菌根类型对亚热带森林主要树种根叶功能性状关联的影响

叶片和吸收根(即1级根)是植物地上和地下资源获取器官，研究二者功能性状的关系及其影响因素，有助于深入理解植物生长过程中对资源的利用和分配。本研究在江西省九连山国家自然保护区选择了10种丛枝菌根(AM)树种和8种外生菌根(EM)树种，分析了叶片和吸收根的形态性状(叶厚度、比叶面积、叶组织密度、根直径、比根长、根组织密度)和化学性状(叶与根的碳、氮浓度及碳氮比)在不同菌根类型间的变异及关联。结果表明：与AM树种相比，EM树种的叶片较厚、比叶面积较小，且根直径较细、根组织密度和根碳浓度及碳氮比较低。AM和EM树种的叶片与吸收根的形态性状均不相关，而化学性状(氮浓度和碳氮比)在AM树种中呈正相关，但在EM树种中则不相关。主成分分析结果表明，不管是AM还是EM树种，比叶面积与比根长均呈正交分布，可见叶片与吸收根获取资源具有独立性。此外，根直径与根氮浓度在所有树种和AM树种中均表现出显著正相关，而在EM树种则呈临界负相关。根直径与比根长则是在所有树种和不同菌根类型树种中均呈正相关。总之，本研究的结果强调了菌根类型在调节叶片与吸收根功能性状之间的关系上具有重要性，并建议今后在评估木本植物根系的不同功...     

中国亚热带不同菌根树种的根叶形态学性状特征与生长差异: 以江西新岗山为例

探究植物功能性状的种内和种间变异不仅有助于揭示植物对环境的适应, 也能够反映植物的生态策略, 但不同菌根类型树木生长过程中根叶形态学功能性状的适应策略仍有待探究。本研究依托中国亚热带森林生物多样性与生态系统功能实验研究平台(BEF-China)选取7种丛枝菌根(AM)树木和7种外生菌根(EM)树木的纯林, 测定各个树种的比叶面积、叶干物质含量、比根长、根系直径、树高生长速率、地径生长速率及细根生物量等根叶形态学功能性状和生长指标, 探讨了两种菌根类型树种间的根叶形态学特征的差异。结果表明: 与AM树种相比, EM树种具有较小的比叶面积、吸收根平均直径和生长速率, 但具有更大的叶干物质含量; 两种菌根树种之间的比根长和细根生物量无显著差异。比叶面积、叶干物质含量、树高生长速率、地径生长速率和细根生物量等功能性状及生长指标在不同菌根类型、树种及二者的交互作用中均存在显著差异; 且树种、根功能型、菌根类型及三者之间的交互作用均对根功能性状有显著影响。EM树种地上指标的种内变异均大于种间变异, 而AM树种地上指标的种内和种间变异程度类似; 但两种菌根树种细根生物量的种间变异均大于种内变异。尽管两种菌根树种地上部分生长速率较快通常表现为较低的叶干物质含量, 但AM树种通常拥有较高的吸收根比根长, 而EM树种拥有较粗的运输根平均直径。吸收根比根长越低, 两类菌根树种的细根生物量就越多。由此可见, 根叶功能性状对植物地上部分的生长具有一定的协同效应, 其中运输根主要在EM树种地上生长过程中发挥重要作用, 吸收根主要与AM树种的地上部分生长有关; 但两类菌根树种的地下细根生物量均与吸收根有关。     

川西亚高山带森林生态系统外生菌根的形成

利用样方法于2003年8月对四川西部亚高山带分布的川滇高山栎(Quercus aquifolioides)、云杉(Picea asperata)、红桦(Betulaalbo-sinensis)、山杨(Populus davidiana)、铁杉(Tsuga chinensis)、华山松(Pinus armandi)、落叶松(Larix japonica)和冷杉(Abiesfaxoniana)8个主要森林类型的外生菌根进行了调查。结果表明,所有调查的森林类型均被外生菌根真菌所侵染,不同森林类型的宿主植物外生菌根的侵染强度不同,同种森林类型由于受海拔高度、坡度、林龄等条件的影响,植物的菌根侵染率、侵染强度指数以及细根生物量都发生相应的改变。高山栎林型随着海拔高度的增加,土壤上层(0~20cm)菌根侵染率增高、下层(20~40cm)菌根侵染强度指数增大,土壤上下层有效磷浓度都明显减少;坡度小的云杉林型内上下两层细根生物量、菌根侵染率都高于坡度大的云杉林,但是菌根侵染强度指数却较低;相同立地条件下,云杉林型在种群建立(幼林龄)和衰退(成过熟林)时菌根侵染率和侵染强度指数都显著高于种群相对稳定(中林龄)时期,在养分较为肥沃的土壤环境中,菌根侵染率、侵染强度指数与营养因子不存在明显的相关性;山杨、落叶松、冷杉和红桦林型土壤上层菌根侵染率都超过了65%;华山松林型由于坡度最大(50°),其土壤上层菌根侵染强度指数也最大(55.78%);铁杉林型菌根形成状况最差,但细根生物量最大。亚高山带森林类型中的上层植物细根生物量都显著高于下层,表明植物的营养主要由上层根系所输送。     

常绿阔叶林外生和丛枝菌根树种细根形态和构型性状对氮添加的可塑性响应

以中亚热带常绿阔叶林外生菌根树种罗浮栲和丛枝菌根树种木荷为研究对象,采用根袋法进行野外原位氮添加试验,研究了细根形态性状(比根长、比表面积、组织密度、平均根直径)和构型性状(分枝数、分枝比、根长增长速率、根尖密度、分枝密度),分析不同菌根树种细根形态和构型性状对氮沉降的响应.结果表明:随序级增加,外生和丛枝菌根树种细根...     

帽儿山天然次生林20个阔叶树种细根形态

 细根在森林生态系统C分配和养分循环过程中发挥着重要作用。细根形态不但影响养分和水分的吸收, 而且与细根寿命和周转有密切关系。因此, 研究森林树种的细根形态对了解根系结构与功能、预测寿命与周转具有重要理论意义。该文根据细根分枝等级划分方法, 研究了东北帽儿山天然次生林20个阔叶树种1～5级根直径、根长和比根长等形态指标。结果表明, 20个树种中, 除5个树种1级根直径略大于2级和比根长略小于2级根外, 其余15个树种均表现为1级根直径和根长最小、比根长最高, 随着根序增加, 直径和根长增加, 而比根长降低。20个阔叶树种前3级根的累积根长均占前5级根总根长的80%以上。9个内生菌根侵染的树种的平均直径、根长和比根长均大于11个外生菌根侵染的树种。     

落叶松(Larix)细根形态特征沿纬度梯度的可塑性

选择5个不同纬度的落叶松人工林,比较了落叶松细根(2 mm)的直径、根长、比根长和比表面积等形态指标、外生菌根及其侵染率的纬度分异特征,分析了形态特征与主要影响因子间的关系。结果表明:随纬度增加,落叶松1、2级根的外生菌根真菌侵染率降低,菌根颜色变深,分叉减少;细根直径变细,根长缩短,细根比根长和比表面积显著增加;同一地点的细根在不同根序以及侵染与未侵染细根间形态差异明显;冗余分析和回归分析显示,细根直径和根长与年均温、年降水、土壤含水量呈显著正相关,而比根长和比表面积则与土壤全碳、土壤养分含量呈正相关。综上,落叶松细根的形态特征沿纬度梯度呈现出有规律的可塑性响应,外生菌根的宏观形态具有明显的地带性差异,直径和根长主要受气候因子影响,而比根长和比表面积则主要与土壤因子有关。     

氮有效性增加对细根解剖、形态特征和菌根侵染的影响

氮(N)有效性增加对森林生态系统结构和功能有重要影响.细根作为树木地下最为活跃的组分,其对N有效性增加的响应已成为森林生态学研究的热点.本文对N有效性增加条件下细根解剖构造、形态和菌根侵染的响应趋势及潜在机制进行了综述.N有效性增加导致细根皮层厚度、皮层层数和皮层细胞直径下降,外皮层上通道细胞数量减少,而中柱和木质部横截面积,以及导管(或管胞)直径、数量和壁厚度均增加,根解剖构造的响应与植物激素浓度变化有关;N有效性增加后菌根侵染率下降,比根长(单位根干质量的长度)在外生菌根树种中普遍下降,而在内生菌根树种中增加;根直径和组织密度的变化趋势则表现出较大的种间差异.这些个体根和树种水平上的结果对于理解森林生态系统水平上的碳和养分循环具有重要意义.最后,根据目前研究中存在的不足提出了今后的研究方向与问题.     

紫椴根际土壤肥力与外生菌根侵染关系

调查帽儿山老山生态站紫椴(Tilia amurensis Rupr.)外生菌根的侵染情况与根际土壤肥力指标,结合Pearson相关性分析与逐步回归分析的统计方法,分析紫椴外生菌根侵染率与根际土壤肥力指标的相关性。结果表明:紫椴外生菌根侵染率与碱性磷酸酶、碱解氮、有效磷、土壤水分含量呈极显著负相关,与脲酶呈极显著正相关,与速效钾呈显著正相关。逐步回归分析发现,影响紫椴外生菌根侵染率的主要土壤肥力因子是碱性磷酸酶和土壤水分含量。     

亚热带典型树种根毛特征及其与共生真菌的关系

根毛和共生真菌增加了吸收面积,提高了植物获取磷等土壤资源的能力。由于野外原位观测根表微观结构较为困难,吸收细根、根毛、共生真菌如何相互作用并适应土壤资源供应,缺乏相应的数据和理论。该研究以受磷限制的亚热带森林为对象,选取了21种典型树种,定量了根毛存在情况、属性变异,分析了根毛形态特征与共生真菌侵染率、吸收细根功能属性之间的关系,探讨了根表结构对低磷土壤的响应和适应格局。结果表明:1)在亚热带森林根毛不是普遍存在的, 21个树种中仅发现7个树种存有根毛, 4个为丛枝菌根(AM)树种, 3个为外生菌根(ECM)树种。其中,马尾松(Pinus massoniana)根毛出现率最高,为86%;2)菌根类型是理解根-根毛-共生真菌关系的关键,AM树种根毛密度与共生真菌侵染率正相关,但ECM树种根毛直径与共生真菌侵染率负相关; 3) AM树种根毛长度和根毛直径、ECM树种根毛出现率与土壤有效磷含量呈负相关关系。该研究揭示了不同菌根类型树种根毛-共生真菌-根属性的格局及相互作用,为精细理解养分获取策略奠定了基础。     

6种外生菌根真菌对西南桦幼苗的接种效应

【背景】西南桦是兼具内生、外生菌根的典型菌根营养型树种,菌根化育苗是其壮苗培育的有效措施。【目的】揭示外生菌根真菌对西南桦无性系幼苗生长和养分含量的影响,为其菌根化育苗筛选优良外生菌根真菌提供科学依据。【方法】以BY1、FB4、FB4+和A5等4个西南桦优良无性系为研究对象,选用土生空团菌(Cenococcumgeophilum)、松乳菇(Lactariusdeliciosus)、黄硬皮马勃(Scleroderma flavidum)、多根硬皮马勃(S. polyrhizum)、褐环乳牛肝菌(Suillus luteus)和红绒盖牛肝菌(Xerocomuschrysenteron)6个外生菌根真菌进行盆栽接种试验,分析接种处理间及无性系间苗高、地径、生物量以及养分含量差异。【结果】6个菌种均能与西南桦无性系幼苗形成外生菌根共生体,接种多根硬皮马勃与黄硬皮马勃显著促进了幼苗生长和养分吸收(P0.05),说明其与幼苗的亲和力明显优于其它菌种。尽管菌根侵染率在4个无性系之间无显著差异(P≥0.05),但各菌种对FB4、BY1幼苗生长的促进作用显著强于其它2个无性系。【结论】多根硬皮马勃和黄硬皮马勃可作为西南桦菌根化育苗的优选菌种。     

Effects of ectomycorrhizal colonization and nitrogen fertilization on morphology of root tips in a <Emphasis Type="Italic">Larix gmelinii</Emphasis> plantation in northeastern China

Root morphology is important in understanding root functions in forest ecosystems. However, the effects of ectomycorrhizal colonization and soil nutrient availability on root morphology is not clear. In this study, root morphology in relation to season, soil depth, soil nitrogen (N) availability, and mycorrhizal fungal colonization were investigated in a larch (Larix gmelinii) plantation in northeastern China. The first-order roots (or root tips) of larch were sampled four times in May, July, and September of 2005, and May of 2006 from two depths of upper soil layer (0–10 and 10–20 cm) in the control and the N-fertilized plots. The results showed that ectomycorrhizal (ECM) colonization rates for the first-order roots were reduced by 17% under N fertilization. The peak of root colonization rates occurred in summer and was positively correlated with soil temperature. ECM colonization significantly altered root morphology: root diameter was increased by 19 and 29%, root length shortened by 27 and 25%, and specific root length (SRL) reduced by 16 and 19% for the control and the N-fertilized plots, respectively. N fertilization led to decreased root length, but did not affect root diameter and SRL. In addition, effects of ECM colonization on root morphology varied with season and soil depth. The observed relationships among ECM fungal colonization, soil N availability, and root-tip morphology should improve our understanding of how root tips respond to environmental changes in soil in temperate forest ecosystems.     

Fine root architecture, morphology, and biomass of different branch orders of two Chinese temperate tree species

We have limited understanding of architecture and morphology of fine root systems in large woody trees. This study investigated architecture, morphology, and biomass of different fine root branch orders of two temperate tree species from Northeastern China—Larix gmelinii Rupr and Fraxinus mandshurica Rupr —by sampling up to five fine root branch orders three times during the 2003 growing season from two soil depths (i.e., 0–10 and.10–20 cm). Branching ratio (R _b) differed with the level of branching: R _b values from the fifth to the second order of branching were approximately three in both species, but markedly higher for the first two orders of branching, reaching a value of 10.4 for L. gmelinii and 18.6 for F. mandshurica. Fine root diameter, length, SRL and root length density not only had systematic changes with root order, but also varied significantly with season and soil depth. Total biomass per order did not change systematically with branch order. Compared to the second, third and/or fourth order, the first order roots exhibited higher biomass throughout the growing season and soil depths, a pattern related to consistently higher R _b values for the first two orders of branching than the other levels of branching. Moreover, the differences in architecture and morphology across order, season, and soil depth between the two species were consistent with the morphological disparity between gymnosperms and angiosperms reported previously. The results of this study suggest that root architecture and morphology, especially those of the first order roots, should be important for understanding the complexity and multi-functionality of tree fine roots with respect to root nutrient and water uptake, and fine root dynamics in forest ecosystems.     

Specific root length as an indicator of environmental change

Abstract

Specific root length (SRL, m g^?1) is probably the most frequently measured morphological parameter of fine roots. It is believed to characterize economic aspects of the root system and to be indicative of environmental changes. The main objectives of this paper were to review and summarize the published SRL data for different tree species throughout Europe and to assess SRL under varying environmental conditions. Meta-analysis was used to summarize the response of SRL to the following manipulated environmental conditions: fertilization, irrigation, elevated temperature, elevated CO₂, Al-stress, reduced light, heavy metal stress and physical disturbance of soil. SRL was found to be strongly dependent on the fine root classes, i.e. on the ectomycorrhizal short roots (ECM), and on the roots <0.5 mm, <1 mm, <2 mm and 1 – 2 mm in diameter SRL was largest for ECM and decreased with increasing diameter. Changes in soil factors influenced most strongly the SRL of ECM and roots <0.5 mm. The variation in the SRL components, root diameter and root tissue density, and their impact on the SRL value were computed. Meta-analyses showed that SRL decreased significantly under fertilization and Al-stress; it responded negatively to reduced light, elevated temperature and CO_2. We suggest that SRL can be used successfully as an indicator of nutrient availability to trees in experimental conditions.     

亚热带6种树种细根序级结构和形态特征

以福建省建瓯市万木林自然保护区内占优势的6种天然林树种(沉水樟Cinnamomum micranthum,CIM;观光木Tsoongiodendron odorum Chun,TOC;浙江桂Cinnamomum chekiangense,CIC;罗浮栲Castanopsis fabri,CAF;细柄阿丁枫Altingiagracilipes,ALG;米槠Castanopsis carlesii,CAC)为研究对象,对其1—5级细根的结构,形态特征及生物量进行了分析。结果表明:沉水樟,细柄阿丁枫和米槠细根分支比表现出在1,2级(4倍以上)明显大于其它序级(3倍左右);其余3种树种则是在3,4级的细根分支比最大,其中浙江桂达到8.65倍,其它序级则大致为3倍左右。6种树种1,2级细根数量占到总数的70%—90%。6种树种细根直径,根长,组织密度随序级升高逐渐增大,比根长减小,生物量未表现出一致的变化规律,6种树种生物量主要集中在高级根部分。方差分析表明,树种对细根分支比例有显著影响(P<0.05),浙江桂和米槠细根分支水平对分支比例有极显著影响(P<0.01),其余4种树种分支水平对分支比例有显著影响(P<0.05),树种和分支水平的交互作用对6种树种细根分支比均有极显著的影响(P<0.01);树种对细根根长,直径以及生物量均有极显著影响(P<0.01),对比根长有显著影响(P<0.05),而对组织密度的影响则不显著(P>0.05);树种和序级的交互作用对细根根长,直径以及生物量均有极显著影响(P<0.01),对组织密度有显著影响(P<0.05),对比根长影响不显著(P>0.05)。序级对6种树种细根根长,直径,比根长以及生物量的影响并未达到一致,对6种树种细根组织密度有极显著影响(P<0.01)。树种间1—4级根的比根长变异主要由组织密度引起,而5级根的比根长变异则由直径引起,同时在1级根中组织密度与直径呈现出权衡的关系。6种树种细根数量,直径,根长,比根长,组织密度以及生物量与序级之间回归分析发现它们与序级之间具有指数函数,线性函数,二次函数,三次函数或者幂函数关系。     

半附生榕树和非附生榕树的细根性状

榕树作为热带雨林生态系统中的一个关键类群,在维持生物多样性方面发挥着重要作用。本研究以中国科学院西双版纳热带植物园内的榕树专类园区的10种榕属树种(5种半附生,5种非附生)为对象,采用根序法对其细根直径、根长、比根长、比表面积、分枝密度、组织密度、氮含量、碳含量和碳氮比等9个细根功能性状进行了研究,分析了半附生榕树和非附生榕树的细根性状差异;同时结合其原始分布生境,从植物的细根形态功能性状角度阐释其生存策略。结果表明:半附生榕的细根根长、细根直径显著高于非附生榕树(P!0.01),而其比根长和分枝密度显著低于非附生榕树,其余性状之间无显著差异(P>0.05); 10种榕树的细根形态特征与养分特征呈微弱或无相关关系,细根的直径与分枝密度、比根长和比表面积呈显著的负相关。研究认为,不同生活型榕树的根系结构和性状特征差异是对环境的适应表现,分布于山脊干旱环境的半附生榕树细根具有直径较粗、根系长、分枝密度和比根长低的特性,使其具有较好的水分吸收能力,并可能与菌根真菌有更紧密的互利共生关系,从而能适应相对干旱的山脊环境。     

Anatomical traits associated with absorption and mycorrhizal colonization are linked to root branch order in twenty-three Chinese temperate tree species

* Different portions of tree root systems play distinct functional roles, yet precisely how to distinguish roots of different functions within the branching fine-root system is unclear. * Here, anatomy and mycorrhizal colonization was examined by branch order in 23 Chinese temperate tree species of both angiosperms and gymnosperms forming ectomycorrhizal and arbuscular-mycorrhizal associations. * Different branch orders showed marked differences in anatomy. First-order roots exhibited primary development with an intact cortex, a high mycorrhizal colonization rate and a low stele proportion, thus serving absorptive functions. Second and third orders had both primary and secondary development. Fourth and higher orders showed mostly secondary development with no cortex or mycorrhizal colonization, and thus have limited role in absorption. Based on anatomical traits, it was estimated that c. 75% of the fine-root length was absorptive, and 68% was mycorrhizal, averaged across species. * These results showed that: order predicted differences in root anatomy in a relatively consistent manner across species; anatomical traits associated with absorption and mycorrhizal colonization occurred mainly in the first three orders; the single diameter class approach may have overestimated absorptive root length by 25% in temperate forests.     

岷江上游4个栽培树种细根功能性状垂直分布的差异性

细根(直径≤2 mm)功能性状及垂直分布格局是反映植物对土壤资源吸收策略和影响森林地下生态过程的关键。本研究以岷江上游4个人工林树种连香树(Cercidiphyllum japonicum)、白桦(Betula platyphylla)、华山松(Pinus armandii)和油松(P. tabuliformis)为对象,调查不同海拔树木细根功能性状及其在不同土层间的垂直分布格局,并分析细根功能性状分布与构型之间的相关关系。结果表明:阔叶树种比针叶树种有更大的根长密度、生物量、比根长和比表面积,而直径反之; 4个树种细根集中在0～20 cm土层,根长密度和生物量在较高海拔地段均显著大于较低海拔,且均随土壤深度增加而减少,但比根长、比表面积和直径无显著的海拔差异,随土层加深也无明显的垂直变化规律;针阔树种间的细根构型差异显著,但不受海拔差异的影响,阔叶树的细根分支强度与一级根数量显著大于针叶树种;一级根数和根尖密度与比根长以及分根比与根长密度和生物量均呈显著正相关,而分叉与几个细根功能参数均呈负相关;随着土层深度增加,细根总生长量明显减少,但细根资源利用效率和策略不变; 5个细根功能性状...     

施肥对日本落叶松人工林细根直径、根长和比根长的影响

以辽宁东部山区16年生日本落叶松人工林为研究对象,探讨施肥对日本落叶松1～5级根序中细根直径、根长和比根长的影响.结果表明：随着根序等级的增加,日本落叶松细根平均直径和根长显著增加（P<0。05,P<0。01）、比根长则显著下降（P<0。01）.在日本落叶松的5级根序中,1级根的平均直径最细、根长最短、比根长最高,而5级根则相反;随着根序等级的增加,日本落叶松细根平均直径、根长和比根长的变异系数逐渐增大.除1级根外,土层对细根的平均直径、根长和比根长没有显著影响(P>0。05).与对照样地相比,施肥对各级细根平均直径、根长和比根长的影响主要表现在1～2级根上,对3级根序以上的细根影响不显著（P>0.05）.其中,施氮肥显著降低了1～2级根的平均直径（P<0.05）,施氮肥以及氮磷肥显著降低了表层土壤（0～10 cm）中1级根的平均根长（P<0.05）,表层土壤中细根的比根长在施氮肥的条件下显著增加（P<0.05）.     

Patterns in root traits of woody species hosting arbuscular and ectomycorrhizas: implications for the evolution of belowground strategies

Root traits vary enormously among plant species but we have little understanding of how this variation affects their functioning. Of central interest is how root traits are related to plant resource acquisition strategies from soil. We examined root traits of 33 woody species from northeastern US forests that form two of the most common types of mutualisms with fungi, arbuscular mycorrhizas (AM) and ectomycorrhizas (EM). We examined root trait distribution with respect to plant phylogeny, quantifying the phylogenetic signal (K statistic) in fine root morphology and architecture, and used phylogenetically independent contrasts (PICs) to test whether taxa forming different mycorrhizal associations had different root traits. We found a pattern of species forming roots with thinner diameters as species diversified across time. Given moderate phylogenetic signals (K = 0.44–0.68), we used PICs to examine traits variation among taxa forming AM or EM, revealing that hosts of AM were associated with lower branching intensity (r_PIC = −0.77) and thicker root diameter (r_PIC = −0.41). Because EM evolved relatively more recently and intermittently across plant phylogenies, significant differences in root traits and colonization between plants forming AM and EM imply linkages between the evolution of these biotic interactions and root traits and suggest a history of selection pressures, with trade-offs for supporting different types of associations. Finally, across plant hosts of both EM and AM, species with thinner root diameters and longer specific root length (SRL) had less colonization (r_PIC = 0.85, −0.87), suggesting constraints on colonization linked to the evolution of root morphology.