Coastal Vascular Plants Species of Southeast Asia Yee. A. T. K. 1 and Tan, H. T. W. 2

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1 Abstract Coastal Vascular Plants Species of Southeast Asia Yee. A. T. K. 1 and Tan, H. T. W. 2 Department of Biological Sciences, Faculty of Science, National University of Singapore 10 Kent Ridge Road, Singapore A checklist of coastal vascular plant species for Southeast Asia was constructed as there is no such compilation done perviously. A total of 867 coastal species sensu lato from 133 families and seven phyla are included. There are 392 sandy coast, 129 rocky coast and 380 mangroves species. A simple linear regression analysis has revealed that there is no linear relationship between length of coastline of a Southeast Asia country and the number of coastal species found in that country, however this is mostly like to be confounded by various reasons. The largest family of coastal plants in the Orchidaceae, which is also the largest family of mangrove species. Fabaceae is the largest family in sandy coasts while Moraceae is the largest family in rocky coasts. The habit of tree/ treelet is common among coastal plants. Coastal plants with height less than 1.0m, between 2.0. to 10.0 m and more than 20.0 m are common in Southeast Asia. A large proportion of coastal plants are distributed in the Asian/ African/ Australian region. More research are required on the coastal plant species as they are poorly known. Introduction. Most of the Southeast Asia countries is in the tropics except the northern most part of Burma. Most Southeast Asia s coasts are occupied by mangrove forests, coral reefs and carbonate beaches in which corals are sources of sediments, which are characteristics of tropical coasts (Wong 2003). Wong (2005) further recognized two types of coasts, the rocky coasts and the sandy coasts. These are harsh environment as plants growing there are subjected to salt spray, high light intensity, high maximum temperature, high wind speeds, low relative humidity. Rocky coasts is even harsher as there is little or no soil in it and the rocks absorb heat during the day to high temperature and releasing it slowly at night (Tan et al 2007). Hence plants growing there are generall posses xeromorphic characteristic. Another coastal vegetation found in Southeast Asia is the mangrove forests. Plants growing there are subjected to harsh condition such as anaerobic, unstable soil substrates, fluctuating salinity caused by the tides (Tan et al 2007). Whitmore (1984) has stated that there is no sharp boundary between mangrove forests and sandy or rocky coasts because coastlines are ever changing. However destruction of these habitats has became more common in recent years due to human development. Yet not much has been studied on the coastal vegetation, especially the rocky and sandy coasts. Moreover, no compilation has been done to enumerate the coastal plant species for the whole of Southeast Asia. Hence the objectives of this research is to construct a checklist of coastal vascular species found in Southeast Asia and determine key characteristic of coastal species. 1. Student 2. Associate Professor, Supervisor

2 Methods Only the vascular plants (ferns and fern allies, gymnosperm, and angiosperm) found growing on sandy and rocky coasts and mangroves are considered of Burma, Thailand, Cambodia, Vietnam, Malaysia, Singapore, Indonesia, the Philippines, Brunei and Timor Leste were included but aquatic species (sea grasses) were excluded Data on the specific coastal habitat (where available), habit, maximum height, distribution were also included. The classification system of the angiosperms (the majority in the list) was that of the Angiosperm Phylogeny Website (Stevens 2001 onwards). Data were compiled by going checking through published flora and recent taxonomic revisions for specific taxa. Some data on nomenclature, habit, height and distribution were obtained from several databases online. Four categories of habitats were considered, which are sandy coasts; rocky coasts, mangrove forests and near the sea category which includes species with vague habitats description but like to be coastal. Hence, The first three categories are coastal species sensu stricto (strictly coastal) and the when the last one is included, they are considered as coastal species sensu lato (broadly coastal). The habit of a plant in this checklist was divided into: (1) herb (erect, herbaceous); (2) shrub (erect, woody, multiple trunked); (3) tree/treelet (erect, woody, single trunked); (3) epiphyte, strangler, mistletoe or parasite and (4) climber, creeper, scandent, scrambler, decumbent or procumbent.the maximum height of a plant was be categorized as: (1) mechanically dependent; (2) 1.0 m; (3) >1.0 m to 2.0 m; (4) >2.0 m to 10.0 m; (5) >10.0 m to 20.0 m and (6) > 20.0 m. The distribution of a plant was: (1) limited (endemic or restricted distribution); (2) Southeast Asian; (3) Asian/African/Australian (which is further divided into throughout the Asian/African/ Australian; African/South Asian; temperate Asian; and Australasian/ Pacific) and (4) pantropical. The Southeast Asian country that the species naturally occurs was also noted in this checklist. Laos was not included as it is landlocked Statistical analysis was done using the R (R Development Core Team 2007) software package. Result and discussion A total of 876 species from 133 families across seven vascular plant phyla were found to be coastal. Of those, 192 were placed in the near the sea category which means no clear coastal habitat description was given by the references. Hence, only 684 species were recorded from sandy coasts, rocky coasts and mangrove forests with 392 species found in sandy coasts, 129 species in rocky coasts and 380 species in mangrove forests. The latter three numbers do not add up to 684 as some species are found in more than one habitat. Of this 876 coastal vascular plant species sensu lato, only 97 species are recorded to be found in all coastal ten countries of Southeast Asia. Table 1 summarises occurrence of coastal plant in each country. Indonesia has the highest number of coastal species (709 species sensu lato) follow

3 by Malaysia (702 species sensu lato) while Timor-Leste has the lowest number of species (204 species sensu lato). Table 1: Number of coastal vascular plant species found in each coastal Southeast Asian country. a. Data take from The World Factbook (CIA, 2008). b. Excluding islands. Country Coastline (km) a Sandy coasts species Rocky coasts species Mangroves spesies Total Coastal species sensu stricto Total number of coastal species sensu lato Singapore Malaysia Brunei Indonesia Timor-leste Thailand Burma Cambodia Vietnam b Philippines A simple linear regression was conducted to determine linear relationship between coastlines of a Sotheast Asia country and the number of coastal species found there. From that analysis, it shows no significant linear relationship between the size of mangrove in a particular Southeast Asian country and the number of mangrove species found in that country (R-squared value , p value , α=0.05). The raw data was placed in Appendix 3 and the size of mangroves was taken from Giesen et al (2007). This might be because of many Southeast Asian country are well studies for biodiversity. Hence, this would confound the above finding. A total of 133 families are recognized in this study. Out of those, 114 families are angiosperms. According to Angiosperm Phylogeny Website (Stevens 2001 onwards), there are 468 angiosperms families world wide. Hence, this 114 families represent 24.35% of total family of the world. This shows that coastal plant species are very diverse in Southeast Asia Orchidaceae contains the most coastal speciess, with 94 species sensu lato or 80 species sensu stricto. This is followed by the Fabaceae which has 73 species sensu lato or 58 species sensu

4 stricto. Among the 19 families, 18 families are angiosperms The family Orchidaceae has also the most mangrove species (73 species), followed by the Fabaceae (26 species). The Fabaceae also has also the most sandy coast species (48 species), followed by the Poaceae (30 species). The Moraceae has the most rocky coasts species, numbering eight. In this study the top two most common habits of coastal plant species were tree/treelet and shrub. This has confirm the studies of Ghazanfar et al (2001), which those are the most common habits coastal vegetations of islands of Fiji. Of all the mechanically independent coastal plants (herbs, shrubs and trees/treelets), plants less than 1.0 m, between 2.0 to 10.0 m, or more that 20 m tall are quite common. However, the Wilcoxon rank sum test conducted shows that there is no significant difference between the height of coastal species and dryland species. Hence, height is not a key characteristic of coastal species. Coastal vascular plants are generally very widespread. Most of them are distributed in the Asian/ African/ Australian category (517 coastal species sensu lato or 414 coastal species sensu stricto). 98 species sensu lato or 78 species sensu stricto are pan-tropical which is reasonable, considering that coastal species are usually water-dispersed, and water dispersal is effective over long periods of time. A number of such species are native to America but naturalized in this region. This includes Passiflora foetida from South America and Argemone mexicana from the Caribbean. Interestingly there are 55 coastal species sensu lato or 37 coastal species sensu stricto that has a limited distribution. This is quite a surprise finiding as coastal species are thought to be widely distributed as they are mostly bird-, bat-, wind- or water-dispersed. Some of them are endemic, such as Eulalia ridleyi that can only be found east coasts of Pahang and Johor, Malaysia; while others are limited to one or two areas such as Dracaena maingayi, which can be found in Peninsular Malaysia and Singapore. Such coastal species with limited distribution might be more prone to extinction from habitat destruction as a result rapid coastal development. Conclusions A total of 876 species from 133 families across seven vascular plant phyla were found to be coastal. Although the simple linear regression shows that there is no linear relationship between number of coastal species and length of coastlines of Southeast Asia country. Orchidaceae has been to be the most speciose family among coastal plants. Most coastal plants have the habit of tree and shurbs. However, height is not a key determinant for coastal species as shown by statistic. Most species are generally widespread in Asia, Africa and Australasia. Lastly, more research is necessary for the coastal environment of Southeast Asia, especially the rocky coasts and sandy coasts vegetation both of which are little studied. References 1. Central Intelligence Agency, Field Listing Coastline. The World Factbook. [Online] Washington: Central Intelligence Agency. Retrieved at the-world-factbook/fields/2060.html. [22/3/2008] 2. Ghazanfar, S. A., Keppel, G. & Khan, S., Coastal Vegetation of Small Islands near Viti Levu and Ovalau, Fiji. New Zealand Journal of Botany 39: Wong, P. P., The Coastal Environment of Southeast Asia. In: Gupta, A., ed. The Physical Geography of Southeast Asia. Oxford: Oxford University Press., pp Tan, H. T. W., Chou, L. M., Yeo, D. C. J & Ng, P. K. L., The Natural Heritage of Singapore. 2nd ed. Jurong, Singapore: Prentice Hall

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