中文摘要：

叶附生是指维管植物叶片表面附着以隐花植物苔藓和地衣为主,兼有少量藻青菌及微型无脊椎动物的现象,在热带、亚热带雨林中普遍存在。叶附生生物的群落组成直接反应了森林水分、温度及光照等生境因子特征,是森林生境的季节性变化和微生境异质性的敏感反应指标。叶附生不仅对森林生物多样性形成及维持、生态系统养分与水分循环具有重要意义,在全球变化森林响应的研究中也具有重要的指示作用。叶附生生物不依赖宿主叶片获得营养,但已有实验证明叶附生与宿主叶片之间存在营养物质交换。其次,叶附生生物覆盖宿主叶片,对宿主叶片光合作用造成的影响一直存在争议,最近的研究发现宿主叶片对叶附生群落的遮蔽作用存在光合调节。近年来更多的学者开始关注叶附生在森林生态系统养分及水分循环过程中的重要作用,尤其是叶附生群落内固氮菌对森林氮循环过程所产生的重要影响。叶附生群落的固氮作用可为其宿主群落内的高等植物提供10%～25%的氮养分来源,被认为是森林生态系统中重要的＂氮库＂之一;再次,叶附生群落对森林云雾水表现出较强的截留作用,可有效地缓解在降水偏少的旱季森林生态系统受到的水分胁迫。该文在综述叶附生苔类和地衣研究的基础上指出叶附生生物与宿主间存在互利互害的进化平衡, 但受多种因素共同作用。

英文摘要：

Leaves of vascular plants in tropical and subtropical rain forests are frequently colonized by epiphylls. Most epiphylls are lichens and liverworts,but a few algae,cyan-bacteria and minute invertebrate animals also can occur. The composition of epiphyll communities is a sensitive indicator of seasonal changes of forest environments and microenvironment heterogeneity,and it can directly reflect habitat factors including moisture,temperature and illumination. Furthermore,epiphylls play significant roles in the formation and maintenance of biodiversity, as well as in the circulation of nutrients and wa- ter in ecosystems. In addition, they are indicators of forest responses to global changes. EpiphyUs obtain nutrients independently. However, some experiments have provided evidence that substances can be exchanged between epiphyUs and their host plants. Although epiphylls cover host leaf surface, whether the shading affects photosynthesis of the host plant is controversial. It has been hypothesized recently that leaves can photo-acclimate to the cover of the epiphyll community and photosynthesis of covered leaf areas can be compensated fully. The functions of epiphylls in nutrient and water circulation of forest ecosystems have attracted more attention in recent years. Nitrogen fixed by the epiphyll community provides 10%--25% of the nitrogen for the understory of tropical forest ecosystems. Epiphylls can also retain atmospheric moisture to alleviate drought in the dry season. There may be evolutionary balances between epiphyllous organisms and their host plants, and the relationships are likely influenced by multiple, poorly understood factors. More research is needed on relationships between epiphylls and their hosts.