BIOTROPIA Vol. 27 No. 2, 2020: 134 - 142 DOI: 10.11598/btb.2020.27.2.1182 DIVERSITY AND VERTICAL DISTRIBUTION OF VASCULAR EPIPHYTES ON A MALAYSIAN MANGROVE ISLAND** SHAHRUDIN ROHANP, FEI LIN LEE AND ABDUL SHUKOR YUSOFF Vacuity Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Malaysia Received 01 January 2019 / Accepted 07 February 2019 ABSTRACT Many studies have attempted to explain the diversity and abundance of epiphytic plants in major ecosystems, worldwide. However, investigations on the abundance of epiphytic plants in mangroves have remained rare. The aim of this research was to study the diversity and vertical distribution of vascular epiphytes in a mangrove forest in peninsular Malaysia. The sampling was done over a 0.1 hectare of Pulau Telaga Tujuh, a mangrove island in Terengganu, Malaysia. Trees with vascular epiphytes were divided into three strata: basal, trunk and canopy. The vascular epiphytes were identified, and the number of individuals in each stratum was recorded. In total, 8 species of vascular epiphytes from 6 genera and 4 families were recorded. Pulau Telaga Tujuh mangrove forest exhibited a relatively low diversity of vascular epiphytes (FF = 1.43). The dominance of Hydnopytum formicarum significantly contributed to the diversity of vascular epiphytes in this forest. The highest abundance of epiphytes was observed on the trunks of the host trees. The vertical distribution pattern observed in this study is associated with the adaptation of the epiphytic plants to stresses in the mangrove ecosystem, particularly, drought and salt spray. Pulau Telaga Tujuh had a high density of vascular epiphytes but lower diversity compared with other ecosystems. Keywords: epiphyte ecology, mangroves, Setiu Wedands, spatial distribution INTRODUCTION vascular epiphytes decompose and create organic matter on the ground or form humus on Epiphytes are plants that germinate and live tree branches or trunks (Coxson & Nadkarni on trees without taking nutrients from the soil 1995). This organic matter provides nutrients or the host tree. Vascular epiphytes such as and increases the biomass of the ground, orchids and ferns are able to adapt to an aerial especially in primary forest (Nadkarni et al. environment, resulting in their morphological 2004). Vascular epiphytes also provide a variety variations. Diversity of vascular epiphytes of food resources for many organisms such as cannot be overemphasized as it contributes to birds and insects. For example, 59% of 33 vascular plants diversity constituting roughly 9% species of birds in a tropical rain forest in Costa of all the vascular plants (Zotz 2013). Since the Rica were observed foraging epiphytes resources 18th century, studies of vascular epiphytes have (Nadkarni & Matelson 1989). Some epiphytes been conducted around the world, particularly in exhibit a positive association with ants. Ants tropical regions known for their rich biodiversity help to disperse seeds for epiphytes, and the (Zotz 2016). plants provide a nest for the ants (Kaufmann et Vascular epiphyte diversity plays an al. 2001; Dejean et al. 2003). important role in forest ecosystems especially of The distribution of vascular epiphytes tends those epiphytes living in the canopy zones as to be affected by the availability of substrate and these plants help to regulate the cycling of the distance of dispersal of seeds rather than the nutrients (Coxson & Nadkarni 1995). Dead mode of dispersal (Nieder et al. 2000). The microhabitat (e.g., light intensity, proximity to ^Corresponding author, e-mail: [email protected] soil or exposure to wind and precipitation) is ** This paper was presented at the 3rdInternational Conference on associated with the availability of substrate and Tropical Biology 2018, 20-21 September 2018, Bogor, West Java, Indonesia therefore, influence species richness and the 134 Diversity and vertical distribution of vascular epiphytes — Rohani et al abundance of vascular epiphytes in each stratum species diversity and vertical distribution of and host trees (Quaresma & Jardin 2014; Woods vascular epiphytes in a mangrove ecosystem in et al 2015; Getaneh & Gamo 2016; Wang et al the Setiu Wetlands in the east coast of 2016). Vascular epiphytes also tended to peninsular Malaysia. colonize zones with similar microhabitats indicating that vascular epiphytes may be specific to a particular strata (Woods 2013). MATERIALS AND METHODS Strata specificity shed light on the pattern of vertical distribution of vascular epiphytes Study Site (Kersten et al 2009). The research was conducted in Pulau Telaga The tendency of epiphytes to occupy a Tujuh, Setiu Wetlands, Terengganu, Malaysia similar microhabitat can also stem out from (05°41.800’ N; 102°41.770’ E). The Setiu their resource-utilizing mechanisms. Since major Wetlands is an ecosystem with nine portion of epiphytes do not attach to the soil, interconnecting habitats of beach, sea, mudflat, epiphytes show several strategies to obtain fresh and brackish water, river, islands, coastal nutrients and water supply from their and mangrove forests ( et al 2015). This microenvironment (Benzing 1990). Epiphytes Jamilah unique ecosystem, gazetted as state park in May get nutrients from internal and external inputs; 2018, support a myriad of biodiversity and are internally from leaves leachate from host-tree equally important to local people’s livelihoods. and nitrogen fixing bacteria (Hietz et al 2002) The study site was one of the small islets in the and externally through dry deposition and Setiu Lagoon (5.42 ha), situated side by side with (Fiirnkranz et al 2008; Zotz 2016). precipitation 13 other islands. Epiphytes also receive nutrients input from and stemflow Awasthi et al 1995; throughfalls ( Data Collection Chuyong et al 2004). Moreover, different epiphytes use different nutrient uptake Ten plots of 10 m2 each (1,000 m2 in total) mechanisms, hence, the co-occurrence of were randomly established along the island. different assemblage of epiphytes (Cardelus & Every tree in each subplot was inspected for the Mack 2010). occurrence of vascular epiphytes. The To adapt to drought environment in the abundance of all vascular epiphytes, the strata canopy, epiphytes developed morphological and the host characteristics (e.g., stem diameter adaptations such as succulent leaves and water and height) were recorded. The host’s strata absorbing structures (Benzing 1990; Hietz et al were classified into three: 1) canopy - first 1999). Physiological adaptation such as branch to the tip of the tree; 2) trunk - 1.3 m Crassulacean Acid Metabolism (CAM) above the ground to the first branch; and 3) photosynthesis also occurs among many basal - ground up to 1.3 m high in the host tree. epiphytes (Silvera et al 2010). CAM For trees with an enlarged stem the base was 1.3 photosynthetic plants, like many epiphytes, open m above the ground (Getaneh & Gamo 2016). their stomata during night time to capture CO2 All of the vascular epiphytes were included in and close the stomata during daylight. the census except for the seedlings that were Many studies have focused on documenting difficult to identify up to the species level. The the richness of mangrove flora yet, little epiphytes that grew in clusters that were difficult attention has been given to epiphytic plants in to count individually were counted as an this forest type. Epiphytes are perhaps the most independent individual (Getaneh & Gamo susceptible to mangrove destruction because 2016). Binoculars were used to observe the they depend on having large trees as their hosts. epiphytes that were located high in the trees. Recently, the epiphyte Hydnophytum formicarum The names of the epiphyte species and host was found to be remarkably abundant in Pulau plants were referred to A Catalogue of the Telaga Tujuh, Malaysia (Rohani et al 2017). This Vascular Plants of Malaya (Turner 1995). finding motivated the authors to investigate the Voucher specimens were deposited at the occurrence of other vascular epiphytes on the Universiti Malaysia Terengganu Herbarium island. Hence, this study aimed to determine the (UMTP). 135 BIOTROPIA Vol. 27 No. 2, 2020 Data Analysis largest number of individuals in the study site. Vascular epiphyte diversity was In many previous studies on epiphytes, species analyzed using two diversity indices; Shannon with dust-like seeds have been found to be diversity index (H’) and Simpson’s index (D) dominant. Orchidaceae was recorded as the (Magurran & McGill 2011). To check the dominant epiphyte family in the natural forests similarity between the epiphyte communities of as well as in rubber plantations in Malaysia each host tree, a Cluster analysis was carried out (Kiew & Anthonysamy 1987). Most species using the Jaccard similarity index based on the from Orchidaceae have small seeds which number of individuals of each vascular epiphyte facilitated their dispersal by wind. species on each host tree. The data were The rank-abundance curve (Fig. 3) revealed analyzed using PAST version 3.15 software an of common and (Hammer et al. 2001). unequal proportion species rare species. The steep line in the graph was derived from the dominance of Hydnophytum RESULTS AND DISCUSSION formicarum. This plant, which has a close association with ants (hence sometimes called Species Diversity the “ ant plant” ), was also reported as a common species and more abundant than other non-ant- A total of 929 individuals belonging to 8 species, 6 genera and 4 families were recorded in associated