三峡库区珍稀濒危植物荷叶铁线蕨的生物学特性及保护对策

荷叶铁线蕨为三峡库区珍稀濒危植物 ,已被国家列为二级保护植物。本文较系统地综述了荷叶铁线蕨的生物学特性 ,包括其形态特征、生长特性、地理分布、生态学特性和群落学特性 ,分析了荷叶铁线蕨濒危的可能原因 ,并提出了保护措施     

论荷叶铁线蕨的分布特点

荷叶铁线蕨是我国近年来在四川发现的又一特有珍稀植物。仅产于万县至西沱的长江河谷。为了弄清它的分布规律,为今后更好地保护和发展这一特有珍稀植物提供科学依据,我们于1985年对该植物进行了实地考察。本文就是在此基础上分析整理而成的。作者从分析荷叶铁线蕨产地的土壤、气候、植物种类等要素入手,初步阐明了荷叶铁线蕨的分布状况及其群落特点。     

论荷叶铁线蕨的分布特点

荷叶铁线蕨是我国近年来在四川发现的又一特有珍稀植物。仅产于万县至西沱的长江河谷。为了弄清它的分布规律,为今后更好地保护和发展这一特有珍稀植物提供科学依据,我们于1985年对该植物进行了实地考察。本文就是在此基础上分析整理而成的。作者从分析荷叶铁线蕨产地的土壤、气候、植物种类等要素入手,初步阐明了荷叶铁线蕨的分布状况及其群落特点。     

荷叶铁线蕨自然居群的遗传多样性研究

荷叶铁线蕨(Adiantumreniformevar. sinense)为我国特有植物,具有重要的经济价值,目前仅分布于重庆的少数地区。近几十年来,由于过度开发,该种的分布范围日益缩小,已处于灭绝的边缘。本研究利用等位酶标记检测了荷叶铁线蕨 6个自然居群共 136个个体的遗传多样性,共检测到了 5个酶系统的 14个位点,获得了 7个多态位点。结果表明:与其他蕨类植物相比,荷叶铁线蕨居群内的遗传多样性水平比较低。平均每位点的有效等位基因数(Ae)为 1. 778,多态位点百分率(P)为 0. 441,期望杂合度(He)为 0. 199,观察杂合度 (Ho)为 0. 235。其居群间的遗传分化也很低,居群间的遗传变异仅占总变异的 1. 49%,而 98. 51%的变异存在于居群内部。采用Hardy Wein berg平衡和固定指数F对荷叶铁线蕨的居群遗传结构进行了分析,结果表明其种群可能是以配子体间异交为主的混合交配体系。导致荷叶铁线蕨濒危的主要原因是生境的破坏以及过度开采所导致的生境片断化使其居群变小、近交率加大、遗传变异趋低,降低了其生存以及进化的潜力。     

三峡大坝下的珍稀植物园

<正>在长江上游与中下游交界处,伫立着一座举世瞩目的水利发电工程——三峡大坝。在大坝脚下,有着一座神秘的珍稀植物王国,上千种特有珍稀植物在此安家,这里就是全国最大的三峡库区特有珍稀植物保育基地,保护了荷叶铁线蕨(Adiantum nelumboides)、疏花水柏枝(Myricaria laxiflora)、丰都车前(Plantago fengdouensis)等三峡库区明星植物。     

三峡地区特有植物荷叶铁线蕨的群落特征及其保护对策

荷叶铁线蕨(Adiantum reniforme var．sinense)是三峡库区特有植物,国家二级保护物种,仅分布于重庆市万州区和石柱县。采用随机样方法对该物种的生境和群落特征进行了调查,讨论了十多年来该物种的种群动态和群落演替,并提出了适宜的保护对策。研究结果表明：荷叶铁线蕨主要集中分布在武陵、新乡、燕山、溪口等乡镇,位于长江两岸纵深5km内、海拔80～480m之间的低山丘陵地区;该物种的野生资源量已锐减,其种群正急剧缩小,种群平均密度仅为0．55蔸／m^2;大多数分布点位于河沟边西南坡向的崖壁或灌丛中,光照和空气湿度对该物种的生长较为重要;该物种在群落中处于伴生地位,其所在群落有4种类型,即：化香-槲栎-芒群落(Ass．Platycarya strobilacea-Quercus aliena-Miscanthus sinensis)、盐肤木-鸢尾群落(Ass．Rhus chinensis-Iris japonica)、水麻-细穗腹水草群落(Ass．Debregeasia edulis-Veronicastrum stenostachyum)和黄荆条-海金沙群落(Ass．Vitex negundo-Lygodium japonicum);荷叶铁线蕨所在群落共有物种189种,其中乔木5种、灌木86种、草本89种、藤本9种,且多为单叶和落叶类型,生活型以高位芽植物为主。在综合分析荷叶铁线蕨分布现状和特点的基础上,提出了相应的保护对策。     

三峡库区特有植物荷叶铁线蕨种群分布格局研究

通过相邻格子样方法采集数据,应用点格局分析技术研究了荷叶铁线蕨(Adiantum reniforme var.sinense)种群空间格局,结果表明:荷叶铁线蕨的空间分布格局和空间关联性与空间尺度、植株大小密切相关.在较小的空间尺度上(4.5 m),荷叶铁线蕨种群趋向于聚集分布,个体间有较强的空间正关联;在较大的空间尺度上(>5 m),荷叶铁线蕨呈随机分布,空间关联性减弱.成熟植株具有更明显的聚集分布趋势.大小级差异越小,植株间的正关联关系越强.荷叶铁线蕨的更新较好,但更新苗分布不均匀.建议在该物种原生种群的就地保护和恢复重建中,在减少人为采挖的同时,适当加大灌木层密度、降低草本层的郁闭度.     

基于保护基因组学揭示荷叶铁线蕨的濒危机制

理解物种的濒危机制对生物多样性的科学保护至关重要。荷叶铁线蕨(Adiantum nelumboides)作为国家一级重点保护野生植物, 其遗传多样性状况和濒危机制一直存在较大争议。本文利用简化基因组测序技术(genotyping by sequencing, GBS)对来自6个居群的28个荷叶铁线蕨样本测序, 共获得29.6 Gb的数据, 并筛选得到9,423个高质量单核苷酸变异位点(SNP), 通过遗传多样性和居群遗传结构分析, 并结合不同气候情景下物种潜在分布区差异, 探讨了荷叶铁线蕨的濒危原因和科学保护策略。结果表明: (1)荷叶铁线蕨具有较低的遗传多样性(H_o = 0.138、H_e = 0.232、P_i = 0.373), 同时种群间具有较低的遗传分化(F_st = 0.0202)和基因流(N_m = 1.9613); (2)所有样本均来自2个遗传分组, 基因组大小为 5.01‒5.83 Gb, 且均为四倍体, GC含量约为 39%‒41%; (3)生态位模拟表明, 与现代气候相比, 在未来气候变化下荷叶铁线蕨的潜在分布区面积略有增加, 但高适生区面积减小。其主要适生区向北迁移, 影响其分布的主导因子为昼夜温差月均值和最冷季降水量。正是由于荷叶铁线蕨遗传多样性低, 不同种群间遗传分化较低, 再加上气候条件的变化, 其适生区狭窄, 导致其遗传多样性和种群数量急剧下降。因此, 自身更新能力低以及过度的人为活动干扰可能是导致其濒危的主要原因。建议加强对荷叶铁线蕨的就地保护; 通过生境恢复及自然回归等措施, 增加居群间的基因交流, 防止遗传资源丢失加剧。     

长江小流域环境治理的奇迹——柑橘间作技术

<正>当我初次踏入长江珍稀植物研究所时,并没有想到我将经历如此独特的科研之旅。这里带给我的不仅是一份职业,更是一种生活态度,一种对生态环保和长江大保护的激情。初入长江珍稀植物研究所时,我在前辈的带领下缓缓步入植物的天堂,见到了婀娜多姿的疏花水柏枝（Myricaria laxiflora）,如精灵一般的荷叶铁线蕨（Adiantum nelumboides）,     

三峡库区两种特有植物天然生境与迁地生境土壤特征的比较

对库区特有的濒危植物荷叶铁线蕨、疏花水柏枝天然生境和迁地保护区生境及其土壤性质进行了调查分析和比较,结果表明：荷叶铁线蕨适宜于温暖湿润且排水良好的条件下发育的酸性淋溶土,养分含量高,多为粘土。疏花水柏枝适宜于亚热气候下弱碱性、养分含量低的冲积性砂砾质初育土、能耐一定程度的盐分。中国科学院武汉植物研究所内的迁地保护区土壤为湖滨沉积物上发育的中性粘土、主要养分和盐分含量介于两种天然生境土壤之间。微量元     

中国自然保护地体系分类研究

建设自然保护地体系是为子孙后代保留生物多样性资源与自然遗产最有效的途径。自1956年我国建立第一个自然保护区以来,已建设形成覆盖森林、草地、湿地、海洋、荒漠各类生态系统,珍稀濒危动植物物种和种质资源,自然遗迹和自然景观,以及水源保护等各类自然保护地。但由于缺乏自然保护地体系的顶层设计,各类保护地面临功能区分不清晰、空间重叠、管理成效不高等问题。建设以国家公园为主体的自然保护地体系的部署,为理顺我国保护地体系,明确各类保护地的功能定位提供了难得的机会。在分析我国现有自然保护地类型,并参考国际自然保护地体系分类经验的基础上,探讨了我国保护地体系分类,建议将我国自然保护地分为5大类,第I类为自然保护区,第Ⅱ类为国家公园,第Ⅲ类为自然公园,第Ⅳ类为物种与种质资源保护区,第Ⅴ类为生态功能保护区,并分析了各类自然保护地的功能定位和管理目标,以期为自然保护地体系规划建设提供参考。完善我国自然保护地体系分类,根据各类保护地的特点,创新保护地建设政策与机制,加大政府对自然保护地建设力度的同时,发挥全社会力量建设自然保护地,我国自然保护地建设将大有可为。     

Genetic variation and conservation of the endangered Chinese endemic herb Dendrobium officinale based on SRAP analysis

Dendrobium officinale (Orchidaceae) is used for traditional medicine and is critically endangered in China. To investigate the genetic structure of this species and to offer some advice on conservation strategies, 84 individuals from nine wild populations of D. officinale were analyzed using the method of sequence-related amplified polymorphism. A high level of genetic diversity was detected (PPB = 88.07%, H _E = 0.2880) at the species level. However, the genetic diversity at the population level was lower (PPB = 51.68%, H _E = 0.1878) in comparison with other species with similar life history characteristics. Based on analysis of molecular variation, there was moderate variation between pairs of populations with Φ _ST values ranging from 0.1327 to 0.4151 and on average 27.05% of the genetic variation occurred among populations. Two main clusters were shown in UPGMA using TFPGA, which is consistent with the result of principal coordinate analysis using NTSYS. In situ conservation is the first advocated and and ex situ should be proposed at the same time to protect the endangered plant and to preserve germplasm resources.     

Genetic variation and structure of the endangered Lady Fern Athyrium viridescentipes based on ubiquitous genotyping

To clarify the genetic status and provide effective information for the conservation of Athyrium viridescentipes, a critically endangered fern species with only 103 individuals remaining in the wild, we conducted ubiquitous genotyping to determine the genotypes of all remnant individuals of the target species. We analyzed the genetic variation of the 103 known individuals in four populations by using 13 microsatellite loci. The genotypes of single spores from a sporophytic individual were also determined in order to reveal the breeding system of this species. The level of allelic variation in A. viridescentipes was significantly lower than that of closely related Athyrium species. The genetic composition of the four populations was rather similar. Sixty-nine individuals (67%) possessed an identical pattern in the allele combinations at 13 microsatellite loci. The mean pairwise F (ST) among four populations was 0.018. The segregated pattern of alleles, determined by single-spore genotyping, revealed that allelic recombination occurs through meiosis. The results indicate that this species contains a low level of genetic variation, has low population differentiation, and maintains populations by sexual reproduction. These findings could lead to more effective conservation programs, the selection of the most appropriate individuals for ex situ conservation efforts, and separate management of extant populations.     

姜科花卉种质资源的引种保存、评价与创新

为科学开发利用姜科花卉种质资源,收集84种姜科花卉种质资源进行引种,结合生长情况、观赏特点和经济用途进行引种保存的分析与评价,采用人工杂交育种的方法进行种质创新。结果表明,84种姜科花卉种质资源引种成活了77种,成活率91.7%,成活种类的开花率98.7%,结果率63.6%。生长状况优的种类占59.5%,生长良好的占7.1%,生长中等的占25%,死亡的占8.3%。分布于中低海拔热带亚热带地区的大部分姜科种类能在粤港澳大湾区保存,而分布在热带、中高海拔及特殊生境地区的则不适宜。阶段驯化法可用于引种保存工作;有60.7%的种类为多用途花卉。杂交育种法既可创新种质又可转移保存优良姜科花卉基因。     

Low genetic diversity and high genetic divergence caused by inbreeding and geographical isolation in the populations of endangered species Loropetalum subcordatum (Hamamelidaceae) endemic to China

Loropetalum subcordatum (Hamamelidaceae) is one of the most endangered angiosperm species in China. It is narrowly distributed in a few localities in the evergreen broadleaved forest of southern China. Up to now only a few dozen remnant individuals have been found in the four extant populations. In this project, we studied its genetic diversity and population genetic structure using the high resolution molecular marker of amplified fragment length polymorphism. In total, 47 individuals from all the four populations (including all individuals in three populations) were analyzed. Comparably low genetic diversity within populations was revealed and significantly high genetic differentiation among the populations was detected. Four independent groups were identified which corresponded with their geographical ranges. Autogamy is considered to be the major factor contributing to the low genetic variation and high genetic divergence within this species. In addition, small population size, restricted distribution range, geographical isolation and limited seed dispersal may also contribute to the low genetic diversity and high population genetic differentiation. Clonal reproduction was inferred to occur in the two island populations. Suggestions for conservation strategies are provided to preserve the genetic resources of this species.     

三峡库区消涨带特有濒危植物丰都车前Plantago fengdouensis的迁地保护

丰都车前(Plantago fengdouensis)为近年在三峡库区消涨带发现的一特有植物。通过多年的调查,发现该种仅分布于重庆市忠县、丰都县和巴南区等3个长江江心岛上,总共290株。随着三峡水库的逐步蓄水,丰都车前的自然分布区将于2006年全部水淹,使其成为因三峡工程建设而导致自然生境和野生居群全部毁灭的唯一的草本植物。为保护这一即将野外灭绝的稀有植物,在对其地理分布、生态学和群落学调查的基础上,对其形态特征、年生长周期和生殖值与同属植物车前(P.asiatica)和北美车前(P.virginica)进行了调查、试验和比较研究,表明丰都车前果期长、种子不适宜长距离传播和生殖值低以及长江水淹干扰是其狭域分布和数量稀少的主要原因。同时探讨了其迁地保护策略,并提出了下一步的研究和保护建议。     

Genetic Variation in a Chilean Endangered Endemic: <Emphasis Type="Italic">Gomortega keule</Emphasis> (molina) Baillon

Gomortega keule (Molina) Baillon is an endangered, rare species, the only representative of its genus, and endemic to Central Chile. Populations of this tree are now fragmented and few individuals can be found in any of them. Genetic diversity was studied in 33 individuals from three populations in Cauquenes, a coastal mountain area (35°58'S-72°41'W). Fifteen InterSimple Sequence Repeat primers were used to determine the degree of similarity between and within populations. This revealed that 30% of the variation exhibited was between populations while 70% was within; nevertheless individuals were clearly clustered in a pattern which reflected a narrow base of diversity. Three other species from the Laurales order were used in order to provide an external reference as to the degree of diversity. In addition, an external wild population from the native species, Peumus boldus, was used to verify the utility of the markers. We show that the primers are effective in quickly giving an estimate of the degree of diversity of a population, thus giving important topical information relevant to preserving endangered species. Aspects of the conservation and management policy for the species in order to maintain the remaining populations and to preserve the genetic resources are discussed.     

三峡库区消涨带特有濒危植物丰都车前Plantago fengdouensis的迁地保护

丰都车前(Plantago fengdouensis)为近年在三峡库区消涨带发现的一特有植物。通过多年的调查,发现该种仅分布于重庆市忠县、丰都县和巴南区等3个长江江心岛上,总共290株。随着三峡水库的逐步蓄水,丰都车前的自然分布区将于2006年全部水淹,使其成为因三峡工程建设而导致自然生境和野生居群全部毁灭的唯一的草本植物。为保护这一即将野外灭绝的稀有植物,在对其地理分布、生态学和群落学调查的基础上,对其形态特征、年生长周期和生殖值与同属植物车前(P.asiatica)和北美车前(P.virginica)进行了调查、试验和比较研究,表明丰都车前果期长、种子不适宜长距离传播和生殖值低以及长江水淹干扰是其狭域分布和数量稀少的主要原因。同时探讨了其迁地保护策略,并提出了下一步的研究和保护建议。     

Genetic conservation: our evolutionary responsibility

The conservation of the crop varieties of traditional agriculture in the centers of genetic diversity is essential to provide genetic resources for plant improvement. These resources are acutely threatened by rapid agricultural development which is essential for the welfare of millions. Methodologies for genetic conservation have been worked out which are both effective and economical. Urgent action is needed to collect and preserve irreplaceable genetic resources.

Wild species, increasingly endangered by loss of habitats, will depend on organized protection for their survival. On a long term basis this is feasible only within natural communities in a state of continuing evolution, hence there is an urgent need for exploration and clarification of the genetic principles of conservation. Gene pools of wild species are increasingly needed for various uses, from old and new industries to recreation. But the possibility of a virtual end to the evolution of species of no direct use to man raises questions of responsibility and ethics.

     

三峡库区特有植物疏花水柏枝的调查研究

疏花水柏枝是三峡大坝建成后唯一１种痊全部被淹没的库区特有植物物种。在实地系统调查的基础上,阐述了疏花水柏枝的形态特征,分布现状,生长环境和群落结构等特点;从生物学,生态学角度分析了它在长江沿岸消涨带内汛期被洪水淹没的生长特性。