28 Accepted by Dietmar Quandt: 22 Jun. 2017; published: 30 Jun. 2017 Bry. Div. Evo. 39 (1): 028–037 http://www.mapress.com/j/bde Copyright © 2017 Magnolia Press Article https://doi.org/10.11646/bde.39.1.6 BRYOPHYTE ISSN 2381-9677 (print edition) ISSN 2381-9685 (online edition) DIVERSITY & EVOLUTION Are epiphytic bryophyte communities characterized by changes along an elevational gradient?—A preliminary study on eastern Viti Levu, Fiji Islands MEREIA TABUA 1 , RALPH RILEY 2 , MATT A. M. RENNER 3 , LARS SÖDERSTRÖM 4 , ANDERS HAGBORG 5 & MATT VON KONRAT 5 1 Institute of Applied Science, The University of the South Pacific, Suva, Fiji 2 Western Washington University, 516 High Street, Bellingham, WA, U.S.A 3 National Herbarium of New South Wales, Royal Botanic Gardens Sydney, Sydney, NSW, Australia 4 Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway 5 Gantz Family Collections Center, The Field Museum, 1400 South Lake Shore Drive, Chicago, IL, U.S.A Abstract A comparative study of epiphytic bryophytes on tree trunks was undertaken in three principal vegetation types along an el- evational gradient on the windward wet side of the largest island in Fiji, Viti Levu. This ecological study is the first of its kind for Fiji and the islands of the South Pacific and it serves as groundwork for any future ecological research in the region for bryophytes. This study set out to test if elevational range of study sites and height along host tree stem influenced bryophyte species diversity and distribution in Fiji. This was done by assessing bryophyte species presence/absence on the lower stems of the Calophyllum spp. trees and tree fern species at three elevations (~160 m, 590 m, and 1260 m). There were two main findings that emerged from this preliminary assessment. Firstly, there was a hump-shaped distribution of bryophyte diversity with a peak of species richness observed at mid-elevation or in the upland forest; with a dominance of liverworts at each of the three elevations. Secondly, the bryophyte communities showed good separation at both host tree level and at the site level, reflecting the ecological differences between the different host trees and between the three sites along the elevational gradient. The results from this survey alone suggest the need for priority to be given to upland forest protection and conserva- tion. It also demonstrates the usefulness of bryophyte communities in discerning vegetation of different environmental and microclimatic conditions along an elevational gradient. Keywords: Calophyllum, Cyathea, Dicksonia, Ecology, Pacific Islands, Liverworts, Mosses, Pacific Islands, Vegetation Introduction Epiphytism is often thought as a strategic survival adaptation to scarcity of water and nutrients for plant growth (van Leerdam et al., 1990). Epiphytic bryophytes are a significant component of the tropical rainforests and are known to respond sensitively to environmental changes (Frahm and Gradstein, 1991; Sporn et al., 2009). They constitute important floristic and functional components of tropical rainforests and are pivotal to our understanding of forest health and integrity (Benzing, 1998) with potential usefulness as indicators of changes in microclimate (Gignac, 2001). Their diversity, however, is threatened by continued deforestation, habitat loss and modification worldwide (Söderström, 2005). Studies on the epiphytic bryophyte diversity on trees has been investigated in many areas throughout the world, e.g., tropical America (Acebey et al., 2003; Cornelissen and ter Steege, 1989; van Leerdam et al., 1990; Vital and Prado, 2006; Wolf, 1993), Africa (Pócs, 1980), Southeast Asia (Gradstein and Culmsee, 2010; Sporn et al., 2010) and in cool temperate regions of Oceania (Beever, 1984; Roberts et al., 2005). These studies focusing on trunk-inhabiting bryophytes have demonstrated the importance of microclimate and bark structure as a factor influencing epiphytic bryophyte distribution (Sporn et al., 2010). The external texture of the substrate plays a fundamental role in retaining moisture and chemical substances, trapping spores, and supporting rhizoids (Tewari et al., 2009). Also, the subtle differences in water supply, nutrients, light, microclimate regimes and inclination of the substrate affect the ability of bryophytes to establish themselves (Frahm and Gradstein, 1991; Fritz, 2009). Although there are an abundance