TDA-IME Project Final Report June, 2013 There are little more than 70 species of true mangrove plants worldwide (Spalding et al., 2010 list 73 species), plus a handful of apparent hybrids (see Duke, 2006). Some 50 species, or around 70% of all mangrove species occur in Southeast Asia. Globally, 17 genera of flowering plants from 12 families have contributed mangrove species. But even within each of the genera that form the main constituents of mangrove forests in Southeast Asia, namely Avicennia, Bruguiera, Ceriops, Lumnitzera, Rhizophora, Sonneratia and Xylocarpus, there are not more than six species. This low level of diversity indicates just how challenging it has proved for terrestrial flowering plants to evolve in the harsh conditions represented by intertidal habitats. In adopting the ecosystem-based approach as the most suitable way to address the issues and challenges for transboundary mangrove management, this report takes an inclusive view of “mangroves” meaning both true mangrove plants and mangrove associates, because both groups of species are important at the ecosystem level, through the goods and services they provide to coastal dwellers. And when considering mangrove management at a transboundary scale, it is almost certain that various habitat types will be represented, including mixed plant communities of true mangroves, mangrove and mangrove-associate species, other coastal or estuarine habitats dominated by associates like Barringtonia and Nypa, as well as non-mangrove plant communities. The six countries covered by the TDA-IME Project: Cambodia, Malaysia, Philippines, Singapore, Thailand, Viet Nam share 42 true mangrove species, including the fern Achrostichum speciosum and the palm Nypa fruticans; the other species are trees or shrubs. According to FAO (2007) the species total per country ranges from 31 (Viet Nam) to 42 (Malaysia). These countries have the greatest mangrove species diversity in the world, with the exception of Indonesia with 48 species. A recent revision of the mangrove flora in Singapore updates the mangrove species there to 36 species (Yang et al., in press). Uncertainty over what constitutes a mangrove-associated species explains the much wider variation in species numbers per country reported for this group (Table 6). TABLE 6: Reported “true” mangrove plant species and “mangrove-associated” species, by country. 18 Country No of “true” mangrove species Mangroveassociated species Near threatened, vulnerable or endangered species Source Cambodia 30* 12-15 Not reported MOE/Danida (1999); TDA Cambodia country report Malaysia 40* 66 Bruguiera hainesii Sonneratia griffithi FAO (2007); Japar Sidek (1994) Philippines 28 (other reports list from 26 to 51 species) 34 Avicennia rumphiana Camptostemon philippinense Aegiceras floridum Ceriops decandra Kandelia obovata TDA Philippines country report Singapore 36* (one species is locally extinct) Not reported Bruguiera hainesii B. sexangula Ceriops zippeliana Davison et al. (2008); TDA Singapore country report Thailand 38* 43 Bruguiera hainesii Brownlowia tersa Santisuk et al. (1988); TDA Thailand country report; FAO (2007) Viet Nam 38* 72 Not reported TDA Viet Nam country report * The data include the mangrove-associates Acanthus (2-3 species) and Achrostichum (2 species). See definition and discussion of “true” mangrove species in the text (pp. 16-17).
Transboundary Diagnostic Analysis of Indochina Mangrove Ecosystems
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