Ecology and Management’ of Mangroves 1UCN - The World Conservation Union , Founded in 1948, IUCN - the World Conservation Union brings together States, government agencies and’ a diverse range of non-governmental organizations in a unique world partnership:-more than 720 members in all, spread across 118 countries. As a union, IUCN exists to serve its members - to represent their views on the world stage and to provide them with the concepts, strategies and technical support they need to achieve their goals. Through its six Commissions, IUCN draws together over 5000 expert volunteers in project teams and action groups. A central secretariat coordinates the IUCN Programme and leads initiatives on the conservation and sustainable use of the world’s biological diversity and the management of habitats and natural resources, as well as providing a range of services. The Union has helped many countries to prepare National Conservation Strategies, and demonstrates the application of its knowledge through the field projects its supervises. Operations are increasingly decentralized and are carried forward by an expanding network of regional and country offtces, located principally in developing countries. IUCN - The World Conservation Union seeks above all to work with its members to achieve development that is sustainable and that provides a lasting improvement in the quality of life for people all over the world. IUCN Wetlands Programme The IUCN Wetlands Programme coordinates and reinforces activities of the Union concerned with the management of wetland ecosystems. The Programme focuses upon the conservation of ecological and hydrological processes, in particular by developing, testing, and promoting, means of sustainable utilisation of wetlands. It does so in collaboration with IUCN members and partners, in particular those other international institutions with a specific wetlands mandate, especially the Ramsar Convention Bureau, and the International Waterfowl and Wetlands Research Bureau (IWRB). The core of the Programme is a series of field projects which develop the methodologies for wetland management, in particular in the countries of the developing world where wetlands are used intensively by local communities which depend upon these for their well-being. Related strategic and policy initiatives draw upon the results of these projects and present their conclusions in a form useful for government decision makers and planners. The activities of the Programme are designed on the basis of the concerns and information provided by IUCN members. To facilitate this, the Programme works through IUCN’s regional offices. The Programme also works closely with the major development assistance agencies to ensure that conservation considerations are adequately, addressed in their projects. The Wetlands Programme receives generous financial support from the World Wide Fund For Nature (WWF), the Swiss Directorate of Development Cooperation and Humanitarian Aid (DDA), the Finnish International Development Agency (FINNIDA) and the Government of the Netherlands. Project support has been received from the Swedish International Development Authority (SIDA), Norwegian Agency for Development Cooperation (NORAD), United States Agency for International Development (USAID), the Ford Foundation and a number of IUCN members including the Finnish Association for Nature Conservation (FANC), Institut Francais pour le Developpement en Cooperation (ORSTOM), the Royal Society for the Protection of Birds (RSPB), the United States National Park Service (USNPS) and the World Wide Fund For Nature (WWF). It is coordinated from the IUCN Headquarters in Switzerland, with regional coordinators in Central America, South America, Brazil, West Africa, southern Afrfca and Asia. Ecology and Management of Mangroves Shit Aksarnkaae IUCN 1993 I J Published by : copyright : 1993. The International Union for Conservation of Nature and Natural Resources This publication may be produced in whole or part and in any form for education or non-profit uses, without special permission from the copyright holder, provided acknowledgement of the source is made. IUCN would appreciate receiving a copy of any publication which uses this publication as a source. No use of this publication may be made for resale or other commercial purpose without the prior written permission of IUCN Citation : Aksomkoae, Sanit, 1993. Ecology and Management of Mangroves. IUCN, Bangkok, Thailand. ISBN : 2-8317-0165-I Designed and Typeset: IUCN, Bangkok, Thailand. Printed by : Dyna Print Ltd. Part., 39219 2nd Siam Square, Soi 5, Bangkok, Thailand. Cover design : Sarah Skinner Cover photograph : Mangrove Forest in Ranong, Thailand. Sanit Aksomkoae Available from : IUCN South-East Asia Regional Oflice, G.P.O. Box 2754, Bangkok 10501, Thailand. IUCN Wetlands Programme, Rue lvlauvemey 28, 1196 Gland, Switzerland ThC designations of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of the participating organizations concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries The opinions expressed by the authors in this publication do not necessarily represent the view of IUCN . c SANIT AKSORNKOAE has been involved with mangrove forest ecosystems for more than 20 years. He is an international figure in the field of mangrove . ecology and forest management. He has played a leading role in the study of many mangrove research projects and in national (Thai) and multinational symposia, conferences and workshops, involving the diverse scientific ’ disciplines which find their focus in mangroves. His participation has taken him on study tours to different parts of the world including Australia, Brazil, Bangladesh, Brunei, . Costa Rica, Ecuador, Honduras, Fiji, India, Indonesia, Japan, Malaysia, Philippines, Puerto Rico, Singapore, the U.S.A. and Vietnam. Sanit Aksomkoae holds the degrees of B.S. in Forestry; M.S. in Silviculture from Kasetsart University, Bangkok and a Ph.D. in Plant Ecology from ’ Michigan State University, U.S.A. ’ He is, at present, Vice-President for Academic Affairs and Professor of Silviculture in the Faculty of Forestry at Kasetsart University, Bangkok, Thailand. ’ i , J Contents Foreword ix List of Figures X . List of Tables XI11 Acknowledgements xv CHAPTER 1 INTRODUCTION 1 1.1 Historical background 1 1.2 The definition of mangroves 1 1.3 Distribution of mangroves 2 1.4 Distribution of mangroves in Thailand 6 CHAPTER 2 THE SIGNIFICANCE AND VALUE OF MANGROVES 11 2.1 Forestry 11 2.1.1 Charcoal 11 2.1.2 Firewood 11 2.1.3 Poles 14 2.1.4 Tannin extraction 14 2.1.5 Wood distillation 15 2.1.6 Wood-chips 15 2.1.7 Medicines 17 2.1.8 Other products 17 2.1.9 Nipa 17 2.2 Mangrove Forest and Fisheries 20 2.2.1 Mangroves as an important food source 20 2.2.2 Mangroves as shelters and nurseries 22 2.2.3 Fisheries 24 2.2.4 Maintaining a Natural Ecological Balance 25 CHAPTER 3 ENVIRONMENTAL FACTORS 27 3.1 The mangrove ecosystem 27 3.1.1 Structure 27 3.1.2 Functions 28 3.2 Concepts regarding Environmental Factors 32 3.3 Environmental factors 33 3.3.1 Coastal Physiography 33 3.3.2 Climate 35 3.3.3 Tides 36 3.3.4 Waves and Currents 38 3.3.5 Salinity 38 3.3.6 Dissolved oxygen 39 3.3.7 Soil 40 3.3.8 Nutrients 43 3.4 Climatic conditions of mangroves in Thailand 43 ‘CHAPTER 4 MANGROVE FLORA . 47 Mangrove flora 47 4.1.1 Species formation 47 i 4.1.2 Epiphytes in the mangroves . 50 4.1.3 Algal flora in the mangroves 50 4.2 Zonation of mangrove species 55 4.2.1 Physio-chemical factors of soil 55 4.2.2 Salinity of soil water 56 4.2.3 Drainage and tidal currents 56 4.2.4 Soil moisture 57 4.2.5 Frequency of inundation 57 4.3 Adaptations of Mangrove Plants 61 62 4.3.1 Adaptation characteristics. of. mangrove plants CHAPTER 5 MANGROVE FAUNA 69 5.1 Diversity of mangrove fauna . 69 5.1.1 Shrimps 69 5.1.2 Fishes 70 51.3 Crabs 70 5.1.4 Molluscs 74 5.1.5 Other animals of the mangroves 75 5.2 Distribution of mangrove fauna 77 5.2.1 Tidal inundation and exposure 77 5.2.2 Substrate preference 77 5.2.3 Salinity 78 ’ 5.2.4 Temperature 78 5.3 Adaptations of mangrove fauna 78 5.3.1 Adaptation to salinity 78 5.3.2 Adaptation to high temperature 81 5.3.3 Adaptation in respiration 82 5.3.4 Adaptations in food and feeding 82 5.3.5 l. Adaptation in reproduction 83 i CHAPTER 6 MANGROVE PRODUCTIVITY. 85 6.1 Mangrove plienology 85 6.2 Growth of mangrove 89 6.2.1 Natural mangrove forest 89 6.2.2 Mangrove Plantation 92 6.3 Litter fall and decomposition 94 6.3.1 Litter Production or Litter Fall 94 6.3.2 Litter Decomposition 96 6.3.3 Nutrient recycling via litter decomposition 97 6.4 Standing biomass 98 6.5 Mangrove phytoplankton productivity 101 6.6 Mangrove fauna productivity 101 / J CHAPTER 7 MANGROVE DEGRADATION AND DEPLETION 103, 7.1 The present situation 103 _ 7.2 Factors contributing to mangrove degradation and depletion 109 ‘X 7.3 Environmental impacts of mangrove degradation 110 7.3.1 Aquaculture 110 7.3.2 Mining 113 7.3.3 Agriculture 114 7.3.4 Urbanization 114 7.3.5 Industry 114 7.3.6 Other Activities 114 CHAPTER 8 SILVICULTURAL SYSTEMS FOR MANGROVE MANAGEMENT 117 8.1 Objectives of mangrove management 117 8.2 Silvicultural systems for mangrove management 117 8.2.1 Silviculture for natural forests 117 8.2.2 Silviculture for mangrove plantations 121 8.3 Silvicultural systems in Thailand 122 8.3.1 Natural forests 122 8.3.2 Mangrove plantations 128 8.4 Recommendations