BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 43 TAIWAN / MANGROVES Mangroves in Taiwan: current status and restoration projects Kuei-Chu Fan Department of Forestry This paper presents an overview of Taiwan’s mangroves, including diversity National Pingtung University and distribution, uses, major threats, conservation and other problems. The restoration of Science and Technology of mangroves in Taiwan is also discussed, and five partially successful mangrove 1 Hseuh Fu Road restoration projects are described, with particular reference to the Anping Harbor Nei Pu, Pingtung restoration project in Tainan City that successfully restored Rhizophora stylosa Taiwan and Lumnitzera racemosa. Photo 1. Arrested mangrove growth due to adverse environmental conditions in Chinglo, Penghu; example of a seven year-old Avicennia marina with a sapling height of only 35-70 cm. August 2001. Photo K.-C. Fan. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 44 DOSSIER MANGROVES / TAIWAN Kuei-Chu Fan RÉSUMÉ ABSTRACT RESUMEN LA MANGROVE DE TAIWAN : MANGROVES IN TAIWAN: MANGLARES DE TAIWÁN: ÉTAT ACTUEL ET PROGRAMMES CURRENT STATUS ESTADO ACTUAL Y PROYECTOS DE RESTAURATION AND RESTORATION PROJECTS DE RESTAURACIÓN Taiwan a une ligne de côte longue de Taiwan has a shoreline 1 140 km long, 1 140 km, mais c’est seulement dans and the western coastal zone is a Taiwán tiene una línea costera de la partie ouest de l’île que la man- suitable habitat for mangroves. The 1140 km de longitud y la costa occi- grove trouve un habitat favorable à total mangrove area in Taiwan covers dental es un hábitat favorable para son développement. Elle y occupe only 287 ha, a tiny proportion of the los manglares. La superficie total une surface de 287 ha, ce qui peut total area of mangroves in the world. ocupada por el manglar de Taiwán es être considéré comme négligeable au Four main mangrove species are sólo de 287 ha, representando una regard de l’aire totale de cet écosys- found in Taiwan, namely Avicennia proporción insignificante de la super- tème dans le monde. Avicennia marina, Lumnitzera racemosa, ficie total de los manglares del pla- marina, Lumnitzera racemosa, Kandelia candel and Rhizophora sty- neta. En Taiwán se encuentran cuatro Kandelia candel et Rhizophora sty- losa, all of which have been declared especies principales de mangle: losa sont les quatre espèces princi- as endangered. This paper aims pri- Avicennia marina, Lumnitzera race- pales de palétuviers de cette man- marily to present an overview of mosa, Kandelia candel y Rhizophora grove, considérées chacune pour le Taiwan’s mangroves, including diver- stylosa. Especies que han sido decla- pays comme étant en voie d’extinc- sity and distribution, uses, major radas plantas amenazadas. Este artí- tion. L’objectif de cet article est de threats, conservation and other prob- culo intenta, en primer lugar, presen- présenter les caractéristiques géné- lems. The restoration of mangroves in tar una visión global estos manglares, rales de la mangrove taiwanaise, Taiwan is also discussed, and five incluidas su diversidad y distribución, notamment sa distribution et sa partially successful mangrove su utilización, características princi- diversité, l’utilisation du milieu, les restoration projects are described. In pales, conservación y problemas. problèmes de gestion et de protec- particular, the Anping Harbor restora- También se examina la restauración tion. Les questions de restauration tion project in Tainan City used a de los manglares en Taiwán y se des- sont aussi discutées et cinq projets, planting method that employed criben cinco proyectos de restaura- ayant réussi au moins en partie, sont polyvinyl chloride (PVC) pipes and ción del manglar que fueron, en présentés. Le programme d’Anping successfully restored R. stylosa and parte, exitosos. En particular, el pro- Harbor (Tainan City) suit une méthode L. racemosa seedlings in flooded yecto de Anping Harbor, en Tainan originale (utilisation de tubes PVC areas. Finally, the problems of man- City, con un método de plantación pour protéger des plants de R. sty- grove restoration in Taiwan are dis- que utiliza tubos de policloruro de losa et de L. racemosa) qui a permis cussed. vinilo. Permitió restaurar R. stylosa y de réhabiliter avec succès des sec- L. racemosa, a partir de siembra en teurs inondés. Keywords: mangrove, Taiwan, preser- zonas inundadas. vation, restoration, Kandelia candel. Mots-clés : mangrove, protection, Palabras clave: manglar, preserva- restauration, Kandelia candel, ción, restauración, Kandelia candel, Taiwan. Taiwán. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 45 TAIWAN / MANGROVES Introduction Diversity and distribution of Taiwan is located at the western Taiwan’s mangroves (diversity, distri- species edge of the Pacific Ocean, between bution, uses, major threats, conser- 21° 45’ 25” and 25° 37’ 53” N, and vation and current problems) and Historical data suggest that the 119° 18’ 13” and 122° 6’ 25” E (fig- describes current mangrove restora- earliest record of collecting the man- ure 1). The Tropic of Cancer runs tion projects in Taiwan. Information grove species Kandelia candel (L.) through Chiayi County, roughly divid- on this specific aspect of Taiwan’s Druce in the Tanshui area (figures 1 ing the island into the tropical south- mangroves will hopefully provide a and 2) could date from 1864, and that ern and subtropical northern half different perspective on mangrove it is likely to be a native Taiwan (Hsueh, 1995). The current popula- ecosystems around the world. species (Liu, Lai, 1982). The other tion of this island exceeds 21 million. mangrove species were transplanted With an area of only 36 000 km2, the from Thailand and Malaysia during population density in Taiwan stands the 1940s (Yang, 1974). at over 580 persons per square kilo- meter today (Chiau, 1998). Taiwan’s climate varies in each region because of the diverse terrain and the mon- soon season. The coastal lowlands are subtropical to tropical, with a hot, windy climate and abundant rainfall. The average annual temperature in Taiwan is about 22-25 °C, and annual precipitation averages 2 500 mm, with nearly 80 % falling during the May-October typhoon season. The cli- mate is suitable for mangrove growth. Mangrove forests are among the most productive ecosystems in the world. They enrich coastal waters, supply commercial forest products, protect coastlines, and support coastal fisheries. Mangroves are an ideal niche ecosystem for birds, crabs, and other animals, and offer a natural “classroom” for learning and Figure 1. Geographical location of Taiwan (based Photo 2. leisure. The total area of mangroves on Spalding et al., 1997). The Tanshui River Mangrove Nature around the world is between 181 077 Reserve protects an unusually pure and 198 818 km2 (Spalding et al., stand of Kandelia candel. December 1997), with Taiwan’s mangroves only 2001, at low tide. accounting for 287 ha in 1995. Photo K.-C. Fan. Mangroves have therefore been declared as endangered species requiring special care (Hsueh, 1995). Because mangroves in Taiwan represent a negligible proportion of the total mangrove area in the world, very few authors have focused on mangrove research in this country and only a small number of general articles have been published, mostly in Chinese. International mangrove literature therefore has little informa- tion on Taiwan’s mangroves. This report provides an overview of BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 46 DOSSIER MANGROVES / TAIWAN racemosa (L.) Spreng., B. asiatica (L.) Kurz., Pongamia pinnata (L.) Pierre, Hibiscus tiliaceus L. and Thespesia populnea (L.) Sol. However, B. asiat- ica is found only in the Kenting and Henchuan areas in southern Taiwan, whereas B. racemosa grows only in the Ilan area in north-east Taiwan. Pemphis acidula is not found in inter- tidal areas but grows on the dry coral rocks on Kenting and Lanyu Island. These three species have also become rare because their habitats are fairly restricted. The other man- grove associates such as C. manghas, P. pinnata and H. tiliaceus have recently been widely planted in the coastal windbreak and urban environ- ments. Clerodendrum inerme Gaertn., Scaevola sericea L. and Myoporum bontioides also occur in the transi- tional habitats in southern Taiwan, and should be considered as man- grove associates. Distribution and surface areas Taiwan has a shoreline of 1 140 km (Chiau, 1998). The western coastal zone is characterized by tidal flats, offshore sandbars, lagoons and sand dunes, which form suitable habi- tats for mangroves. The eastern shore- line contains no mangroves because the coastal areas are rocky and Mangrove steeply sloping and therefore unsuited to mangrove growth. The lit- erature does not give exact indica- Figure 2. tions as to the total area of mangroves Hsueh Mangrove distribution in Taiwan (based on , 1995). in Taiwan. According to the earliest estimate (Liu, 1982), economic devel- Extinction and coast of Taiwan. However, mangrove opment by that time had reduced the introduction of species habitats have rapidly diminished due mangrove area to only 120 ha. In a to intensive industrial and urban new survey, of mangrove distribution According to Tomlinson’s (1994) developments, to the extent that R. (figure 2) and areas (table II), Hsueh classification, Taiwan once hosted six stylosa and L. racemosa have recently (1995) estimated the total mangrove major mangrove species (table I). become rare species. area at 287 ha, an insignificant total However, harbor construction had Three minor components and compared with the world total. already caused the extinction of seven mangrove associates exist on Table II also shows that cold Ceriops tagal C.B. Rob. and Bruguiera the island (table II). These trees and shocks below 15 °C are a constant gymnorhiza (L.) Lam. by the 1960s shrubs occupy peripheral tidal areas feature during December and January (Liu, 1982). Four species, namely along the western coastline. They in the areas north of Chiayi, including Avicennia marina (Forssk.) Vierh., include Excoecaria agallocha L., Taipei, Taoyuan, Shingchu, and Lumnitzera racemosa Willd., K.