光强对比度对大米草克隆整合作用的影响

通过温室控制试验,分析不同光强及光强对比度处理下克隆植物大米草生长性状的差异,研究同质异质光强条件下克隆整合对大米草响应遮阴能力的修饰作用.结果表明： 在同质条件下,大米草在无遮阴(高光强：温室内自然光照强度)条件下的生物量显著大于中度遮阴(中光强：光照强度为高光强的70%)和深度遮阴(低光强：光照强度为高光强的30%).在低对比度异质性光强条件下(分株对的一个分株不遮阴,另一个分株中度遮阴),大米草遮阴分株的叶片数、根长和生物量均显著高于同质中度遮阴处理,而无遮阴分株各生长指标与同质无遮阴处理相比均无显著差异.因此,在低对比度异质性光强下,大米草受体(遮阴)分株通过克隆整合显著受益;同时,对供体(非遮阴)分株没有显著的耗损.然而,在高对比度处理下(分株对的一个分株不遮阴,另一个分株深度遮阴),克隆整合对受体(遮阴)分株的效应不显著.大米草的克隆整合并不随着光强对比度的增加而增加.在自然生境中度遮阴情况下,克隆整合可以提高大米草的生长和克隆繁殖能力,但在深度遮阴情况下,克隆整合对大米草适应性的作用可能很小.     

杉木宿存叶片的分解及稳定性碳氮同位素和化学组成

杉木枯死枝叶由于长期宿存于树冠,不易脱落,且生物量大,其分解和养分释放对杉木人工林营养循环具有重要意义。用比叶质量法估算了我国亚热带地区福建南平17年生杉木树冠层不同高度宿存叶片的分解程度,测定了碳氮含量、碳氮稳定性同位素及有机碳化学组成。结果表明:杉木宿存叶片的比叶质量呈现出由上向下逐渐减小的趋势,树冠8~10 m处宿存叶片的比叶质量(26.02 mg·cm-2)显著大于刚死杉木叶片的比叶质量(23.12 mg·cm-2)和6~8 m处宿存叶片的比叶质量(15.39 mg·cm-2),而0~2、2~4和4~6 m这3层宿存叶片的比叶质量无显著差异。刚死杉木叶的碳含量(50.67%)和氮含量(0.75%)显著低于不同高度宿存叶片的碳氮含量,而不同高度宿存叶片的碳氮含量和碳氮比均无显著差异。刚死杉木叶片的碳氮比(67.58)显著高于不同高度宿存叶片的碳氮比。当杉木宿存叶片的C/N为45.91±0.45时开始净氮释放。刚死杉木叶片和8~10 m高度处宿存叶片δ15N值显著高于其他高度宿存叶片,而其他高度宿存叶片的δ15N含量无显著差异。不同高度杉木宿存叶片的δ13C无显著差异。杉木宿存叶片中多糖碳和乙缩醛碳首先被分解,而烷基碳、芳碳、酚碳和羧基碳的分解速度比多糖碳和乙缩醛碳的慢。     

养分异质条件下结缕草克隆分株生长及光合作用的生理整合

通过对连接和断开的分株进行不同养分处理,研究养分异质条件下结缕草克隆分株生长及光合作用的变化.结果表明:在养分异质条件下,处于中、高养分水平的母株可以提高与其相连子株的叶长、叶宽、根质量、叶质量、光合速率、气孔导度、蒸腾速率和水分利用效率,高养分条件下分别提高16.0%、8.3%、24.4%、58.1%、30.3%、54.0%、9.2%和21.9%,降低根冠比和胞间CO2浓度,在高养分下分别降低21.6%和31.5%;处于中、高养分水平的子株对与其相连母株的生长及光合特性没有显著影响.在养分异质条件下,结缕草母株对子株存在生理整合,养分梯度越大,整合强度越强.结缕草克隆子株可以从母株获益,但母株不能从子株获益,子株是生理整合单向获益者.     

养分异质条件下结缕草克隆分株生长、碳水化合物及可溶性蛋白的生理整合

通过对连接和断开的结缕草分株进行不同的养分处理,研究了养分异质条件下结缕草克隆分株生长、碳水化合物及可溶性蛋白含量的变化.结果表明: 在养分异质条件下,处于中、高养分水平的母株可以显著提高与其相连子株的地上、地下及总生物量,高养分下分别提高32.5%、22.1%和24.8%,降低根冠比、可溶性糖及非结构性碳水化合物(NSC)含量,高养分下分别降低7.7%、15.2%和13.1%,但是对淀粉、纤维素、可溶性蛋白含量无显著影响.处于中、高养分水平的子株对与其相连的母株生长、碳水化合物及可溶性蛋白含量没有显著影响.养分异质条件下结缕草母株对子株生物量、根冠比、可溶性糖及NSC含量有明显的生理整合,其整合强度与养分梯度呈正比,而对淀粉、纤维素及可溶性蛋白含量没有显现显著的生理整合效应.子株对母株各项指标都没有显著的生理整合,结缕草母株和子株间是一种单向的生理整合.     

Responses to mineral nutrient availability and heterogeneity in physiologically integrated sedges from contrasting habitats

Clonal plants from poor habitats benefit less from morphologically plastic responses to heterogeneity than plants from more productive sites. In addition, physiological integration has been suggested to either increase or decrease the foraging efficiency of clonal plants. We tested the capacity for biomass production and morphological response in two closely related, rhizomatous species from habitats that differ in resource availability, Carex arenaria (from poor sand dunes) and C. disticha (from nutrient-richer, moister habitats). We expected lower total biomass production and reduced morphological plasticity in C. arenaria, and that both species would produce more ramets in high nutrient patches, either in response to signals transported through physiological integration, or by locally determined responses to nutrient availability. To investigate mineral nutrient heterogeneity, plants were grown in boxes divided into two compartments with homogeneous or heterogeneous supply of high (H) or low (L) nutrient levels, resulting in four treatments, H-H, H-L, L-H and L-L. Both C. arenaria and C. disticha produced similar biomass in high nutrient treatments. C. disticha responded to high nutrients by increased biomass production and branching of the young parts and by altering root:shoot ratio and rhizome lengths, while C. arenaria showed localised responses to high nutrients in terms of local biomass and branch production in high nutrient patches. The results demonstrated that although it has a conservative morphology, C. arenaria responded to nutrient heterogeneity through morphological plasticity. An analysis of costs and benefits of integration on biomass production showed that young ramets of both species benefited significantly from physiological integration, but no corresponding costs were found. This suggests that plants from resource-poor but dynamic habitats like sand dunes respond morphologically to high nutrient patches. The two species responded to nutrient heterogeneity in different traits, and this is discussed in terms of local and distant signalling of plant status.     

匍匐茎草本植物形态可塑性、整合作用与觅食行为研究进展

综述了匍匐茎型克隆植物在形态可塑性、整合作用及觅食行为方面的研究进展。资源斑块性分布是生境异质性的特征之一,适应于异质性生境,匍匐茎植物对环境资源表现了一系列可塑性反应。本文着重从匍匐茎植物对光、水、肥的可塑性反应及其整合作用以及觅食行为等方面的研究进行总结分析,以期对匍匐茎型克隆植物进行更广泛深入的研究。     

Thoughts on clonal integration: Facing the evolutionary context

Summary In this essay, I have pointed out that the appropriate evolutionary context for plant clonality dictates a focus on the impact of the derived trait of potential independence of subunits on the evolutionarily primitive trait of obligate interdependence of plant subunits, i.e. the advantages of independence. This fact prescribes a major shift in approach from previous lines of investigation which have assumed that clonal plants should fall apart and sought to determine the advantages of interdependence. The delineated reorientation calls for a significant change in the investigation of the ecology of clonality in higher plants, emphasizing factors that select for physical and physiological disintegration of the genet and de-emphasizing the need to derive ecological explanations for properties a plant will possess entirely by reason of its phylogenetic and developmental heritage. I suggest that (1) patterns of ramet independence may result from selective pressures on the cost of interconnections (2) programmed ramet independendence may be a response to the selective pressure of a high possibility of traumatic breakage and (3) programmed ramet independence may allow escape of the genet from mortality due to pathogen infestation.     

芦苇克隆整合对石油污染湿地土壤微生物群落结构和生物量的影响

克隆植物形体相连的无性个体(分株)之间可以进行水分、养分和光合产物的传递和共享,并且这种克隆整合可以显著提高分株对环境胁迫的耐受能力,从而可能进一步影响分株周围的土壤微生物群落结构和生物量。尽管国内外已经开展了大量有关克隆整合对分株耐受胁迫能力影响的研究,但克隆整合对土壤微生物群落结构和生物量影响的研究却十分缺乏。以黄河三角洲芦苇(Phragmites australis)湿地生态系统为研究对象,将直径60 cm的圆形样方进行三个水平的石油添加处理(不添加石油或每年添加5 mm或10 mm厚的石油),同时通过切断或不切断样方内外芦苇根状茎的连接来控制克隆整合的有无。实验连续开展了两年(2014—2015年),每年8月份在样方内进行土壤样品取样,在实验室内采用磷酸脂肪酸(PLFA)法测定土壤微生物总量及主要微生物类群含量,并测定土壤微生物生物量碳和氮含量。取样时间显著影响土壤微生物PLFA总量、微生物碳和氮含量,这3个变量在2015年均显著高于2014年。石油添加在2015年显著增加了土壤微生物PLFA总量,但在2014年却无显著效应;同时,石油添加在2014年降低了土壤微生物碳和氮含量,而在2015年却增加了其含量。然而,无论在2014年还是2015年,芦苇的克隆整合对土壤微生物PLFA含量、微生物碳和氮含量均没有显著影响。土壤微生物PLFA总量与土壤微生物碳和氮含量呈正相关关系。这些结果表明,石油污染可以显著影响湿地土壤微生物动态,但克隆整合却无显著效应。     

植物组合及水体营养梯度对三种功能性植物生物量累积与分配的影响

设置4个营养水平(I: 0.5 mg N·L^-1, 0.1 mg P·L^-1; II: 1.5 mg N·L^-1, 0.3 mg P·L^-1; III: 4.5 mg N·L^-1, 0.9 mg P·L^-1; Ⅳ: 13.5 mg N·L^-1, 2.7 mg P·L^-1), 研究了水体营养水平、物种组合及其交互作用对入侵漂浮植物凤眼莲、本地扎根浮叶植物黄花水龙和沉水植物苦草生物量累积与分配的影响.结果表明：随营养水平的升高,4个营养水平的凤眼莲和黄花水龙单种和混种的总生物量及茎叶生物量都呈上升趋势,凤眼莲和黄花水龙的总生物量在Ⅲ、Ⅳ处理下平均比Ⅰ、Ⅱ处理下分别增加了54.47%和102.63%;不同植物组合下,苦草各部分生物量呈下降趋势,Ⅲ、Ⅳ处理的总生物量比Ⅰ、Ⅱ处理平均降低了45.88%;经双因素分析,水体营养水平对凤眼莲和黄花水龙生物量有极显著的正影响（P<0.01）,对苦草生物量有极显著的负影响（P<0.01）;而植物组合的影响随目标植物的不同呈现出差异.     

Clonal plants as cooperative systems: Benefits in heterogeneous environments

All natural environments are spatially and temporally heterogeneous. Consequently, their ability to provide essential resources for the growth of plants is variable. Modular plant species produce repeated basic structures which, in the case of clonal species, are called ramets. Ramets belonging to the same clone are distributed throughout the environment in space and time, and therefore they may be located in sites which differ in resource-providing quality. The connections between ramets may allow resources to be shared, enabling the clone to behave as a cooperative system. As a result of such physiological integration, ramets can survive in conditions where there is lethal shortage of a resource because they are connected to, and supported by, ramets located in conditions where there is ample supply of the same resource. Physiological integration between connected ramets presents opportunities for heterogeneous environments to be exploited to an extent that is only just becoming apparent. As heterogeneity is ubiquitous in natural environments, it may be expected that plants, as relatively immobile organisms, will have evolved the capacity to cope with it by making appropriate localized morphological and/or physiological plastic responses. Recent studies suggest that such responses not only enable clonal species to cope with environmental heterogeneity, but that under some circumstances they can benefit more from environments which are heterogeneous rather than homogeneous, even when both types of environment contain the same amount of resources. Studies on Glechoma hederacea (Lamiaceae) that illustrate this phenomenon are described.     

异质光照环境下克隆整合对南美蟛蜞菊和蟛蜞菊种间关系的影响

很多入侵植物具有克隆性,克隆整合对入侵克隆植物生长和繁殖具有重要的贡献。自然界中,植物生长和繁殖所需的各种资源如光照、水分和矿质养分等在空间上分布通常是异质的,但关于异质环境下克隆整合对入侵植物和本土同属植物种间关系影响的研究相对缺乏。通过温室控制实验,将入侵植物南美蟛蜞菊(Wedelia trilobata)和同属本土植物蟛蜞菊(W.chinensis)的分株对单独种植或者混合种植在异质性光照条件下,同时通过保持或者切断分株之间的连接来控制克隆整合效应的有无,研究异质光照环境下克隆整合对南美蟛蜞菊和蟛蜞菊种间关系的影响。克隆整合对南美蟛蜞菊和蟛蜞菊的生长和繁殖都有促进作用,且南美蟛蜞菊比蟛蜞菊从克隆整合中获益更多。与单独种植相比,两者混种对南美蟛蜞菊的叶生物量有显著影响,而对本地种蟛蜞菊的根生物量有显著影响。克隆整合和种间关系对南美蟛蜞菊的总生物量和叶生物量产生了显著的交互作用,而对蟛蜞菊各指标无显著影响。克隆整合状态显著影响了南美蟛蜞菊和蟛蜞菊的种间关系。这些结果表明,异质环境下克隆整合可以改变入侵植物南美蟛蜞菊和本土植物蟛蜞菊的生长性状及种间关系。