Degree: Master of Science in Biology
Title: Trunk-inhabiting bryophyte diversity on two common native trees along an altitudinal gradient on Viti Levu, Fiji
Principal Supervisor: Dr. Ralph Riley
Fiji has a rich biodiversity in tropical wet forests on high oceanic islands in the Pacific. This rich and distinct biodiversity includes the mosses, liverworts and hornworts, collectively known as bryophytes. This non-vascular group of plants forms a very important component of the vegetation and plays a significant role in soil erosion prevention, nutrient cycling and forest hydrology.
This research focused on the ecology of bryophytes on the lower trunks of two host tree species. Current theory suggests important factors that influence the total species richness of epiphytic bryophytes include the elevation range of the sites being studied, the physiochemical characteristics of host trees, the height along the host tree stem, and the number and surface area of tree stems (i.e. habitat area) studied. Therefore this study set out to test if these factors influenced bryophyte species richness in Fiji by assessing bryophyte species presence/absence on the lower stems of the Calophyllum spp. trees and tree ferns at three elevations (~160m, 590m, and 1260m) on the island of Viti Levu, Republic of Fiji.
There were two main findings that emerged from the analysis. Firstly, there was a humped distribution of bryophyte taxa richness with peak species richness observed at mid-elevation or in the upland forest. Secondly, the bryophyte communities showed good separation at both host tree level and at the site level, reflecting the ecological differences between the host trees and between the three sites along the altitudinal gradient. Additionally, eight new liverwort records were identified, one of which was a new genus record for Fiji.
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 bryological research. While bryology is a fairly new field for Fiji, the results from this baseline 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 forests of different environmental and microclimatic conditions along an altitudinal gradient. This would be of value for long-term monitoring of changes in environmental conditions within these forests.