Mangroves in Taiwan: Current Status and Restoration Projects

Home , Chiayi County Government, Kaohsiung County, Miaoli County Government, Myoporum bontioides, Penghu, Tainan City Government

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 stylosa, 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 climate 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 information 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. asiatica 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 mangrove associates such as C. manghas, P. pinnata and H. tiliaceus have recently been widely planted in the coastal windbreak and urban environments. Clerodendrum inerme Gaertn., Scaevola sericea L. and Myoporum bontioides also occur in the transi- tional habitats in southern Taiwan, and should be considered as mangrove 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 habitats for mangroves. The eastern shoreline contains no mangroves because the coastal areas are rocky and Mangrove steeply sloping and therefore unsuited to mangrove growth. The literature 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. candel Pemphis acidula J.R. Forst, Heritiera Miaolia County. The cold-tolerant and Rhizophora stylosa Griff. are cur- littoralis Dryand, Cerbera manghas L., species K. candel is dominant in these rently widespread along the western Terminalia catappa L., Barringtonia areas, and Chuwei Nature Reserve is BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 47 TAIWAN / MANGROVES

Uses of mangroves Current uses in Taiwan Conservation of mangrove eco- Photo 3. systems around the world is currently Four mangrove seedlings successfully established in a Traditional uses receiving a lot of attention. Mangrove degraded Casuarina stand at the habitats in Taiwan also play a signifi- Shuangchun restoration project in Mangroves were used in the cant role in conservation and recre- Tainan County. August 2001. past for many purposes in different ation, and in research programs on Photo K.-C. Fan. countries, including for timber and nature reserves and locally protected fuelwood, food, pasture, salt and areas. Since 1995, mangroves have bioactive compounds for tanning and thus been used as resources for eco- the biggest mangrove area (50 ha) in medicinal purposes (Kovacs, 1999; tourism or environmental education. Taiwan. On the other hand, the aver- Ellison, 2000). Mangrove areas in age temperature in the Chiayi, Tainan, Taiwan are very small, and the trees Major threats and Kaoshiung areas exceeds 22 °C in do not grow large enough to be the summer months. These areas are employed as building materials for In the last few decades, all of affected by long periods of drought example. Fuelwood is the most Taiwan’s mangroves have been affected from October to the following important traditional use on this by threats as severe as those in other February. These conditions explain island. Fish farmers in the south-west countries. As from the mid 1980s, many why A. marina is the dominant man- coastal areas of Yunlin, Chiayi and mangrove areas were lost to Taiwan’s grove species in southern Taiwan. The Tainan County planted rows of man- rapid economic growth; mangrove Peimen Coastal Reserve in Tainan groves to protect their ponds against swamps were reclaimed for harbor con- County is the biggest A. marina stand, wind, waves and soil erosion in the struction, power plants, road building but only covers 28 ha. development stage (Lee et al., 1977). and industry. Some major threats to mangroves still exist and have in fact become more serious, as described in Table I. the following paragraphs. Major, minor mangrove and mangrove associates in Taiwan.

Family Species Life form Remarks Major components Avicenniaceae Avicennia marina T Combretaceae Lumnitzera racemosa S/T Rhizophoraceae Bruguiera gymnorhiza TRecorded, but not found recently Ceriops tagal TRecorded, but not found recently Kandelia candel T Rhizophora stylosa T Minor components Euphorbiaceae Excoecaria agallocha T Lythraceae Pemphis acidula S Grows on coral rock in Kenting and Lanyu Island Sterculiaceae Heritiera littoralis T Mangrove associates Apocynaceae Cerbera manghas TUsed as a windbreak species Combretaceae Terminalia catappa TUsed as a windbreak and urban greening species Lecythidaceae Barringtonia asiatica T Barringtonia racemosa T Leguminosae Pongamia pinnata S Used as a windbreak and urban greening species Malvaceae Hibiscus tiliaceus S/T Used as a windbreak species Thespesia populnea S/T Other species Verbenaceae Clerodendrum inerme S Goodeniaceae Scaevola sericea S Used as a windbreak species Myoporaceae Myoporum bontioides S

Categories according to Tomlinson (1994); T: tree, S: shrub. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 48 DOSSIER MANGROVES / TAIWAN

Coastal area reclamation may destroy the most aquaculture and the development of sensitive mangrove habitats tourism are exerting increasing pres- sure on Taiwan’s coastal zone. The Coastal zone management has Environmental Protection Administra- become one of the most important tion (EPA) reports that more than 80 issues in Taiwan in the last few years. industrial projects have been pro- The scarcity and high value of avail- posed or undertaken recently. Most able land have attracted both public of these projects, developed on the Photo 4. Extremely strong growth of five and private developers to the island’s western tideland, require areas year-old Rhizophora stylosa coastal zones. Because coastal lands exceeding 1 000 ha, and some of saplings with abundant prop roots, are generally perceived as suitable them even demand 10 000 ha (Chiau, in favorable fringe sites. June 2001. for development, the coastal zone 1998). This situation reveals the Photo K.-C. Fan. has become a complex area of com- increasing negative impact on the peting uses. Rapid urbanization, pol- environmental and ecological state of lution, tideland reclamation, coastal mangrove habitats. Land subsidence : one of the most serious problems Table II. along the west coast Present status of major mangrove areas in Taiwan. Overpumping of groundwater for coastal aquaculture has caused land Location Species Habitat Area Protective measures subsidence. A recent report conducted (ha) (Management Agency) by the Provincial Water Conservancy Taipei County Bureau revealed that an area of Watzuwei K. candel River bank 8.79 Watzuwei Nature Preserve 1 010 km2 – more than 10 % of Taiwan’s (30.00)* (Taipei County Government) flat land – along Taiwan’s south-west- Taipei City ern coastal zone was affected by land Chiau Chuwei K. candel River bank 50.00 Chuwei Nature Preserve subsidence ( , 1998). This situa- (74.61)* (Taiwan Forestry Bureau) tion has obviously exacerbated risks of excessive flooding in mangrove Kuantu K. candel River bank 19.00 Kuantu Nature Preserve habitats. For example, the coastal area (55.00)* (Taipei Municipal Government) in Chiayi County has sunk 90 cm since Taoyuan County K. candel River bank 0.04 1987, causing flooding that killed off Hsingchu County A. marina River bank; 5.69 Hsinfeng mangrove reserve about 10 ha of Avicennia stands in K. candel coastal plains (Hsingchu County Government) 1993 (Chen, 1997). Miaoli County K. candel River bank; 4.03 Chunan mangrove reserve coastal plains (Miaoli County Government) Pest damage in mangrove ecosystems is gradually Taichung County K. candel River bank 2.00 increasing in Taiwan Changhua County K. candel River bank; 3.76 coastal plains All mangrove ecosystems in Chiayi County A. marina River bank; 45.26 Chang-Yun-Cha, Haomeiliao Taiwan have been designated as pro- K. candel coastal plains; Coastal Reserve tected areas. This status restricts all R. stylosa lagoon (Chiayi County Government) human activity and management. Tainan County A. marina Lagoon; river 75.27 Peimen Coastal Reserve However, the legislation does not pro- K. candel bank; sand bar (Tainan County Government) vide for proper management prac- L. racemosa tices to preserve mangrove growth and habitat. Excessive expansion of Tainan City A. marina Drainage bank; 14.92 Sutsa protected area mangroves causes drainage problems L. racemosa protected area (Tainan City Government) and is also encouraging pests. For R. stylosa example, the larvae of Zeuzera cof- Kaohsiung County A. marina River side; Salt 55.53 feae and Anoplophora maculata are K. candel pan; the primary wood borers of K. candel R. stylosa Drainage bank stands and have recently caused the Pingtung County A. marina Drainage and 2.66 death of mature trees. fishpond bank Total 286.95

* Area of nature reserves. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 49 TAIWAN / MANGROVES

Conservation problems strated that mangrove growth increases flow velocity, raises the water level by approximately 18 cm The Tanshui River Mangrove during floods and damages dikes Nature Reserve, the first mangrove (Hsu et al., 1999). However, govern- reserve in Taiwan, was established ment officials think the CHPL is near Taipei in 1986 to protect K. can- presently the best way to protect del. This species is found at the north- K. candel. ern limit of global mangrove distribution, at 31° 23’ N on the Kyushu Island Local level of Japan, and is able to withstand The Executive Yuan established winter chills with temperatures as low Chang-Yun-Cha, Haomeiliao, and as -4 - 5 °C . This species is generally Peimen Coastal Reserve in 1984, in found as an understory or subdomi- line with the Nature Environment nant species within mixed mangrove Protection Plan for Taiwan’s coastal stands in Thailand, Hong Kong, south- areas. Hsingchu, Miaoli County and ern China, and the southern islands Tainan City Governments have also of Japan (Maxwell et al., 1997). established small mangrove reserves. Therefore, the Tanshui reserve is not These reserves do not enjoy the same only the biggest mangrove area in level of protection as reserves under Taiwan, but is also one of the world’s the CHPL, as their management has very few pure stands of this species been desultory. (photo 2). The Kuantu Reserve (protecting waterfowl in particular) and Lack of effective Watzuwei Nature Reserve were estab- protective management lished at a later stage, bringing the Photo 5. total national protected area to 78 ha Designating nature preserves Development of numerous prop roots with superior and covering 27% of existing man- and coastal protected areas is only growth on three year-old Rhizophora stylosa groves (table II). However, mangrove the starting point for mangrove con- seedling grown in 50 cm PVC pipes. August 2001. conservation and protection are still servation; the key issues include the Photo K.-C. Fan. fraught with problems. ensuing proposals, detailed plans, and concrete management practices, Suitability of mangrove with reforms of any inappropriate conservation and practices. However, no effective pro- as possible to provide baseline infor- protection laws tective management serves Taiwan’s mation to integrate policies for mangrove reserves. The present man- Taiwan’s mangrove resources. National level agement policy simply involves regu- The Watzuwei, Chuwei and lar patrols to prevent mangroves from Lack of coordination Kuantu Nature Reserves were estab- being destroyed and to protect them among agencies lished under the Cultural Heritage from certain activities that are harm- Preservation Law (CHPL). Their man- ful to their habitats. Coordination involves horizontal agement agencies are Taipei County and vertical cooperation and consul- Government, Taiwan Forestry Bureau, Lack of database for tation among government agencies and Taipei Municipal Government, individual mangrove and between government and other respectively (table II), but no one ecosystems organizations. Taiwan has so far agency co-ordinates the conservation lacked a national policy on mangrove of the three mangrove reserves. The Many scientific efforts and protection. Moreover, no particular CHPL strictly enforces conservation investigations have focused on the agency manages and preserves man- legislation, and entirely restricts any ecology of Tanshui Nature Preserve groves. Various administrative interference in nature preserves. For since the 1970s. However, baseline departments handle mangrove affairs example, K. candel has recently background data on local mangrove at local government level. For exam- grown well and thus enlarged the reserves or unprotected areas ple, several different projects were sand bar at the mouth of Kellung remains unavailable. An inventory found to overlap in the same pro- River. A simulation of hydrological report on each mangrove ecosystem tected areas due to poor coordination conditions up to 2006 has demon- should therefore be prepared as soon among agencies. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 50 DOSSIER MANGROVES / TAIWAN

Table III. Restoration of Mangrove afforestation projects during 1945-1975 in Taiwan. mangroves in Location Year Area (ha) Species Remarks Hungmaokang, 1945 4 A. marina Spread to 5.3 ha Taiwan Hsinchu County K. candel Lungching, 1952 10 K. candel All died before 1980 More recently, urban and Taichung County aquatic development world-wide has diminished mangrove forests, and Hanpao, 1952-1954 12 A. marina All died before 1980 caused concerns in every country for Changhua County K. candel the conservation of these natural Tungshiao, 1957-1960 5-6 K. candel All died before 1980 resources and their restoration. Miaoli County Mangrove forests have been restored Chinglo, 1958 2.9 A. marina All died before 1980 to achieve various objectives, includ- Penghu County ing commercial uses (silviculture), Chiku, 1962 24.5 K. candel All died before 1980 protection of fisheries habitats and Tainan County R. stylosa shorelines and restoration of bal- anced ecosystems (Kaly, Jones, Chingshui, 1975 8 K. candel All died before 1980 1998; Ellison, 2000). This section Taichung County Lee Huang, Hsu, 1982; Hsueh briefly reviews the history and prob- Sources: et al., 1977; , 1995. lems of mangrove restoration in Taiwan. Mangrove restoration in Taiwan 1976-1993 The concept of restoration/ The mangroves along the west After 1975 the government rehabilitation for a coastal line are all artificial planta- directed no mangrove restoration mangrove ecosystem tions dating from 1945-1975 (Lee et projects; all major work during this al., 1977; Huang, Hsu, 1982), except period focused on protecting man- Some scientists have empha- K. candel, which is native to Taiwan groves. During that time, some local sized the different meanings given to (Liu, Lai, 1982). people and fishermen planted man- terms such as restoration and reha- grove seedlings to protect fish ponds, bilitation. Field (1998) makes a dis- 1945-1975 so that mangroves were planted spo- tinction between rehabilitating an Mangrove reforestation projects radically along the western coastal ecosystem, which he defines as the were initiated in the 1940s, and most area of Taiwan. partial or full replacement of the projects were carried out between ecosystem’s structural and functional 1945 and 1975 by the Taiwan Forestry 1994-present characteristics, and total restoration Bureau, with funding from the Council In 1994, former president Lee vis- of an ecosystem, which aims to bring of Agriculture (table III). Government ited the mangroves of Indonesia and an ecosystem back to its original con- officials employed labor to plant realized the protection value of man- dition. According to this interpreta- seedlings of K. candel, A. marina (the groves. He suggested that the govern- tion, restoration is one possible result major planting species) and R. sty- ment should establish mangroves on a of a successful rehabilitation effort. losa (in small quantities). Most plant- large scale along the coastal area. Non-scientific organizations generally ing areas were very small; the largest Since then, almost every county in have no clear definitions of restora- covered 25 ha at Chiku in Tainan western Taiwan has launched man- tion. Restoration managers have County in 1962. These projects aimed grove planting projects. In most cases, therefore frequently emphasized primarily to protect the coast. the four mangrove species were mangrove planting as the primary However, unsuitable environmental planted in an uncontrolled manner in a approach in restoration (Ellison, conditions and human impacts killed small area (1-5 ha). Only a few man- 2000). Similarly, in Taiwan, scientists, all planted mangrove seedlings grove restorations have been a partial government officials and conserva- before 1980 (Huang, Hsu, 1982). The success, and some mangrove saplings tionists have carried out mangrove only exception was in Hungmaokang have survived and grown well up to restoration projects that also involved in Hsinchu County, where K. candel now. However, these projects are planting mangrove propagules, and A. marina grew well and the rarely documented. The following sec- seedlings, or even saplings in restored area expanded to 5.3 ha. In tion (points ▪) gives limited informa- selected places. However, this report 1988, the County government estab- tion obtained from personal communi- employs the term “restoration” to lished a local mangrove reserve to cation with government officials and avoid confusion. protect the mangrove ecosystem. researchers. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 51 TAIWAN / MANGROVES

▪ Haomeiliao restoration project in Planting methods: mixed planting of two years of the project. However, Chiayi County (1993-1994; 3.0 ha). four mangrove species after remov- growth was arrested by stresses Executive agency: Taiwan Endemic ing the degraded Casuarina stand. from the harsh environment, includ- Species Research Institute. Planters: employed workers for most ing high salinity, heavy low-nutrient Goal: increase biodiversity of the seedlings, with community families soil (fish farmers removed the fer- mangrove ecosystem. and children. tile silt), strong winds and heavy Planting methods: R. stylosa, L. race- Current status: The author visited the salt spray during the winter. The mosa and K. candel propagules site in September 2001. The habi- author visited the site in August and seedlings planted within mixed tat, including favorable tidal inun- 2001, when only 15 R. stylosa stand of Casuarina and A. marina. dation flows, is suitable for man- saplings had survived, and the Planters: paid workers planted all grove growth and canals within the K. candel samples also gradually seedlings and propagules. wetland appear to have been dug declined and died. The salt tolerant Current status: the mangrove is to assist water flow. The venture A. marina is the dominant species reported to have grown very well, has successfully established but a dwarf mangrove form (seven especially R. stylosa and L. race- 75 000 mangrove seedlings in the years old) is present, with a sapling mosa, which have reached over 2 m degraded Casuarina stand, and has height of only 35-70 cm (photo 1). after four years. The current status become the most successful man- Most of the L. racemosa seedlings of this project is unknown. grove restoration project in Taiwan survived, but these have not grown (photo 3). significantly in height either. ▪ Kaoping River restoration project in Kaohsiung County (1994-2000; ▪ Chinglo restoration project in ▪ Anping Harbor restoration project at 4.5 ha). Penghu County (1994-1995; Tainan City (1996-present; 4.6 ha). Executive agency: Kaohsiung County 1.5 ha). Executive agency: National Pingtung Government. Executive agency: National Pingtung University of Science and Techno- Goal: establish a mangrove ecosys- University of Science and logy. tem park. Technology and Penghu County Goal: restore the R. stylosa and Planting methods: R. stylosa, L. race- Government. L. racemosa mangrove species, mosa, K. candel and A. marina were Goal: restore the mangrove ecosys- destroyed by harbor construction, planted in a new wetland along the tem that was destroyed for aqua- using polyvinyl chloride (PVC) bank of the Kaoping River. culture in 1974. planting pipes to restore man- Planters: mainly local students and Planting methods: R. stylosa, groves in flooded areas. members of the public. A. marina and K. candel were Planting methods: R. stylosa, L. race- Current status: a wetland was created directly sowed with propagules, mosa, K. candel, Myoporum bon- by constructing breaching dikes and L. racemosa were planted with tioides and Thespesia populnea along the river. Several petrochemi- one-year-old seedlings. The site propagules and seedlings planted cal plants are near the planting site. has very high salinity and no fresh in an urban wetland. According to field observations in water. Planters: university students planted September 2001, the mangrove Planters: employed workers. most seedlings, but employed growing area diminished to less Current status: The survival rate and workers planted a few. than 2 ha, growth of the mangrove growth of all four mangrove species seedlings was disappointing, and progressed very well during the first many creeping plants were encro- aching on mature A. marina trees. In such circumstances, the future Photo 6. status of the project is uncertain. Three year-old Rhizophora stylosa seedlings grown in 150 cm PVC pipes developed several prop roots but did not reach down to the bottom soil. March 2001. ▪ Shuangchun restoration project in Photo K.-C. Fan. Tainan County (1995-present; 3.5 ha, and the planting work is continuing). Executive agency: Tainan County Government. Goal: replace the degraded Casuarina windbreak and create a coastal recreation park including a planta- tion of mangrove species. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 52 DOSSIER MANGROVES / TAIWAN

The survival rate of L. racemosa seedlings grown in 150 cm PVC pipes was around 80%, and the seedlings produced fruits in the first year. However, the seedling height was only 60 cm throughout the first three years. These results are primarily explained by the seedlings’ shal- low root systems and lack of promi- nent aerial roots to adapt to flood stress. However, the view over the R. stylosa and L. racemosa seed- Photo 7. lings in the flooded area is magnifi- A magnificent view of Rhizophora stylosa and Lummitzera racemosa seedlings in the flooded area. November 2001. cent (photo 7). Photo K.-C. Fan. This research has shown that PVC pipes may be an effective, cheap and easy method for planting mangroves. However, there are still Current status: A. marina trees already exchange. In July 1998, the 150 cm many problems. For example, in occupy the habitat, which is suitable pipes were driven into the soil to a June 2001, over 70% of the for mangrove growth (1.5 ha). The depth of 50 cm in the deepwater seedlings grown in the flooded remaining areas have unfavorable area. The 50 cm PVC pipes were area were attacked and eaten by hydrodynamics or have been degra- placed (with 20 cm inserted into herbivorous caterpillars. Recently, ded by damaging environmental the soil) in a small flood area where many fish habitats have been in the impacts. This project has involved the highest flooding was approxi- tray circle (photo 8), affecting several mangrove replanting trials. mately 50 cm. Each pipe was filled seedlings grown in PVC pipes. Directly sowing R. stylosa propag- with muddy sediment from the sur- ules among Avicennia trees has face, creating an artificial bottom, given a survival rate of only 30%. and the R. stylosa propagules with Problems of The high mortality rate is due to pol- new roots were then planted into mangrove luted soil, algal damage and heavy the top of the PVC pipes. water turbulence. However, some Unfortunately, due to serious multi- restoration saplings have grown very strongly. ple stresses, the seedling survival With abundant prop roots on the rate for this experiment was less In Taiwan, most projects have favorable fringe sites near the water- than 5% after two months. The area been designed and implemented by way, the plants reached a mean was replanted several times during governmental officials and organiza- height over 200 cm, with many November 1998 and November tions. However, the lack of basic knowl- propagules emerging (photo 4). Ten 1999 with R. stylosa propagules and edge and experience in mangrove month old L. racemosa seedlings L. racemosa seedlings. Recent field restoration have caused projects to fail planted in May 1998 had a survival investigations show that some vig- or only partially achieve their goals. rate of 62.4% in the first year. The orous R. stylosa seedlings grew There are no reports or docu- seedlings grew to a height of 110 cm extremely well in 50 cm PVC pipes, mentation illustrating silvicultural and flowered. However, three years with a seedling height of 85-110 cm. techniques for mangrove restoration after planting, the sapling height The proliferating prop roots were in Taiwan. Although methods for plant- was only 160 cm, mainly because the established in muddy soil, which ing individual mangroves species are flourishing canopy of A. marina sup- provides stability and essential familiar and have been developed in pressed the saplings by limiting nutrients, and the first propagule many countries (Fao, 1994; Field, available sunlight. was noted on the seedlings three 1996), they may not be appropriate for The author used PVC planting pipes years after planting (photo 5). the small restoration area in Taiwan. to restore mangroves in a flooded The R. stylosa container seedlings Restoration of mangroves does area of 1.0 ha. The PVC pipes had replanted in the 150 cm PVC pipes not appear to be especially difficult an inside diameter of 10 cm, and in November 1998 also grew well, –mangroves may in fact be among the were cut to lengths of 150 and 50 reaching a height of 75 cm and easiest marine systems to reconstruct cm. Workers drilled five to ten small producing several prop roots. (Kaly, Jones, 1998; Ellison, 2000). As holes along the whole length of However, they had not yet reached long as habitats have the right hydro- each pipes to allow water the bottom soil (photo 6). logical conditions, mangroves can grow BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) DOSSIER 53 TAIWAN / MANGROVES

Almost every county in western Taiwan has undertaken mangrove restoration since 1994. Unfortunately, many projects have failed because of unsuitable habitats and participants’ lack of basic knowledge and experience in mangrove restoration. A few mangrove restorations have been Photo 8. partially successful, and some man- The deepwater area at low tide for numerous fish habitats. August 2001. grove saplings have survived and Photo K.-C. Fan. grown well. This valuable experience urgently needs to be integrated with in a variety of coastal environments, areas. Furthermore, mangrove spe- technology to develop practical approaching the biomass, stand struc- cies planted to protect coastal areas guidelines for mangrove restoration ture, and productivity of natural forests may compete with native plant in Taiwan. The Anping Harbor man- within two decades. Unfortunately, species and produce negative effects grove restoration project, in particu- some conservation organizations in in the near future. lar, is the first attempt to restore a Taiwan have convinced the public that ▪ Excessive replanting of man- mangrove ecosystem in an urban mangrove seedlings seldom survive groves in western coastal areas grad- area. This restoration site is very and that a mangrove forest is difficult to ually destroys the habitat of Uca for- small compared to the world’s other establish. mosensis (an endemic species in restoration sites, and the areas Furthermore, in the restoration Taiwan). Excessive replanting of man- involved are affected by unfavorable projects managed by County govern- groves may drive this unique crab to hydrodynamic conditions and too ment and local organizations, volun- extinction because its habitat is hard many negative environmental teer groups and school children are clay mud on spacious flatlands with- impacts. Nevertheless, this project invited to take part in planting. They out mangroves (Shih, 1997). has included several mangrove usually enjoyed the job, but they also replanting trials, which have been damaged planting stock or handled it successful in some places and unsuc- improperly, which lowered the cessful in others. All of these experi- seedling survival rate. In fact, most ences may be valuable for other man- Taiwanese people do not know Conclusion and grove restoration projects. enough about mangrove ecology and prospects ecosystem restoration, and lack con- Acknowledgements cepts for subsequent management, maintenance and remedial work. For Mangrove areas in Taiwan are The author would particularly like example, when mangrove seedlings very small and attention is presently to thank Dr. François Fromard of the have survived or grown moderately focused on conserving mangrove Laboratoire d’Ecologie Terrestre at the well for as little as 3-5 years, govern- habitats. Conservation legislation, Paul Sabatier University in Toulouse, ment officials and conservationists especially the Cultural Heritage for his invitation to write this article have been too quick to introduce eco- Preservation Law (CHPL), prohibits and his valuable suggestions and com- tourism into the mangrove restoration any interference or human activity in ments on the manuscript. The author areas, not realizing the need for con- mangrove reserves. Accordingly, man- also thanks Dr. Ching-Long Yeh for pro- tinuing silvicultural work such as thin- groves may proliferate excessively, viding useful papers, Mr. Gang Yang for ning to control forest density, and pest causing serious flooding and pest drawing the maps, the officials of and disease control to prevent defoli- problems. Therefore, the efforts of dif- Kaohsiung, Pingtung County Govern- ation or death of mangrove trees. ferent institutions in various regions ment for providing useful data, and Mr. Otherwise, scientists themselves should be better coordinated, espe- Chiao-Tseng Chen and Mr. Kao-Liang sometimes argue against restoration cially those of ecologists and foresters Chen at Penghu County Government projects in Taiwan’s coastal area for who have been disregarded until now. and Mr. Yang at Tainan County Govern- the following reasons: Firstly, the protective legislation must ment for their assistance with field ▪ Most restoration areas are be revised again and strictly enforced, work and their offer of valuable experi- located at the mouth of a river or on and secondly, appropriate and practi- ence. Finally, special thanks are also river banks. Mangroves that prolifer- cal management guidelines must be due to Ms. Mei-Ling Yang, Jung-Sheng ate too vigorously, like Kandelia can- developed for mangrove reserves, to Hsia and Mr. Der-Far Pan at the Taiwan del at the Kellung and Tanshui River, ensure sustainable development of Forestry Bureau for providing many can cause drainage problems in those mangroves in Taiwan. useful references. BOIS ET FORÊTS DES TROPIQUES, 2002, N° 273 (3) 54 DOSSIER MANGROVES / TAIWAN

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