海南岛4个热带阔叶树种前5级细根的形态、解剖结构和组织碳氮含量

细根具有复杂的分支系统, 以根序(root order)为取样单元的细根生理生态学研究正在成为根系生态学研究领域的重要内容。该研究以海南岛尖峰岭4个热带阔叶树种海南蕈树(Altingia obovata)、厚壳桂(Cryptocarya chinensis)、山杜英(Elaeocarpus sylvestris)和黄桐(Endospermum chinense)为研究对象, 测定了1-5级细根的形态、解剖结构和组织碳(C)、氮(N)含量, 旨在探讨这些根系特征之间的联系。研究表明: 4个树种的细根形态差异较大, 但在树种水平上直径、根长和组织密度均随着根序的升高而增加, 比根长则随着根序的升高而降低; 低级根(前2级根或前3级根)具有皮层组织, 是典型的吸收根, 而高级根皮层组织消失, 是典型的运输和储藏根; 影响直径大小最重要的因子是皮层厚度, 它可以解释细根直径变异的97%, 而维管束直径仅能解释细根直径变异的70%; 根组织N和C浓度受维管束-根直径比(维根比)的影响, 随着维根比增加, 组织N浓度显著降低, 组织C浓度显著升高。4个树种细根的C/N比的变异受组织N浓度的影响程度为76%, 而受C浓度的影响程度不足10%。上述结果表明, 细根的形态特征、解剖结构和组织化学含量之间存在着紧密联系, 这为我们理解根系结构与功能变异提供了重要依据。     

树木不同着生位置1级根的形态、解剖结构和氮含量

树木根系中1级根在养分和水分吸收方面发挥着重要作用。研究1级根的形态结构与功能的联系,对了解1级根的生理功能和寿命,以及森林生态系统碳和养分的循环具有重要的理论意义。但是,1级根在根系统中,因着生的位置不同,可能表现出不同的生理生态功能。该研究以胡桃楸(Juglans mandshurica)、黄波罗(Phellodendron amurense)和水曲柳(Fraxinus mandshurica)人工林根系的1级根为研究对象,研究了不同着生位置的1级根的形态、解剖结构和组织化学特征。将1级根按着生位置的不同分成3类:Ar类根为2级根上的1级根;Br类根为2级–4级根的根尖;Cr类根为3级–5级根上的1级根。结果表明:不同着生位置的1级根,形态、解剖结构和组织化学方面都具有高度的异质性。3类1级根中,Ar类根数量多、根长较短、直径细,N含量高,皮层比例高、维根比低,主要由二原型原生木质部的根组成;Br类和Cr类根数量较少、单根较长、直径粗,N含量低,皮层比例低、维根比高,主要由多原型原生木质部的根组成。研究结果对了解不同着生位置的1级根的吸收功能和寿命具有重要的理论意义。     

短期氮磷配施对刨花楠细根形态及其土壤微生物的影响

以1年生刨花楠幼苗为研究对象,通过不同的氮磷配施实验,采用扫描根系法和磷脂脂肪酸法,研究不同氮磷配施处理对刨花楠幼苗1—4级细根根序形态特征及其土壤微生物的影响。结果表明:(1)4种氮磷配施处理均显著增加了刨花楠1—2级根的比根长和比根面积(P0.05),降低了3—4级根的比根面积(P0.05);(2)通过不同梯度的氮磷配施,1—2级细根的根组织密度呈下降态势,而3—4级根的组织密度则显著增加(P0.05),体现低级根与高级根之间的权衡;(3)4种氮磷配施处理都显著降低刨花楠1—4级细根的平均直径(P0.05);(4)随着氮磷比的增加,微生物总量及细菌、真菌与放线菌数量等均呈现先增加后降低的趋势,并均在N∶P为10∶1时达到最大;(5)氮磷配施条件下,细菌、真菌等与1—2级细根的比根长和比根面积呈显著正相关,而与4级根的比根长和比根面积则呈显著负相关,革兰氏阳性菌、真菌等与3—4级根的组织密度存在显著正相关,而与1—2级根的组织密度无显著相关性。各级根序的平均直径均与土壤微生物无显著相关性。研究结果表明,短期氮磷配施以N∶P为10∶1的效果最好,其最有利于提高刨花楠苗木细根的养分吸收能力与养分吸收效率,苗木通过调整细根形态来适应氮沉降,其地下生物群落如土壤微生物及其与细根的关系也发生变化,进而影响地下生态系统碳氮循环和养分流动。     

施肥对日本落叶松不同根序细根养分浓度的影响

以辽宁东部山区16年生日本落叶松人工林为对象,探讨施肥对落叶松1～5级不同根序等级细根养分浓度的变化.结果表明：不同根序等级细根全碳浓度差异不显著,施肥对各级根序全碳浓度没有显著影响;在前5级根序中,1级根非结构性碳水化合物（TNC）浓度最低,N和P浓度最高;而5级根TNC浓度最高,N和P浓度最低.TNC浓度随着根序增加而升高,N和P浓度则相应下降.施肥仅对1级根组织中N和P浓度有显著影响;不同根序根组织中C/N/P具有明显差异,1级根平均C/N/P为423∶16∶1,5级根为726∶16∶1,随着根序增加,C在3种元素中的比例显著增加,而N的比例变化不大.施N肥并没有改变C的比例;但施P肥或施N+P肥均降低了前3级根（0～10 cm）或前2级根（10～20 cm）C和N在3种元素中的比例.     

Relating root structure and anatomy to whole-plant functioning in 14 herbaceous Mediterranean species

This study investigated the relationships between root structure and anatomy and whole-plant functioning in herbaceous species. Fourteen annual and perennial species representative of a Mediterranean old-field succession were grown in monocultures in a common-garden experiment. Whole-plant functioning was assessed by inherent relative growth rate (RGR(max)), measured in standardized conditions, and maximum height (H(max)). Root tissue density (TMD(r)), considered as a major component of root structure, was measured on roots harvested within in-growth cores. Anatomical characteristics were analysed on cross-sectional areas (CSA). TMD(r) was correlated positively with H(max) and negatively with RGR(max). Root CSA explained interspecific variation in H(max) but not that in TMD(r) and RGR(max). Root xylem CSA and xylem proportion in root CSA were positively correlated with TMD(r) and H(max) and negatively with RGR(max). Mean xylem vessel CSA did not account for variations in TMD(r), H(max) and RGR(max). These results suggested that RGR(max) and H(max) are constrained by opposite root structural and anatomical traits, which have potential links with hydraulic conductance, support and longevity.     

Fine root branch orders respond differentially to carbon source-sink manipulations in a longleaf pine forest

Fine roots are a key component of carbon (C) flow and nitrogen (N) cycling in forest ecosystems. However, the complexity and heterogeneity of the fine root branching system have hampered the assessment and prediction of C and N dynamics at ecosystem scales. We examined how root morphology, biomass, and chemistry differed with root branch orders (1–5 with root tips classified as first order roots) and how different root orders responded to increased C sink strength (via N fertilization) and reduced carbon source strength (via canopy scorching) in a longleaf pine (Pinus palustris L.) ecosystem. With increasing root order, the diameter and length of individual roots increased, whereas the specific root length decreased. Total root biomass on an areal basis was similar among the first four orders but increased for the fifth order roots. Consequently, total root length and total root surface area decreased systematically with increasing root order. Fine root N and lignin concentrations decreased, while total non-structural carbohydrate (TNC) and cellulose concentrations increased with increasing root order. N addition and canopy disturbance did not alter root morphology, but they did influence root chemistry. N fertilization increased fine root N concentration and content per unit area in all five orders, while canopy scorching decreased root N concentration. Moreover, TNC concentration and content in fifth order roots were also reduced by canopy scorching. Our results indicate that the small, fragile, and more easily overlooked first and second order roots may be disproportionately important in ecosystem scale C and N fluxes due to their large proportions of fine root biomass, high N concentrations, relatively short lifespans, and potentially high decomposition rates.Electronic Supplementary Material Supplementary material is available for this article at     

Effects of root diameter,branch order,root depth,season and warming on root longevity in an alpine meadow

Fine root is of importance in biogeochemical cycles especially in terrestrial ecosystems. The lack of understanding of the factors controlling root lifespan has made accurate prediction of carbon flow and nutrient cycling difficult. A controlled warming experiment was performed in an alpine meadow on the northern Tibetan Plateau (near Nagchu Town). We used a minirhizotron technique to measure root dynamics in situ during the growing season of 2013 and 2014 and survival analyses to assess root lifespan and the effects of root diameter, branch order, birth season, root depth and warming on root lifespan. Root diameter, branch order and root depth were all positively correlated with root lifespan. With an increase in diameter of 0.1 mm, mortality hazard ratio of roots declined by 19.3 %. An increase in one level in branch order was associated with a decrease of 43.8 % in root death ratio. Compared with roots born in May–mid-July, the mortality hazard ratio of roots born in late July–August and September–October reduced by 26.8 and 56.5 %, respectively. In warming treatments, roots tended to be thinner, less branched and deeper, and there was a higher proportion of roots born in spring compared to ambient conditions. Warming shortened the median root lifespan 44 days. However, in single warming condition, root diameter had no significant influence on root lifespan. Root diameter, branch order, root depth and season of birth were all factors affecting root lifespan in the alpine meadow; however, root branch order was dominant.     

施肥对日本落叶松不同根序细根养分浓度的影响

以辽宁东部山区16年生日本落叶松人工林为对象,探讨施肥对落叶松1～5级不同根序等级细根养分浓度的变化.结果表明：不同根序等级细根全碳浓度差异不显著,施肥对各级根序全碳浓度没有显著影响;在前5级根序中,1级根非结构性碳水化合物（TNC）浓度最低,N和P浓度最高;而5级根TNC浓度最高,N和P浓度最低.TNC浓度随着根序增加而升高,N和P浓度则相应下降.施肥仅对1级根组织中N和P浓度有显著影响;不同根序根组织中C/N/P具有明显差异,1级根平均C/N/P为423∶16∶1,5级根为726∶16∶1,随着根序增加,C在3种元素中的比例显著增加,而N的比例变化不大.施N肥并没有改变C的比例;但施P肥或施N+P肥均降低了前3级根（0～10 cm）或前2级根（10～20 cm）C和N在3种元素中的比例.     

施肥对盆栽香樟幼苗不同根序细根养分的影响

以盆栽的1年生香樟实生苗为研究对象,采用指数施肥的方式,测定1~5级细根的C、N、P、K含量,并探讨施肥对香樟幼苗细根养分浓度的影响。结果表明:(1)不同根序细根的全C浓度差异不显著,施肥对细根全C浓度影响不显著(P0.05);(2)在所有根序中,N、P浓度最高的是1级根,但其K浓度却最低;N、P含量最低的是5级根;(3)细根的N、P含量随着根序的增加呈显著的下降趋势(P0.05);(4)施N肥能显著增加1~2级细根的N含量,施P肥能显著增加1级根的P含量,N+P肥较之P肥更能提高1级根对P的吸收;(5)C∶N∶P受根序的影响非常明显,1级根平均为366∶16∶1,5级根则为807∶12∶1,而且C∶N∶P随着根序增加而显著升高,但N∶P无显著影响;(6)虽然施肥对细根C含量无影响,但施N肥或N+P肥对1~2级细根中N的含量有显著性增加。综合分析可知,处理9对香樟苗期养分浓度指标影响最为显著,即施肥量为氮素4g·株-1、磷素4g·株-1、钾素2g·株-1时,对香樟幼苗细根的生长发育有较好地促进作用。研究结果可为香樟的速生丰产及资源的高效利用提供理论依据。     

Are developing xylem vessels the site of ion exudation from root to shoot?

Abstract This paper describes experiments to test the suggestion that developing xylem vessels are the site of exudation of ions from the root to the shoot. Electron microscopy is used to define the stage of development of xylem vessels in young barley roots along the length of the root. The amino acid analogue p-fluorophenyl-alanine (FPA) is used to inhibit ion transport from the stele to the xylem vessels at varied distances from the apex. In the presence of FPA protein synthesis is not inhibited but ineffective proteins are formed. It is shown that exudation of Cl^? from the root can be inhibited in this way in parts of the root where all the xylem vessels are mature. This is in contradiction to the suggestion that root exudation is due to the activity of developing vessels. The hypothesis is thus strengthened that ion transport proceeds into the xylem vessels, which are fully mature and devoid of cytoplasm, and is due to release from the xylem parenchyma cells.     

鄱阳湖南矶湿地22种植物根系碳氮及其化学计量研究

探讨湿地植物根系碳(C)、氮(N)浓度及其化学计量关系对于进一步阐明湿地生态系统细根周转及养分循环具有重要意义。基于Pregitzer的根序分级法分析了鄱阳湖南矶湿地22种植物根系全C和全N浓度。结果表明:根系全C、全N浓度及C/N值变化范围分别为:267.15—423.22 mg/g、2.22—31.05 mg/g和2.27—71.78。1—2级根全C、全N及C/N之间具有显著相关性,但与3级根不相关。根系全C和C/N随根序的升高而增加,全N则随根序升高而降低,根系分级在湿地植物C、N化学计量关系研究中十分必要。根序、物种及其交互作用均显著影响研究区植物根系的全C、全N浓度及C/N计量关系。根系C/N化学计量关系在不同生境间未发生显著变化,表明群落尺度下的C/N稳定性高于个体水平。     

Exogenous zeatin accumulation in wheat root cells shows its role in regulation of cytokinin transport

Here we have shown that 24 hours after addition of zeatin to the nutrient solution the cytokinin content in xylem sap of wheat plants appears to be about 10 times lower that in the nutrient solution. Cytokinins accumulated mostly in roots and not in shoots of treated plants. These data demonstrate the existence of some barrier on cytokinin pathway from the nutrient solution to the plant shoot. With the help of Sudan III an increase in lignin and suberin deposition in the endodermis could be detected, being stronger with the increase in the distance from the root tip. The increase in deposition of suberin and lignin coincided with the decrease in cytokinin immunolabeling in root cells revealed with the help of monoclonal cytokinin antibodies and the second gold-labelled antibodies. Simultaneously exogenous cytokinins accumulated in root stele cells showing that the Casparian band was not only barrier on cytokinin pathway to plant shoot. It is concluded that high cytokinin immunolabe ling in the stele parenchyma cells around the stele vessels demonstrated accumulation of cytokinins by these cells, which could be important in regulation of cytokinin loading to the xylem vessels during there transport to the shoot. The role of cytokinin transporters is discussed.     

柠条人工林细根不同分枝根序寿命估计

植物细根在发育结构上表现的形态特征和生理功能异质性影响细根寿命的准确估计,因此了解分枝根序细根寿命差异对于深入认识细根的周转过程和陆地生态系统碳分配具有重要意义。采用微根管(Minirhizotron)技术对晋西北黄土区的五年生柠条(Caragana Korshinskii Kom.)人工林细根的生长过程进行了为期3a(2007—2009年)的追踪观测,分析了不同因素(土层深度、季节变化、空间位置)对一级根和高级根寿命的影响。结果表明:(1)在各土层深度处,一级根的中值寿命均低于高级根中值寿命,其中一级根中值寿命表现随土层深度增加而增加趋势,而高级根除表层0—20 cm中值寿命较短外,各土层间变化趋势不明显,40—60 cm、80—100 cm土层高级根在观测期结束时其累积存活率仍在50%以上;(2)不同季节出生一级根和高级根的中值寿命季节性表现为:秋季夏季春季,并且在各个季节均表现,高级根寿命显著大于一级根寿命(P0.01);一级根仅夏季与秋季差异性不显著(P0.05),而高级根仅春季与秋季存在极显著差异(P0.01);(3)一级根和高级根距树干基部0 cm处细根中值寿命均大于50 cm处一级根和高级根细根的中值寿命。同一位置处高级根寿命要大于一级根寿命。在距树干基部0 cm处和50 cm处,一级根和高级根的寿命均存在极显著差异(P0.01),但高级根却在距树干基部0 cm和50 cm处差异不明显,而一级根却表现极显著差异(P0.01)。     

Effects of night warming on spruce root around non-growing season vary with branch order and month

Background and aims

The Root is an important plant organ and has high heterogeneity; how it responds to global warming is yet to be answered. This study examined the growth and physiological responses of fine roots to warming around the non-growing season.

Methods

Plants from 4-year-old Picea asperata were grown under experimental warming conditions. A detailed investigation was conducted by measuring biomass, triphenyltetrazolium chloride (TTC) reducing capacity, carbon (C) and nitrogen (N) concentration, non-structural carbohydrate (NSC) of the primal five branch order roots in early (April) and late (September) growing seasons as well as in the non-growing season (December).

Results

Warming promoted fine root growth in April and fine root turnover was mostly in the first four orders. It decreased root C, N concentration in the early and late growing seasons but increased N concentration in the non-growing season. Moreover, it increased NSC concentration (especially soluble sugar) in April but decreased its concentration (soluble sugar and starch) in December. TTC reducing capacity in April was higher than in the other 2 months.

Conclusions

The effect of warming on tree roots varied with its branch order and month. The lower order (first three or four order, in general) roots were sensitive to warming, especially in April (early part of growing season) and December (non-growing season). Warming accelerated the carbon input from root to soil. It is indicated that any changes in winter temperatures could alter the sink strength of terrestrial ecosystems considerably. Moreover, TTC reducing capacity could reflect more information about root, but it was more sensitive than N concentration.     

连作杨树人工林细根寿命的代际差异及其影响因素

细根寿命是调控森林生产力形成的关键。通过在连作Ⅰ、Ⅱ代杨树人工林固定样地内埋设微根管,对杨树不同根序细根年度生长动态开展连续观测并进行生存分析。结果表明,杨树不同根序细根累积生存率存在显著差异,高级根(3—5级)寿命较长,其累积生存率显著高于1级和2级细根。杨树细根寿命存在显著的代际差异,连作Ⅱ代人工林活根量、死根量和细根总量均高于Ⅰ代林。连作Ⅱ代人工林细根中位值寿命为(90±16)d,显著低于Ⅰ代人工林((102±22)d)。连作Ⅱ代林各根序细根数量、分布比例均高于Ⅰ代林,低级细根累积生存率低于Ⅰ代林而高级细根累积生存率显著高于Ⅰ代林。连作杨树人工林细根寿命显著受制于土壤环境,1级细根寿命与土壤速效氮相关性极显著(r=-0.861),2级细根寿命与土壤物理性状相关性较强且与土壤酚酸含量呈现极显著相关(r=0.870),高级根序细根寿命与土壤物理性质和养分状况等也具有一定相关性。连作杨树人工林土壤酚酸累积和养分有效性下降影响了细根寿命和周转,并进而造成净初级生产力损耗,相关结论为连作杨树人工林生产力衰退机理模型的建立提供了科学依据。     

Lower order roots more palatable to herbivores: a case study with two temperate tree species

Determining which kinds of roots are likely to be consumed by root herbivores may improve our understanding of the mechanistic control on fine root dynamics. Here, we tested the hypothesis that root herbivores prefer to consume the distal lower order roots in their branching networks. Insecticide was applied to soil to quantify effects of root herbivores on root biomass and production in the first five orders (the distal roots numbered as first-order) in Fraxinus mandshurica and Larix gmelinii plantations from May 2008 to July 2009. Root morphology, chemistry, anatomy and physiology were measured simultaneously across branching orders. Among the first five order roots, significant consumptions by herbivores were found only for the two distal lower order roots throughout growing seasons, with 62% of biomass and 57% of production for F. mandshurica, and 71% and 79% for L. gmelinii, respectively. Our results suggest that the distal lower order roots are more palatable and attractive to root herbivores in both plantations, probably because they have higher tissue N, greater respiration rates and lower cellulose. Thus, overlooking herbivore consumption may lead to large underestimation in root biomass and production, which are critical in determining C budget and nutrient cycles in forest ecosystems.     

施肥对台湾桤木-扁穗牛鞭草复合模式下桤木细根形态特征、生物量及组织碳氮含量的影响

细根具有良好的可塑性, 不同根序等级的细根会表现不同的策略来适应土壤资源有效性的改变, 了解各级细根对土壤资源有效性的可塑性反应对认识细根的养分和水分吸收规律、预测碳(C)在地下的分配特点具有重要意义。该文以四川省丹陵县台湾桤木(Alnus formosana)-扁穗牛鞭草(Hemarthria compressa)复合模式为研究对象, 采用施肥处理, 应用土柱法采样, 探讨了施肥对台湾桤木-扁穗牛鞭草模式土壤表层(0-10 cm)和亚表层(10-20 cm)台湾桤木1-5级细根的生物量、形态特征(直径、比根长)、全C和全氮(N)含量的影响。结果表明: (1)台湾桤木1-5级细根直径随根序的增大而增加, 施肥降低土壤表层台湾桤木各级细根直径而增加了土壤亚表层台湾桤木各级细根直径; 台湾桤木1-5级细根比根长则随根序的增加而减小, 施肥增加了台湾桤木各级细根的比根长, 且施肥极显著增加了表层和亚表层台湾桤木前三级细根的比根长(p < 0.01)。(2)台湾桤木1-5级细根生物量均随土层深度的增加而减小, 施肥减少了台湾桤木各个土层各级细根生物量, 且显著降低了台湾桤木前三级细根生物量占总生物量的比例(p < 0.05), 而增加了4、5级细根生物量。(3)台湾桤木3级细根全C最大, 1级根最小, 且土壤表层台湾桤木各级细根全C含量大于亚表层; 施肥降低了台湾桤木各级细根全C含量, 但影响并不显著(p > 0.05)。台湾桤木细根全N含量随根序的增加而降低, 且土壤表层1-5级细根全N含量均高于亚表层; 施肥极显著(p < 0.01)增加了土壤表层1级细根及亚表层1、2级细根的全N含量, 而对于3-5级细根全N含量则影响不显著(p > 0.05)。以上结果显示, 当土壤资源有效性变化时, 各级根序细根会作出不同的可塑性反应, 且施肥对各级细根的影响主要表现在低级根上。     

常绿阔叶林外生、内生菌根树种细根化学计量学性状对N添加的响应

为揭示不同菌根类型树种细根化学计量学性状对N添加的塑性响应,在福建省建瓯市万木林自然保护区常绿阔叶林内选择外生菌根树种罗浮栲(Castanopsis faberi)和内生菌根树种木荷(Schima superba)为研究对象,采用根袋法开展N添加试验,细根在根袋内生长半年后测定化学计量学指标(C、N、P、C/N、N/P、C/P)。结果表明:根序对细根化学计量学性状有显著影响,随着根序的增加,罗浮栲与木荷细根C浓度、C/N、C/P明显增加,N浓度与P浓度明显下降。N添加对细根C、N浓度均有极显著的促进作用,但对细根P浓度影响不显著,从而导致细根C/N维持稳定,但N/P、C/P升高,细根受P限制增加。细根化学计量学性状对N添加的塑性响应在不同序级间以及在外生菌根树种罗浮栲和内生菌根树种木荷之间均无显著差异。结论表明,研究所选内生、外生菌根树种细根化学计量学性状对N添加具有基本相似的响应。     

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）.     

亚热带天然常绿阔叶林林下9种灌木细根形态和C、N化学计量特征

林下灌木是亚热带常绿阔叶林重要的构成部分,但林下灌木细根功能性状变异规律及地下生态策略仍不清楚。以福建建瓯万木林自然保护区内9种灌木为研究对象,对细根直径、根长、比根长、组织密度、碳浓度和氮浓度6个细根性状进行研究,采用序级划分法,分析不同树种细根性状序级间的变化特征、常绿和落叶灌木细根性状之间的差异,不同序级细根性状之间的关系以及细根性状变异维度。结果表明:树种和序级对9种灌木细根形态和化学性质有显著影响。直径、根长、根组织密度随着序级的增加而逐渐增加,比根长和氮浓度逐渐减小,碳浓度在序级间的变化趋势不一,未表现出明显的规律。落叶灌木细根直径、根长和氮浓度均显著高于常绿灌木,碳浓度和组织密度显著低于常绿灌木,表明与常绿灌木相比落叶灌木更偏向于资源获取型生态策略,常绿灌木则更偏向于保守型策略。灌木细根在不同序级间的直径与比根长、组织密度,氮浓度与组织密度有较强的相关性,细根其他性状间的关系并不密切或因序级而异。主成分分析结果表明灌木细根性状变异沿一个主成分轴发生变异,该轴表示灌木细根的资源获取和保守的权衡策略。