【作者】 何平荣；

【导师】 薛跃规； 宋希强；

【作者基本信息】 广西师范大学 ， 生态学， 2008， 硕士

【摘要】 兰科植物是世界上有花植物中的四大科之一,它们的花部构造高度特化,在植物界的系统演化上是属于最进化、最高级的类群,这是与传粉昆虫协同进化的结果。兰科植物的生长和繁衍需要特定的环境条件,对环境条件的要求较其它科的植物更为苛刻。而距离海口市区仅十几公里的琼北火山岩地区兰科植物正面临着人类生活、经济活动等的影响而逐渐减少,甚至海口市政府即将搬迁至该地区致其生境面临进一步大规模破坏和丧失,兰科植物的生存岌岌可危。因此,全面摸清琼北火山岩地区野生兰科植物资源状况,揭示其致濒机制,提出种质资源保护方法已成为当务之急。本研究主要采用野外实验生态学、保护生物学的方法,通过收集各种文献资料以及多次野外调查,对琼北火山岩地区兰科植物的野生资源、附生宿主和伴生植物进行较为详尽的调查与分析;为深层次揭示兰科植物濒危机制,以火山岩和其它地区分布的同时具备药用和观赏价值的美花石斛(Dendrobium loddigesii)为例,对其进行野外实地传粉生物学观察研究,并对该地区的兰科植物提出了相应的保护措施与建议,结果表明:(1)琼北火山岩地区兰科植物种类有9属13种,其中4种在中国仅分布于海南岛(包括局限于琼北火山岩区分布的2种),物种丰富度低,但是特有分布种占有率高,因此具有较高的保护价值。该地区兰科植物区系成分单一,都属热带区系成分;由于农业用地的特殊性,导致兰科植物呈斑块状分布。(2)琼北火山岩地区13种兰科植物中,地生兰3种,附生兰有10种,占76.9%;各附生兰宿主表现出广泛的多样性;同种兰科植物可选择不同科、属的树种为其宿主(如叉子股等);不同的兰科植物也可附生于相同的树种或同一棵树甚至相同的位置(如鞭叶隔踞兰与叉子股等);同属兰科植物倾向选择相同宿主(如白点兰属);并且果树如龙眼、荔枝、番石榴等与玄武岩成为兰科植物很重要的宿主,这种兰科植物对宿主的可塑性和倾向性为人工开发栽培基质提供了参考依据。(3)琼北火山岩地区开垦果园、果树品种的更替、人为砍伐、开发建设、开采火山石等人类生活、经济活动及外来物种入侵等导致生境的丧失,兰科植物、宿主、伴生物种的减少。(4)在自然条件下,美花石斛自然结实率仅为0.48%,人工授粉实验成功率也比较低,可能是长期干旱导致其自然结实与人工授粉结实率都非常低,通过传粉过程的观察发现,其自然结实率低还有个关键的原因就是传粉昆虫稀少;但是自花授粉亲和得到验证。(5)蜜蜂总科中准蜂科的栉距蜂属Ctenoplecta florisomnis是美花石斛的专性传粉的昆虫;美花石斛与栉距蜂的形态对应关系是传粉昆虫与植物的协同进化的有力证据。花部构成即花的结构、颜色、气味和蜜汁产量等单朵花的所有特征对与传粉者的觅食动力学之间的关系是传粉生物学研究的一条重要纽带。从美花石斛传粉昆虫访花时的动作来看不存在性欺骗行为,但花香、花色对栉距蜂属这一单食油性传粉昆虫的觅食行为所产生的影响还有待进一步研究,继续深入野外观察和实验设计有助于揭示改种的繁育机制。总之,琼北火山岩地区人类生活、经济活动及外来物种入侵等导致兰科植物生境的丧失,兰科植物宿主、伴生物种的减少,加速了本身已经斑块化即生境破碎化的兰科植物减少。因为传粉昆虫的稀少导致美花石斛野外自然结实率极低,琼北火山岩地区没有观察到传粉昆虫,即缺乏传粉昆虫,这也是美花石斛在当地数量减少的原因之一,因此,生境的破坏以及传粉昆虫的稀少都成为制约琼北火山岩地区兰科植物生长繁殖的影响因素乃至致其濒危原因。更多还原

【Abstract】 Orchidaceae is one of the four major flowering plant families in the world. Because of co-evolution with the pollinators, there is special flower structure in the family. It is the most evoluted and advanced family in the phylogeny of the plant kingdom. The growth and propagation of orchidaceae need special environmental conditions which are more harsh to the family than other plants. There are only a dozen kilometers from our research region (the volcanic lava region Northern Hainan Island) to Haikou city. Because of the impacts of human life, economic activities, and even ingoing of city, orchid plants are dramaticly reducing. Their habitat is destroyed and even lost, and orchidaceae is endangered plant. Therefore, it is urgent to investigate the status of their germplasm resources in order to understand the endangered mechanism of population and explore measurement of germplasm conservation.Based on field experiment, conservation biology and collecting of document, wild orchidaceae germplasm resources, the host and concomitants plants from the Northern Hainan Island are studied in the research. The pollination biology of Dendrobium loddigesii help to understand the endangering mechanism of the family. And the protection measurement and constructive advice for sustainable management are proposed for the orchid plants in the region. The main results and conclusions are summarized as the following:·There are 9 wild orchids genera including 13 species in Northern Hainan Island volcanic lava region. Among them, four kinds occur only in Hainan Island and two kinds are limited distributed in Northern Hainan Island volcanic lava area. The richness of species is low while the endemic distribute species are high, so it is valuable to conservation in the region. Orchid plants belong to tropical flora with a single type. Because of invasion of agriculture, the habite of orchid plants is a macular distribution.·Among the 13 orchids species, ten are epiphytic orchids (76.9%) and three are terrestrial orchids (23.1%) in Northern Hainan Island volcanic lava region. The hosts of epiphytic orchids show a huge diversity. The same species of orchid might choose different genera and even family plants as the host while different orchid plants can also be born of the same species tree and even a tree with the same location. But the same genera is apt to choose the same host. Basalt and fruit trees such as longan, litchi, guava are very important hosts to the orchidaceae. And the plasticity and orientation for the hosts provides an important measurement of artificial cultivation.·The human life and economic activities such as reclamation orchards, fruit tree species turnover, man-made felling, development and construction, mining volcanoes, and alien species invasion led to reduction of habitats, hosts and the associated species with orchids.·Under natural condition, there is only a 0.48% fruit setting in the species.Even with hand pollination, there is still a low fruit setting. The long time drought may be the main reason. Another reason is rare the pollinator. In our field observation, self- pollination is approved to affinity.·Ctenoplecta florisomnis, a species of Apoidea is the sole pollinator for the D. loddigesii. The morphology correspondence between the D. loddigesii and C. florisomnis is the power proof co-evolution of the pollinator and plant.The relationship between the dynamics of looking for food in the pollinators and flower character such as structure, colour, scent and honeydew is an important ligament of pollination biology research. According to the behavior of the pollinator, there is not sex deceptive. Tenoplecta most of them collect floral oil only for food, but the influence of potpourri , colour to the action of pollinator deserves further research. Well-prepared field works and elaborate experiment plans will help to understand the natural pollination mechanism and mating system. In conclusion, the human life, economic activities and alien species invasion led to reduction of habitats, hosts and the associated species with orchids, accelerate the decreasing speed of the arethusa which its habitat have been fragmented already. The rare pollinator lead to low fruit setting under natural condition. Therefore, the destroyed habitats and rare pollinators are the inhibition for the develop and propagate of the orchidaceae in Northern Hainan Island, and even lead it to be endangered.更多还原