RELATIONSHIP BETWEEN MICROENVIRONMENT OF MANGROVE FORESTS AND EPIPHYTIC FERN SPECIES RICHNESS ALONG THE PAN YI RIVER, THAILAND
Keywords:Epiphytes, habitat differences, host tree, mangroves, Shannon–Wiener diversity index
HAYASA KA D, KIMURA N, FUJIWARA K, THAWATCHAI W & NA KAMURA T. 2012. Relationship between microenvironment of mangrove forests and epiphytic fern species richness along the Pan Yi River, Thailand. To clarify the habitat dependency of epiphytic ferns in mangrove forests, we surveyed their species composition and habitat requirements along the Pan Yi River, Thailand. In a multiple regression analysis, the Shannon–Wiener diversity index of epiphytic ferns was most strongly related to the diversity index (H')
of mangrove trees. Cynometra iripa, Heritiera littoralis and Xylocarpus moluccensis were utilised as host trees by almost all epiphytic ferns. The occurrence of Nephrolepis acutifolia has a positive association with Xylocarpus
moluccensis trees by a chi-square goodness-of-fit test. At the family level, Polypodiaceae and Davalliaceae were most prominent in mangroves of the Pan Yi river basin. Based on canonical correspondence analysis (CCA),
the factors associated with the occurrence of epiphytic ferns were distance from the edge of the river (p < 0.05), water salinity (p < 0.05), relative light intensity (RLI) (p < 0.05) and diameter at breast height (dbh) (p < 0.05). Our results showed that Drynaria quercifolia, Davallia denticulata, N. acutifolia and Pyrrosia lanceolata were dominant species in the mangrove environment, although each of them had a different habitat. Nephrolepis
acutifolia and Davallia solida are epiphytic ferns occurring almost exclusively in mangroves.