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     

科尔沁沙地农田-沙丘交错区白草无性系的生态适应性分析

对生长在不同沙地生境下的白草无性系进行了个体生长与形态以及种群生物量等指标的比较研究,结果表明,生长在不同生境下的白草无性系表现出显著的形态可塑性和不同的生物量分配模式,生长在农田-沙丘过滤带上的白草无性系与生长在半固定沙丘上的白草无性系相比,具有更大的生物量,更快的叶片延伸速率,根茎总长度和节间长度更长,不定芽更多,地下生物量所占比例更大且分布更深;这些特征的出现与农田-沙丘过渡带上土壤表层比较疏松而下层水分状况相对优越有着密切关系,因而生长在农田-沙丘过渡带上的白草无性系能更快地拓展其生存空间,在固沙和沙生植被演替中起重要作用。     

斑苦竹无性系种群克隆生长格局动态的研究

采用“例逐龄级累加法”（ＲＡＡ）研究了缙云山斑苦竹无性系种群的克隆生长格局动态,以及无性系分株克隆生长型的动态趋势．结果表明,作为复轴型的斑苦竹,其无性系种群随时间进程表现为聚集程度逐渐降低的集群分布格局．在自然条件下,斑苦竹更多地表现出单轴型的繁殖趋势．应用ＲＡＡ分析植物种群,尤其是竹类植物种群前期的克隆生长格局的动态,结果可靠,具有重要的应用价值．     

匍匐茎草本活血丹(Glechoma longituba)在不同养分条件下的克隆形态

通过人工施肥的方法 ,对活血丹无性系实验种群在不同养分供应情况下的形态特征进行了研究。研究结果表明 :施肥可以显著改变克隆植株的形态 ,无性系分株产生能力增强 ,个体生长旺盛 ;匍匐茎总长增长 ,生物量增大 ,节间短 ,匍匐茎较粗壮 ;相对叶面积小 ,叶片厚 ,叶柄较粗短。在未施肥条件下 ,克隆植株形态表现则正好相反。养分供应的差异对叶片的形态以及根重和根量的影响较其对隔离者和叶柄的特征的影响更大。     

亚高山暗针叶林不同林冠环境下华西箭竹的克隆可塑性

以亚高山暗针叶林3种林冠环境中以及暗针叶林林缘的华西箭竹（Fargesia nitida）为对象,对其无性系数量特征、无性系根茎特征、分株生物量以及分株形态特征进行了对比研究。结果表明：（1）林冠环境的差异导致了不同种群的基株密度和每基株分株数的显著差异,但林冠环境差异不影响分株密度。林冠郁闭度愈大,每基株分株数愈少,分株分布愈均匀。（2）不同林冠环境间。分株生物量、分株构件生物量和分株构件的生物量分配百分率均有显著差异。开敞的林冠环境有利于华西箭竹的生长和生物量积累。（3）随着林冠郁闭度的增加,华西箭竹通过增大分枝角度、叶生物量分配百分率、比叶面积和叶面积率以提高光能利用效率,有效适应弱光环境。（4）隔离者长度、隔离者直径和分枝强度在林缘和林窗环境中要显著大于林内环境;同级隔离者分枝角度随林冠郁闭度的增加而最大,其值在林下显著大于林窗和林缘,而异级隔离者分枝角度的变化则正好相反。研究表明,华西箭竹种群在不同的林冠环境中发生了明显的可塑性变化,这些可塑性变化是种群对林冠郁闭度差异的适应性反应的结果,有利于增强种群对环境中有限光资源的利用。     

光强梯度对羊草无性系分化与生长的影响

在温室内用透光率分别为 60 %、45%、30 %的遮阴网盖在花盆上遮阴 ,研究不同光照强度对羊草无性系分化与生长的影响 .结果表明 ,低光强影响羊草基株的生物量积累 ,抑制羊草无性系的分化和生长 .减少羊草地下根茎的数目 ( A=61 4个 ,D=2 31个 )和无性系分株数 ( A=70 4个 ,D=1 52个 ) .羊草根茎长度和节数、无性系分株干重等性状在不同的光强梯度之间存在显著差异 ( P<0 .0 1 ) ,这种差别在春季尤其显著 .     

川西北高寒沙区切断根茎对赖草和沙生苔草克隆生长的影响

为了研究高原亚寒带沙化生境中切断根茎对克隆植物基株扩展能力和分株定居能力的影响,在川西北若尔盖高原沙化区内,对根茎禾草赖草和沙生苔草进行了以切断根茎为处理的野外实验。结果表明,赖草和沙生苔草基株的幼小部分(观测单元)地上枝总长度增量、主根茎长度增量和根茎总长度增量显著减少,而对根茎数增量、主根茎节增量和根茎节总数增量影响不显著;赖草观测单元地上枝数增量显著减少,而对沙生苔草地上枝数增量无影响;赖草地上枝与根茎的相关性质发生逆转。这表明．在高原亚寒带半湿润沙化生境中．克隆整合效应显著促进基株幼小部分地上枝和根茎的伸长生长,但对新生根茎的产生和根茎节分化没有影响;切断根茎处理导致赖草、沙生苔草生殖生长与营养生长间竞争加剧,同时使赖草地上部分与地下部分间竞争加剧;观测单元在缺少与基株(或上级株系)的克隆整合作用时,赖草受到的影响大于沙生苔草。     

高寒草甸退化对鹅绒委陵菜克隆生长特征的影响

为了揭示高寒草甸典型匍匐茎克隆植物对不同生境的生态适应对策,验证生境适应假说,并为高寒草地的退化演替机理研究提供依据,以调查统计和比较样地法研究了江河源区高寒草甸退化对鹅绒委陵菜克隆生长特征的影响。研究表明,重度退化草甸的植物群落结构、功能以及土壤特征发生了明显的变化,继而对鹅绒委陵菜无性系的克隆生长行为和形态特性产生了影响。高寒草甸退化后鹅绒委陵菜的匍匐茎增多,分支强度加大。退化草甸内鹅绒委陵菜的基株高度小于未退化草甸,根长大于未退化草甸,基株的叶片数目问没有明显差别。退化草甸的分株高度显著小于未退化草甸,而分株叶数大于未退化草甸,根长小于未退化革甸且差异不显著。未退化草甸内鹅绒委陵菜无性系的问隔子长度、粗度和匍匐茎长度大于退化草甸,间隔子平均数目少于退化草甸,差异都不显著。随着鹅绒委陵菜无性系匍匐茎数目的增加,不论重度退化草甸与未退化草甸,用于鹅绒委陵菜克隆繁殖的能量投资也逐渐增加。鹅绒委陵菜在未退化草甸用于克隆繁殖的能量投资比例高于退化草甸,其中未退化草甸内鹅绒委陵菜基株的干重占无性系总生物量的比例略低于退化草甸,分株和匍匐茎的干重占无性系总生物量的比例高于退化草甸。高寒草甸退化对鹅绒委陵菜克隆生长特征的这些影响,与植物群落结构和功能的变化导致生境变异密切相关,是其对高寒草甸退化导致的资源和生境差异的反应,也是对资源利用达到的最合理状态,是一种选择适应的结果,有利于克隆繁殖潜力的发挥。同时为生境适应假说提供了又一例证。     

黑龙江扎龙湿地芦苇种群构件数量特征及其相关性

采用刈割和挖土取样,对扎龙湿地旱生、湿生、水生和盐碱生境芦苇种群分株、根茎和根茎芽进行调查。结果表明:6—10月,4个生境芦苇种群分株密度、根茎长度和根茎芽库存量、输入量、休眠量均以湿生生境最大,盐碱生境最小;根茎芽输出量均以水生生境最大,盐碱生境最小,构件间的差异及其差异序位均相对稳定,构件种群均存在明显的环境效应,构件水平上存在较大的可塑性;构件间又均表现出一定的协同进化性,其中分株密度与根茎长度、根茎芽库存量和输入量之间呈显著或极显著正相关,与根茎芽休眠量之间呈显著负相关;根茎芽库存量、输入量和输出量与根茎长度之间呈显著或极显著正相关;芦苇分株均由根茎芽萌发形成,根茎芽对分株的贡献率为100%,80%以上的根茎芽萌发形成新根茎,根茎的生长又可形成更多的根茎芽,不同构件形态结构的更替改变维持着种群的稳定和持续更新。     

克隆植物蝴蝶花在光梯度环境上的形态适应性研究

对四川缙云山毛竹林和针阔叶混交林具有林窗、林缘和林下3种光照差异明显生境下的克隆草本植物蝴蝶花的形态可塑性进行了研究．统计了分株、根茎和叶生长方向等特征．经方差分析和t检验后表明．蝴蝶花在光梯度环境下,其形态特征表现出适应性变化．从林窗→林绿→林下,随着光强度的减弱,分株的高度、密度相应减小．在林下达到最小;而根茎的长度、节间长则相反,在遮荫大的林下最大．研究发现,叶片数目和根茎直径在不同的样地和生境中无明显变化,但叶片的生长方向和光照方向关系极大,表现出极强的向光性．此外,文章还对蝴蝶花表现出的可塑性进行了分析和讨论．     

Clonal plasticity in response to rhizome severing and heterogeneous resource supply in the rhizomatous grass Psammochloa villosa in an Inner Mongolian dune, China

In a field experiment, Psammochloa villosa plants were subjected to rhizome severing. Severing rhizomes reduced growth in the young, detached rhizome segments compared to the controls in terms of all measured clonal growth-related characters, i.e. number of rhizomes and shoots, total rhizome length and total number of rhizome nodes. In a container experiment, the control ramets received uniform water and nutrient supply but in heterogeneous treatments high and low levels of water and nutrient supply, respectively were established. The number of ramets, total rhizome length, dry weight per ramet and biomass allocation to the rhizome had higher values at high water and nutrient supply, while spacer length (length of rhizome between shoots) and rhizome internode length were not affected. The local response of ramets given low water supply was enhanced due to connection to a well watered parent ramet in terms of number of ramets, total rhizome length and dry weight per ramet. A remote effect was not observed in the other treatments or in the other measured characters.     

Trade-offs among growth, clonal, and sexual reproduction in an invasive plant Spartina alterniflora responding to inundation and clonal integration

The purpose of this article was to study the trade-offs among vegetative growth, clonal, and sexual reproduction in an aquatic invasive weed Spartina alterniflora that experienced different inundation depths and clonal integration. Here, the rhizome connections between mother and daughter ramets were either severed or left intact. Subsequently, these clones were flooded with water levels of 0, 9, and 18 cm above the soil surface. Severing rhizomes decreased growth and clonal reproduction of daughter ramets, and increased those of mother ramets grown in shallow and deep water. The daughter ramets disconnected from mother ramets did not flower, while sexual reproduction of mother ramets was not affected by severing. Clonal integration only benefited the total rhizome length, rhizome biomass, and number of rhizomes of the whole clones in non-inundation conditions. Furthermore, growth and clonal reproduction of mother, daughter ramets, and the whole clone decreased with inundation depth, whereas sexual reproduction of mother ramets and the whole clones increased. We concluded that the trade-offs among growth, clonal, and sexual reproduction of S. alterniflora would be affected by inundation depth, but not by clonal integration.     

Evolutionary impacts of the goldenrod ball gallmaker on Solidago altissima clones

Summary Three ramet clones of Solidago altissima were grown under greenhouse conditions to determine the effects of varying levels of attack by the goldenrod ball gallmaker (Eurosta solidaginis) on biomass allocation, leaf senescence rate and rhizome connections among ramets. The results, examined at both the individual ramet level and the clone level, showed that galled ramets became isolated from their clone through deterioration of rhizome connections. Gall effects were only observed at the ramet level although rhizome connection effects were detected at both the ramet and clone levels. The goldenrod ball gallmaker may therefore have little evolutionary impact on large clones but could appreciably affect newly established clones.     

Clonal plant allocation to daughter ramets is a simple function of parent size across species and nutrient levels

The evolution of clonal growth is a widespread phenomenon among plant species, characterized by the production of genetically identical clonal fragments (ramets) via rhizomes or stolons that form an interconnected clonal organism (genet). Clonal plant species are known to differ in their investment into ramet production, and exhibit considerable variation in ramet morphology both within and among species. While patterns of resource allocation are thought to be linked to a number of plant characteristics, many analyses are limited by uncertainty in how clonal plants determine the morphology and resources allocated to new ramets. In this study, we attempted to discern what aspects of parent ramets best predicted resource allocation to new daughter ramets, and the relationship between resource allocation and daughter ramet rhizome morphology. We grew two sedge species, Schoenoplectus tabernaemontani and Eleocharis elliptica, in a greenhouse under two levels of fertilizer addition. By harvesting daughter ramets that had initiated stem production, yet remained aphotosynthetic, we were able to isolate parental investment into non-independent daughter ramets at a point where daughter ramet spacer length became fixed. Our results indicate that parent ramets allocated a non-linear proportion of parent rhizome biomass to the production of daughter ramets. Moreover, this relationship was unaffected by environmental nutrient availability. Daughter ramet biomass, in turn, was strongly correlated with daughter ramet spacer length. These observations shed light on key processes governing clonal growth in plants, and their potential application in unifying allocational and morphological perspectives to explore the fitness implications of variability in clonal growth.     

毛乌素沙地根茎禾草拂子茅对异质性水分供应的表型可塑性

拂子茅(Calamagrostis epigejos（L.)Roth)为根茎型多年生禾草,具细长根茎。为了探讨拂子茅在异质性水分环境中的表型差异,在内蒙古鄂尔多斯高原的毛乌素沙地对拂子茅由母株、子株组成的分株对给予了高水、低水两种不同的异质性土壤水分处理。实验结果表明：土壤水分状况显著地影响着拂子茅分株的生长表型。在高土壤水分条件下,拂子茅的分株产生的根茎、新生后代分株较多,并使生物量主要分配于地上部分,地上生物量积累多;在低土壤水分条件下,拂子茅分株产生较少的根茎与新生后代分株,并且分配到根系的生物量明显增大。在具有一定对比度的异质性土壤水分环境中,拂子茅分株并不因相连的其他分株所处的土壤水分状况而在根茎生长、新生后代分株的产生和生物量分配等特征上,与同质环境中的具有相同土壤水分状况的分株相比,有明显差异。这些结果揭示：拂子茅仅以分株的形式对异质性水分供应发生表型反应;相连的克隆分株在向顶向和向基向这两个基本方向上,不能对另一分株的土壤水分状况在生K表型上发生反应,它们在水分关系上可能是相互相对独立的。分株的相对独立可能有利于在气候干旱、扰动强烈的沙地环境中实现风险分摊,提高基株的存活几率。     

Functional specialization of ramets in Scirpus maritimus – Splitting the tasks of sexual reproduction, vegetative growth, and resource storage

Clonal plant species can be considered as populations of interconnected ramets which are basically identical in form and function, and potentially independent from each other. Experimental studies and field observations suggest that an intra-clonal specialization of ramets with different roles (division of labour) can increase the performance of clonal systems under heterogeneous conditions. This paper explores structural and functional variation in the emergent macrophyte Scirpus maritimus, which forms ramets that specialize in three main activities: sexual reproduction, photosynthetic assimilation and vegetative growth, and reserve storage. The main question asked in this study is whether such specialization is a developmentally programmed syndrome in this species, and whether environmental conditions can alter the pattern of ramet differentiation along rhizome systems.We analyzed clonal fragments collected from a population in the field, and grew clones individually in pots of two sizes to simulate different degrees of crowding and shoot density. Specialization of ramets was largely predictable from their position along the rhizome system, indicating that specialization is an inherent feature (developmentally programmed) of clone ontogeny in S. maritimus. In the field, sexual ramets were always situated at the base of rhizome systems, vegetative ramets were in first and intermediate positions, and shoot-less storage ramets were almost always formed distally on rhizomes (terminal ramets). In the pot experiment flowering ramets were observed in all positions along rhizome systems, suggesting that specialization for sexual reproduction shows a plastic response to environmental conditions.S. maritimus can adjust the relative numbers of ramets with and without above-ground shoots when grown in different shoot densities, i.e. the frequency of individual ramets responsible for a certain functional or developmental process can be adjusted to environmental conditions and internal needs. In S. maritimus, the density-dependant regulation of storage versus vegetative growth and sexual reproduction may represent a mechanism to limit shoot competition in crowded populations.     

A trade-off between guerrilla and phalanx growth forms in Leymus secalinus under different nutrient supplies

BACKGROUND AND AIMS: A phalanx growth form enables clonal plants to make better use of resource-rich patches, whereas a guerrilla growth form provides them with opportunities to escape from resource-poor sites. Leymus secalinus produces both spreading (guerrilla form) and clumping ramets (phalanx form). Here, the hypothesis that a trade-off between the two growth forms in L. secalinus exists under different resource levels is tested. METHODS: Ramets of L. secalinus were grown under three levels of nutrient supply. KEY RESULTS: With increasing nutrient supply, the proportion of clumping ramets (in total number of ramets) increased, whereas that of spreading ramets decreased. With increasing nutrient supply, the number of buds increased, whereas biomass per bud decreased. A trade-off between bud number and size further supports the above hypothesis because larger buds were more likely to develop into spreading ramets, and smaller buds into clumping ramets. Mean spacer length between spreading ramets was significantly smaller under the high than under the medium nutrient supply. CONCLUSIONS: The results suggest that a trade-off between the two growth forms in L. secalinus exists under different nutrient supplies. Such a trade-off together with plasticity in spacer morphology may enable L. secalinus to make better use of small-scale heterogeneity in resource supply.     

Nutrient and biomass allocation in Solidago altissima: effects of two stem gallmakers,fertilization, and ramet isolation

Summary The allocations of biomass, N, P, and K were determined by standard methods in goldenrod ramets (1) parasitized by dipteran and lepidopterous gallmakers, (2) from fertilized and unfertilized plots, and (3) whose rhizome connections to their parental clone were severed. The presence of ball galls and their larvae increased allocation to stem but decreased allocation to leaves and seed production, and reduced the number of new rhizomes. There was a marked magnification of N and P concentrations going up the food chains; from goldenrods to gallmakers to the gallmaker's parasitoid/inquiline guild. Nutrient budgets expressed as flow diagrams indicated that N and P costs of gall presence were similar to energy costs under conditions where nutrients did not limit plant growth. Our data do not indicate that the growth of the galls of these gallmakers is limited by either N or P. Ramets from fertilized plots contained more N and P than controls but decreased the percentage of biomass allocated to leaves and inflorescences; ramets isolated by rhizome-cutting compensated their loss by increased allocation to roots, current rhizomes, and new rhizomes but at a cost of lower allocation to seed production and leaves. Gallmakers have a negative impact on host plant fitness characteristics. This may be especially important to establishing perennial hosts, given that herbivore effects would reduce clonal expansion and hence the ultimate clone size, thereby decreasing lifetime plant fitness.     

Do clonal growth form and habitat origin affect resource-induced plasticity in Tibetan alpine herbs?

To investigate how growth form and habitat origin affect phenotypic plasticity to resource supply in the Tibetan alpine herbs, the phalanx-type species Stipa capillacea and the guerilla-type species Carex montis-everestii were sampled from two different habitats (alpine steppe and alpine scrubland) and grown under three levels of light intensity and two levels of nutrient supply. Interspecific differences in light-induced plasticity were detected only in number of ramets, specific leaf area and leaf sheath length. Plasticity in plant biomass, number of ramets and rhizome length in response to light intensity differed between the two habitats. Stipa plants were more plastic than Carex plants in number of ramets and specific leaf area in response to light intensity. Carex plants from the alpine scrubland expressed greater light-induced plasticity in plant biomass and number of ramets than those from the alpine steppe, and Stipa plants showed less interhabitat differences in plasticity, which may be closely related to their contrasting growth forms. Clonal growth form and habitat origin affected nutrient-induced plasticity in none of the measured traits. It may be the guerilla growth form that makes Carex plants more efficiently adapted to highly heterogeneous light conditions in scrubland, and less habitat-dependent plasticity contributes to success of the phalanx-type Stipa plants in alpine habitats. The results are discussed in the context of foraging for heterogeneously distributed essential resources and adaptation to habitat origin.