中国特有濒危植物扇蕨的保护生物学研究

	中国特有濒危植物扇蕨的保护生物学研究
其他题名	Conservation Biology of Neocheiropteris palmatopedata, an endangered plant endemic to China
	邓亚妮
导师	成晓
学位专业	植物学
关键词	扇蕨濒危细胞学土壤配子体发育保护生物学濒危机制
摘要	扇蕨（Neocheiropteris palmatopedata（Baker）Christ）是中国特有的珍稀濒危蕨类植物，仅零星分布于云南中部、贵州西部和四川西南部。本文在广泛调查扇蕨的资源分布和破坏状况的基础上，对扇蕨的形态学特征、细胞学、生长特性、种群生态及群落特征、土壤性质、配子体发育、形态多样性分化等方面进行了系统研究，以探索扇蕨的濒危机制，为有效保护这一濒危物种提供理论依据。 1. 形态学特征扇蕨叶片扇形，呈鸟足状掌形分裂，叶脉网状，中央裂片偶有羽裂现象。孢子囊群紧靠主脉着生。在扇蕨叶柄的不同部位做横切，呈网状中柱。从叶柄基部至叶柄顶部，维管束渐趋合并，数目越来越少。维管束呈环状排列，其中２条较粗，其余较细。此外，与蕨类植物典型的周韧维管束不同，这2条较粗的维管束均可见两部分木质部。 2. 细胞学对扇蕨的染色体数目进行了观察，实验结果表明，扇蕨染色体数目为2n=72，基数为x=36，这与Gibby报道扇蕨2n=70的结果不一致。 3. 生长特性结合野外调查和迁地保护，观察其生长状况、物候及繁育习性。表明扇蕨对湿度、光照的要求较为苛刻。扇蕨萌生习性强，但利用根状茎进行繁殖，扩散能力十分有限。 4. 种群生态及群落特征扇蕨种群稀少，各种群呈隔离状态。扇蕨在群落中处于受支配的地位，且其地理分布特征表明其分布区具有明显的地域局限性和生态脆弱性。 5. 土壤性质扇蕨喜生长在有较厚腐殖质层的褐红壤、黑色石灰土和红色石灰土上，土壤化学性质测定表明有机质、有效钙镁、有效硼是影响扇蕨生长发育的关键土壤因子。原生植被遭受破坏引起的林下腐殖质土消失、红壤裸露进一步加剧了扇蕨的濒危。 6. 配子体发育采用改良Knop’s固体培养基、原生境腐殖质土、红壤和无菌水分别培养扇蕨孢子，观察其配子体发育过程并比较了4种培养方法对其配子体发育和有性繁殖的影响。结果表明：成熟孢子黄褐色，单裂缝，赤道面观为豆形，极面观椭圆形。孢子萌发类型为书带蕨型，原叶体发育为槲蕨型。成熟原叶体呈心脏形。毛状体在原叶体阶段出现。配子体培养过程中易受污染，主要污染物有真菌、藻类和藓类。 7. 形态多样性分化测定了来自6个居群的扇蕨72个个体的叶柄长、裂片数、结孢裂片数、孢子囊群及孢子等21项形态指标，采用方差分析、欧氏距离聚类分析、相似系数聚类分析等方法，研究了各项形态指标在居群间的差异显著性、形态多样性及其反映出的居群间的近缘关系。结果表明：（1）扇蕨21个形态指标中差异显著的特征占4.76％，20个性状指标差异不显著，占95.24％，表明绝大多数性状在个体及居群间没有较大的变异；（2）相比较而言，营养器官的变异受环境条件的影响较小，相对稳定，而繁殖器官的变异受环境条件的影响较大。（3）扇蕨形态特征在居群水平上未表现出明显的分化，而在不同地理种源上却表现出一定的分化。 8. 濒危原因及保护措施扇蕨可能存在的濒危原因：(1）扇蕨起源时间较近，传播和分布区的形成历史都不长；（2）扇蕨的生长对湿度、光照和土壤的要求较为苛刻；（3）扇蕨有性生殖周期长及配子体发育成幼孢子体的百分率低是扇蕨在配子体世代的主要濒危原因；（4）自身的无性繁殖不能扩展其分布范围；（5）人类活动导致的生境丧失及相伴的生境片断化加速了扇蕨的濒危。（6）自然灾害如旱灾是扇蕨出现濒危的一个不可低估的原因。保护措施：（1）对扇蕨进行就地保护和迁地保护；（2）采用分株繁殖和人工孢子繁殖，促使其复壮和扩展；（3）将分株繁殖和人工孢子繁育的个体回归原产地和适合扇蕨生长的生境，让其归化自然。; Neocheiropteris palmatopedata（Baker）Christ, a rare and endangered species endemic to China, has a scattered distribution only in central Yunnan, west Guizhou and southewest Sichuan provinces. To explore endangerment mechanisms and provide theoretical basis for the effective protection of N. palmatopedata, its morphological characteristics, cytology, growth characteristics, population and community structure, soil property, gametophyte development and morphological differentiation were investigated based on the extensive investigation of its distribution and destruction. 1. Morphological characteristics A fan-shaped, pedatifid, palmate and reticulate fern, the central lobe of N. palmatopedata was occasionally pinnatifid. Sori were grown close to the midvein. Transverse section was made in different portion of petiole, showing a dictyostele. The vascular bundles of the petiole converge gradually and decrease in number from bottom to top. The vascular bundles were arranged in circularity, two of which were thicker than the others. In addition, two parts of xylem were seen in the both thicker vascular bundles, which was different from typical amphicribral bundle of ferns. 2. Cytology Chromosome number of N. palmatopedata was investigated. The result showed that the chromosome number was 2n=72 and the basic choromosome number is x=36, which differed from Gibby’s result—2n=70. 3. Growth characteristics Growth status, phenology, propagation habit of N. palmatopedata were investigated. The result showed that it was exigent over humidity and light. Despite of its strong rhizome initiation, population growth was not affected by rhizome propagation. 4. Population and community structure N. palmatopedata was scarce in population, and each population was isolated from each other. It was dominated by other species in the community, and its geological distribution indicated obvious regional limit and ecological fragility of its distribution area. 5. Soil property N. palmatopedata grew in brown-red soil, rendzina and red limestone soil, all with thick humus layer. Analysis of the soil chemical property showed organic matter, potent Ca and available Mg were key factors for growth and development of N. palmatopedata. When the humus soil under woods disappeared and the red soil appeared owing to primary vegetation destruction, the endangerment situation of N. palmatopedata was further aggravated. 6. Gametophyte development The spores of N. palmatopedata were cultured in improved Knop’s medium, in-situ humus soil, red soil, sterile water respectively. Spore germination and gametophyte development were observed, and the impact of four culture methods on the gametophyte development and sexual reproduction was compared. The results showed that the mature spores were yellow-brown, monolete, and bean-shaped in equatorial view and elliptical in polar view. The germination was of the Vittaria-type and the gametophyte development of the Drynaria-type. The adult prothalli were cordate. Trichomes occurred in prothallus stage. Gametophyte culture process was susceptible to contamination of fungi, algae and moss. 7. Morphological differentiation 21 morphological indicators, including petiole length, lobe number, spore sori, spores etc. of 72 individuals from 6 populations of N. palmatopedata were determined. The significance of differences, morphological differentiation, and phylogeny relationship reflected between populations were studied with variance analysis, Euclidean distance clustering and COSINE clustering. The results showed:（1）Morphological indicators of significant differences and of no significant differences accounted for 4.76％ and 95.24％ respectively.（2）Variation in vegetative organs was less influenced by environment and more stable than that of the reproductive organ.（3）Morphological characteristics showed no significant differentiation at population level but certain differentiation in geographically different origins 8. Endangerment factors and conservation measures Endangerment factors: (1）The history of its spreading and distribution area formed was not long owing to its late origin. (2）It was exigent over humidity, light and soil. (3）The long period of sexual reproduction and the low seedling rate at which gametophytes developed into sporophytes were the main reason for the endangerment of N. palmatopedata in sporophyte generation. (4）It couldn't enlarge distribution area by rhizome propagation. (5）Human-induced habitat loss and accompanying habit fragmentation likely accelerated the endangerment process.(6）Natural disaster such as drought was a factor causing the endangerment of N. palmatopedata that can’t be underestimated. Conservation measures: (1）Introduce in-situ and ex-situ conservation. (2）Rejuvenate and expand N. palmatopedata by adopting division propagation and artificial reproduction by spores.(3）Return N. palmatopedata to nature by naturalizing the plants reproduced by division and spores to its home and habitats that suit its the growth.
语种	中文
	2009-05-27
学位授予单位	中国科学院昆明植物研究所
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/424
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	邓亚妮. 中国特有濒危植物扇蕨的保护生物学研究[D]. 昆明植物研究所. 中国科学院昆明植物研究所,2009.

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