光照强度和基质养分对匍匐茎草本金戴戴克隆生长和克隆形态的影响

在深度遮光(光照强度为高光条件的6.25%,约为自然光照的5.3%)或低养分条件下,金戴戴(Halerpestes ruthenica Ovcz.)生物量、初级分株叶面积、分株总数、匍匐茎总数和总长度均显著减小,而比节间长和比叶柄长显著增加.在低养分条件下,金戴戴匍匐茎平均节间长显著增加,而匍匐茎分枝强度和分株数显著减小.这些结果与克隆植物觅食模型相符合,表明当生长于异质性生境中,金戴戴可能通过以克隆生长和克隆形态的可塑性实现的觅养行为来增加对养分资源的摄取.在深度遮光条件下,金戴戴平均间隔子长度(即平均节间长和平均叶柄长)均显著减小.这一结果与以往实验中匍匐茎草本间隔子对中度和轻度遮光(光照强度为高光条件的13%～75%,>10%的自然光照)的反应不同.这表明,在深度遮光条件下匍匐茎克隆植物可能不发生通过间隔子可塑性实现的觅光行为.光照强度和基质养分条件的交互作用对许多性状如总生物量、匍匐茎总数和总长度、二级和三级分株数、分株总数、初级分株叶面积以及分枝强度均有十分显著的效应.在高光条件下,基质养分对这些性状有十分显著的影响;而在低光条件下,基质养分条件对这些性状不产生影响或影响较小.这表明,光照强度影响金戴戴对基质养分的可塑性反应.在深度遮光或低养分条件下,金戴戴可能通过减小匍匐茎节间粗度(增加比节间长)来增加或维持其相对长度,从而更有机会逃离资源丰度低的斑块.     

光照强度和基质养分对匍匐茎草本金戴戴克隆生长和克隆形态的影响

在深度遮光 (光照强度为高光条件的 6 .2 5% ,约为自然光照的 5.3% )或低养分条件下 ,金戴戴 (HalerpestesruthenicaOvcz.)生物量、初级分株叶面积、分株总数、匍匐茎总数和总长度均显著减小 ,而比节间长和比叶柄长显著增加。在低养分条件下 ,金戴戴匍匐茎平均节间长显著增加 ,而匍匐茎分枝强度和分株数显著减小。这些结果与克隆植物觅食模型相符合 ,表明当生长于异质性生境中 ,金戴戴可能通过以克隆生长和克隆形态的可塑性实现的觅养行为来增加对养分资源的摄取。在深度遮光条件下 ,金戴戴平均间隔子长度 (即平均节间长和平均叶柄长 )均显著减小。这一结果与以往实验中匍匐茎草本间隔子对中度和轻度遮光 (光照强度为高光条件的 1 3%～ 75% ,>1 0 %的自然光照 )的反应不同。这表明 ,在深度遮光条件下匍匐茎克隆植物可能不发生通过间隔子可塑性实现的觅光行为。光照强度和基质养分条件的交互作用对许多性状如总生物量、匍匐茎总数和总长度、二级和三级分株数、分株总数、初级分株叶面积以及分枝强度均有十分显著的效应。在高光条件下 ,基质养分对这些性状有十分显著的影响 ;而在低光条件下 ,基质养分条件对这些性状不产生影响或影响较小。这表明 ,光照强度影响金戴戴对基质养分的可塑性反应。在深度遮光     

Physical connection decreases benefits of clonal integration in Alternanthera philoxeroides under three warming scenarios

Physical connection between ramets usually allows clonal plants to perform better but can have the opposite effects in some cases. Clonal integration and the effects of climate warming have been extensively studied, but to date little is known about how climate warming affects the benefits of clonal integration. We conducted a field experiment in which Alternanthera philoxeroides segments with connected and severed stolons were subject to four climate regimes (ambient, day warming, night warming and daily warming), and measured final biomass, number of ramets and total length of stolons. Across the three warming treatments, temperature rise suppressed growth of clonal fragments with connected stolons but increased growth of fragments with severed stolons; temperature rise affected the biomass of distal ramets but not proximal ramets, and had similar effects on the numbers of proximal and distal ramets. When the three warming treatments were considered separately, they had contrasting consequences for the benefits of clonal integration. Specifically, when fragments were exposed to day and night warming, physical connection evened out the advantages of clonal integration that occur under ambient conditions; when fragments were exposed to daily warming, physical connection led to smaller clonal plants. These findings suggest that physical connection between ramets may be disadvantageous to overall performance of A. philoxeroides fragments under climate warming, and also indicate that the net consequences of daily warming outweigh those of day or night warming.     

Response of galling invertebrates on Salix lanata to reindeer herbivory

Browsing and defoliation often increase the densities of insect herbivores on woody plants. Densities of herbivorous invertebrates were estimated in a long-term grazing manipulation experiment. More then 30-yr-old fences allow us to compare densities of invertebrate herbivores on Salix lanata in areas heavily grazed and areas lightly grazed by reindeer. The number of gall-forming insects ( Pontania glabrifons) and gall-forming mites were higher on the heavily grazed shrubs than on lightly grazed shrubs. In contrast to most short-term studies, the heavily grazed S. lanata had shorter current annual shoots. No difference in leaf size, leaf nitrogen content, or C:N ratio between grazing intensities were detected. However, the enhanced natural δ15N value indicates that heavily grazed shrubs get a higher proportion of their N directly from reindeer faeces. Leaf weight per unit area and relative fluctuating asymmetry of leaf shape increased in heavily grazed S. lanata . Enhanced relative fluctuating asymmetry might indicate higher susceptibility to herbivores. Long-term grazing seems to increase the density of invertebrate herbivory in the same way as short-term grazing, even if the plant responses differ substantially.     

Demography and modelling of clonal fragments in the pseudoannual plant shape Trientalis europaea L.

The clonal growth pattern and demography of clonal fragments (aggregation of ramets derived from a common parent ramet) in the pseudoannual plant Trientalis europaea were studied in field conditions from 1991 to 1993. During this period the population of clonal fragments declined, with a half-life of 7.4 years. Number and size of the clonal progeny and stolon length were positively related to the size of the mother ramet. Survival rates of ramets and tubers increased with size. The rate of clonal growth was low: after three years, about 70% of the clonal fragments had only one ramet. This suggests that the pseudoannual growth habit in T. europaea is more important as mechanism of perennation than of ramet multiplication.Field data were used in a simulation model of architecture and population dynamics of clonal fragments. About 10% of the clonal fragments survived to the end of the simulation (15 years) and the mean survival was 4.7 years. The model predicted a positive correlation between persistence of the clonal fragment and number of ramets produced. Sensitivity analysis showed that the production of a daughter ramet of at least the same size as the parent ramet was the most important pathway for the survival and the number of ramets of the clonal fragment, whereas the production of secondary ramets had a very small effect. This confirms the interpretation of the pseudoannual life-cycle as a mechanism of ramet replacement in this species. Sensitivity analysis also revealed that changes in survival probabilities of the smallest ramets had the largest impact on clonal fragment dynamics. This reflects the important role of the smallest size class of ramets as a source of new vegetative propagules, maintaining a hierarchy in the size structure of the population.     

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree

Background and Aims

Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation.

Methods

In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits.

Key Results

Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection.

Conclusions

Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.     

Systemic induced resistance: a risk-spreading strategy in clonal plant networks?

Clonal plant networks consist of interconnected individuals (ramets) of different sizes and ages. They represent heterogeneous ramet assemblages with marked differences in quality and attractiveness for herbivores. Here, feeding preferences of a generalist herbivore (Spodoptera exigua) for differently-aged ramets of Trifolium repens were studied, and changes in herbivore preference in response to systemic defense induction were investigated. Dual-choice tests were used to assess the preference of herbivores for young versus mature ramets of induced and uninduced plants, respectively. Additionally, leaf traits related to nutrition, biomechanics and chemical defense were measured to explain variation in tissue quality and herbivore preference. Young ramets were heavily damaged in control plants. After systemic defense induction, damage on young ramets was greatly reduced, while damage on mature ramets increased slightly. Defense induction increased leaf strength and thickness, decreased leaf soluble carbohydrates and substantially changed phenolic composition of undamaged ramets connected to attacked individuals. Systemic induced resistance led to a more dispersed feeding pattern among ramets of different ages. It is proposed that inducible defense acts as a risk-spreading strategy in clonal plants by equalizing herbivore preference within the clone, thereby avoiding extended selective feeding on valuable plant tissues.     

Modelling the morphological response to nutrient availability in the clonal plant Trientalis europaea L.

The morphological responses to changes in environmental quality shown by many clonal plants have been interpreted as an expression of foraging behaviour, as they allow the ramets to become concentrated in more favourable microhabitats. The morphological response to increased nutrient availability in the pseudoannual plant Trientalis europaea was studied in a field experiment. The response was largely size-dependent and consistent with enhanced clonal growth. Fertilized ramets produced more tubers and a larger main tuber. In contrast, stolon length was not affected by the treatment. A spatially explicit simulation model calibrated with data from the field experiment examined the population dynamics of T. europaea ramets in a spatially hetereogeneous, temporally constant, environment. The model showed that T. europaea was effective at concentrating its ramets in favourable patches, but this process was strongly influenced by patch size. The analysis of this response at the clone level showed that ramet aggregation was mainly due to the enhanced performance of clones located initially in the favourable patches, or clones that located a favourable patch by chance. In these clones, the simultaneous increase of ramet size and survival accelerated the production of ramets. The temporal and spatial scale at which the aggregation of ramets in favourable patches was manifested suggests that the effectiveness of the morphological response in T. europaea is favoured by a high spatio-temporal predictability in the environment. Overall, the model emphasized the important role of population dynamics in understanding the nature of the foraging response.     

不同放牧强度对鹅绒委陵菜克隆生长特征的影响

在中国科学院海北高寒草甸生态系统定位站,对通过17 a不同放牧强度干扰后金露梅灌丛草甸内鹅绒委陵菜克隆生长特征进行实地调查统计研究.结果显示:长期放牧并增加放牧强度后,植物群落的高度、盖度和草场质量指数下降.随着放牧强度增大,鹅绒委陵菜无性系匍匐茎数目增加,分枝强度加大;基株变矮,逐渐由直立、半直立型变为匍匐状,形态可塑性明显;根长有逐渐增加的趋势;放牧强度对鹅绒委陵菜无性系分株高度、根长和分株叶数影响不显著;间隔子有变短、变粗的趋势,间隔子数目和分株数目有增加的趋势,但影响不显著;轻牧和不牧样地中用于鹅绒委陵菜克隆生长的平均能量投资(分株和匍匐茎的干重及其所占比例)小于重牧样地.表明随放牧强度增大,鹅绒委陵菜无性繁殖能力增强,呈现出典型的生态适应策略.     

酸雨和采食模拟胁迫下克隆整合对空心莲子草生长的影响

研究表明克隆整合可以显著提升异质环境中克隆植物的生长,然而当克隆植物遭受均质环境压力时,整合对植物生长影响的研究相对较少。本文以典型入侵克隆植物空心莲子草（Alternanthera philoxeroides）为例,研究均质环境压力酸雨和采食模拟胁迫对空心莲子草生长的影响,以及克隆整合在空心莲子草适应不利环境过程中所起的作用。酸雨设3种浓度梯度：pH值3.5 、pH值4.5和 pH值6.5（对照）;采食设3种水平：不去叶、去叶50%和去叶90%;整合水平：匍匐茎切断和连接。结果表明：无论保持或切断匍匐茎的连接,酸雨处理都不影响空心莲子草生物量。当保持匍匐茎连接时,pH值4.5酸雨处理增加了空心莲子草匍匐茎长度和分株数目,因此,低度酸雨可能对空心莲子草生长有一定的促进作用。同样,无论匍匐茎是否被切断,采食处理都显著降低了空心莲子草克隆片段生物量,而显著增加了叶片数目。当切断匍匐茎连接时,采食处理使空心莲子草分株数目显著增加。本文得出的结论是：空心莲子草能较好地适应酸雨和采食的环境压力,当空心莲子草全部克隆分株遭受均质环境胁迫时,克隆整合并不能显著改善它的生长。     

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.     

Effects of cattle and rabbit grazing on clonal expansion of spiny shrubs in wood-pastures

Spiny shrubs protect non-defended plants against herbivores. Therefore, they play a role for the diversity in grazed ecosystems. While the importance of these keystone nurse shrubs is presently recognized, little is known about the factors controlling them. This knowledge is required to understand the functioning of grazed ecosystems and for sustainable management.We studied effects of cattle and rabbits on clonal expansion of Prunus spinosa in two ancient wood-pastures in the Netherlands. At each site we set up five blocks in grassland perpendicular to the edges of mature Prunus thickets, each block containing three herbivore treatments: (1) open-to-cattle-and-rabbits, (2) open to rabbits, cattle excluded, (3) cattle and rabbits excluded. We monitored the number and volume of Prunus ramets from 1998 to 2000 and again in 2003, 3 years after exclosure-removal to restore grazing.For 1998–2000 ramet volume, but not ramet number, differed between treatments. Ramet volume was highest when both cattle and rabbits were excluded. Ramet volume did not differ between grazing by rabbits or cattle and rabbits combined, indicating that rabbits alone may be as effective in inhibiting clonal expansion as cattle and rabbits combined. Three years after exclosure-removal ramet number and volume had increased in all treatments. Number of ramets remained unaffected by (former) treatments. Ramet volume remained highest in the former cattle-plus-rabbits exclusion treatment, differing significantly from the ‘open-to-cattle-and-rabbits’ treatment. So, once successfully established during herbivore absence, further expansion is not prevented by cattle and rabbit grazing.This study shows that vertebrate herbivory controls the keystone nurse-shrub in wood-pastures: combined cattle and rabbit grazing, and notably rabbits alone, inhibit expansion. Temporary herbivore absence allows expansion of ramets, which persists after herbivore-reappearance. Sustainable management of wood-pastures should allow spatial-temporal fluctuations of herbivore densities, leading to increased vegetation structure and associated biodiversity.     

Relative costs and benefits of clonal integration of Zoysia japonica under various N:P ratios

Clonal plants adaptively respond to abiotic stress, but to date little is known about under what circumstanses clonal integration is beneficial, or costly. To study the costs and benefits of clonal integration on clonal growth, we cultivated Zoysia japonica under three ratios of N:P (N:P ≈ 7, 14:1 and 21:1), and four types of stolon severing treatments (connected stolon CS, light severing LS, moderate severing MS, serious severing SS). The results showed that Z. japonica performed best at a low ratio of N:P (N:P ≈ 7:1). When the stolons were connected (CS), the growth of primary A‐ramets, multiple‐nodes and stolons benefited from clonal integration; however, the growth of primary B‐ramets on the primary stolons, A and B ramets was significantly reduced (p < 0.05). In the moderate stolon severing treatment MS_7:1 (N:P ≈ 7:1), clonal integration appeared more cost effective than in all other treatments. On the whole, with increasing stolon severing intensity, the cost of clonal integration increased and the clonal growth of Z. japonica declined significantly. The pattern of biomass allocation may be useful for Z. japonica to adapt to the various environments, and clonal integration plays a significant role under adverse environmental conditions.     

Is analysing the nitrogen use at the plant canopy level a matter of choosing the right optimization criterion?

Herbivores can have strong deleterious effects on plant growth, reproduction, and even survival. Because these effects might be strongly interrelated, the direct consumptive effects of herbivores and a variety of indirect effects are difficult to untangle. Reductions in growth, for example, may strongly impact the flowering behaviour of plant species in the current season, but at the same time incur costs to survival, growth and reproduction in the next growing season(s). To get better insights in the effects of herbivory on the flowering behaviour of the long-lived polycarpic grassland herb Primula veris L., flowering patterns were monitored over ten consecutive years under two treatments (grazing and control mowing regimes). We tested the hypothesis that the size at flowering was affected by the presence of herbivores, and whether this translated into costs to future reproduction and survival. Overall, grazed plants were significantly smaller than control plants, and the size at which plants flowered was also significantly smaller when herbivores were present. The transition probability of flowering and of surviving into the next year was significantly smaller for all plants in the current year if they had been grazed than if they had been mown, indicating that herbivory incurred costs to both flowering and survival. Grazed plants also needed longer to start flowering, had fewer flowers and flowered less frequently, causing a significantly lower proportion of flowering adults in the population. These results suggest that the observed regression in plant size due to herbivory does not allow plants to capture enough resources to guarantee regular flowering in the longer run.     

Effects of organ removal on trade‐offs between sexual and clonal reproduction in the stoloniferous herb Duchesnea indica

Resource allocation patterns and trade‐off between sexual and clonal reproduction in clonal plants have been extensively studied, but little is known about effects of organ removal on the trade‐offs in clonal plants. To examine the effects, we conducted an experiment with the stoloniferous herb Duchesnea indica in which we removed plant organs like roots, flowers, or fruits. Removing roots significantly increased number of ramets and biomass allocation to stolons, but decreased number of fruits. Removing flowers or fruits greatly increased number of ramets and biomass allocation to stolons and roots, but decreased spacer length, number of fruits, and fruits set. Onset and median date of flowering phenology of D. indica shifted after flowers, fruits, or roots were removed. These results may indicate that removing organs can affect trade‐off between sexual and clonal reproduction of D. indica.     

Fitness Implications of Clonal Integration and Leaf Dynamics in a Stoloniferous Herb, Nelsonia canescens (Lam.) Spreng (Nelsoniaceae)

Very little has been published on the life-history significance of clonal plants inhabiting southern African savanna environments. This study investigated the fitness implications of clonal integration, resprouting behaviour and growth phenology in a stoloniferous herb, Nelsonia canescens (blue pussyleaf) at a savanna site in Zambia, central Africa. Census data on growth and survival were obtained regularly on permanently marked ramets over a 4-year period, from 2001 to 2005, and analyzed to assess how physiological integration and module demography contribute to fitness in Nelsonia. Above ground and below ground growth occurred during the dry and rainy seasons, respectively. Dry season growth was characterized by resprouting and production of stolons that bore small pubescent leaves with high mortality (30–80% month⁻¹). Deep roots and high leaf turnover appear to contribute to sustained growth during the dry season when topsoil moisture and nutrient availability are low. The interaction between maximum temperature and precipitation explained a significant proportion (59%, p<0.01) of the monthly variation in leaf size and increasing evapo-transpiration levels appeared to trigger the shift in leaf size from a large wet season type to a small dry season one. During the dry season Nelsonia resprouted from dormant buds buried at the time of root development in daughter ramets in the rainy season. Temporal integration significantly (p<0.05) enhanced survival of daughter ramets. However, daughter ramets with severed mother–daughter ramet inter-connectors experienced high initial mortality that was caused by both early stolon severing and drought stress during the root development phase. The majority of ramets lived for 5–10 months and 25% were still alive at the age of 3.5 years. The study showed that although the growth phenology of Nelsonia has serious ecological implications for accessing scarce resources during the dry season, the species utilizes a number of strategies to overcome resource limitations in a seasonally heterogenous environment. Co-ordinating editor: G. P. Cheplick     

克隆植物沙拐枣的母株和分株对风蚀沙埋的生理生态响应

以中国荒漠区优良的防风固沙克隆灌木沙拐枣为对象,研究了长期风蚀、沙埋环境下沙拐枣母株和克隆分株的同化枝对环境异质性的响应。结果发现:(1)风蚀母株、风蚀分株的叶绿素含量、净光合速率、气孔导度、蒸腾速率、胞间CO2浓度和水分利用效率只有沙埋分株的一半左右,导致同化枝的长度、数量、簇数也仅是沙埋分株的一半,而且风蚀母株的果实宽和果实长也都最小,但浅沙埋有利于沙拐枣的生长和繁殖,表明严峻的风蚀对母株和分株的生长与繁殖都产生了胁迫,但浅沙埋有利于沙拐枣的生长和繁殖。(2)风蚀母株倒伏后同化枝的形态特征是基部优于中部优于顶部,表明严峻风蚀下母株的死亡是从顶部-中部-底部逐渐舍弃的过程。(3)母株的全部根系以及风蚀水平根全部裸露在外但依然能够存活,间接证明沙拐枣克隆整合的方向性——不仅可在分株间进行传递,分株-母株间也可进行传递,否则遭受严峻风蚀胁迫的母株和克隆分株会直接死亡。本研究结果为沙拐枣克隆生长对风沙环境的生态适应机制提供了基础,也是对植物克隆生态学在自然异质环境中研究缺乏的有效补充。     

莲草直胸跳甲取食对空心莲子草和莲子草克隆整合的影响

很多外来入侵植物都具有克隆生长习性,探究克隆整合特性与外来克隆植物入侵性间的关系对阐明其生态适应性及入侵机制具有重要的意义。本研究以入侵植物空心莲子草及其本地同属种莲子草为研究对象,比较在生防昆虫莲草直胸跳甲的取食下,克隆整合对两种植物先端分株、基端分株及整个克隆片段生长和生物量分配的影响。结果表明: 在莲草直胸跳甲取食下,有克隆整合的空心莲子草先端分株的叶片数、茎长、分株数及整个克隆片段的地径均显著高于无克隆整合植株,其基端分株及整个克隆片段的地下生物量和总生物量相较于无克隆整合植株分别降低了78.2%、60.9%和48.7%、37.2%;有克隆整合的莲子草先端分株的地径及整个克隆片段的叶片数与无克隆整合植株相比显著增加,其基端分株数显著降低了21.7%,而其先端分株、基端分株及整个克隆片段的生物量均无显著差异。耗益分析表明,在莲草直胸跳甲取食下,空心莲子草先端分株的分株数与生物量及莲子草先端分株的分株数均能通过克隆整合显著受益,而两种植物基端的分株数、生物量的耗益则不受克隆整合处理的影响。这些结果表明,克隆整合虽能在一定程度缓解莲草直胸跳甲对于两种植物先端分株的取食压力,且空心莲子草的克隆整合作用要强于莲子草,但在整个克隆片段水平上,两种植物并不能通过克隆整合显著获益。     

匍匐茎草本绢毛匍匐委陵菜对局部遮荫的克隆可塑性

采自林窗和林内生境的绢毛匍匐委陵菜 (PotentillareptansL .var.sericophyllaFranch)“分株对”(即由一匍匐茎节间相连着的两个分株 ,其一为“目标分株” ,另一为“相连分株”)在一户外实验中经历了全不遮荫、全部遮荫和局部遮荫处理。该植物的基株生物量、匍匐茎总长度、分株数、匍匐茎比节间重、叶柄长、比叶柄重在遮荫条件下较小。匍匐茎节间长度没有对遮荫处理发生反应。在局部遮荫处理 ,遮荫斑块的分株的叶柄长度由于连着未遮荫斑块中分株而变得更长。这种克隆整合对克隆形态可塑性的修饰作用只在林窗生境来源的实验植物中观察到。其他克隆生长和克隆形态特征的可塑性在不同生境来源的实验植物间没有差异。     

Hydraulic conductivity and PAT determine hierarchical resource partitioning and ramet development along Fragaria stolons

Co-ordination of metabolic and physiological activity between plant parts is key to the control of growth and development. Here the movement of resources and their allocation between mother plants and daughter ramets along Fragaria stolons was quantified with respect to hierarchy. Gradients of internodal ramet leaf water potential (ψ) and stolon and ramet hydraulic conductivities (L) were measured together with apparent stolon IAA movement via the polar auxin transport pathway (PAT). These processes are linked with measurements of stolon vascular development. The pattern of tissue differentiation and lignification in sequential stele sections of stolons demonstrated the rapid acquisition of the capacity for water transport, with transpiration potentially varying systematically with stolon lignification and the acropetal decline in stolon xylem ψ. Stolon and ramet L declined acropetally, with L across older ramets being significantly lower than that of the connecting stolons. The capacity for polar IAA transport increased with stolon age; this was due to increased transport intensity in older tissues. The partitioning of dry matter was strongly hierarchical with younger ramets smaller than older ramets, while foliar concentrations of N, P, and K were greater for the younger ramets. The results show that stolon anatomy develops rapidly at the apical end, facilitating hierarchical ramet development, which is evident as a basipetal increase in L. The rapid development of transport tissue functionality enables young unrooted ramets to acquire water, in order to supply an expanding leaf area, as well as mineral ions disproportionally with respect to older ramets. This facilitates colonization and self-rooting of apical ramets. The unidirectional increase in basipetal PAT along stolons facilitates hierarchical ramet development.