【作者】 邓涛；

【导师】 陈功锡；

【作者基本信息】 吉首大学 ， 生态学， 2010， 硕士

【摘要】 湘西北地处湘、鄂、渝、黔边区,以武陵山脉为主体,属“水杉植物区系”范畴,是我国三个特有现象中心之“鄂西—川东中心”的核心地带,在我国乃至整个东亚植物区系中具有重要意义。河谷是该区河流深切形成的一个自然生态系统,属于典型特殊生境,是组成该区植物区系的关键地带。然而,目前对这一重要和关键地区的研究还很不深入,是亟待研究的薄弱或者空白地带。受山体陡壁或悬崖的隔离,河谷特殊生境犹似“岛屿”状态,有着独特多样且非地带性植物区系,是研究植物物种分化和多样性形成机制最为理想的地域。同时,由于特殊的生态环境因子作用,植物在形态、生理、繁殖等方面有着丰富的多样化形态和特殊的适应机制,该地域亦是研究生态系统结构、功能和适应进化机制的独特场所。本研究选择湘西北德夯峡谷和猛洞河两条典型河谷特殊生境为代表,进行详细的植物调查、标本采集和分类研究,在查清该区植物种类基础上作进一步区系特征和适应特性分析,揭示有关区系地理问题,功能型和繁育系统多样性及生态关联性,特殊种系(如地区特有种、河谷专性种等)的分布及特点,物种辐射分化和生态适应性规律,为研究特殊生境区域物种分化和适应进化、植物多样性形成与维持机制等重大科学问题提供理论依据,也为正在进行的《湖南植物志》和地方自然资源持续利用、保护和综合管理提供科学资料。研究结果如下:1.首次定义河谷特殊生境,初步探讨其形成原因,结合外部形态特征将其分为9个小生境类型,认为河谷特殊生境为系列小生境的有机组合,提出河谷特殊生境生态效应理论及模型。系统归纳和总结了河谷特生境生态系统的环境特征和生态特性,深入分析其脆弱性原因,并提出治理和保护方案。2.从科、属、种3个层面系统分析德夯峡谷和猛洞河河谷植物区系的组成、特征、性质、起源及与其他区系的关系。德夯峡谷有维管束植物1162种,隶属于148科566属,蕨类和藤本植物相当丰富。组成德夯峡谷植物区系的科、属以泛热带分布最多,是德夯风景区植物区系的主体。猛洞河有维管植物129科,389属,670种(含变种),特有程度高,属区系地理分析表明其是一个从热带向温带过渡的区系。种水平分析表明其属于东亚和热带亚洲植物区系交汇。利用STATISTICA统计软件对武陵山区内和我国其他类型(干热、干暖)河谷植物区系进行聚类和主成分分析,揭示该区河谷的特殊性及其在该区植物区系中的重要作用。选择相对丰富度、分化指数, IM值等指数对各小生境多样性分析表明土台小生境各指数均比较高,岩溶洞穴最低。3.提出“生境专性植物(obligate plant)”概念,并初步调查湘西北河谷特殊生境有专性植物160种,隶属于71科121属。群落中灌木层和草本层的优势物种大部分为峡谷生境专性种,乔木层优势植物中专性种较少。河谷特殊生境专性种在生长型、器官形态、生活史、生态适应类群及适应性分区等方面形成了一系列与环境相适应的特征以及特定的适应分布结构。随着群落演替的进行,峡谷生境专性植物由少逐步增多,演替后期则逐步减少。4.以典型河谷专性植物吉首蒲儿根Sinosenecio jishouensis、凤凰蜘蛛抱蛋Aspidistra fenghuangensis为代表,研究河谷专性植物生物生态学特性、辐射分化适应及物种形成过程。从生态分布、物候特征、繁殖特性三个方面系统研究表明吉首蒲儿根的花部构成、高度同期的开花模式和“刷状机制”、瘦果小且无冠毛、以克隆繁殖为主兼有种子繁殖及间隔子自动断裂等是对峡谷瀑布特殊生境长期分化、选择和适应性进化的结果。利用形态学和细胞学方法研究凤凰蜘蛛抱蛋的形态辐射分化特征,修订和补充描述了凤凰蜘蛛抱蛋形态,从染色体数目和核型动态讨论其亲缘关系,从细胞地理学角度探讨其可能的起源、演化和物种形成过程,并提出随体缺失可能有利于物种适应新的环境,是进化的表征。5.从根、茎、叶、花和果实各方面探讨了河谷特殊生境植物功能性状多样性及其适应意义。河谷特殊生境植物根分为5种类型,茎有3种形态;叶级以中型叶为主,叶质以纸质占绝对优势,两面均无毛的种类最多;花性状中以小花类居多,颜色以浅色为主;果实性状以干果占较大比例,以机械传播作为主要的传播方式。从区系成面探讨河谷特殊生境繁育系统与生态关联性,分析进一步印证河谷植物区系的热带亲缘性,并讨论了系统发生关系对性系统和生态关联性的限制和生态环境对性系统分化与进化中的作用。更多还原

【Abstract】 The northwestern region of Hunan province, located next to Hubei, Chongqing and Sichun provinces, belonging to the Metasequoia Flora, is made up largely by the Wulingshan Mountains. It forms the core of one the three“Centers of Endemism”in China, the eastern Sichuan and western Hubei Center, and is an important element of the Chinese and East Asian Flora. A typical and important physical feature of this region is the natural habitats associated with the deeply cut river valleys. Much like isolated mountains and cliffs, these river valley microhabitats are isolated“islands”of diverse endemic plants, making them ideal for studying species differentiation and diversity. In addition, plants of this region show a great diversity of adaptive morphological features, obviously as a result of the special environment of these microhabitats. Therefore, the plant species these valley microhabitats are of special interest for studying ecosystem structures and functions, and adaptive evolutionary mechanisms. However, previous studies on the flora of this region are few.Two typical canyons of this kind, the Dehang Canyon and Mengdong River Canyon, in the northwestern Hunan region were chosen as research sites in this study. We made extensive collections of plant specimens in both sites throughout the growing season. All specimens collected were later identified to species. The floristic characteristics and apparently adaptive plant features were analyzed. We further examined the functional type and reproductive system diversity and ecological correlates, the distribution characteristics of notable species (i.e., endemic and niche-specific species), and patterns of diversification and adaptation of plant species in the two sites. The results of this study is sumarized as below:1. The term Canyon micohabitat was defined for the first time in this study, and the possible causes for the formation of this speical habitat were discussed. Based on geomorphologic features, 9 submicrohabitats were identified. The environmental characteristics of this special ecosystem were systematically characterized, the factors likely to disrrupt this fragile ecosystemwere fully analyzed, and corresponding management and conservation measures were suggested.2. The plant floristic components, characteristics and origins of the special Eco-environment of Dehang Canyon and Mengdong River were analyzed at the Family, Genera and Species levels, and its floristic correlations with other floras were made. The results showed that there were 1162 vascular species belonging to 566 genera and 148 families in this region. Fern and Vine plants were the most diverse groups. The flora in Dehang Canyon were mainly tropical components at Family and Genera levels. Mengdong River, where the species were rather endemic, contained 670 vascular species belonging to 389 genera and 129 families. Floristic geographical analysis at the genera level indicated that this flora was an obvious transitional one from tropical to temperate flora. The species level analysis showed that this flora was the mixed one of East Asia and Tropical Asia. The results of clustering and principal components analyses between Wulingshan region and other domestic Areal Types by using STATISTICA software showed the importance of the Canyon microhabitatin this region. The parameters, such as relative richness, differentiation index, and IM value, were used to evaluate the diversity characters of microhabitats. The results showed that all the parameters of Tutai were high, while the Yanrong low.3. There were 160 niche-specific species belonging to 71 families and 121 genera in the canyon microhabitat of North Western Hunan. Most of the niche-specific species distributed in the herb layer and the shrub layer, while seldom in the tree layer. The Canyon microhabitat niche-specific species evolved a series of ecological features, including growth type, organ morphology, life history, ecological adaptation groups and areas of ecological adaptation, adapting to the special habitats,. With the succession of plant community, the niche-specific plant species increased, while in the later stage they were fewer.4. Two typical Canyon microhabitat species (Sinosenecio jishouensis and Aspidistra fenghuangensis) were studied in detail for life history traits, differentiation and speciation of the niche-specific species. Results of the study on the ecological distribution, phenology and reproductive characteristics of S. jishouensis showed that the floral structures, high degree of synchronization in the flowering pattern and "brush-like mechanism", and small achene without pappus, together with relying mainly on clone production while making sexual production subsidiary, are the consequences of long-term ecological adaption to the Canyon Fall special habitat. The morphological and cytologic methods were used to studied the patterns of morphological differentiation of A. fenghuangensis. Amendment and supplement on morphology of A. fenghuangensis were made. The genetic relationship was discussed by analyzing chromosome number and karyotype dynamic, and the possible origin, evolution and speciation of A. fenghuangensis were stuided from the cytogeographical aspect. The loss of satellite chromosomes was an evolutionary features, because this might be beneficial to its adaptation to new environment.5. The roots, stems, leaves, flowers and fruits of species in the Canyon microhabitat were studied to reveal their functional diversity and adaptive significance. There were 5 types of roots and 3 types of flowers. The leaf with medium size was the main leaf type, leaf quality was mainly paper type, and most leaves were hairless on both sides. Small type flowers accounted for a large proportion, and most flowers were light colored. Most of the fruits were of dry type, and mainly dependent on mechanical transportation. The analysis of sexual reproduction systems further corroborated the relationship between the canyon microhabitat and the Tropical Flora. The phylogenetic constraint on sexual reproduction systems and ecological correlations, and the effects of ecological environment on the differentiation and evolution of sexual reproduction systems were discussed.This study could provide further evidence for solving the major scientific issues, such as the differentiation and adaptive evolution of specific habitated species, and the plant diverstiy formation and its maintaining mechamisms. It also provided important data for the compilation of the Hunan Flora, and for the conservation, sustainable utilization, and comprehensive management of local natural resources.更多还原