarpic species of disturbed habitats. Seeds of Atriplex tatarica do not germinate immediately after shedding, but may remain in a dormant but viable state indefinitely. We investigated whether there were genetic and fitness differences between plants derived from seeds of the different fruit types germinated in different temperatures and salinities. Seeds that germinated in optimal and suboptimal conditions differed significantly in their genetic composition due, in part, to their source population. Seeds that germinated in the suboptimal conditions produced more homozygous plants. Plants that were primarily heterozygous were generated from nondormant fruit types as well as from fruits that germinated in the optimal conditions. Moreover, there was a positive correlation between the degree of heterozygosity and plant fitness measured as the mass of the stem and reproductive structures. In conclusion, the genetic variation of natural populations may be at least partly due to the ability of particular seed genotypes to germinate in the specific environmental conditions of a particular locality. In some circumstances, the process of differential germination may select not only for genetic variability but also for higher fitness if heterozygosity-fitness correlations are present.     

不同居群准噶尔无叶豆果实和种子特性及种子萌发差异

研究准噶尔无叶豆(Eremosparton songoricum) 6个居群间果实和种子特性及种子萌发差异, 以揭示异质生境下准噶尔无叶豆果实和种子的生态适应机制。结果显示: 居群间准噶尔无叶豆的植株距离(F = 2.34, p = 0.03)和植株冠幅(F = 8.49, p < 0.01)存在显著差异, 沙漠北缘E、F居群和沙漠腹地C居群(受人类干扰剧烈)的植株距离和植株冠幅高于沙漠腹地A、B、D居群; 居群间准噶尔无叶豆果实和种子的长度、宽度、厚度、重量存在显著差异, 居群E、F和C的大部分参数显著高于其他沙漠腹地居群; 居群间果实多子性(F = 6.96, p < 0.01)也存在显著差异, 居群C的果实多子性最高((32.50 ± 4.79)%); 萌发结果表明, 居群间新鲜的成熟种子萌发不存在显著差异, 且萌发率都低于15%; 所有居群的大部分种子都存在物理性休眠现象, 人为划破种皮能显著提高种子萌发率, 但在低温(15/5 ℃)条件下, 所有居群的种子萌发率都较低, 说明低温抑制了种子萌发; 经人为划破种皮解除物理休眠后, 种子的休眠没有完全释放, 居群C、E和F (大种子居群)的种子萌发率显著高于居群A、B和D (小种子居群) (F = 30.77, p < 0.01), 说明准噶尔无叶豆种子不仅存在物理性休眠现象, 也可能存在生理休眠现象。不同程度的种子复合休眠可能是准噶尔无叶豆不同居群适应古尔班通古特沙漠的重要生存策略。     

When genes go to sleep: the population genetic consequences of seed dormancy and monocarpic perenniality

In many annual plant populations, seeds may be dormant for several seasons before they germinate. Here, we investigate the consequences of both conditional (dispersed seeds cannot enter a dormant stage) and unconditional seed dormancy on the amount and the distribution of neutral genetic diversity within and among populations. We present joint demographic and population genetics models for single and subdivided populations and derive the effective size and population differentiation at both local and metapopulation scales. We suggest that a Wahlund effect is unlikely to result from age structure alone. Furthermore, the differentiation among populations is decreased by the presence of seed banks. We also extend these models to describe monocarpic (semelparous) perennial life cycle, where the nonreproductive stages are vegetative rosettes instead of dormant seeds. The main difference between the models relies in the way the density-dependent regulation is acting. The effective size of monocarpic perennial species may be less than the census number of individuals, and among-population differentiation is always larger than in annual species. We discuss our results in the light of recent population genetics surveys of annual plants with seed banks.     

Genetic diversity within and among 11 juvenile populations of green alder (Alnus crispa) in Canada

Germinated seeds from 11 populations of green alder [ Alnus crispa (Ait.) Pursh] sampled in four Canadian provinces were analysed for electrophoretically demonstrable diversity of 10 enzymes encoded by 15 structural loci. Of these, nine were polymorphic, and on average, 52% of the loci per population were polymorphic. Assuming a diploid model of expression, average level of expected heterozygosity was 0.11 with nearly all populations in Hardy-Weinberg equilibrium for the set of polymorphic loci analysed. No significant inbreeding and associated subpopulation structuring were noted. Rates of gene flow appeared high within and among populations. Although little divergence was observed among populations, genetic and geographical distances between populations were related. Discriminant and cluster analyses revealed a pattern of genetic variation associated with geography. Populations from northern Quebec were poorly differentiated, whereas western populations from Alberta exhibited a larger degree of genetic differentiation. Introgresive hybridization with the sympatric species Alnus sinuata (Regel) Rydberg and partial isolation in the West are suggested as an explanation for this larger differentiation. The occurrence and significance of rare alleles is discussed in relation to the importance of geographical distance in the process of population differentiation in this species.