Mangrove and Other Coastal Forests

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38.6Mangroves and othercoastal forests


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Sustainable management of coastalmangrove forest development and social

needs

Junaid K. Choudhury 1

INTRODUCTION

In the absence of any internationally accepted definition of "coastal zone", the landward bound-ary of the zone is represented by the furthest extent of marine influences, while the seaward limit ofthe zone, often the edge of the continental shelf, extends to a maximum of up to the limit where themarine environment is influenced by terrestrial factors (ADB 1991). Mangroves, freshwater swamps,peat swamps, coral reefs, sea-grass beds, coastal lagoons, open beaches and islands are the eightmain types of wetland habitats that constitute the "coastal zone" wherein mangroves play the mostvital role. Mangroves are the characteristic littoral plants, grouped under unique ecosystems, inhab-iting mostly the sheltered coastlines, within the intertidal zone of tropical and subtropical regions.Globally mangrove ecosystems contain about 60 species of trees and shrubs and about 20 additionalspecies associated with the mangrove flora, but not necessarily restricted to it (Hamilton and Snedaker1984).

VALUES OF MANGROVES

The mangrove lands that, used to be considered as "waste land" in the past, have recently beentreated as a valuable ecosystem, especially for their unique features. Mangrove forests have beentraditionally utilized by the local people for a variety of purposes. Values of mangroves are recog-nized as "tangible" and "intangible" benefits. The forest of the mangrove ecosystem is capableto yield the following tangible or direct benefits:

1. Lumber or similar construction wood;2. Poles, fuelwood, fishing gear, etc.;3. Raw materials for the wood-based industry of various nature and including board mills, rayon

mills, match factories and charcoal products, etc.;

4. Non-timber products including tannin (mostly from bark) to supply raw materials for leathertanning industries, fishing net processing units, thatching material for roofing and raw mate-rials for indigenous medicine;

5. Edible products including honey and wax, game animals, meat and fish, fruits, drinks andsugar .

The mangrove ecosystem can yield the following intangible or indirect benefits:1. Natural spawning ground for fish and crustaceans, especially for shrimps and prawns, protec

1 Forest Department, Banabhaban, Gulshan Road, Mohakhali, Dhaka 1212 Bangladesh


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tion and conservation of wildlife habitats of a rare nature, control and regulation of the foodchain in stores;2. Contribution to mud flat formation and control of erosion;3. Capability to check inland salinity intrusion;4. Enhanced capability to combat the impact of cyclone and tidal surge;5. Enhanced capability to function as a shelter belt during storms and cyclones.

CONVERSION AND DEGRADATION OF MANGROVES

Like the tropical rain forests, mangroves are being degraded and destroyed globally. Mangroves and mangrove ecosystems used to be regarded as "wastelands" of little or no value till they

were put under a variety of uses such as fish ponds, salt beds, rice fields, urbanization, housingestates, human settlement (transmigration), roads, mining and similar uses for the so-called "devel-opment", which at times resulted into a complete destruction of the whole ecosystem.

The mangrove forest in Thailand depleted from 360 000 ha in 1960 to 174 000 ha in 1991 andthat in Malaysia decreased from 505 300 ha to 269 000 ha between 1980 and 1990 (Clough 1993). InIndonesia 75% of the major cities having over 100 000 inhabitants are located in coastal areas, mostof which were mangrove forests. By 1990 about 269 000 ha of mangroves in Indonesia were con-verted to fishponds (Choudhury 1996). Even in small nations such as Fiji, major urbanization hastaken place by converting the mangroves of its coastal zones. In the Philippines, 169 852 ha ofmangroves disappeared between 1967 and 1976 (Srivastava).

Factors of mangrove degradation

The major factors that caused mangrove degradation around the world, in general, may beenumerated as follows:1. Population expansion: Increase of population, coupled with economic growth, inevitably

caused the use of mangrove lands for various purposes such as construction of roads, portsand harbours, industries, urbanization, etc. Due to land scarcity and population increase, theSingapore mangrove ecosystem in 1978 had decreased from 73 km2 to 18 km2 during theprevious 150 years (Hamilton & Snedaker 1984). In Hong Kong mangroves are facing rapiddestruction resulting in the extinction of Rhizophora and Avicennia (Hu 1974). With the ex-pansion of Bombay in India over 1 000 ha of mangroves were lost to housing and factories(Hamilton & Snedaker 1984).

2. Higher short-term benefits: Alternative uses of mangrove lands, specially for the productionof fish and prawns, succeeded in fetching higher monetary gains over a short period and ledto the conversion of mangroves to fish ponds. At the same time, the conversion of mangrove

lands to salt beds and rice fields brought in higher monetary returns within a short period.Vast tracts of Indonesian mangroves and reasonable areas of Thailand mangroves have be-come fish ponds for such reasons.

3. Lack of government attention and overall awareness. Most of the mangrove lands all over theworld were left unattended by governments. In most countries, government agencies, untilvery recently, did not take up the management of mangrove lands and that caused their indis-criminate use leading to serious depletion. In the 18th century the Sunderbans was twice itspresent size, which was lost to agricultural lands of the adjoining landlords (Chowdhury et al.1994). Mangroves in Indonesia, Thailand, the Philippines, and in many other countries of the


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Asia Pacific region, have suffered for the same reason. Many of the mangrove countries suchas Indonesia, Maldives, Vietnam, etc., are yet to formulate the required coastal zone manage-ment plans incorporating the details of mangrove management.

4. Obscure regulations: Government regulations with respect to mangrove lands are often eithertoo complicated or inadequate to ensure the required conservation. This situation led to ille-gal encroachment of many mangrove lands all over the world. Most of the Indonesian man-groves, large tracts of Thailand mangroves and Chokoria-Sunderban mangroves in Bangla-desh, suffered from such a situation.

5. Inefficient reforestation techniques: The reforestation and restoration of degraded mangroveareas and afforestation techniques were almost unknown in the recent past. These techniquesare yet to be well understood and standardized for most of the mangrove countries in theworld, though some progress has been achieved in this respect in a few countries like Bang-ladesh, Malaysia and Indonesia.

6. Inadequate manpower and logistics: The mangrove management agencies, mostly the localforestry departments, very often do not have the adequate manpower and logistics requiredfor the implementation of effective management. Very often they do not even have the mini-mum required watercrafts. The forestry departments of Bangladesh, India, Sri Lanka andIndonesia are examples of such situations.

Besides these, the use of herbicides in Vietnam by the US Army caused the depletion of 104123 ha of mangroves which are yet to recover (FAO 1982). Along with the complete depletion ofmangroves, the so called "coastal development" has posed various other stresses on the existingmangrove ecosystems through solid and liquid waste disposal, oil and other hazardous chemicalpollution.

Waste water effluent produced by factories, direct dumping of municipal wastes into the rivers,

pesticide run-off from neighbouring agricultural areas, including accumulation of heavy metals intothe mangrove ecosystems, are causing definite stress on them.Oil pollution is unavoidably increasing in mangrove areas from shipyards, ship breakers, off-

shore oil wells, oil tanker accidents and washing of tanks in coastal waters. A new parameter ofthermal pollution is being added to these. Though research findings on these issues are still limited,the potential for major disturbances to mangroves and related ecosystems from thermal and otherassociated impacts from power stations is high.

WORLD MANGROVES AND THEIR DISTRIBUTION

Mangroves are generally found along the coastlines of tropical and subtropical regions, usu-

ally between 25oN and 25oS latitude, throughout the world. As an exception to these, mangroves arefound as far south as New Zealand and as far north as Japan. Local environmental factors such aswarm sea current, frost, salinity stress, wave action, etc., determine the occurrence of mangrovesbeyond the above-mentioned latitudinal limits. Most tropical countries had mangroves in the past.

Walsh (1874) considered the world mangroves to be broadly divided into two main areas, (1)the Indo-Pacific region and (2) western Africa and American regions. He also suggested five basicrequirements for extensive mangrove development which are: (1) tropical temperature, (2) fine grainedalluvium, (3) low wave and tidal action, (4) salt water and (5) large tidal range. Some other authorsdivided the world mangroves into two groups: (1) the old world mangrove swamps and (2) the new


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world and west African mangrove swamps. The mangroves of the Indo-West Pacific region, underthe old world mangrove group ARAE prominent and diverse, having over 40 species as against about10 species in the other group. There is also a great deal of segregation between the mangrove vegeta-tion found in the old world region and the new world of the Americas and West Africa. Two of theprimary genera of mangrove, Rhizophora and Avicennia, contain separate species in the old and newworlds, suggesting independent speciation in each region, though there are views that suggest theIndian-Malaysian region as the original centre of distribution for mangroves. The estimated areas othe worlds existing mangroves are shown in Table 1 (Aksornkoae 19937).


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Table 1. Estimated areas of existing mangroves

CountryArea in

Thousand HaCountry

Area inThousand Ha

Angola 125 Jamaica 7

Australia 1 150 Kampuchea 10

Bangladesh 450 Kenya 45

Belize 75 Liberia 20

Brasil 2 500 Madagascar 300

Brunei 7 Malaysia 674

Burma 812 Mexico 660

Cameroon 272 Mozambique 455

Colombia 440 Nicaragua 60

Costa Rica 39 Nigeria 970

Cuba 400 Pakistan 345

Dominican Republic 9 Panama 486

Ecuador 235 Papua New Guinea 553

El Salvador 45 Peru 28

Equatorial Guinea 20 Philippines 240

Fiji 39 Senegal 169

Gabon 140 Sierra Leone 170

Gambia 60 Somalia 20

Guatemala 50 Sri Lanka 4

Guinea 260 Surinam 115

Guinea-Bissau 230 Tanzania 96

Guyana Frances 55 Thailand 287

Guyana 150 Trinidad & Tobago 4

Haiti 18 Venezuela 260

Honduras 145 Vietnam 320

India 96 Zaire 50

Indonesia 2 500

The exact area of currently existing mangroves is still unknown for several countries of the world.


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SOCIAL NEEDS, DEMAND AND UTILIZATION

Most of the work on mangroves has mainly focused on their physical and technical aspects.Information regarding the involvement of communities in conservation, management and sustain-able development of mangroves is scanty. The social needs of the communities that are directly orindirectly involved with nearby mangroves should be duly considered in coastal zone planning, spe-cially at national levels. It is observed that the adjoining communities often look for a few directoutputs such as (1) firewood for home consumption or for small scale marketing (2) wood for char-coal making (3) wood and poles for housing (4) Nypa leaves for roofing (5) Nypa juice collection (6)honey collection and (7) open fishing. In some parts of the world the local communities convert themangrove lands into fishponds that are mostly operated at a subsistence level. The large-scale con-version of mangroves to fish ponds is very often linked to the investment from the communities orentrepreneurs that do not live nearby the mangroves and such activities are often more intensive,which is definitely regressive for the mangrove ecosystem, leading to its depletion.

The social needs of the people who live in and around mangroves or within a reasonableproximity of the mangroves are important issues. The major factors that influence the social needsare: (i) Ethnic composition which is important to know for assessing how their habits impact on theconservation and development of mangroves; (ii) language in view of extension work; (iii) religion;(iv) gender issues; (v) housing patterns and living standards; (vi) land tenure which has a very impor-tant impact on land-use decisions and investments; (vii) access to mangroves; (viii) awareness ofmangrove values in that social needs are very likely to be judged by the mangrove dwellers againsttheir awareness of mangrove values.

MANGROVE MANAGEMENT STRATEGYMangroves constitute a rich, diverse and complex ecosystem which is generally a productiveresource base, but poor management practices in general have caused severe widespread degradationof this resource around the world. In some countries, however, mangrove forest management wasinitiated long back, mostly with the aim to produce forest products such as wood, fuelwood andthatching materials. The use of silvicultural systems as the tool for the management of natural orplanted mangroves is accepted world-wide. The newly added dimension to this is the "sustainable"management of "the ecosystem" as a whole or an "integrated management" of the resource. Demon-strated successful adaptation of such management techniques is yet to be recorded though manycountries are seriously thinking or starting such practices. Very brief descriptions of past and presentmangrove management activities in a few selected countries are given below.

Mangrove management in Malaysia

The mangrove forests are under the jurisdiction of the Forest Department in each of the threestates of Malaysia. The mangrove management practices in Malaysia vary from state to state. Matangmangroves in Malaysia are among the best managed forests in the world. Historically the ForestDepartment in Perak, Malaysia, started the management of Matang mangroves (Hassan 1981). Themain objective is to maximize the sustained yield of wood for charcoal production. In the past a 25 to40-year rotation was in practice, but the present prescription is for a 30-year rotation. Clear-felling inalternate strips, with the retention of standards at the rate of seven trees per hectare for regeneration,supplemented with artificial planting in poor areas, is the prescribed silvicultural system. Supple-mentary planting is done with Rhizophora apiculata and Rhizophora mucronata at 1.2 m x 1.2 m and


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1.8 m x 1.8 m spacing respectively (FAO 1985). A narrow belt of 3 m width along the banks of therivers and creeks and the coast is kept as an unworkable area to prevent erosion.

Malaysian mangroves generally yield charcoal, poles, firewood, wood-chips and Nypa. TheMatang mangrove forest produces about 43 000 t/a of charcoal. The charcoal kilns produce aboutone ton of charcoal from five tons of green wood. The poles are generally the outcome of thinning. InMatang about 2 000 ha are thinned annually to yield approximately three to four million poles. Theareas with Bruguiera parviflora, to the extent of about 100 ha/a in the Matang forest are used forfirewood production. Sabah and Sarawak mangroves with annual coupes of about 4 000 and 600 ha,respectively, produce wood chips which are exported to Japan as raw material for the production ofrayon (FAO 1985). Nypa leaves are mainly used for thatch. The young leaves of Nypa are used forwrapping tobacco. Nypa is also tapped for juice that is fermented to produce alcohol.

Mangrove management in Thailand

Mangroves in Thailand were estimated to cover 368 100 ha, and were depleted to 287 308 haby 1979 (FAO 1985). The best developed mangrove forests of Thailand are found in Phangnga,Ranong, Trang and Satun, while the mangroves in the inner and western parts of the Gulf of Thailandare mainly composed of small-sized trees. Most of the mangrove forests have been declared reservedforest though large areas of mangroves, estimated to be about 42 956 ha, particularly in the inner partof the Gulf of Thailand, are under illegal private possession, mostly for shrimp farming and saltproduction, for a long period of time. A new land distribution policy has been promulgated since1982 by the Royal Forestry Department to combat this illegal occupancy on mangrove reserves,wherein certain rights have been admitted over a fixed area per family, which can only be inheritedby a member of the immediate family.

Before 1961 the only objective of management was to log the mangroves for charcoal produc-tion. The management plans formulated by the Royal Forest Department of Thailand adopted a

shelterwood system under sketchy regulations of a 10-year felling cycle, wherein the forest area isdivided into 10 equal coupes, each of which is worked on permits issued for one year. The prescrip-tions allowed the felling of trees measuring 10 cm or more diameter at breast height (dbh), leaving190 to 250 big trees per hectare (FAO 1985). In 1961 the Royal Forest Department revised themangrove management plans to suit auction leasing and incorporated different spacing for the treesto be retained as shelter trees in the forest depending on their size. The minimum dbh limit was keptat 10 cm but the felling cycle was changed from 10 to 15 years. The areas were to be auctioned forthree years. Felling within the 5 m wide strip along the banks of rivers and creeks was prohibited toprevent erosion.

The experience gained in the application of the above-mentioned shelterwood system did givesatisfactory results. It was found that in many areas the stock was depleted causing site deterioration.Some areas dried up and developed thick undesirable undergrowth that prevented the regeneration ofmangrove species. Some areas were left with only non-commercial species. Besides these, it was

found that the harvesting of the "shelter trees" without damaging the established regeneration wasnever possible. In view of the above, the Royal Forest Department of Thailand revised the mangrovemanagement plan to its present form, the salient features of which are: (1) clear-felling in alternatestrips of 40 m width, laid at 45o to tide, (2) 30-year rotation with 15-year felling cycles and (3)prohibiting the felling of valuable species (Rhizophora spp.) measuring below 5 cm dbh in the clear-felling strips. At present 176 653 ha of mangroves are under the management of the Royal ForestDepartment of Thailand. The main objective is to produce fuelwood and charcoal.

It is estimated that there are about 33 000 ha of private mangrove plantations in Thailand,mostly in the upper part of the Gulf of Thailand. Most of these plantations consist of Rhizophora


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apiculata, 90% of which is used for charcoal making and the rest for poles and fuelwood. The RoyalForest Department of Thailand assists these private mangrove planters on aspects of silviculture,planting and harvesting techniques. The Government is also planning to promote the establishmentof large-scale private plantations of mangroves.

Management of mangrove forests in Bangladesh

There are two types of mangrove forests in Bangladesh, i.e. (1) natural mangroves and (2)man-made mangroves. The Sunderbans is the natural mangrove of Bangladesh. It is the single largestchunk of productive forest in the world, extending over 577 356 ha, of which 175 724 ha is waterarea. At the advent of British rule in India, the Sunderbans was twice its current size, a and was lostto agriculture in general.

The Sunderbans was declared reserve forest during 1875-76 under Act VII of 1865 and wasplaced under the Forest Department for management. Since then its area in Bangladesh has remained

unchanged except the de-reservation of 7 025 ha in 1896 and in 1904.The management of the Sunderban mangroves was initiated during 1983-84 under the 10-

year management plan written by R.L. Heinig. Selection felling, at ten year felling cycles, of majortrees species such as Heritiera fomes, Sonneratia apetala, Xylocarpus mekongensis, Bruguieragymnorhiza and Amoora cucullata having a minimum girth of 91 cm at breast height, was prescribed,while felling of other species remain unregulated. The felling cycle was increased to 40 years by W.F. Lloyd during 1903-08. Sir Henry Farrington prepared a working scheme enhancing the girth limitto 106.6 cm which was applied from 1906 to 1912. He also prescribed thinning of "over crowded"stands. The first detailed working plan was prepared by F. Trafford for the period 1912 to 1932. Hechanged the minimum girth limits to 122 and 106.6 cm for Sonneratia apetala and Heritiera fomes,respectively, and 61 cm for Amoora, Bruguiera and Xylocarpus. The unregulated felling of otherspecies started to show injurious affects on the stocks of Excoecaria agallocha, Avicennia officinalis,

Xylocarpus granatum, Ceriops decandra and Nypa fruticans by 1930. S. J. Curtis formulated thedetailed working plan for the Sunderbans suggesting rotations, felling cycles and correspondingminimum exploitable girth for major species including "yield calculations". He also suggested ex-ploitation of other species and thinning. This had very intensive prescriptions and by 1937 it wasrealized that the existing infrastructure was not capable to adopt these elaborate prescriptions. Thusthe working plan was revised by S. Choudhury to meet the requirements, and his modifications weremore or less in force till 1960 (Chowdhury et al. 1994).

Forestal Forestry carried out a very scientific inventory of the mangroves of Sunderbans indetail and published the report in 1960, which indicated that the average net merchantable volumefrom trees over 12.7 cm dbh and above is 53.62 m3/ha (Forestal 1960). Based on this inventory. A.M.Choudhury prepared the working plan of Sunderbans for the period 1960 to 1980. The main objec-tive of this was to manage the forest on a sustained yield basis. He also recommended the selectionfelling system under three major working circles namely (1) Excoecaria agallocha working circle (2)

Heritiera fomes working circle and (3) Sonneratia apetala working circle. He prescribed a 20-yearfelling cycle for all the important species with different exploitable diameter limits for differentspecies at different sites. The second detailed inventory of the Sunderbans was done by the OverseasDevelopment Administration of the United Kingdom. The report was published in 1985. This inven-tory clearly reflected the depletion of the growing stock specially in case of the two most importantcommercial species namely Heritiera fomes and Excoecaria agallocha. There has been a 41.9% and34% depletion of Heritiera fomes and Excoecaria agallocha stems per hectare in the case of treeswith a breast height diameter of 7.5 cm and above (Chowdhury et al. 1994). The regeneration wasreported to be satisfactory. The present management regulations are of an interim nature whereby the


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extraction of pulpwood, fuelwood and other minor products are allowed, under strict control overextraction of timber. But extraction of top dying Heritiera fomes is being done.

An integrated management plan for the Sunderbans is being prepared through an FAO project,wherein consultants from various disciplines work together. The major objective in a nutshell is tohave sustainable management of the resource to yield wood, fish, wild life, recreation, and non-woodproducts.

Besides these natural mangroves, Bangladesh foresters pioneered in the field of mangroveafforestation on the newly formed mud flats along its coast. Till 1994 a total of 104 339 ha have beenplanted, of which 57 508 ha are in good shape. Species used are Sonneratia apetala, Rhizophora andBruguiera. Silvicultural practices (thinning at 5 and 14 years) had no impact on growth. A manage-ment plan is being prepared for these plantations.

Table 2 (Mangrove Afforestation up to 1994)

Name of theAdministrative

Unitor Division

Gross AreaPlanted inHectares

Area Failedin Hectares

Area Erodedin Hectares

AreaEncroachedin Hectares

Not Area inHectares

Noakhali 35 400 2 486 8 866 22 24 026

Patuakhali 16 007 3 061 2 546 565 9 835

Bhola 20 732 2 733 6 371 606 11 022

Chittagong 32 200 10 868 6 334 2 373 12 625

Source : Bangladesh Forest Department.

Management of mangroves in the Philippines

According to the Forest Management Bureau the total area of mangrove forest in the Philip-pines is 232 065 ha with the following geographical distribution (Zamora 1989).

Table 3. Mangrove forests of the Philippines. (Forest Management Bureau 1984)

Category Luzon Areain Hectares

VisayasArea in

Hectares

MindanaoArea inHectares

PalawanArea inHectares

Total Areain Hectares

Reproductive bush 2 583 63 893 23 692 22 915 113 083

Young growth 14 186 1 226 84 471 9 200 109 083

Old growth - - 4 582 5 317 9 899

Total 16 769 65 119 112 745 37 432 232 065

Of the estimated total mangrove forest area, approximately 49% is classified as reproductive


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bush, 47% as young growth and 4% as old growth. The volume of the standing timber in the existingmangrove forest is estimated to be about 4 million m3 (Zamora 1989). The major species are ofRhizophora, Bruguiera, Avicennia, Xylocarpus, Sonneratia, Heritiera, Ceriops, Excoecaria and Nypa.Most of these are timber yielding, while Xylocarpus and Ceriops are used for the extraction of dyesand Nypa is used for thatching leaves and tapping of juice for brewing alcohol.

Mangrove dependent human habitation, adjoining the mangroves, is very common in thePhilippines. The five types of mangrove dwellers in the Philippines are (1) "Magsisisi", shell gather-ers, (2) "Mangingsida", fishermen, (3) "Magaayam", crab gatherers, (4) "Magsasasa", Nypa gather-ers, and (5) "Mamamaroy", baroy shell gatherers (Velasco 1979). Mangrove dwellers have their ownconcept of preservation and utilization of mangroves. They are also aware of the importance ofmangroves and their products. Most of them are satisfied with their subsistence level of economy,inflicting very little ecological disturbance, while the artificial fishery groups are involved in moreintensive operations causing higher ecological disturbance to the mangrove ecosystem. The tapping

and use of Nypa juice is more intensive in the Philippines than in any other country of the world.Under the existing technology of sap collection and fermentation, the production of alcohol perhectare per year is 6 000 to 10 000 litres, which can be enhanced to 18 000 litres per hectare per yearwith improved management and fermentation technology (Zamora 1989).

In view of the drastic decrease of mangrove forests from 450 000 ha in 1920 to 232 000 ha in1984, the Department of Environment and Natural Resources of the Philippines, adopted a fewconservation measures. Presidential Decree No. 705 was promulgated which enforces (1) a seed treemethod of silvicultural system for mangroves, wherein 20 seed trees per hectare are to be retained,(2) adaptation of 50-year rotation and (3) regulation of annual allowable cut. Besides these thousandsof hectares of denuded mangrove areas in the form of open mudflats, sandy beaches and mine tailingareas are available for reforestation. Small-scale afforestation with species such as Rhizophoraapiculata, Bruguiera cylindrica, Avicennia officinalis and Ceriops tegal has been undertaken at vari-

ous sites. A World Bank funded project aims to afforest 200 000 ha with mangroves.

Mangrove management in Indonesia

As an archipelago country of about 13 667 islands, with a coastline of over 81 000 km, Indo-nesian mangroves extend over 4.25 million ha (FAO 1985). In terms of total coverage, the mangroveforest in Indonesia is believed to be the largest in the world. Mangroves are found in almost allislands though the tree size and extent vary. With a very few exceptions, Indonesian mangroves aremostly discontinuous, very often narrow and smaller in size. Very large continuous chunks are rare.The mangrove forests in Java, Sumatra, Sulawesi, Kalimantan and Irian are more developed. Man-grove stands in the eastern parts of Indonesia, namely Maluku and the Nusa Tenggara, are much lessextensive and the trees are relatively small of about 25 m in height and 16 cm diameter at breastheight (Soemodihardjo 1989).


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The distribution of mangroves is shown below.

Table 4. Distribution of Indonesian mangroves. (FAO 1985)

Name of main island Area in thousandhectares

Sumatra 667.34

Kalimantan 383.45

Java and Bali 51.89

Tenggara 5.51Sulawesi 99.83

Maluku 100.00

Irian Jaya 2 943.00

Mangroves are found to grow on a variety of substrates such as mud, sand, reef flat and even onrelatively solid rock. They are well developed on protected muddy coastal plains having adequatefresh river water discharge. Mangrove trees on the south and east coasts of Sumatra and Kalimanthan,and on the north west coast of Muna in Sulawesi are found to be as big as 50 m in height and 50 cmdiameter at breast height. Their species composition vary from locality to locality wherein over 37

species of trees have been found (Soemodihardjo 1989). The major species are from genera Rhizophora,Bruguiera, Xylocarpus, Avicennia, Ceriops, Excoecaria, Lumnitzera, Sonneratia, Heritiera,Scyphiphora, Aegiceras, Phoenix and Nypa.

During the past decades, the demand for mangrove resources has been steadily increasing, notonly for the products but also for the land itself for conversion to fish ponds, which is continuouslydestroying the ecosystem. Mangrove forest management, in the true sense of the term was neverpracticed in Indonesia. Indonesian mangroves suffered most, during the second world war, to meetwood energy needs (Soemodihardjo 1994). Mangrove forest was leased out to concession-holders inJava and Sumatra on the condition they reforest after felling. Commercial exploitation of mangrovesfor charcoal has taken place in Sumatra under some sort of working plan with very little managementimpact. In Java, the State Forestry Corporation is managing some mangrove areas, while the Direc-torate of Nature Conservation has established a nature reserve over a small area. About 771 121 ha of

virgin mangrove forest in Indonesia has been identified as production forest and large concessionshave been given over 454 000 ha (FAO 1985). The harvests from mangrove forests are used mainlyfor (1) charcoal making, (2) firewood, (3) logs and chips (4) poles, (5) pulpwood, (6) tannin, (7)thatching material and (8) traditional medicines.

In the recent past, the Government of the Republic of Indonesia, has started to pay attention totheir mangroves. The Government has issued the following office orders and "decrees" from time totime, in an attempt to conserve, and impart an order in, the mangroves in general (Giesen 1993).These relate to mangroves but do not lead to the constitution of any management programme. From1975 to 1990 four important instructions and decrees have suggested a number of improvements in


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the management of mangroves including coastal greenbelts, felling regulations, etc.The Government of Indonesia has, however, launched an ambitious two-year Asian Develop-

ment Bank assisted "Mangrove Rehabilitation and Management Project" in Sulawesi from October1996, for the development of integrated coastal zone management guidelines, especially for Sulawesimangroves, which in future can be extended to other parts of Indonesia with slight modifications.

SUSTAINABLE MANAGEMENT OF MANGROVE ECOSYSTEM

The mangrove ecosystem is a complex one. It is composed of various inter-related elementsin the land sea interface zone which is linked with other natural systems of the coastal region such ascorals, sea grass, coastal fisheries and beach vegetation. The mangrove ecosystem consists of water,

muddy soil, trees, shrubs and their associated flora, fauna and microbes. It is a very productiveecosystem sustaining various forms of life. Its waters are nursery grounds for fish, crustacean andmollusk and also provide habitat for a wide range of aquatic life, while the land supports a rich anddiverse flora and fauna. It also influences the micro climate, prevents coastal erosion, enhances ac-cretion and combats natural calamities such as cyclones and tidal bores.

The concept of mangrove management has considerably evolved, as these formations havebecome better understood. Instead of simple management of the first stand, it is now realized that thewhole ecosystem must be considered. It was also realized that, due to the diversity of mangroveformations, specific regulations are essential.

For most of the mangrove areas of the world, "fishery" and "forestry" are the two conflictingdemands on mangrove lands. Apportioning of the mangrove land resource to these two major usesunder the concept of sustainable management of the ecosystem needs further research though a ratio

of 20:80 is suggested for ponds to mangroves, on 25 ha allocations as "woodlot silvo-fishery"(Choudhury 1996). It is suggested that the mangrove area that may be sacrificed for fish ponds, canbe calculated by using the following formula (Llaurado and Lindquist 1982).

The Max. Area that can be brought under Aquaculture = (S-F) / 2Swhere:S = Value of fish yield per hectareF = Value of forestry per hectare, which must include the linkage values such contribution to open

fishing, near-shore fishing, erosion control, biodiversity value, eco-tourism, shelterbelt value,etc.

This formula seems to be too simple and is based completely on monetary aspects.

MANGROVE AFFORESTATION

Plantation raising is an age old forestry event. Until recently this activity was confined toupland forestry alone. In the recent past mangrove afforestation attempts have gained some momen-tum in some countries such as in Bangladesh, Malaysia, China and Indonesia. Bangladesh foresterspioneered in the field of mangrove afforestation by successfully raising over 113 000 ha of mangroveplantations since 1966 (Dano 1996). Malaysian foresters are managing the Matang mangroves, in-corporating the assistance of planting of mangroves to their natural regeneration for the establish-


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ment of required forest cover since 1980 (Hassan 1981). Mangrove afforestation was first startedduring the late 1950s in China, with a break during 1966 to 1979 and was initiated again in 1980(Baowen et al. 1997). In Indonesia mangrove afforestation, which was started at Sinjai, Sulawesiduring 1985 under the initiative of a private fishermen's group, achieved success and recognitionthroughout the country (Choudhury 1996).

Planting material

In most of the countries the initial planting of mangroves started with the planting of propagulesor seedlings collected from the natural forest floor. At present the commonly used planting materialsare (1) natural seedlings, termed as "wildlings"; (2) seeds and propagules; and (3) nursery seedlings.Natural mangrove forest generally carries a large number of wildlings, that grow to a height of aboutone meter and survive till about six years. They often look to be of the same height even though theirage may vary from one to six years. Tall and young wildlings exhibit better planting success and thus,

while collecting wildlings, those with smoother barks and slender stems at their collar zone arelooked for and collected by using a semi-circular shovel (Choudhury 1996). Rhizophora, Bruguiera,Ceriops and Excoecaria species have been successfully raised using "wildlings" in Bangladesh. Useof seeds and propagules in mangrove afforestation is common. The use of viviparous propagules ismore common than seeds. The planting of Rhizophora propagules, to help natural regeneration inMatang, Malaysia, is in practice since 1980. Rhizophora propagules were planted to establish over500 ha of mangrove plantations since 1985 for the first time at Sinjai, Indonesia. The availability ofthe propagules around the year, along with the success of wildlings planting, reduced the demand fornursery raised seedlings, but raising of nursery seedlings is gaining importance with the extendedmangrove afforestation programmes, especially in Bangladesh. Raising of plantations of some spe-cies such as Avicennia, Sonneratia, and Xylocarpus need nursery seedlings for achieving success.

Successful nursery practices have been developed in Bangladesh for raising seedlings of cer-

tain mangrove species. Similar attempts are in progress at Bali, Indonesia, under a JICA project tostandardize the nursery practices of various mangrove species. Information on the nursery tech-niques of mangroves are still scanty and centers around only a few major species out of about 60known species of mangroves. Nursery techniques for five mangrove species are described below.

Avicennia marina

The fruits generally ripen twice a year, once in May-June and again in November-December(JICA 1996). The seeds are smaller than those of Avicennia officinalis. JICA (1996) reported thatthese seeds sprout in 7 to 15 days and recommended shading of the nursery for the first two months.Attack of crab is comparatively common on this species of Avicennia. The fruits are treated byhanging them from a pole, inside a fishing net, while subjected to normal tide inundation for aboutthree to five days, without touching the ground, to reduce the crab damage in the nursery. The fruitsare dribbled into 25 cm x 15 cm polyethene bags, filled with soft soil, as soon as the tide water

recedes from the nursery, so that the seeds get the next low tide period to anchor into the substrate.During the first week of dribbling, dikes and regulators are used to regulate the tide water, so that thetops of the bags just immerse during high tide. As an alternative to this, the polyethene bags may becovered with thick bamboo mat, prior to every high tide and removed when the tide recedes, till theseed starts to germinate, to prevent the fruits from floating away. The germination starts by the thirdday and ends in about ten days (Choudhury 1994). JICA (1996) reported that the seedlings grow to aheight of 41 cm in 4 months.


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Avicennia officinalis

The fruits of Avicennia officinalis are heart-shaped and 2-3 cm long. They have a velvety beak.Each fruit has only one seed. About 300 seeds weigh a kilogram. Mature, bigger, good and healthylooking fruits, free from any sign of insect attack, are collected either from the trees by climbing orfrom the forest floor. Collection of fruits from the trees should be preferred. The fruits generally ripetwice a year, once in May-June and again in November-December. The rest of the nursery practicesare similar to those of Avicennia marina.

Rhizophora apiculata

The propagules, shorter than those of Rhizophora mucronata, measure about 20 to 40 cm inlength and are available round the year, though those collected in August are reported to give betterresults (Sinjai experience). JICA (1996) reported that the maximum of propagules are available dur-

ing the month of February. Good, stout and healthy looking propagules with redder apex are themature ones, to be collected for the nursery. The propagules collected as such may be heaped andstored under shade at a dry saline site for 2 to 5 days to combat crab damage in the nursery (Bangla-desh experience). The propagules from the storage heaps are planted into the polythene bags measur-ing 25 cm x 15 cm filled with soft soil and subjected to normal tide inundation which leads to 100%germination in about 4 to 7 weeks. JICA (1996) recommended 75% shading for the first few weeks.Since direct planting is very successsul, a nursery for Rhizophora apiculata is not commonly used.

Excoecaria agallocha

The fruits are round and remain green even when mature. Each fruit contains about 2 to 3seeds and about 2 500 seeds weigh one kilogram. The seeds taken out of the collected fruits areplanted directly into polyethene pots. Generally 75% of the seeds germinate in 3 weeks and grow toa height of about 40 to 70 cm in 10 months. Light initial shade in the nursery for the first 2 to 3months is recommended.

Xylocarpus granatum

The flowers are small, whitish, and typically unisexual. The fruits are large, heavy and ball-shaped, measuring about 15 cm in diameter, each of which weighs about 1 to 2 kilogram. The fruitsare available throughout the year. Each fruit contains about 3 to 20 semi-triangular seeds. The seedssown in 25 cm x 15 cm polythene bags sprout in 2 to 3 weeks and grow to a height of about 42 cm in4 months. JICA (1996) recommended an initial 2 months' shade in the nursery.

Planting technique

Planting of seedlings is preferred over direct sowing of the propagules. In general nurseriesare raised during December and January. Matching of species to given micro-sites is very important

in mangrove afforestation and thus the species-wise requirement of the number needs to be deter-mined for nursery establishment. Only young vigorous and healthy seedlings are to be used afterculling at the nursery site. Transportation of seedlings by boat is recommended which prevents themfrom being exposed to a non-coastal non-saline environment. Generally about 60 cm tall seedlingsare used for planting though taller seedlings are preferred for areas subjected to higher inundation,but no seedling over 1.5 m in height should be used. In general the planting should be done at the thebeginning of the rainy season. In addition, the lunar calendar should be considered for fixing theplanting period which should be one week beginning from the fifth or the nineteenth lunar dates. InMalaysia and in Indonesia planting of the propagules is the practice.


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The success of mangrove afforestation is closely linked with the intensity of beating up opera-tions and after care, including the choice of species for the given micro-site. Site characteristics to beconsidered for the selection of species are (1) area covered by tide, (2) tide inundation heights, (3)run-off and tide velocity, (4) salinity of tide water, (5) fresh water inflow, (6) sediment load in the tidewater, (7) soil texture, (8) physical exposure to tidal wave action and (9) ocean water temperature.Above all, field experience has no substitute on this issue. There are about 60 species of trees andshrubs that are pure mangroves with another 20 species that may be termed as "mangrove associ-ates". Out of these 80 species, 12 commonly used genera are Rhizophora, Bruguiera, Sonneratia,Heritiera, Lumnitzera, Ceriops, Avicennia, Excoecaria, Xylocarpus, Nypa, Cassurina and Hibiscus.Generally 1 m x 1 m spacing is used for planting but in Matang, Malaysia, Rhizophora conjugata andRhizophora mucronata propagules are planted at 1.2 m x 1.2 m and 1.8 m x 1.8 m spacing, respec-tively (Hassan 1981). A very simple matrix for selecting a species based on three major site charac-teristics, such as soil texture, salinity and inundation may be suggested as shown in Annex 1 (Choudhury

1996).In Table 5 below their suitability to these three criteria is divided into 15 hypothetical posi-

tions. Selection of a species for a given micro-site using this matrix should integrate all the threephysical factors of the site to arrive at a decision.

Table 5. Site species matrix

Position Soil Texture Salinity Tide inundation

Sandy Concentreted Greater

1 Cs & Hi R N

2 L & Cs L B3 X Cr R

4 A B S

5 E Cs A

6 H E Cr

7 Cr X E

8 R A H

9 B S L

10 A R R

11 R A B

12 B B X

13 N H A

14 S N X

15 R H Cs & Hi

Clayey Dilute Less


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Mangrove afforestation requires a period of about 75 days of "intensive care" from the date ofplanting, while replacement of washed-off, eroded, crab damaged, sickly and dead seedlings needs tobe undertaken along with action to facilitate drainage, remove rubbish and dump brush wood tocombat erosion (Choudhury 1996).

MANGROVE RESERVES

The influence of mangrove ecosystems extends beyond the mangrove forest limits into thecoastal waters. The organic detritus produced by the mangroves is exported at high rates into thecoastal zone and supports the productivity of these waters. Some authors believe that a world-widelink may exist between mangroves and coastal fisheries. The realization of the fact that mangroves

are being constantly depleted and that existing management techniques are inadequate to maintainthis valuable ecosystem as a whole, has raised awareness of the need to create mangrove reserves inan attempt to conserve this ecosystem including its flora, fauna and other biotic and abiotic compo-nents in its natural state.

The creation of mangrove reserves is expected to have a positive impact on biodiversity con-servation. Strict implementation of conservation approaches and maintenance of the reserves need tobe observed to assess its effective impact. It is known, however, that in some countries as in Bangla-desh some sort of collection of forest products is allowed from the reserves declared as such.

RECOMMENDED MANAGEMENT STRATEGYThe old strategy of managing mangroves for forest products alone needs to be reviewed andan integrated ecosystem management approach on a sustained yield basis, under the umbrella of abigger national coastal zone management plan, should be the ultimate present-day aim of mangrovemanagement. Mangrove users, along with the mangrove dwellers, need to receive due considerationand to be incorpored into such management activities to ensure people's participation at large. It issuggested that the following may be considered in this connection.

1. Mangrove management should be a component of the total coastal zone management of thecountry.

2. Mangrove management planning should be a consultative effort between government, non-governmental agencies, resource users, mangrove dwellers and the scientific community.

3. Public awareness should be raised regarding the value of mangroves with special emphasison their linkage effects.

4. An information database needs to be improved with systematic investigations under nationaland international sponsorships.

5. Political commitments towards the sustainable management of mangrove ecosystems will berequired at the national levels.

6. Cooperation among international mangrove institutions should be enhanced to exchange ideasand experience in the field of the mangrove ecosystem and its management.


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CONCLUSIONS

Mangroves owe their existence to the mangrove ecosystem. Mangrove habitats are among themost intriguing places on earth and are special places on the threshold of time, where the life of thesea and the life of the land merge in a biological blur. The continuous world-wide depletion of man-groves through conversion of mangrove lands to other uses is alarming. Present mangrove manage-ment techniques have often failed to retain the original level of the resource. The dynamic nature ofthe ecosystem needs to be duly considered and an integrated management approach on a sustainedyield basis, under the umbrella of a total coastal zone management plan for the country concerned,needs to be initiated with the creation of true mangrove reserves to conserve biodiversity at large.

BIBLIOGRAPHYAksornkoae, S. 1993. Ecology and management of mangroves. IUCN Publication. pp 176Asian Development Bank. 1991. Environmental evaluation of coastal zone projects: Methods and

approaches. pp 72Choudhury, J.K. 1994. Mangrove re-afforestation in Bangladesh. Proceedings on the Workshop on

ITTO Project "Development and Dissemination of Re-afforestation Techniques on MangroveForests" : 18-20 April 1994. Bangkok Thailand. P 186-202.

Choudhury, J.K. 1996. Mangrove forest management. Mangrove rehabilitation and managementproject in Sulawesi. pp 297

Chowdhury, R. A. & Ahmed, I. 1994. History of forest management. Mangroves of the SunderbansVolume two : Bangladesh. Zakir Hussain and Gayatri Acharya (eds.). IUCN Publication. P 155-180

Clough, B. F. 1993. The status and value of mangrove forests in Indonesia, Malaysia and Thailand:Summary. The economic and environmental values of mangrove forests and their present stateof conservation in the South-East Asia/Pacific Region. P 1-10

Baowen, L. et al. 1997. The present sSituation and prospects of mangrove afforestation in China.World Forestry Congress 1997 pp 7FAO. 1985. Mangrove management in Thailand, Malaysia and Indonesia. FAO Environment Paper 4

pp 60FAO. 1982. Management and utilization of mangroves in Asia and the Pacific. FAO Environment

Paper 3 pp 160Forestal Forestry and Engineering International Ltd. 1960. Inventory of Sunderbans Forests.Vencouver, Canada.Giesen, W. 1993.Indonesia's mangroves: An update on remaining area and management issues. Inter-

national Seminar on Coastal Zone Management of Small Island Ecosystem, Ambon. April 7-10,1993. pp 10

Hamilton, L.S. & Snedaker, S.C. 1984 Handbook for Mangrove Area Management. pp 123Hassan, H.H.A. 1981. A working plan for the second 30-year rotation of the Matang Mangrove

Forest Reserve Perak 1980-89. State Forestry Department Publication, Perak, Malaysia. pp 109Hu, S.Y. 1974 Sea-shore plants of Hong Kong. Journal of the Chinese University of Hong Kong vol

2(2). P 315-344JICA 1996 Preservation and development of the Indonesian mangrove forest resource. Intermediate

Report. pp 149.Llaurado, J.P. & Lindquist, A. 1982. Management and utilization of mangroves in Asia and the Pa-

cific. FAO Environment Paper No 3. pp 160Rahman, A.A. 1989. Country report: Malaysia. Mangrove management: Its ecological and economic

considerations. BIOTROP Special Publication No. 37 P 39-41


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Saenger, P., Hegeri, E.J. & Davie, J.D.S. 1983 Global status of mangrove ecosystems. Commissionof Ecology Paper Number 3. IUCN Publication. pp 88

Soemodihardjo, S. & Soerianegara, I. 1989. The status of mangrove forests in Indonesia. Mangrovemanagement: Its ecological and economic considerations. BIOTROP Special Publication No.37 P 73-114

Soemodihardjo, S. & Sumardjani, L. 1994. Re-afforestation of mangrove forests in Indonesia. Pro-ceeding of the Workshop on ITTO Project. 18-20 April 1994, Bangkok, Thailand. P 99-116

Srivastava, P.B.L. Environmental trade-off in mangrove forest management. Marine environmentand coastal zone mangrove forest management. P 105-123

Walsh, G.E. 1974. Mangroves: A review. Ecology of Halophytes. R. J. Reinhold and W. H. Queen(ed.). New York: Academic Press. P 51-174

Velasco, A.B. 1979. Socio-cultural factors influencing the utilization of mangrove resources in thePhilippines: Fishpond vs other uses. D. J. Ganapin, Jr. (ed.). Ecology: Philippine issues and

challenges. P 159-160Zamora, P. M. 1989. Mangroves of the Philippines. Mangrove management: Its ecological and eco-

nomic considerations. BIOTROP Special Publication No 37 P 43-71

ANNEX 1

The 10 genera (+ 2 Mangrove associate) used in the matrix are:

1. Rhizophora = R 2. Bruguiera = B3. Sonneratia = S 4. Heritiera = H5. Lumnitzera = L 6. Ceriops = Cr

7. Avicennia = A 8. Excoecaria = E9. Xylocarpus = X 10. Nypa fruticans = N11. Cassurina = Cs 12. Hibiscus = Hi


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Summaries of voluntary papers

(also published in French, Spanish and Turkish)

TECHNOLOGY TRANSFER FOR MANGROVE AFFORESTATION

Junaid K. Choudhury 1

Mangrove afforestation as a recent addition to plantation forestry involves the use of wildlings,seeds or propagules and seedlings. Mangrove afforestation experience gained by the author whileworking in Bangladesh and Indonesia is briefly described in this paper with an intention to share theknowledge with the foresters in other parts of the world. This describes the nursery technique of fourmangrove species out of 15 so far outlined, along with a brief and general planting technique ofcommon mangrove species.

Keywords:Mangrove, afforestation, nursery, wildlings, propagules.

1 Forest Department, Banabhaban, Glshan Road, Mohakhli, Dakha 1212, Bangladesh.

THE PRESENT SITUATION AND PROSPECTS OF MANGROVE AFFORESTATION IN

CHINA

Zheng Dezhang1; Liao Baowen1; Zheng Songfa1; Li Yun1;

The mangrove afforestation history in China could be divided into three stages: starting, stag-nating, recovering and developing. In the early stage of 1980s, mangrove afforestation began toattract attention. Mangrove nature reserves and production zones were established along the coastalareas, and researchers began to conduct research relevant to mangrove afforestation. Some achieve-ments were made and papers published since then. At present there still exist some problems inmangrove afforestation such as low survival rate of plantations, shortage of funds for afforestationand the superficial knowledge of mangrove importance and values by local people. To deal withthese problems, this paper recommends that work such as research on afforestation techniques, reha-bilitation of secondary forests, management and protection of young plantations should be strength-ened in the future.

1 The Research Institute of Tropical Forestry, Chinese Academy of Foresty, Guangzhou 510520, China.


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DETERMINATION OF MANGROVE FORESTS DISTRIBUTION AND AREAS BY

REMOTE SENSING AND GLOBAL INFORMATION IN IRAN

Sh. Safiary1

The distribution, areas and evaluation of mangrove forests in the Persian Gulf and sea ofOman have been investigated by remote sensing and global observation. The project is divided inthree main parts: Part I focuses on the condition of the forests assessed by global observation; Part IIevaluates the areas of mangrove forests and their distribution in the coastal parts of the Persian Gulfand along the sea of Oman and completes the results of part I by landsat data application and moni-toring; Part III classifies the mangrove forest according to its density assessed by remote sensingtechniques and global information.

The results of the investigation are digitized maps of the forest which shows its distribution,

area and classification. Different tables, figures, histograms and computerized analysis complete thisinvestigation.

1 Scientist, Forest Research Division, research Institute of Forest and Ranglands, P.O. Box 13185-116 Tehran, Iran.Facsimile (98 21) 6026575

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