浑善达克沙地赖草分株种群与土壤资源异质性分析

对浑善达克沙地低湿滩地、滩地 -风沙沉积过渡区到风沙沉积区的赖草分株数、地上生物量、土壤水分和养分异质性进行了研究。结果表明 ,从低湿滩地、滩地 -风沙沉积过渡区到风沙沉积区 ,赖草的分株数和地上生物量与养分含量具有不同的变化趋势。赖草的分株数在 3种生境中都存在空间自相关 ,并且 ,从低湿滩地、过渡区到风沙沉积区空间自相关的变程逐渐增加。地上生物量同样存在空间自相关 ,但变程以过渡区最大 ,风沙沉积区最低。土壤水分仅仅在风沙沉积区存在空间自相关。在 3种生境条件下 ,土壤全氮和有机质的空间分布格局相似 ,都在低湿滩地和过渡区存在空间自相关且变程相似 ,在风沙沉积区不存在空间自相关。赖草的空间分布格局在低湿滩地为偏离随机适度聚集的分布格局 ,在过渡区近似于聚居分布 ,而在风沙沉积区为均匀分布格局     

内蒙古锡林河流域不同生境中羊草的克隆构型和分株种群特征

 克隆植物的形态可塑性在基株和种群水平上分别表现为克隆构型和分株种群特征的变化。研究对象为内蒙古锡林河流域草地、林地、沙地3种生境下的羊草(Leymus chinensis)种群,通过对羊草根茎节间长度、间隔子长度、分枝强度、分枝角度、株高和分株密度等指标的测定和分析,对这3种不同生境中羊草的克隆构型及分株种群特征进行了研究。结果表明羊草克隆构型相关特征,如,根茎节间长度,根茎节间长度频次分布格局、间隔子长度、间隔子长度频次分布格局,在不同生境差异较大。同时,羊草的分枝角度在不同生境间差异显著。而每间隔子所     

根茎草本披针叶黄华自然分株种群多尺度分布格局

通过在鄂尔多斯高原毛乌素沙地的实地调查 ,应用相邻格子样方和空间自相关分析方法 (Moran′sI) ,研究了在 0 .2m、0 .4m、0 .6m、0 .8m和 1.0m等 5个尺度上根茎豆科草本披针叶黄华 (ThermopsislanceolataR .Br.)自然分株种群的分布格局。同时 ,研究了基株特征和其他分株种群特征。研究显示 ,披针叶黄华自然分株种群具有 4个尺度的非随机分布格局 ;其中 0 .2m尺度的聚集分布格局频率最高。该植物的根茎分枝类型为合轴型(sympodial) ,克隆构型接近于密集型 (phalanx) ,根茎分枝角度为 10°～ 30° ;分株种群密度为 35～ 131株·m-2 ;种群平均分株高度为 11.0～ 2 5 .9cm。在所调查的 2个样方中 ,种群生物量平均分别为 2 6 3.6 3g·m-2 和 30 6 .19g·m-2 ;分株种群的根茎生物量分配分别为 33.71%和 44 .97% ,根生物量分配分别为 2 9.91%和 2 9.95 % ,地上枝叶生物量分配分别为 2 5 .12 %和 36 .35 % ;根冠比均为 0 .44 ,地下 /地上生物量比分别为 2 .12和 3.5 9。     

羊草种群克隆多样性的初步研究

 采用水平淀粉凝胶电泳技术检测了松嫩草原上两种叶色类型(灰绿型和黄绿型)羊草(Leymus chinensis)种群的克隆多样性。羊草种群中克隆多样性较高,Simpson指数平均为0.983,97.7% 的基因型为局部分布;在克隆特性上,灰绿型和黄绿型羊草也明显不同,黄绿型种群的克隆多样性低于灰绿型。由基株数据计算的种群遗传多样性与由分株计算的结果一致,进一步确认了黄绿型和灰绿型羊草间存在着明显的遗传分化。种群中不时有实生苗补充及环境异质性引起的分化选择作用可能是维持种群内基因型多样性的重要因素。     

缙云山不同生境蝴蝶花(Iris japonica Thumb.)分株种群格局及对草本多样性的影响

运用空间格局、生态位及多样性分析,探讨了重庆缙云山自然保护区林缘旷地(OAFE)、竹林(BF)及常绿阔叶林(EBF)3类生境蝴蝶花(Iris japonica Thumb.)自然种群分株格局特征及对草本多样性的影响机制.结果表明:方差均值比(V/m)和Moristia指数(Iδ)的格局判别分析表明,3类生境中蝴蝶花分株种群从0.5 m×0.5 m至2 m×2 m尺度均为聚集分布;从林缘旷地-竹林-常绿阔叶林,种群分株密度逐渐降低,总体格局规模与格局强度(PI)在各尺度均呈下降趋势.林缘旷地与竹林生境中,蝴蝶花的分布,降低了原优势种的优势度,并显著降低草本层物种多样性(p<0.05),但在常绿阔叶林生境中对原优势种的优势度及草本物种多样性的影响很小.不同生境中蝴蝶花种群格局对草本多样性的影响机制各不相同:林缘旷地生境,通过强的更新生态位(地上空间与根生态位)与营养生态位(获取水分与养分资源)竞争,降低草本物种丰富度尤其是偶见种丰富度;竹林生境,通过更新生态位(根生态位)与营养生态位(获取光与养分资源)竞争,降低了草本偶见种丰富度;常绿阔叶林生境,物种间生态位重叠较低,表现一定的资源竞争,但对草本多样性影响很小.林冠决定蝴蝶花分株种群格局强度、克隆生长的强弱及林下土壤状况,从而影响蝴蝶花与草本层其它物种之间生态位竞争的强弱是决定蝴蝶花种群对草本层物种多样性影响机制的重要因素.     

珠芽蓼种群克隆多样性及克隆结构的初步研究

珠芽蓼(Polygonum viviparum)是青藏高原东缘广泛分布的克隆植物,具有有性和无性(根状茎和珠芽)两种生殖方式。该研究采用RAPD技术对分布于不同海拔的珠芽蓼7个自然种群进行了克隆结构和克隆多样性(是单克隆种群还是多克隆种群)以及克隆多样性与海拔因子之间的相关性研究,为了解高山克隆植物对环境的适应性策略及揭示克隆植物的繁殖和分布特点提供科学依据。研究结果表明:1)采用13条RAPD引物对珠芽蓼7个种群共140个样本进行扩增分析,共扩增到117个位点,其中多态性位点84个,多态位点百分率PPL达到71.79%,检测到43个基因型,且全部为局限型基因型;2)与Ellstrand和Roose(1987)总结的克隆植物的克隆多样性平均值相比(PD=0.17,D=0.62),珠芽蓼种群克隆多样性水平稍高,Simpson指数平均为0.639,基因型比率PD平均为0.307;3)克隆结构分析表明,珠芽蓼种群内克隆之间的镶嵌明显,这可能与珠芽蓼过渡型的克隆构型有关。研究中珠芽蓼种群的构型有游击型、密集型以及这两者之间的过渡类型;4)采用SPSS软件对珠芽蓼种群的克隆多样性与海拔高度进行相关性分析,结果显示它们之间并无明显的相关性。     

艾纳香野生种群克隆多样性及克隆结构研究

艾纳香是具有克隆生长习性的多年生宿根性草本植物,其广布于中国南部,为了更有效地保护和合理利用艾纳香资源,本文利用RAPD分子标记技术,对4个野生艾纳香种群进行了克隆结构和克隆多样性(单克隆种群或多克隆种群)进行了初步研究。结果表明:(1)10对10bp随机引物共检测到70条谱带,其中多态带为60条,占85.71%,检测到64个基因型,且全部为局限基因型;(2)与Ellstrand Roose(1987)总结的克隆多样性平均值(PD=0.17,D=0.62)相比艾纳香的种群克隆多样性水平稍高,Simpson指数平均为0.973,基因型比率PD平均为0.800;(3)遗传一致度和遗传距离分析表明,4个艾纳香野生种群被分成两组,一组是海南的所有种群,另外一组是云南类群。     

塔里木河流域胡杨和灰叶胡杨克隆分株空间分布格局

以叶尔羌河下游阿瓦提县天然胡杨和灰叶胡杨混交林、塔里木河上游农一师16团天然灰叶胡杨林和塔里木河中游轮台县天然胡杨林为对象,研究胡杨和灰叶胡杨克隆分株种群的空间分布格局.结果表明: 8种不同取样尺度(5 m×5 m、5 m×10 m、5 m×15 m、10 m×10 m、10 m×15 m、15 m×15 m、15 m×20 m、20 m×20 m)下,3个研究区2物种克隆分株种群的空间分布格局均表现为集群分布,表明集群分布是研究区胡杨和灰叶胡杨克隆分株种群空间分布格局的基本属性;在5 m×5 m尺度上,3个研究区2物种克隆分株种群均表现出负二项参数最小、Cassie指标和聚块性指标最大、聚集强度最大的分布特征.     

湿地克隆植物的繁殖对策与生态适应性

湿地是地球上独特的生态系统,它是水陆交替的过渡带,而湿地植物为了适应这种特殊的环境,必须有其相应的生长格局（ｇｒｏｗｔｈｐａｔｔｅｒｎ）和繁殖对策（ｒｅｐｒｏｄｕｃｔｉｖｅｓｔｒａｔｅｇｙ）。有些湿地植物具有密丛型的生态特点,这是对过湿的土壤和氧气供给不足环境的一种适应方式。随着有机质的不断积累,每年从分蘖节向上长出新枝,向下生长不定根,其分蘖节不断上移,以便从地表面上获得氧气,并使植物体免遭埋没,这样年复一年的生长,在地表面上形成了草丘。生殖是生物繁衍后代延续种族最基本的行为和过程,它不仅是…     

水分胁迫条件下草莓克隆分株间水分调控及其对光合功能的影响

以盆栽草莓(Fragaria×ananassa)为材料研究了水分胁迫下克隆植物草莓母株和子株间的水分调控机制及其与碳同化、光系统Ⅱ激发能分配的关系.实验材料分为匍匐茎连接和剪断两个大组,进行两步实验.第1步实验,对连接组和剪断组的所有母株控水,子株充分供水;4d后进入第2步实验,把连接组分为两小组,对其中一组充分供水子株开始控水,另一组保持不变.结果表明,土壤干旱引起母株叶片失水,并使其净光合速率和气孔导度显著降低.但是连接组中供水良好的子株能有效缓解缺水母株的水分胁迫.当供水良好的子株也开始受到干旱处理的时候,则会加剧与之相连母株的水分胁迫.受胁迫母株可以通过加强渗透调节能力和降低水势从相连子株获取水分.虽然土壤干旱会造成受胁迫母株叶片脱落酸(abscisic acid, ABA)含量的大幅度增加,但是与之相连子株的叶片ABA含量并没有增加;并且气孔导度与ABA变化趋势一致.(1)草莓母株和子株间的水分运输是由二者的水势差驱动的;(2)ABA不会通过匍匐茎在母株和子株间传递并影响相邻子株气孔导度;(3)在水分异质性较大情况下,生理整合可明显提高克隆系统的碳同化能力和光系统Ⅱ激发能利用效率.     

Resource transport between ramets alters soil resource pattern: a simulation study on clonal growth

Clonal plants spread horizontally, and can transport nutrients between ramets. Decaying biomass feeds back nutrients into the soil, but importantly, the place of deposition may differ from the place of uptake. To our knowledge, the present model is the first attempt to couple population dynamics with resource dynamics with the consideration of lateral transport. The simulations start from various initial resource patterns. Six types of clonal plants are compared, which differ in the birth and survival rates of ramets. Size of the ramet population and the amount of translocated resource are recorded over time. In addition, we consider the pattern of gaps in the canopy of the clonal plant from the aspect of two colonizer species: a strong and a weak competitor. The results suggest that the most important factor determining the impact of a clonal plant on its environment is ramet survival; the rate of ramet production is only secondary. Phenotypic plasticity in the production of ramets does not appear to be important: it has only minor effect on resource translocation and on the availability of colonizable gaps.     

The path of photosynthate translocation into citrus fruit

Abstract The path of [¹⁴C]photosynthate translocation into citrus fruit was examined to determine which anatomical and physiological features were involved in this process. Experiments were conducted during the final pre-harvest months of 2 years grapefruit crops (Citrus paradisi Macf. cv. ‘Marsh’). A source leaf nearest the fruit was exposed to ¹⁴CO₂ for 1 h + 5 h ambient air, followed by dissection of vascular and phloem-free tissues in the fruit quarter directly aligned with the source. Radioactivity in each tissue was quantified after separation and extraction in boiling 80% ethanol. Peel (flavedo+albedo) contained an average 35% of the label in the quarter fruit, but an additional 20% was localized entirely in dorsal vascular bundles along exterior walls of juice segments. Less [¹⁴C]photosynthate was recovered from other vascular tissues and was nearly absent from adjacent mature seeds. Radioactivity in the single layer of segment epidermis, however, averaged 17% of that in the quarter fruit. Juice tissues interior to this accumulated only 17% of the total. No phloem tissue was evident in either the segment epidermis or juice tissues, but over 70% of the [¹⁴C]assimilates in the latter were localized in thread-like stalks which attach juice vesicles to dorsal vascular bundles. In addition, labelled hexose/sucrose ratios in these structures increased with distance from the vascular bundle. The majority of photosynthates, therefore, entered citrus fruit via dorsal vascular bundles and were partially hydrolysed during slow transfer through non-vascular segment epidermis and juice stalks.     

The ideal free distribution of clonal plant's ramets among patches in a heterogeneous environment

The plastic response of clonal plant to different patch quality is not always the same and the degree is different too. So the result of this kind of foraging behaviour is different. In order to make clear whether the ramtes stay in favourable patches and get the quantitative relationship between the ramets distribution among patches and the available resource amount in heterogeneous environment, we develop a theoretical work under ideal free distribution (IFD) theory framework by neglecting some morphological plasticity of the spacer in this article. The results of our general model show that the ramet distribution should obey input matching rule at equilibrium. That means the ratio of ramet number in different patches should be equal to the ratio of available resource amount in these patches. We also use the simulation to predict the distribution pattern under history mattering. The results show that the initial ramets number has significant influence on the final distribution: over matching and under matching both can occur. More initial ramets in favourable patch result in over matching and more initial ramets in unfavourable patch result in under matching. The degree of the deviation from input matching rule is great when the difference of patches is small. These results prove that ideal free distribution theory works the same with animals. The ramets can stay in favourable patches sometimes in spite of the plasticity of the spacer, and the distribution depends on both patch quality and the history factors. But these results are true only when the functional response is type II.     

野古草种群克隆的遗传变异和遗传结构

用酶电泳法和同工酶分析对东北松嫩草原西北部野古草种群克隆遗传变异性和种群遗传结构做了探讨。讨论了遗传多样性、地理距离和遗传距离之间的关系、大种群和小种群的遗传变异性和种群间的基因流 ;种群间 ,包括大种群和小种群间基因流、遗传和地理距离对遗传多样性的影响、昆虫和风传粉、种群籽苗的补充、遗传多样性的发生和保持 ,自交不亲和性和无性繁殖及体细胞突变     

Analyses of spatial patterns and population processes of clonal plants

The nonrandom spatial structure of terrestrial plants is formed by ecological interactions and reproduction with a limited dispersal range, and in turn this may strongly affect population dynamics and population genetics. The traditional method of modelling in population ecology is either to neglect spatial pattern (e.g. in transition matrix models) or to do straightforward computer simulation. We review here three analytical mothods to deal with plant populations in a lattice-structured habitat, which propagate both by seeds that scatter over the whole habitat and by vegetative reproduction (producing runners, rhizomes, etc.) to neighboring vacant sites. [1]Dynamics of global and local densities: Dynamical equations of population density considering nearest-neighbor correlation (spatial clumping) are developed as the joint dynamics of global average density and local density (comparable to mean crowding) based onpair approximation. If there is a linear trade-off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximized by engaging both means of reproduction. This result is accurately predicted by the pair approximation method, but not by mean-field approximation (neglect of spatial structure). [2]Cluster size distributions: Using global and local densities obtained by pair approximation, we predicted cluster size distribution, i.e. the number of clusters of occupied sites of various sizes. [3]Clonal identity probability decreasing with distance: Multi-locus measurement of allozymes or other neutral molecular markers tells us whether or not a given pair of individuals belong to the same clone. From the pattern of clonal identity probability decreasing with the distance between ramets, we can estimate the relative importance of two modes of reproduction: vegetative propagation and sexual seed production.     

不同干扰类型下羊草种群的空间格局

生态系统各层次的空间格局与生态学过程的相互关系一直是生态学的研究热点之一,这一问题的关键是选取合适的观察尺度。羊草(Leymus chinensis)作为呼伦贝尔草原的地带性植被,研究其种群空间格局对理解种群生态过程和草地资源可持续利用具有重要意义。利用Ripley's K函数和Monte Carlo随机模拟方法,对两块样地3种干扰下的羊草种群格局进行定量分析。结果表明:(1)刈割、围封、放牧3种干扰对羊草草甸草原恢复改良样地(LM)和贝加尔针茅试验样地(SM)的羊草种群空间格局具有显著影响,空间格局在不同尺度上存在差异。(2)在较小的空间尺度内,羊草种群倾向于非随机分布,在LM样地、SM样地分别为均匀分布和聚集分布;当空间尺度大于临界值后,羊草种群在围封(30-100cm)、放牧干扰(84-100cm)下倾向于随机分布,刈割干扰下仍为聚集分布。这主要与羊草的繁殖对策、群落地位以及各种干扰下对资源的竞争能力有关。(3)空间结构的规律性表面上取决于观察尺度,但更小尺度的数据对局域空间结构的生物学解释可能更有效。     

Partial mechanical stimulation facilitates the growth of the rhizomatous plant Leymus secalinus: modulation by clonal integration

Background and Aims

Mechanical stimulation (MS) often induces plants to undergo thigmomorphogenesis and to synthesize an array of signalling substances. In clonal plants, connected ramets often share resources and hormones. However, little is known about whether and how clonal integration influences the ability of clonal plants to withstand MS. We hypothesized that the effects of MS may be modulated by clonal integration.

Methods

We conducted an experiment in which ramet pairs of Leymus secalinus were subjected to three treatments: (1) connected ramet pairs under a homogeneous condition [i.e. the proximal (relatively old) and distal (relatively young) ramets were not mechanically stressed]; (2) connected ramet pairs under a heterogeneous condition (i.e. the proximal ramet was mechanically stressed but the distal ramet was not); and (3) disconnected ramet pairs under the same condition as in treatment 2. At the end of the experiment, we harvested all plants and determined their biomass and allocation.

Key Results

Clonal integration had no significant influence on measured traits of distal L. secalinus ramets without MS. However, under MS, plants with distal ramets that were connected to a mother ramet produced more total plant biomass, below-ground biomass, ramets and total rhizome length than those that were not connected. Partial MS exerted local effects on stimulated ramets and remote effects on connected unstimulated ramets. Partial MS increased total biomass, root/shoot ratio, number of ramets and total rhizome length of stimulated proximal ramets, and increased total biomass, root weight ratio, number of ramets and total rhizome length of connected unstimulated ramets due to clonal integration.

Conclusions

These findings suggest that thigmomorphogenesis may protect plants from the stresses caused by high winds or trampling and that thigmomorphogenesis can be strongly modulated by the degree of clonal integration.