Are epiphytic bryophyte communities characterized by changes along an elevational gradient?—A preliminary study on eastern Viti Levu, Fiji Islands

Abstract

A comparative study of epiphytic bryophytes on tree trunks was undertaken in three principal vegetation types along an elevational 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 conservation. It also demonstrates the usefulness of bryophyte communities in discerning vegetation of different environmental and microclimatic conditions along an elevational gradient.