Wood and biomass production of Leucaena in subtropical Australia

Although only Leucaena leucocephala is widely used, most members of the Leucaena genus have potential as multipurpose species for tropical agroforestry systems. To investigate the wood and biomass production potential of the Leucaena genus, 116 accessions covering the 22 species were evaluated over a two-year period at Brisbane, southeast Queensland, Australia. Trees were planted into replicated line plots 5 m long, with rows spaced 3 m apart. Trees were initially planted at 0.5 m spacings within the plots, but were thinned to 1 m spacings prior to the evaluation period. The hybrid accessions, KX2 (L. pallida × L. leucocephala) and KX3 (L. diversifolia × L. leucocephala), were the most productive, yielding over 50 kg dry matter (DM)/tree. L. trichandra OFI53/88 and L. diversifolia CPI33820 were the most productive non-hybrid accessions producing total yields of 41 and 37 kg DM/tree, respectively. Cultivar Tarramba (26 kg DM/tree) was the most productive of the 26 L. leucocephala accessions assessed in the trial but all these accessions suffered from psyllid (Heteropsylla cubana) attack at this site. A series of non-destructive growth measurements was recorded every three months over the two-year evaluation period. Root collar diameter (RCD), stem number and plant height were found to be the most useful of the measurements for non-destructive assessment of accession agronomic characteristics. A relationship between yield and a growth index (calculated as RCD² × Height/1000), was derived from data from all accessions and could be used as a reliable predictor of yield (r ² = 0.94). The widespread use of the F1 hybrid leucaenas is currently limited by a lack of seed. Technologies to economically produce F1 hybrid seed on a commercial scale are required before the potential of these accessions in agroforestry systems can be fully realized. This revised version was published online in June 2006 with corrections to the Cover Date.     

Vegetative propagation of twelve fodder tree species indigenous to the Sahel,West Africa

In the Sahel region, many woody species are used as fodder because of their high nitrogen content, especially during the dry season, in contrast to grasses and crop residues. Unfortunately, this resource is being threatened by regular pruning, increasing livestock browsing and impeding their natural regeneration. Therefore, there is a need to find appropriate regeneration options to sustain fodder production. Thus, a series of vegetative propagation experiments were conducted to identify the most appropriate multiplication methods of some of the species used as fodder. This series included testing the effects of naphthalene acetic acid (NAA) and indole butyric acid (IBA) on rooting ability of stem cuttings of 12 species: Afzelia africana, Balanites aegyptiaca, Bauhinia rufescens, Commiphora africana, Faidherbia albida, Ficus gnaphalocarpa, Guiera senegalensis, Kigelia africana, Pterocarpus erinaceus, Pterocarpus lucens, Pterocarpus santalinoides and Terminalia avicennioides. The series also evaluated the impacts of the size (C. africana) and the age (P. erinaceus) of the cuttings on their rooting success. Pterocarpus santalinoides was revealed to be an easy-to-root species, showing a high percentage of rooted cuttings (up to 88±3%), followed by P. erinaceus, P. lucens and B. aegyptiaca (up to 37±4%, 31±5% and 26±6%, respectively), in contrast to A. africana, cuttings of which did not root at all. The application of NAA and IBA enhanced the number of roots and secondary roots per rooted cutting. Large-diameter cuttings (15–20?mm) of deeply planted C. africana gave the highest percentage of rooted cuttings (78.3±4.4%). Tree pruning improved the rooting capacity of cuttings collected from P. erinaceus with one-month resprouts giving the highest percentage of rooted cuttings (50.0±6.7%). These results indicate that P. santalinoides, C. africana, P. erinaceus, P. lucens and B. aegyptiaca are amenable to vegetative propagation as an alternative to sexual propagation.     

Zur Massenvermehrung des Schlehenspinners,Orgyia antiqua (L.) 1971/72 in Bayern

Summary On an outbreak of Orgyia antiqua L. (Lepid., Lymantriidae) at Memmingen, Bavaria, 1972.The number of larvae ofO. antiqua on pine trees at Memmingen reached its high level during autumn 1971. About 350 ha mainly the old trees were infested. The number of egg masses per stem was more than 42 in max. with an average of 205 eggs per egg mass (n = 40). The percentage of hatching was found to be 74,5%. The rest of the eggs was mainly parasitized byTelenomus dalmanni (Ratz.). The pest had only one generation. The old larvae were infected with a virus disease and a great part of pupae was killed by fungi. These two diseases were the main factors in regulating the population ofO. antiqua.     

滇杨多倍体苗期叶片形态及光合生理比较分析

[目的]以前期研究诱导获得的滇杨种质为试验材料,比较分析其苗期叶片形态及光合生理与基因剂量的关系,为滇杨多倍体育种提供理论指导。[方法]利用前期研究所获得的滇杨多倍体当年生苗为材料,测定其叶片大小、叶片厚度、栅栏组织厚度、气孔特性及叶绿素含量,并以滇杨二倍体为对照,分析滇杨不同程度多倍化后的叶片形态及光合生理特性。[结果]表明:嵌合体及四倍体滇杨的叶片长、宽均大于二倍体植株;滇杨嵌合体及四倍体叶片厚度分别为二倍体的1.16、1.41倍,栅栏组织厚度分别为二倍体的1.10、1.23倍,叶片单位视野内气孔数明显少于二倍体,气孔体积则大于二倍体,叶绿素总含量分别为二倍体的127%和141%;滇杨嵌合体及四倍体植株的净光合速率在日变化过程中均高于二倍体;气孔导度、蒸腾速率则与二倍体差别较小;嵌合体、四倍体及二倍体的胞间CO₂浓度在日变化过程中变化不明显。 [结论]滇杨多倍化后,由于其基因数量的增加,在叶片形态及光合生理特性等方面,表现出了明显区别于其二倍体的剂量效应。     

崖柏属植物的核型分析

[目的]为了从细胞学角度探讨崖柏属植物分类与进化问题,[方法]采用根尖压片法对崖柏属5种植物进行核型研究。[结果]表明:崖柏和日本香柏的核型公式为2n=2x=22=18m(2SAT)+4sm,朝鲜崖柏、北美乔柏和北美香柏的核型公式为2n=2x=22=20m(2SAT)+2sm,5种植物的核型均属于1A类型。[结论]该属在柏科中可能处于比较进步的进化地位;通过进化趋势图分析发现,崖柏在该属中分化最晚,而朝鲜崖柏则较原始。     

基于森林空间规划问题的模拟退火算法参数敏感性研究

[目的]以森林空间收获安排问题为基础,系统探讨模拟退火算法参数(初始解数量、初始温度、降温速率和每温度下重复次数)设置对森林空间规划问题目标解质量的影响。[方法]规划模型以10个5年规划分期内的最大化木材收获为基本目标,同时满足均衡收获和最大连续采伐面积约束。模拟数据由5个假设的栅格数据组成,共产生了3 300 81 600个0-1型决策变量。[结果]表明:各规划问题目标函数值的平均变异系数仅在0.18%14.95%间波动,说明模拟退火算法优化结果的高度稳定性;每温度下重复次数和初始温度分别与林分数量呈显著的多项式(R~2=0.85)和指数(R~2=0.66)关系,而降温速率则与林分数量倒数呈显著的多项式(R~2=0.98)关系,初始解数量虽不受林分数量影响,但至少应维持在500次以上。同时,研究还表明规划问题规模不仅显著影响各参数的取值,同时还显著影响算法获得满意解概率(PN)和求解效率(RE),其中满意解概率随林分数量的增加而呈显著线性增加趋势(R~2=0.98),但求解效率则呈显著线性下降趋势(R~2=0.55)。[结论]模拟退火算法优化结果具有高度稳定性,能够适应复杂森林规划问题的需求;模拟退火算法优化结果对参数设置和林分数量具有高度的敏感性,因此森林经营决策人员在采用模拟退火算法解决具体的森林规划问题时应慎重选择各参数的取值,以确保规划结果的稳定性和可靠性。     

Within-tree density gradients in Gmelina arborea in Venezuela

Abstract. Variation of wood specific gravity from the base to the top of tree and from pith to bark was investigated for Gmelina arborea Roxb. plantations in western Venezuela. Increment cores were taken from thirty trees at five different sections up the stem: 0.1?m; 1.3?m, half total height, 3/4 total height and at the top. These trees were chosen from commercial plantations located at three different sites. Specific gravity was obtained using an X-ray densitometer. The results show that there is an increase in specific gravity from pith to bark. It was also evident that specific gravity decreased from stump to half of the total height, then increased towards the top of the stem. No correlation between specific gravity and height of the tree was found. Correlations in specific gravity with height categories were generally small, and non-significant at level α=0.05.

Palabras clave: Gmelina arborea, Propiedades de la madera, Gravedad específica

Resumen. En la Gmelina arborea Roxb se estudió la variación de la gravedad específica desde la base hasta el tope del árbol y desde la médula hasta la corteza. Se tomaron muestras de madera provenientes de treinta árboles a cinco alturas diferentes a lo largo del fuste a 0.1?m; 1.3?m, mitad de la altura total, 3/4 de la altura total, y del tope, las cuales fueron seleccionadas de plantaciones comerciales localizadas en tres sitios distintos al occidente de Venezuela. La gravedad específica fue determinada con la ayuda de un densitómetro de rayos-x. Los resultados muestran un incremento de la gravedad especifica desde la médula hacia la corteza. También se encontró que la gravedad específica disminuye de la base a la mitad del fuste y luego aumenta hacia el tope del fuste. No se encontró correlación entre la gravedad específica y la altura del árbol. La correlación entre la gravedad específica y las categorías de altura donde las muestras fueron tomadas son generalmente pequeñas y poco significativas a un nivel de probabilidad α=0.05.

     

Effect ofCronartium quercuum on cell chromosome of Xingkai Lake pine

The microscopical observation and karyoltype analysis of embryo root cells of healthy Xingkai Lake pine and Xingkai Lake pine infected byCronartium quercuum were conducted. The results showed that the dividing phase of embryo root cells decreased and the viscidity of cells in dividing phase increased when Xingkai Lake pine was infected byC. quercuum. The karyoltype changed from the contract 4A to 4B, but the number of cell chromosome and karyoltype component did not change. (Responsible Editor: Zhu Hong)     

杨树PtROP家族基因的表达分析与功能预测

[目的]为探究ROP基因在林木中的功能。[方法]本研究以杨树为模式,在全基因组水平上对ROP基因的家族成员、基因结构、保守结构域、氨基酸序列相似性及表达模式进行了分析。[结果]显示,杨树PtROP基因家族包含13个成员,不同成员间在进化上相对保守,均存在与GTP结合与水解相关的结构域。这些基因在不同组织、不同胁迫条件下的表达具有明显差异,说明它们参与不同的生物学过程。通过构建功能基因网络(functional gene network for poplar)发现PtROP基因主要参与了信号转导过程。[结论]杨树PtROP基因家族包含13个成员参与不同的生物学过程,可能主要参与了信号转导过程。     

基于微卫星DNA标记分析刺槐叶瘿蚊遗传多样性指数与样本量的相关性

[目的]探讨基于微卫星标记分析刺槐叶瘿蚊遗传多样性指数与样本量的相关关系。[方法]设置了12个样本量梯度,选取11对微卫星引物分析了我国刺槐叶瘿蚊5个种群的遗传多样性指数。[结果]表明,样本量的大小与平均等位基因数(Na)呈显著正相关,与有效等位基因数(Ne)呈中度正相关,与观测杂合度(Ho)呈负相关,而与期望杂合度(He)、Nei’s遗传多样性指数(H)和多态信息含量(PIC)没有明显相关性。此外,当样本量小于25时,随着样本量的增加,有效等位基因数增幅明显,观测杂合度起伏变化较大,但当样本量大于30时,随着样本量的增加,上述两个指数增(降)幅度平缓。[结论]在利用微卫星DNA标记对我国刺槐叶瘿蚊种群的遗传多样性研究中,选取的最适样本量应为25～30,分析的最适遗传多样性指数应为期望杂合度、Nei’s遗传多样性指数和多态信息含量。该研究结果将为我们后续研究提供科学数据,并有助于分析其他入侵昆虫种群遗传结构的研究,同时可为其他双翅目昆虫的遗传多样性研究提供样本量参考。     

滇东南濒危植物长梗杜鹃转录组微卫星特征分析

[目的]全面了解滇东南特有濒危植物长梗杜鹃转录组SSR位点的分布及序列特征,为长梗杜鹃的保护和合理开发利用提供遗传学资料,为同属植物及近缘种SSR标记的开发及遗传研究提供便利。[方法]利用Illumina Hiseq 4000高通量测序平台对长梗杜鹃叶片进行转录组测序,再通过MISA软件对测序所得Unigenes进行SSR位点的发掘和分析。[结果]发现含SSR的序列17 354条,共得到23 192个SSR,出现频率为31.30%,平均每3 kb出现1个SSR。二碱基和三碱基重复为长梗杜鹃SSR主要重复单元类型,分别占SSR总数的69.25%和15.07%,187种重复基元中,所占比例最高的是(AG/CT)n(62.01%),其次是(A/T)n(12.34%)、(AC/GT)n(4.52%)和(AAG/CTT)n(4.23%)。在SSR和CDS的交集基因中,共发现15 908个SSR位点,其中2 792个位于编码区,出现频率为0.076 SSR/kb,而非编码区为0.344 SSR/kb,在基因编码区中出现频率最高的是三碱基重复(1 356,48.57%)。在不同长度重复单元中,二碱基重复SSR长度变异程度最高,其次是单碱基重复。长梗杜鹃SSR的频率和长度呈显著负相关(P0.01),相关系数为-0.566。[结论]长梗杜鹃转录组SSR位点的出现频率高、分布密度大、基元类型丰富、重复次数较高、长片段较多,具有较高的多态性潜能,用于遗传分析的潜力很大,能满足该物种的保护遗传学研究。     

Role of caffeic glucoside esters in defense-repair processing of trees II: Synthesis of 2-(3,4-dihydroxyphenyl)-ethyl 3-α-L-rhamnopyranosylβ-D-glucopyranoside

The reference compound (9), with a partial structure of acteoside, was synthesized to elucidate the relation between structural features and the precipitation or solubility of the oxidation products of acteoside: 2-(3,4-dihydroxyphenyl)-ethyl 3-O-(-L-rhamnopyranosyl)--D-glucopyranoside (9). The glycosyl acceptor 2-O-benzoyl-3-O-(2,3,4-tri-O-acetyl--L-rhamnopyranosyl)-4,6-O-benzylidene--D-glucopyranosyl trichloroacetimidate (7) was prepared from allyl 2-O-benzoyl-3-O-(2,3,4-tri-O-acetyl--L-rhamnopyranosyl)-4,6-O-benzylidene--D-glucopyranoside (4) via isomerization of the allyl group with an iridium complex to the 1-propenyl group and its hydrolysis with HgCl₂lHgO, followed by treatment with CCl₃CN and DBU in a 65.5% overall yield. The glycosyl acceptor 3,4-diacetoxyphenethyl alcohol (16) was prepared from homoveratric acid via demethylation with 57% HI and its acetylation with Ac₂O and 85% H₃PO₄, followed by selective reduction of the carboxyl group to the alcohol with a borane-tetrahydrofurane complex in a 61% overall yield. The glycosylation of7 with16 in dichloromethane promoted by BF₃-Et₂O gave a 74.3% yield of8. Hydrolysis of8 with 90% CF₃COOH gave the debenzylidenated product, which was treated with NaOMe to afford a 32% overall yield of the desired compound9. This compound9 was identical with the natural specimen.This study was presented in part at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 3–5, 1996     

巨桉EXP基因家族的生物信息学分析

[目的]本研究有助于了解EXP基因家族的基本特征,为深入研究其功能搭建平台。[方法]本研究对从巨桉(Eucalyptus grandis Hill)中筛选出35个EXP基因家族成员(Egr EXP1 Egr EXP35),利用生物信息学方法对其基因特征与表达模式进行综合分析。[结果]巨桉EXP基因分布在8条染色体之上,EXP蛋白均定位在细胞质膜上发挥作用,大多数的家族成员具有信号肽。巨桉EXP编码的蛋白质由α-螺旋、延伸链、无规卷曲、β-转角组成。进化分析结果表明,巨桉EXP蛋白与毛果杨(Populus trichocarpa) EXP蛋白的进化关系接近。35个巨桉EXP基因在巨桉未成熟木质部、成熟叶片、韧皮部、茎尖、木质部以及幼叶组织中表达模式存在显著差异。[结论]EXP基因家族各成员的表达模式不同,Egr EXP17、Egr EXP18可能在巨桉木材形成过程中起重要作用。     

Synthesis of β-O-4 type oligomeric lignin model compound by the nucleophilic addition of carbanion to the aldehyde group

A synthetic method for obtaining lignin oligomer that contains only the β-O-4 structure is described in detail. This method consists of three reaction steps: (1) the synthesis of t-butoxycarbonylmethyl vanillin (2), (2) the nucleophilic addition oligomerization of compound 2, and (3) the reduction of the oligomeric β-hydroxyl ester. In the first step, compound 2 was synthesized from vanillin in 96.8% yield. In the second step, compound 2 was oligomerized with commercial lithium diisopropylamide (LDA) to obtain oligomeric β-hydroxyl ester (3) in 87.2% yield; the repeating units of this oligomer were joined only by β-O-4 linkages as confirmed by nuclear magnetic resonance (NMR) spectroscopy. In the third step, the oligomeric β-hydroxyl ester (3) was reduced with LiAlH₄ to give compound 4 in 42.4% yield. On the basis of NMR, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and gel permeation chromatography analyses of compound 4, it was concluded that compound 4 was an oligomeric lignin model compound containing only β-O-4 interunit linkages. The number average degree of polymerization (DPn) of obtained compound 4 was about 7.0 (M _w/M _n = 1.42). Using this oligomeric lignin model compound, conventional degradation and analytical methods will give new information.     

毛红椿天然群体遗传多样性及取样策略探讨

[目的]研究毛红椿天然群体遗传多样性取样策略,为其种质资源收集、保存和遗传多样性保护等提供参考依据。[方法]利用8对微卫星分子标记进行毛红椿天然群体遗传多样性和空间自相关分析,综合制定其天然群体合理取样策略。[结果]毛红椿天然群体等位基因数平均为7.5个,期望杂合度(H_e)和多态性信息指数(PIC)均值分别为0.643 7和0.636 0,基因分化系数(G_(ST))均值为0.290 7。在遗传多样性取样策略方面,提出了根据毛红椿群体基因分化系数来确定取样群体遗传变异所占总变异比例的运算公式为1-(G_(ST))~(n-1),其中,n为取样群体的数量。当取样群体达到4个时,基本上能包括该树种97.5%的遗传变异;同时确定了目标群体的选择方法,应选择与其它群体间基因分化系数均值较大的4个群体,即贵州册亨(CH)、浙江遂昌(SC)、浙江仙居(XJ)和云南师宗(SZ)。通过构建云南宾川(BC)、云南师宗(SZ)和江西宜丰(YF)群体内取样单株数量与基因多样性和等位基因之间的捕获曲线,确定了群体内取样单株数量应达到15个以上;毛红椿天然群体内300～520 m范围内的单株间存在相似关系,超出此范围个体间差别较大,说明在进行群体内单株取样时,单株间距应大于520 m。[结论]取样群体数量、群体间遗传分化系数、群体内单株数量以及单株间距离等影响了毛红椿取样群体的遗传多样性。毛红椿天然群体遗传多样性取样策略为取样群体4个、每个群体最少取样15个单株,单株间距大于520 m。     

AFLP fingerprinting of <Emphasis Type="Italic">Populus deltoides</Emphasis> and <Emphasis Type="Italic">Populus </Emphasis>×<Emphasis Type="Italic"> canadensis</Emphasis> elite accessions

Amplified fragment length polymorphism (AFLP) was used in genetic fingerprinting of 22 elite Chinese Populus deltoides and Populus × canadensis accessions. The results indicated that each of the nine AFLP primer pairs selected generated fingerprint profiles that were unique to each of the accessions. Therefore, each accession was definitively identified by any of the nine primer pairs. Furthermore, the inter-accession genetic relationships inferred based on 461 polymorphic fragments from the nine AFLP primer pairs were largely consistent with phylogenetic relationships based on morphologic traits. Bootstrap analysis showed that three AFLP primer pairs were required to obtain genetic similarity values with a maximum CV of 10% while 10 AFLP primer pairs could give a maximum CV of 5%. Thus, AFLP can readily be applied for a rapid and accurate evaluation of the degree of similarity between poplar cultivars. In this study, the number of AFLP fragments used was sufficient to establish a reliable estimate of genetic similarity among accessions, with a maximum CV of 5.12%. Therefore, the information on the genetic relationships among the poplar accessions generated in this study in connection with knowledge on agronomic traits may have an impact on poplar breeding and planting in China.     

大兴安岭不同区域落叶松相容性材积方程及异方差研究

[目的]对不同区域立木相容性材积方程以及不同异方差校正方法进行详细对比分析,建立相容性材积方程预估大兴安岭不同区域落叶松的立木材积。[方法]以大兴安岭3个不同区域的落叶松为研究对象,采用误差变量联立方程组的方法构建不同区域立木相容性材积方程。采用非线性额外平方和的方法(F检验)进行区域性检验。使用多种权函数分别对3个区域存在异方差的材积方程进行加权回归。[结果]表明:任何2个区域的立木材积方程都有显著不同(P0.000 1),区域1和区域3的材积相差较大,区域2与区域1和区域3的材积相差较小。不同区域立木材积方程的错误应用会导致较大的预测误差。在参数稳定性和评价指标方面,加权估计会优于普通最小二乘估计。基于平均相对误差(MRE)和总相对误差(TRE),区域1(-0.11、0.97)、区域2(0.04、0.08)和区域3(1.04、0.93)的最优权函数分别为1/F(x)、1/D4.99、1/D3.38。[结论]立木材积方程是森林调查和林分生长与收获模型的主要组成部分,本文所构建3个区域的相容联立方程组模型预测误差均不超过±3%。建立相容性立木材积方程时应考虑其异方差的影响。最优权函数没有统一的形式。为尽可能得到稳定的参数估计,在加权回归估计过程中应选用多种权函数进行对比分析。     

思茅松自由授粉家系遗传参数与早期选择分析

[目的]通过对思茅松自由授粉子代测试林的生长与形质性状遗传参数的估计,进行优良家系选择,为建立思茅松高世代种子园及培育优良无性系苗木提供种质资源。[方法]采用随机区组试验设计,在214个思茅松自由授粉家系子代测试林中选择胸径、地径、树高、枝下高、冠幅、通直度、树干圆满度、树冠圆满度、材积及地上生物量等生长与形质性状,利用线性混合模型进行遗传参数的估计,进行优良家系筛选。[结果]思茅松自由授粉子代测试林生长与形质性状的遗传参数在家系间差异极显著。各性状的家系遗传力较高,其中,地径的家系遗传力最大(1.105)。材积的预期遗传增益高于地上生物量,利用家系/家系内选择方法进行优良家系的筛选,材积的预期遗传增益为60.75%,入选家系为60个;地上生物量的预期遗传增益为44.22%,入选家系为66个。轮盘数、通直度和树干圆满度对材积和地上生物量都有显著影响。[结论]在早期选择中,形质性状的遗传变异对思茅松自由授粉优良家系的选择有重要参考作用,4年生思茅松自由授粉家系子代测试林中各性状存在着丰富的遗传变异,在早期选择中可以筛选出适合不同培育目标的优良家系,最大限度挖掘其遗传潜力。     

Pesticidal Activity of the Leaf and Bark Extracts of Giliricidia sepium on Callosobrucus maculatus

Abstract

The effects of different concentrations of cold and hot aqueous extracts of G. sepium on C. maculatus, the storage pest of cow-pea were examined. The extracts had a killing effect on the weevils. The percentage mortality of the weevils increased with the increase in the extract concentrations. Statistical analyses at 5% level revealed that significant differences abound in the efficacies of the cold and hot aqueous extracts. The hot aqueous leaf and bark extracts tend to have more toxic effect than the cold aqueous extracts. Also, extracts from the bark tend to be more toxic to the weevils than those of the leaves.     

Genetic variation of Taxus baccata L. populations in the Eastern Alps and its implications for conservation management

Abstract

The English yew (Taxus baccata L.) is an endangered rare tree species in Austria. More than 600 bud samples were collected from seven populations in three regions of the Eastern Alpine mountains for estimating their genetic structures by using isozyme gene markers. Nine gene loci encoding for seven enzyme systems were investigated. The revealed 32 alleles indicate a higher multiplicity of the east alpine gene pool compared with other European regions. English yew showed a high level of genetic variation, with a mean number of alleles per locus (A/L) of 2.7. A total of 76.4% of the loci were polymorphic, the average expected heterozygosity was (H _e) 0.274 and the mean observed heterozygosity (H _o) was 0.238. The relative proportion of genetic differentiation among the regions was found to be 6.2%, the level of gene flow was high (Nm=3.78) and the level of inbreeding (0.130) among the regions was medium. The obligatory out crossing (dioecious plant), the long generation time, the ability to regenerate from stump and the seed dispersal by birds and rodents might contribute to the high level of genetic variation found within the population. The conservation propositions are discussed with respect to the genetic structure and the poor recruitment of this species.