七子花的研究进展及其保护对策

从资源状况、土壤的理化性状、种群、群落、遗传多样性以及保护对策6个方面概述了国家二级重点保护植物——七子花的研究进展。七子花间断分布，分布范围小、数量少，并呈衰退的趋势，有灭绝的危险，其主要原因是遗传多样性较低、环境适合度差及人为破坏作用。最后提出七子花的几点保护对策。     

极小种群植物天目铁木的濒危机制

我国的极小种群植物多数为我国特有物种,对物种多样性的维持具有重要意义。天目铁木作为浙江省特有的极小种群野生植物,野生植株仅存5株,分布地域狭窄,其濒危机制的揭示是种群得以保护和恢复的重要基础。本文从气候变化、人为干扰和病虫危害等外部因素,以及天目铁木自身的光合能力、生长节律、种子活力和遗传多样性等内部因素2个角度综述了天目铁木濒危机制的研究进展:1)外部因素:第四纪冰期以来的气候变化,导致天目铁木有效种群数量急剧减少;人为干扰导致天目铁木生存压力增大,种群规模进一步减小;病虫害对其幼苗的存活也存在一定影响。2)内部因素:天目铁木较窄的光适应范围和较低的光合速率使其在群落光照资源竞争中处于劣势,环境适应能力较弱;雌雄花授粉时间短,花粉萌发率低、寿命较短等生长节律特点导致其种子产量低、品质差;种子结构特点及内源营养物质、植物激素的限制造成其种子萌发条件苛刻,萌发率低,自然更新幼苗数量十分有限;极小的种群规模、低水平的遗传多样性引发天目铁木近交严重,子代个体杂合度降低,遗传力、生殖力、生活力、适应力减弱。综上,人为干扰和气候变化应是天目铁木种群规模急剧减小的直接原因;极小的种群规模导致其近亲交配更为频繁,遗传多样性降低,进而导致其生殖生长发育存在潜在的缺陷;加之天目铁木所处群落中其他种群的资源竞争,幼苗自然更新存在很大困难,种群规模难以恢复。然而,针对天目铁木这样遗传多样性低的极小种群植物,早期保护工作多集中于濒危因素的去除或控制,对其特有的遗传学问题则缺乏考虑。因此,为有效保护天目铁木,应当科学设计人工杂交策略、结合无性繁殖技术,增加野生个体繁殖力,在有限基因库中尽可能维持其遗传多样性,结合就地保护、迁地保护、野外回归等多种手段,最终使这一物种得以保护和恢复。     

浙江中部七子花种群结构与空间分布格局的研究

为揭示七子花的种群特征,在浙江中部3个七子花主要分布地设置500 m2样方10个,应用相邻格子法对七子花的种群结构和空间格局进行了研究.结果表明,七子花种群结构呈纺锤型,幼苗极少,大树也不多,种群主要集中在幼树、小树和中树阶段,显示出衰退的变化趋势,不同样地的七子花种群结构特征有所差异;由于生境条件的不同,不同样地表现出复杂的分布格局,其中生境条件较差的种群集群程度较高,在人为干扰后,集群程度有减弱的趋势,而某些生境条件较好种群的集群强度较弱,甚至呈随机分布;不同发育阶段种群空间分布格局有差异,总体上有集群分布向随机分布、聚集度高向聚集度低变化的趋势;不同区组大小的七子花种群分布格局不同,不同样地之间差异不明显.     

七子花种群遗传多样性的RAPD分析

按胸径将浙江省天台山天然七子花划分为大树、中树、小树和幼树 4个大小级种群 ,利用RAPD分子标记技术对 4个大小级种群共 4 5株个体的遗传多样性及遗传分化进行了比较分析 ,结果表明 :通过 12种随机引物扩增共检测到 6 4个可重复的位点 ,4个大小级种群的多态位点百分率高低为大树 >中树 >小树 >幼树。Shannon信息指数估计七子花 4个大小级种群的遗传多样性高低为大树 >中树 >小树 >幼树 ,大小级种群内的遗传变异占总变异的 5 4 4 1% ,大小级种群间的遗传变异占总变异的 4 5 5 9% ,表明不同大小级种群内、大小级种群间个体均存在一定的遗传分化 ,但大小级种群内的遗传分化比大小级种群间高。Nei指数估计的七子花不同大小级种群的基因多样性的高低与Shannon指数估计的一致 ,大小级种群内的遗传分化高于大小级种群间 ,大小级种群间的基因分化系数为 0 3939。不同大小级种群间的遗传相似度以大树与中树最高 ,大树与幼树最低。聚类分析显示大树与中树先聚成一组 ,小树与幼树再聚成一组 ,最后 2组聚在一起     

浙江大盘山七子花萌枝特性及其对种群更新的影响

在对浙江大盘山自然保护区七子花群落全面踏查的基础上,深入调查了七子花种群内萌枝更新特性。结果表明,七子花根颈处多有萌枝产生,萌枝对七子花种群的径级结构具有较大影响。相关性分析表明,萌枝数与平均根径呈显著正相关。从高度来看,七子花集中分布在4~6 m,在高度竞争上处于劣势。然而其平均冠幅均在5m2以上,说明七子花通过增加冠幅提高自身的生态位和竞争力。由于七子花有性繁殖较差,群落生境恶劣,导致七子花主要以萌枝方式来维持种群生存。最后,对七子花的保护提出了相关建议。     

南方红豆杉濒危原因及保育技术

南方红豆杉(Taxus chinensis var.mairei)为我国I级保护植物。在我国,主要分布于长江流域、东南沿海及台湾等地区。本研究从南方红豆杉种群生态学特征、种群生殖生物学特性、种群遗传进化潜力等方面,综合分析其濒危的可能原因。结果表明,南方红豆杉种群生殖能力弱,适应能力差是其濒危的主要内因;生境破坏和不合理砍伐导致其生境片段化、异质性,是其濒危的直接外因。维持南方红豆杉种群遗传多样性,培育南方红豆杉良种人工林,是科学保育和合理开发南方红豆杉资源的重要措施。     

我国圈养麋鹿种群发展面临的挑战及保护管理对策

目前麋鹿在迁地保护方面取得了很大成功,已在湖北石首麋鹿国家级保护区等全国50多处麋鹿饲养场所拥有圈养种群.但其种群的发展尚面临着许多挑战,如受到遗传多样性较低、目标种群数量过小、人类干扰、疾病风险、生存条件的局限、管理方式较传统等制约因素的影响,为此,提出加强种群的遗传多样性管理、强化栖息地保护管理、制定种群数量调控政策、加强安全监测、建立科学监测体系及网络、完善保护管理体系等圈养麋鹿种群的保护管理对策.     

在生境片断化中光对七子花生理特性的影响

研究了浙江北山生境片断化对七子花生理特性的影响,重点研究生境片断化所引起的光胁迫对七子花叶片特征、光合速率及膜脂过氧化和体内一些保护酶类的影响.结果表明在北山七子花生境片断化所导致的强光(大于800μmol@m-2s-1)条件下,七子花光合速率降低,电导率和丙二醛含量显著增加,叶片的叶绿素a/b值上升,叶绿素含量、气孔导度、超氧化物歧化酶、过氧化氢酶、过氧化物酶和抗坏血酸过氧化物酶等保护酶活性下降.光照强度350～650 μmol@m-2s-1对七子花较为适宜.     

秦岭冷杉研究进展

秦岭冷杉是古老的孑遗植物,为我国特有珍稀濒危植物,被称为"植物活化石".阐述了秦岭冷杉的形态与种群特征、起源与分布格局、遗传多样性和群落结构特征、主要功能、应用价值以及物种保护情况.为充分了解秦岭冷杉野生资源的状况,分析了秦岭冷杉濒危成因,提出了物种保护针对性的措施,以期对秦岭冷杉未来有可能进行的物种资源监测、保护规范...     

三尖杉种源遗传多样性

应用ISSR分子标记对我国三尖杉主要分布区16个地理种源的遗传多样性和遗传分化进行分析.结果表明,三尖杉具有丰富的遗传多样性,总的种源基因多样性为0.337 7.研究发现,不同种源的遗传多样性差异较大,遗传多样性较高的种源主要来自三尖杉自然分布区的东部和偏中东部地区.由于小种群效应, 以及缺乏有效的基因流和生境的片断化,三尖杉种源间的遗传分化较大,25.9%的遗传变异存在于种源间,而74.1%的遗传变异来自于种源内.聚类结果显示,来自东部和偏中东部、遗传多样性较高的种源聚成一支.该区域和边缘分布区种源间遗传多样性的差异在很大程度上可能归因于长叶和短叶2种类型三尖杉种源间的差异.研究还表明,种源间的遗传距离与其地理距离相关不显著.     

Factors influencing levels of genetic diversity in woody plant species

The plant allozyme literature was reviewed to: (1) compare genetic diversity in long-lived woody species with species representing other life forms, and (2) to investigate whether the levels and distribution of genetic diversity in woody species are related to life history and ecological characteristics. Data from 322 woody taxa were used to measure genetic diversity within species, and within and among populations of species. Woody species maintain more variation within species and within populations than species with other life forms but have less variation among populations. Woody species with large geographic ranges, outcrossing breeding systems, and wind or animal-ingested seed dispersal have more genetic diversity within species and populations but less variation among populations than woody species with other combinations of traits. Although life history and ecological traits explain a significant proportion (34%) of the variation among species for the genetic parameters measured, a large proportion of the interspecific variation is unexplained. The specific evolutionary history of each species must play an important role in determining the level and distribution of genetic diversity.     

中国竹类多样性及其可持续利用研究现状和展望*

文中从种质资源、竹类多样性、竹林群落和生态景观多样性、珍稀竹种及其保护、竹产业可持续发展等方面 ,就涉及我国生物多样性及其保护的文献资料进行了简要评述 ,并对存在的一些问题作了探讨     

Genetic variation ofAlnus trabeculosa populations in Japan

Alnus trabeculosa Hand.-Mazz. is classed as “near threatened,” and efforts should be made to conserve the species, but effective action would require understanding of its genetic variation and structure. Therefore, the genetic variation at 12 isozyme loci was examined in seven populations of the species in Japan. The expected heterozygosity within species (H _es=0.222) and the expected heterozygosity within populations (H _ep=0.199) were found to be slightly higher than in most other woody species. The coefficient of genetic differentiation (G _ST=0.146) was also high. The northernmost population had the lowest values for almost all measures of genetic variation, and populations in southern Japan tended to show greater within-population variation than those in northern Japan. The level and distribution of genetic variation in this species might be related to its life history and ecological traits, and distribution history.     

乳源木莲种源遗传多样性和遗传分化

乳源木莲(Manglietia yuyuanensis Law)属木兰科(Magnolinaceae)木莲属(Manglietia Blume)常绿大乔木,是近年来发掘推出的优良乡土速生用材和生态造林树种,自然分布于东北部、湖南南部、江西南部、安徽南部、浙江和福建等地,生于海拔700～1 200m的阔叶林中,其生长迅速,适应性和抗寒性强,树干通直圆满,木材结构细,纹理直,耐腐性较好,易加工,是优良的建筑、家具和胶合板用材.     

Allozyme Genetic Diversity and Conservation Strategy of Ten Natural Populations of Pinus bungeana Zuuc. ex Endl

Pinus bungeana is a three-needle pine with typical fragmented distribution in central and northwestern China. Its natural resources are gradually decreasing and need to be conserved. For conserving genetic diversity of P. bungeana, the authors sampled 10 natural populations in its distribution areas and conducted the analysis of isozymes. Thirty one loci with 53 alleles on the basis of 16 enzyme systems were assayed. The parameters of genetic diversity at species and population level are respectively as follows: As= 1.742, Ae[s] = 1.49, Ps= 54.8%, He[s] = 0.162, Ap= 1.39, Ae[p]= 1.30, Pp= 34.85, He[p] = 0.0986. In comparison with other pines, P. bungeana possesses a slightly low amount of genetic variation especially at the population level. By contrast, the level of population genetic differentiation (GST = 0.135) is higher compared to other pines. All ten populations are divided into three groups according to Nei‘s genetic identity (I). There is a slight relation (r = 0.31) between genetic distance and geographical distance.Some populations are obviously deviate from Hardy-Weinberg equilibrium but the total population is basically accordant with Hardy-Weinberg equilibrium. The correlation analysis between allele frequencies and ecological factors showed that the alleles at loci of Idh and Pgi-2 had gradient variation trends of their frequencies. The sample capturing curves‘ analysis indicated that the captured alleles increased when the number of sampled populations increased and 99% out of whole allele pool of ten populations would be captured when five populations were randomly selected. At last,. the population genetic structure of P. bungeana and its conservation strategy were discussed.     

Allozymes Genetic Diversity of Quercus mongolica Fisch in China

INTRODUCTION Analysis of the amount and distribution of genetic variation within and among populations of a species can increase the understanding of the historical processes underlying the genetic diversity (Dumolin- Lapegue et al. 1997) and can also provide important basic information for breeding programmes and for the establishment of programmes to conserve genetic resources. Moreover, information on the genetic structure allows for a more representative sample of the species’ gene p…     

松山自然保护区生物多样性现状与保护策略

地处燕山山脉军都山中的松山自然保护区,具有生态系统多样性、物种多种性、遗传多样性等特点,是首都生物多样性最丰富的地区之一。然而近年来,由于自然和人类活动的双重作用,生态逐渐退化,生物多样性种类数量锐减,生物多样性保护刻不容缓。文章分析了目前保护区生物多样性面临的威胁,提出了今后加强保护、合理开发的对策。     

Modelling exploration of the future of European beech (Fagussylvatica L.) under climate change—Range,abundance, genetic diversity and adaptive response

We explored impacts of climate change on the geographic distribution of European beech by applying state of the art statistical and process-based models, and assessed possible climate change impacts on both adaptive capacity in the centre of its distribution and adaptive responses of functional traits at the leading and trailing edge of the current distribution. The species area models agree that beech has the potential to expand its northern edge and loose habitat at the southern edge of its distribution in a future climate. The change in local population size in the centre of the distribution of beech has a small effect on the genetic diversity of beech, which is projected to maintain its current population size or to increase in population size. Thus, an adaptive response of functional traits of small populations at the leading and trailing edges of the distribution is possible based on genetic diversity available in the local population, even within a period of 2–3 generations.     

RAPD Marker Diversity Within and Among Natural Populations of the Clonal Tree Cryptomeria japonica D. Don.

Abstract

The Japanese cedar, Cryptomeria japonica D. Don., is one of the most important endemic species in Japan. A long history of heavy logging has resulted in natural populations being discontinuously distributed and scattered among small, restricted areas. An understanding of the patterns of genetic variability among and within populations of C. japonica is important for conserving the genetic resources of this economically important species. We studied genetic variation by random amplified polymorphic DNA (RAPD) markers in C. japonica of Kyoto prefecture, western Japan. A total of 398 plants sampled from six natural populations were analyzed by ten arbitrarily chosen decamer primers, resulting in 50 highly reproducible RAPD bands. Analysis of molecular variance partitionated the RAPD variation into the among- and within population components. The within-population component accounted for 93.75% of the variation. The among-population component accounted for only 6.25%. Indirect estimates of gene flow indicated that the average number of migrants exchanged among six populations per generation was 3.72. A Mantel test for each population did not yield significant correlations between geographic and genetic distances. The extent and distribution of C. japonica diversity in the Kyoto prefecture is in agreement with the conclusion that long-lived, wind-pollinated, out-crossing species with wide ranges retain a considerable amount of genetic diversity within populations and exhibit little genetic differentiation among populations.     

我国竹类研究展望和竹林生境利用

简要回顾了我国现代竹类研究发展的历程，介绍了我国今后以“数字林业”为特征的研究热点领域，分析了今后竹类生物多样性保护和遗传改良的因子，提出了生物多样性保护的策略和途径，并展望了竹林生态环境、遗传改良、竹子利用技术等研究动态。最后论述了竹林生境利用的必要性、注意事项及发展对策。