DYNAMIC ECOLOGY OF MANGROVE

Description

The study of mangroves has evolved over time, from the earliest historical and biogeographic descriptions of the 16th and 17th centuries made by travellers and explorers who encountered this unique ecosystem in the tropical and sub-tropical areas, to the present century where the ecosystem is among the most endangered in the world. Although the mangrove environment often formed a part of the earlier descriptions, details of habitat preferences and morphological adaptations of the mangrove species were either lacking or highly speculative and did not attract much research interest until the middle 19th century to 20th century. Analytical insights into mangrove structure have only emerged from about 1920 in Southeast Asia and about 1940 in the American continents. The African continent had remained relatively uninvestigated. The importance of the mangrove ecosystem was not realized until its resources had been almost irreversibly depleted.

The mangrove swamps have often been thought of as a simple ecosystem where the occurrence of plant species relates directly to salt concentrations and shore topography. This may be true since mangroves tend to occupy brackish or saline shores where freshwater species intolerant of salt cannot exist. However, the apparent simplicity of the ecosystem has perhaps been over stressed for in seeking a theoretical backing for this relatively less complex vegetation structure, emphases have been placed on the classical concepts of vegetation zonation, succession and the climax. Mangroves may occur in fairly defined zonation in regions of marked wet and dry spells of climate which correspond to high and low salinity values. But in continuously wet areas, fluctuation in salinity may be marginal especially in estuaries that have abundant freshwater inputs from inland streams. An alternative concept to the classical zonation theory appears to offer a more satisfactory approach to the study of mangrove ecosystem; the concept of dynamic equilibrium does not only relate to changing vegetation, but to a landscape constantly influenced by active fluvial processes. These fluvial processes give rise to various physiographic habitats that affect species composition and distribution in the swamps. The book is divided into four sections:

Section One

This section contains a biogeographic description of mangrove forests based on recognized regions which do not necessarily follow eco-regional patterns. It is an introduction to mangrove and how the ecosystem evolved, including some of the species which have been generally observed to occur in mangroves. The general distributional pattern and extent of mangrove growth globally and in Africa are discerned and discussed. It also examines mangrove biodiversity and benefits and the consequences of mangrove destruction. Mangroves in West and Central Africa, with particular assemblages in the River Niger Delta and southeastern Nigeria are discussed including methods of field studies. Included in this section are mangroves of North, Central, Southern America, and the Indo-Pacific and Australian region which are discussed in terms of biodiversity, distribution and coverage.

Section Two

Section two is made up of four chapters and deals majorly with mangrove habitats and environment. It treats the evolution of mangrove habitat, the morphology of the habitats and how species assemblages are indicators of habitats types. Mangrove swamp soils are treated in detail with particular reference to southeastern Nigeria. The soil profiles and characteristics are described, including the hyperspace relations of soil attributes. The importance of salinity, tidal range and other factors are assessed in the section.

Section Three

Section three adopts a quantitative approach to the analysis of mangrove forest structure. It seeks to interpret quantitatively the interrelations of the mangrove vegetation and soils attributes separately and then jointly together through the recognition of environmental gradients. Simultaneous consideration of the vegetation and soil gradients are used to produce non-mapped outputs as alternatives to the understanding of the direction of change in the mangroves.

Section Four

This section deals with mangrove ecosystem threats and functions. The main threats faced by the mangroves are examined, including the scale of mangrove loss globally and in regions. Mangrove ecosystem functions and services are also discussed, including valuation which has been in serious debate as it determines attitude which people adopt to mangrove management. The various approaches to mangrove management, restoration and rehabilitation of degraded forests are also considered in this section.

Imoh Etukudo Ukpong

Department of Geography & Natural Resources Management
University of Uyo, Nigeria

TABLE OF CONTENT
CHAPTER ONE: Introduction To Mangrove
1.1: Definition of Mangroves – – – – – – 2
1.2: Evolution of Mangrove Ecosystem – – – – 3
1.3: General Distribution Pattern of Mangroves – – – 4
1.3.1: Extent of mangrove growth – – – – – 4
1.3.2: Broad categories of mangrove – – – – – 8
1.3.3: Mangrove area coverage – – – – – – 9
1.3.4: Mangrove area coverage in Africa, extent and distribution – – 12
1.4: Mangrove Biodiversity in Africa – – – – – 12
1.5: Natural and Economic Benefits of Mangroves – – – 12
1.6: Destruction of Mangroves and their Consequences – – – 14
1.7: References – – – – – – – 17
CHAPTER TWO: The West Africa and Central Africa Mangroves
2.1: Introduction – – – – – – – 21
2.2: Coasts and Mangroves in West Africa – – – – 21
2.3: Factors Affecting the Development of Coastal Vegetation in
West Africa – – – – – – – 21
2.4: Physiographic Mangrove types in West and Central Africa – – 22
2.5: Mangrove Species of the West and Central Africa Region – – 25
2.6: Mangrove Area in West and Central Africa – – – 26
2.7: The Mangrove of southeastern Nigeria – – – 27
2.8: Community Analysis of the Mangroves – – – 28
2.8.1: Field methods – – – – – – – 29
2.9: General Distributional Patterns of Mangroves in Southeastern Nigeria 30
2.9.1: The Greek Town/Calabar River mangrove swamp – – – 31
2.9.2: The Cross River mangrove swamp – – – – 32
2.9.2.1: Mangrove segments of the Cross River swamp – – – 38
2.9.3: The KwaIboe River mangrove swamp – – – – 42
2.9.3.1: Segments of the Kwa Iboe River mangroves – – – 43
2.9.4: Imo River mangrove swamp – – – – – 45
2.9.4.1: Segments of the Imo River mangrove swamp – – – 46
2.10: Correlations among the Mangrove Swamps – – – 48
2.10.1: Comparison of species populations – – – – 48
2.10.2: Comparison of species structure – – – – 49
2.10.3: Comparison by similarity indices – – – – – 52
2.11: Summary of Analyses – – – – – – 55
2.12: References – – – – – – – 56
CHAPTER THREE: North, Central and Southern America Mangroves
3.1: General – – – – – – – 59
3.2: Mangrove Biodiversity – – – – – 60
3.3: Extent of Mangrove Coverage – – – – – 60
3.4: South America Mangroves – – – – – 62
3.4.1: Southern Dry Pacific Coast mangroves – – – 62
3.4.2: Environment of Moist Pacific Coast Mangroves – – 64
3.4.2.1: Species diversity – – – – – – – 65
3.4.3: Mexican South Pacific coast mangroves – – – 66
3.4.3.1: Location and environment – – – – – 66
3.4.3.2: Biodiversity and productivity – – – – – 66
3.4.4: South America Guiana mangroves – – – – 66
3.4.4.1: Location and Environment – – – – – 66
3.4.4.2: Species distribution – – – – – – 67
3.4.4.3: Coverage and structure – – – – – 68
3.5: References and Suggested Readings – – – – 68
CHAPTER FOUR: East Africa and South Africa Mangroves
4.1: Location and Environment – – – – – 72
4.2: Species Diversity – – – – – – 73
4.3: Mangroves of Tanzania – – – – – 75
4.4: Kenya Mangroves – – – – – – 76
4.5: Somalian Mangroves – – – – – – 77
4.6: Mangroves of Mozambique – – – – – 78
4.7: Mangroves of Madagascar – – – – – 78
4.8: South African Mangroves – – – – – 79
4.9: References and Suggested Readings – – – – 80
CHAPTER FIVE: Indo-Pacific and Australian Mangroves
5.1: General – – – – – – – 83
5.2: Mangroves of Malaysia – – – – – 85
5.3: Sarawak Mangroves – – – – – – 88
5.4: Philippines Mangrove – – – – – – 89
5.5: Mangroves of Papua New Guinea – – – – – 90
5.6: Mangrove of Thailand – – – – – – 91
5.7: Australian Mangroves – – – – – – 93
5.8 References – – – – – – – 96
SECTION TWO
THE MANGROVE SWAMP HABITAT
CHAPTER SIX: Mangrove and Habitat Evolution
6.1: General Habitat Characteristics – – – – 100
6.2: Importance of Tidal Range – – – – – 101
6.3: Coastal Sedimentary Belts, Estuaries and Mangrove Growth – 101
6.4: Estuarine Landforms – – – – – – 102
6.5: Evolution of Mangrove Habitats – – – – – 103
6.6: Mangrove Habitat Evolution in Southeastern Nigeria – – 106
6.6.1: Geomorphic units and vegetation components of the Creek Town
Creek/Calabar River swamp – – – – – 106
6.6.2: Geomorphic units and vegetation components of the
Cross River swamp – – – – – – 106
6.6.3: Geomorphic units and vegetation components of the
KwaIboe River swamp – – – – – – 106
6.6.4: Geomorphic units and vegetation components of the
Imo River swamp – – – – – – 107
6.7: Mangrove Habitat Morphology – – – – 107
6.8: Habitat- Environment Relations – – – – 112
6.9: Mangrove Communities – – – – – 114
6.10: Sedimentation in Mangrove Swamp Forests – – – 116
6.11: References – – – – – – – 120
CHAPTER SEVEN: Morphology of Mangrove Habitats and Species Distribution
7.1: Introduction – – – – – – – 123
7.2: Fluvial Sub-type of the Alluvial Mangroves – – – 123
7.3: Scrub-Mangrove Sub-type – – – – – 127
7.4: Tidal Flats – – – – – – – 128
7.5: Composition and Distribution of Species on Physiographic Habitats 129
7.6: Similarity of Mangrove Habitats – – – – – 136
7.7: Causes of Variation in species Composition – – – 137
7.8: References – – – – – – – 138
CHAPTER EIGHT: Mangrove Swamp Soils
8.1: Introduction – – – – – – – 140
8.2: Mangrove Soil Profiles – – – – – – 140
8.3: Classification of Mangrove Soils – – – – – 140
8.4: Profile Characteristics – – – – – – 142
8.5: Profile Descriptions – – – – – – 144
8.6: Tidal Flats – – – – – – – 149
8.7: Soil Profiles under Different Mangrove Species – – 150
8.8: Variability of Soil Chemical Properties in Mangrove Swamp Soils – 153
8.9: Variability of Soil Properties in Mangrove Physiographic Habitats – 157
8.9.1: Variability of soil properties – – – – – 157
8.9.2: Variability of some soil chemical properties – – – 158
8.9.3: Variability of soil acid properties and micronutrients in
mangrove habitats – – – – – – 159
8.10. The internal Structure of the Mangrove Soil System – – 159
8.10.1: Investigating the internal structure of mangrove soils by
correlation analysis – – – – – – 160
8.10.2: Investigating the internal structure of mangrove soils by principal
componentanalysis – – – – – – 164
8.11: Conclusion – – – – – – – 166
8.12: References and Suggested Readings – – – – 169
CHAPTER NINE: Salinity, Tidal Range and Associated Factors in Mangrove Swamps
9.1: Introduction – – – – – – – 172
9.2: Variation of Soil Salinity in Mangrove Swamps – – 173
9.2.1: Influence of microtopography on the variability of soil salinity in
mangrove swamps – – – – – – 173
9.2.2: Spatial variation of soil salinity from shorelines – – – 175
9.3: Salinity and Limits of Mangrove Growth – – – – 175
9.4: Tidal Range and Mangrove Zonation – – – – 176
9.5: Mangrove Soils and Species Zonation – – – – 179
9.6: Influence of Mangrove Species on the Characteristics of
Mangrove Soils – – – – – – – 184
9.7: Contamination of Mangrove – – – – – 185
9.8: References – – – – – – – 187
SECTION THREE
ENVIRONMENTAL AND VEGETATION GRADIENTS IN MANGROVE SWAMPS
CHAPTER TEN: Structure of the Mangrove Vegetation System
10.1: Introduction – – – – – – – 193
10.2: Ordination of Correlation Coefficients – – – 195
10.3: Species Ordination by Principal Components Analysis – 197
10.4: Stand Ordination by Principal Components Analysis – – 200
10.5: Ecological Distortion of Mangroves through the Introduction of
Nypa Palm – – – – – – – 206
10.5.1: Nypa palm in the River Niger Delta, Nigeria – – – 207
10.5.2: Distribution of Nypafruticans in the River Niger Delta – 208
10.5.3: Mangrove habitats and relationship with Nypa growth – – 209
10.5.4: Influence of Nypafruticans on mangrove swamp soils – 211
10.5.5: The place of Nypafruticans in mangrove vegetation succession 212
10.5.6: The dynamic threat of Nypafruticans – – – – 213
10.6: References – – – – – – – 216
CHAPTER ELEVEN: Factor Gradients in Mangrove Swamps
11.1: Introduction – – – – – – – 219
11.2: Gradient Analysis – – – – – – 219
11.2.1: Principles of Gradient Analysis – – – – 219
11.3: Nature of Gradients in Mangrove Swamps – – – – 220
11.4: Direct Gradient Analysis Procedures – – – – 221
11.4.1: The factor gradient – – – – – – 221
11.5: Implications of Environmental Gradients to Ecological
Species Groups – – – – – – 221
11.5.1: Derivation of Ecological Species Groups – – – 222
11.6: The Environmental Transect – – – – – 222
11.6.1: The salinity of gradient – – – – – 223
11.7: The Nutrient Gradient – – – – – – 226
11.8: Implications of Factors Gradients – – – – – 234
11.9: References – – – – – – – 234
CHAPTER TWELVE: Complex Gradients in Mangrove Swamps
12.1: Introduction – – – – – – – 237
12.2: The Complex Gradient – – – – – – 237
12.3: Multiple Regression Analysis Models – – – – 237
12.4: Multiple Regression Solutions of complex Gradients in
Mangrove Swamps – – – – – – 239
12.5: Inclusion of more Variables – Site factors and Indexes – 244
12.6: Conclusion – – – – – – – 246
12.7: References – – – – – – – 247
CHAPTER THIRTEEN: Floristic Gradation and Continuum in Mangroves
13.1: Introduction – – – – – – – 248
13.2: The Composite Environmental Transect – – – 248
13.3: Data Processing – – – – – – – 248
13.4: Spatial Disposition of Mangrove in Relation to the Complex Gradient 249
13.5: Spatial Distribution of Groundlayer Species along
Environmental Gradients – – – – – – 259
13.6: Spatial Distribution of Mangrove Saplingsalong
Environmental Gradients – – – – – – 259
13.7: Ecological Amplitudes of Mangroves – – – – 261
13.8: The Continuum Index – – – – – – 263
13.9: Conclusions – – – – – – – 266
13.10: References – – – – – – – 269
CHAPTER FOURTEEN: Vegetation-Environment Correlation in Mangroves
14.1: Introduction – – – – – – – 272
14.2: Statistical Approach – – – – – – 273
14.3: Data Processing for Principal Components Analysis – – 273
14.4: Results of Principal Components Analysis – – – – 275
14.4.1: The mangrove biomass analysis – – – – 276
14.4.2: Variation in mangrove biomass/productivity in relation to variation
in the environment – – – – – – 280
14.4.3: Variation in species distribution in relation to variation in the
Environment – – – – – – – 282
14.5: Simple Correlations – – – – – – 282
14.6: Correlations of Mangrove Community Types and Physiographic
Habitat Types with Salinity Factors – – – – 286
14.7: Conclusion – – – – – – – 288
14.8: References – – – – – – – 289
CHAPTER FIFTEEN: Linking the Vegetation and Environment in Mangroves
15.1: Introduction – – – – – – – 291
15.2: Mangrove Biomass- Environment Interrelationship – – – 292
15.3: Mangrove Species – Environment Interrelationship – – – 294
15.4: Analysis of Variations in Vegetation and Environment – 299
15.5: Conclusion – – – – – – – 301
15.6: References – – – – – – – 302
SECTION FOUR
FUNCTIONS AND MANAGEMENT OF MANGROVES
CHAPTER SIXTEEN: Mangrove Ecosystem Threats
16.1: Introduction – – – – – – – 310
16.2: Regional Threats – – – – – – 314
16.2.1: West and Central Africa – – – – – 314
16.2.2: East Africa and South Africa – – – – – 317
16.2.3: Central America and South America – – – – 318
16.2.4: Southeast Asia, China, Indonesia and the Philippines – – 319
16.3: Global Warming and Climate Change – – – – 322
16.3.1: Short-term climate change – – – – – 322
16.3.2: Long –term climate change – – – – – 323
16.3.3: The responses of mangroves to change in sea level – – – 325
16.4: References – – – – – – – 327
CHAPTER SEVENTEEN: Mangrove Ecosystem Functions
17.1: General – – – – – – – 335
17.2: Traditional Uses of Mangroves – – – – 336
17.3: Ecosystem services – – – – – – 339
17.4: Conservation of Biodiversity – – – – – 343
17.4.1: Biodiversity in West Africa – – – – – 344
17.4.2: Biodiversity in Central America and Southern Pacific mangroves – 344
17.4.3: Biodiversity in Eastern Africa mangroves – – – – 346
17.4.4: Biodiversity in Indo-Pacific mangroves – – – – 347
17.5: Ecotourism – – – – – – – 348
17.6: Biotic functions of mangroves – – – – – 349
17.6:1: Firewood ad charcoal – – – – – – 349
17.6.2: Timber and pulp – – – – – – – 349
17.6.3: Aquaculture – – – – – – – 350
17.6.4: Fisheries – – – – – – – – 350
17.7: Benefits of Mangroves Estimated in Market Prices – – – 351
17.8: Climate Change Mitigation – – – – – 354
17.9: References – – – – – – – 355
CHAPTER EIGHTEEN: Management of Mangroves
18.1: Introduction – – – – – – – 360
18.2: Rationale and Objectives for Mangrove Conservation and Management 364
18.3: Approaches to the Management of Mangroves – – 366
18.3.1: Ecosystem Approach – – – – – – 366
18.3.2: Integrated Coastal Zone Management – – – – 368
18.3.3: Policy, planning and development at international level – – 368
18.4: Obstacles to Operation and Management of Mangroves – – 373
18.5: International and Regional Management of Mangroves – – 373
18.5.1: Marine Protected Areas – – – – – 373
18.5.2: Bio-regional management – – – – – 373
18.5.3: Transboundary Protected Areas – – – – 374
18.5.4: Biosphere Reserves – – – – – – 374
18.6: Management of Mangrove Genetic Resources – – 374
18.7: Policy, Planning and Development at the National,
Local Government and Community Levels – – – 375
18.8: Environmental Law – – – – – – 378
18.9: General Management Blueprint – – – – 379
18.10: Mangrove Conservation and Management Guidelines – – 381
18.10.1: International Collaboration – – – – – 381
18.10.2: Legislative framework for management of mangroves – 382
18.10.3: National mangrove plans – – – – – – 383
18.10.4: Mangrove preservation – – – – – 383
18.10.5: Integration of all levels of sectoral planning and decision making – 385
18.11: Socio-Economic Considerations in the Management of Mangroves – 386
18.12: References – – – – – – – 387
CHAPTER NINETEEN: Mangrove Restoration and Rehabilitation
19.1: Introduction – – – – – – – 390
19.2: Rationale for Rehabilitation and Restoration of Management Forests 391
19.3: Mangrove Restoration Framework – – – – 393
19.4: Restoration and Rehabilitation Goals – – – – 394
19.5: General Principles of Restoration – – – – – 395
19.5.1: Importance of the mangrove physical habitat – – – 395
19.6: Criteria for Mangrove Restoration – – – – – 396
19.7: Site Selection for Restoration – – – – – 397
19.7.1: Ecological and hydrological mangrove restoration – – – 398
19.7.2: Mangrove hydrology – – – – – – 401
19.8: Re-Establishing Mangrove Trees – – – – – 402
19.9: Socio-Economic Benefits of Mangrove Restoration – – – 403
19.10: Conclusion – – – – – – – 405
19.11: References and Suggested Readings – – – – 405
INDEX