Epiphylls widely colonize vascular leaves in moist tropical forests. the tropical forests. For example, up to 40% of the leaf surface PHA-848125 was covered by epiphylls in an Australia tropical rain forest [7]. Epiphylls are usually small cryptogams growing on the upper surfaces of the host leaves [8] and commonly consist of two dominant visible groups: epiphyllous liverworts and foliicolous lichens (referred to as liverworts and lichens) [9]. The occurrence of epiphylls would H3F1K induce a series of significant ecological and evolutionary impacts on host plants [10C12] due to the physical separation of epiphylls between the leaf surface and the atmosphere. Therefore, any potential change in epiphyllous communities, including shifting of community compositions and alteration of total coverage [13, 14], may considerably affect leaf traits of host plants subsequently. In addition, compared with vascular plants, epiphylls are more sensitive to environmental changes owing to their particular structure and physiology [15C17]. Whether or not epiphylls exacerbate or mitigate the effects of climate change on host vascular plants is crucial for understanding ecological functions of epiphyllous communities in tropical forests. Previous studies paid more attention to nitrogen (N) transfer between epiphylls and hosts [9, 18C22] due to the ability of N fixation of epiphylls [23]. However, how epiphylls affect leaf physiological traits is still unclear [13, 14]. Some research has found that epiphylls decreased light radiation and photosynthetic capability of host leaves [24C27], while some thought that the photoacclimation of host plants could offset the negative effects of epiphylls [10, 28, 29]. These inconsistencies may result from the diverse composition of epiphyllous communities and undefined succession stages of epiphyllous colonization [14]. For examples, the epiphyllous groups in Monge-Najera (1989) and Anthony et al. (2002) were liverworts and lichens, respectively [10, 30]. Communities dominated by lichens or liverworts may induce different effects on leaf traits of host plants due to their diverse structure characteristics [15] and distribution patterns on host leaves [14, 31]. In addition, the coverage of epiphylls generally varies largely from sporadic to full cover [25, 31] in the successive process of epiphyllous colonization [7, 13, 14], which may be also crucial in understanding the roles of epiphylls on hosts. Therefore, it is necessary to differentiate effects of liverworts and lichens on host plants to better understand the exact roles of epiphylls on their host plants. The tropical Montane rain forests in Hainan Island are the largest and best preserved primary tropical forest in China. The forests harbor diverse epiphylls on the surface of host leaves in the understory. In this study, we studied the effects of liverworts versus lichens, with varying degrees of covers on their host tree speciesPhotinia prunifoliain a tropical Montane forest in Hainan Island. We asked the following questions: (1) Does epiphyllous colonization PHA-848125 affect host’s leaf traits? (2) Do the effects of epiphyllous groups (liverworts versus lichens) on host’s leaf traits vary. (3) How do their coverages affect the effects on host’s leaf traits? 2. Materials and Methods 2.1. Study Site and Species The study was conducted in a tropical Montane rain forest at the Jianfengling National Nature Reserve (JNNR) (1823C1850N, 10846C10902E), which is located in the southwest of Hainan Island, China. JNNR is dominated by tropical monsoon climate, with an average air temperature of 24.5C, relative humidity of 88%, and annual sunshine PHA-848125 of 1467?h [32]. Annual precipitation ranges from 1305 to 3662?mm with a distinct wet season (May to October) and a dry season (November to April) [32]. The monthly temperature and precipitation there had been described by Yang et al. [33]. Due to the humid environment, approximately up to 14.5% leaf area of plants in the understory was covered with epiphylls (average percentage of leaves with epiphylls average coverage on leaves), in which more than 60 species of epiphyllous liverworts have been identified (unpublished data). In order to obtain a relatively consistent species composition in epiphyllous communities, we selected host plants within a plot with a diameter of 5?km. We selected the vascular plants,Photinia prunifoliaas host plants in this study for the following reasons. Firstly,P. prunifoliawas a common species with epiphylls at the study site. Secondly, the average coverage of epiphylls on the mature leaves ofP. prunifoliawas about 31.3%, which was ideal for.