1

THE RESTORATION OF MANGROVE VEGETATION ALONG

THE COASTAL BELT OF GUYANA

BY IVELAW JULIAN EVANS

A thesis paper submitted to the Department of Forestry, University of

Aberdeen in partial fulfilment of the requirements for the degree of

Master of Science in Forest Management.

_______________________________________________________________________

______

August, 1998.

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CONTENTS

ABSTRACT

CHAPTER ONE - INTRODUCTION 1

1. INTRODUCTION 1-2

2. BACKGROUND TO THE PROBLEM OF FLOODING 2

(a) HISTORICAL DESCRIPTION OF THE COAST 2-3

(b) SHORELINE DYNAMICS AND VULNERABILITY OF THE 3-6

COAST TO EROSION

3. MANGROVE AS A POSSIBLE SOLUTION 6-7

CHAPTER TWO - MANGROVES 7

1. MANGROVE VEGETATION 7

(a) GENERAL DESCRIPTION OF MANGROVES 7-8

(i) PHYSICAL ENVIRONMENT OF MANGROVES 8-9

(ii) DISTRIBUTION OF MANGROVE SPECIES 9-10

(iii) MANGROVE ECOLOGY AND COMPOSITION 10-12

(b) NATURAL COMMUNITY STRUCTURE AND DYNAMICS 12

1. NATURAL SUCCESSION 13

(i) REGENERATION AND ESTABLISHMENT OF MANGROVES 13-15

(ii) TOLERANCE TO SHADE 15-16

(iii) PREDATION 16-17

2. ZONATION IN MANGROVES AND DIFFERENCES AMONG 17

SPECIES

(i) ZONATION PATTERNS 17-18

(ii) SALINITY TOLERANCE OF CERTAIN SPECIES 19

2. GLOBAL IMPORTANVE OF MANGROVES 19-20

3. ROLE OF MANGROVES IN COASTAL PROTECTION IN GUYANA 20-21

CHAPTER THREE - CURRENT STATUS OF MANGROVE 21

VEGETATION IN GUYANA

1. CURRENT STATUS OF MANGROVE VEGETATION IN GUYANA 21-22

(a) CAUSES OF DECLINE OF MANGROVE VEGETATION 22-23

2. GENERAL PERCEPTION OF THE MANGROVE FORESTS 24-26

3. SPECIFIC VALUES OF COASTAL GUYANA 26-27

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4. THE NEED FOR RESTORATION OF MANGROVE FOREST 28-30

CHAPTER FOUR - ACTION PLAN FOR RESTORATION 30-32

1. SITE SELECTION 32

(a) IDENTIFICATION OF SITES 32-35

(b) RECONNAISSANCE AND GROUND VERIFICATION SYUVEY 35-36

2. SPECIES SELECTION AND NURSERY CONSIDERATIONS 36

(a) SELECTION OF SPECIES 36-37

(b) PLANTING STOCK 37-38

(c) COLLECTION OF PLANTING STOCK 38-39

3. PLANTING AND MAINTENANCE PROGRAMME 39

(a) PLANTING PROCEDURE 39-41

(b) MAINTENANCE PROGRAMME 41-42

4. CONSIDERATION FOR IMPLEMENTATION 42

(a) EDUCATION AND TRAINING 43

(b) STUDIES AND INVESTIGATION 44-45

(c) MODEL PLOTS 45

(d) REVIEW AND REVISION OF CURRENT LEGISLATION 45-46

CHAPTER FIVE - DISCUSSION AND CONCLUSION 47-52

ACKNOWLEDGMENT 52

LITERATURE CITED 53-57

APPENDICES

APPENDIX 1 - VEGETATIVE MAP OF GUYANA

APPENDIX 2 - ADMINISTRATIVE MAP OF GUYANA

APPENDIX 3 - BROAD ECOLOGICAL ZONES OF GUYANA

APPENDIX 4 - PRODUCTS OF MANGROVE ECOSYSTEMS

APPENDIX 5 - DISTRIBUTION OF STATE FORESTS

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Appendix 4

PRODUCTS OF MANGROVE ECOSYSTEMS (Hamilton and Snedaker, 1984).

Fuel &

Household

Construction Fishing &

Food

Textile Others

Firewood Timber Poles for fish trap Dyes for cloth Paper products

Charcoal Railway ties Fishing boats Tannins Fish

Alcohol Boat building Fish attracting

shelters

Synthetic fibres

(rayon)

Medicines (bark,

leaves and fruits)

Furniture Dock pilings Wood for

smoking fish

Crustaceans

(crab, shrimp)

Glue Beams and Poles Alcohol Shellfish

Tool handles Flooring Cooking oil Wax

Toys Panelling Vinegar Honey

Match sticks Thatch roofing Tea substitutes Mammals

Incense Matting Dessert topping Birds

Mortar Fence posts Vegetables (fruits

or young leaves)

Reptiles/other

fauna

Hairdressing

oil

Chipboards Condiments

(bark)

Wood for drying

tobacco

Packing boxes Sweetmeats

(propagules)

Wood for

bakeries and

brick kilns

Wharfing Fermented drinks

Scaffolds Sugar

Mining props Tannins for net

and line

preservation

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ACKNOWLEDGMENT I am greatly indebted to all those who have assisted me in the fulfilment of my

thesis paper as a requirement for the Master of Science degree, Forest Management by providing information, technical assistance, facilities, advice and guidance.

Special thanks are due to my supervisors Dr. Michelle Pinnard and Dr. Andrew Cameron, Department of Forestry, University of Aberdeen, Mr. Godfrey Marshall, Senior Assistant Commissioner of Forests, and Ms. Janice Bollers, Silvicultural Officer both of the Guyana Forestry Commission, Mr. Kent Apostol and Dr. Enrique Tolentino of the University of Philippines, and the Overseas Development Administration / International Resource Development for their sponsorship.

Appreciation is also given to my wife, Mrs. Elwyn Evans, Dr. Jorge Jimenez of Costa Rica and Dr. June Evans of Sycamore Place, Aberdeen, United Kingdom for their continuous support.

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ABSTRACT The coastal belt of Guyana is regularly subjected to severe erosion resulting from wave action. A sea defence system consisting of masonry and earthen walls or embankments has been constructed over 238 km along the coast, which from time to time, is breached causing economic damage to agricultural crops and housing by intruding saline water. At the time of colonisation, the entire Guyana coast was fringed by mangrove vegetation. Most of it has been depleted or even destroyed by human activities. Mangrove vegetation will take at least 5 to 7 years to be established well enough to be able to provide any protection to the sea defence system. This paper examines the possibility of restoring the mangrove vegetation along the coastal belt of Guyana. It includes the background to the problem of flooding, the current status of mangrove vegetation, indicating the causes of decline and the general perception of the mangrove forests, as well as the need for restoration of mangroves. The paper suggests an action plan for the restoration of mangrove vegetation in the coastal mudflats, to be used as a protective barrier against sea waves and to support the current sea defence system. This involves identification of suitable sites along the coast, species selection, planting and maintenance, and considerations for implementation. The paper strongly recommends a small scale plantation programme be initiated in Regions 2, 3, 4 and 5 with A. germinans and Region 6 with R. mangle, based on evaluation of the performance of the programme before a large scale programme be undertaken. The need to create an infrastucture and professional cadre for the protection and management of mangrove forests, and educating people on the importance and many benefits of mangrove forest on the coastal belt of Guyana will be a necessity. An integrated project for the sustainable management of both forestry and non- forestry resources of a mangrove ecosystem can be taken up involving coastal dwellers. The paper recommends the need for policies, and revision of current legislation on the management of mangrove forest to co-ordinate the responsibilities and interests of relevant institutions. The need for future research on the coastal zone is supported, and four major research programmes are proposed. A multi-disciplinary project along the Barima-Waini coast is suggested, whilst other areas along the coast are suitable for a number of specialist projects. A suggestion to carry out environmental impact assessments on future coastal development is made mentioned of.

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CHAPTER ONE - INTRODUCTION

1. INTRODUCTION

The coastal belt of Guyana lies generally between 0.5 to 1.0 m below high spring tide level, resulting in the coastal belt being vulnerable to flooding by sea water from the Atlantic Ocean. Protective masonry and earthen walls have been constructed over time for the protection of the coastal regions from sea-water, as a consequence, mangrove vegetation was eliminated from most areas along the coastal belt. However, due to shifting sand banks and silty soils, large-scale erosion has led to breaches in the coastal walls, resulting in inundation of agricultural lands and serious economic damage to crops, livestock and properties. In some places along the coastal belt, sea-water flows over the sea wall during high tides.

Due to high rainfall rates and persistent high tides, drainage of excess water into the sea through sluiced canals was impossible. This resulted in the accumulation of water, the breakage of retaining walls in several places, and consequent intrusion of saline water into the already flooded areas. The standing water caused the loss of livestock, damage to crops, housing and other structures.

Major breaches in the seawall occurred at the end of March 1989, January 1991, May 1994 and June 1996 (Chronicle, 1996). In one such incident, a breach had occurred in an earthen dam located near the mouth of the Essequibo River (Orangestein) and extensive areas of crop lands were affected. It was estimated that “about 2000 acres of rice and vegetable crops were destroyed by sea water and this had affected more than 5000 people directly” (Hussain, 1990). Given the relative frequency of flooding and the high costs associated with them, it is important to explore options for reducing the incidence of flooding along the coastline of Guyana.

The aim of the thesis is to develop a plan for the restoration of mangrove vegetation along the coastal region of Guyana as a means of improving protection and a support to the sea defence system. The specific objectives are: 1. to review the background to the problem of coastal flooding 2. to describe mangrove vegetation and natural community structure and dynamics 3. to describe the current status of mangroves in Guyana and their potential role in

coastal protection 4. to develop an action plan for the restoration of mangroves along the coastline for

protection and support to the sea defence system. The action plan will include, site and species selection, planting and maintenance programme, other components of the programme and considerations for immediate and long-term implementation.

2. BACKGROUND TO THE PROBLEM OF FLOODING (a) HISTORICAL DESCRIPTION OF THE COAST

Before colonisation by the Europeans in the 17th century, the Guyana coastal area

was inhabited by a large number of Amerindian tribes (Arawak and Warrou), and was fringed by a belt of mangrove vegetation 3-5 km in width behind which laid swamp savannahs occupied by sedges and aquatic plants (Dalton, 1855).

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When the Dutch settlers came to Guyana in the early 17th century, they found the physical features of coastal Guyana to closely resemble those of the Netherlands (Holland) and adopted methods of land reclamation, which were practised in their native country. The land to be reclaimed was surrounded by dams to keep out water from the land-ward side and a sea wall to protect it from the Atlantic Ocean. This system was developed to reduce flooding of the coastal belt during high rainfall and spring tides.

The European settlers converted the Guyana coastal area into a major seat of agricultural production (cotton, coffee, sugarcane, cocoa and rice) (Appendix 1). The coastal area was cut into sections by irrigation and drainage canals, and drained by means of sluices or kokers in the sea wall. The sluices were normally opened during the low tide. As a result of the conversion of the coastal land into agricultural fields, the original mangrove vegetation of the coastal region was altered and the conditions within the sea wall, therefore, became artificial and provided no scope for mangrove vegetation to thrive. (b) SHOREINE DYNAMICS AND VULNERABILTY OF THE COAST TO EROSION

The foreshore of Guyana is covered by mud flats and sandy deposits (Figure 1).

As a result of frequent changes in ocean currents, the actual shoreline undergoes a continuous process of alteration. In some areas, high tides threaten the sea defence system while in other areas accretion is taking place.

The greater part of the foreshore laid down consists of soft mud flats which are deposited in the form of a bank stretching out from the sea wall. In addition to the mud, sand and broken shells are brought in by spring tides and wave actions and are deposited inshore. This ultimately results in the formation of small sandy beaches in places along the sea wall. In some areas, the sand is mixed with the mud giving it a firmer consistency.

Because the coastal belt of Guyana is below sea level, earthen embankments and masonry sea walls have been erected along the sea-coast as a defence against the intrusion of sea water into these regions. These structures are collectively known as sea defences (sea walls). According to Hussain (1990), 169 km of earthen embankments and 69 km of masonry sea walls have been constructed. In addition, another 78 km of the coastline has been reported to be protected by natural sand banks (Augustinus and Mees, 1984).

Guyana experiences natural dynamics of the shoreline, which threatens the sea defence system. The coastline of Guyana is dominated by the occurrence of large mud banks. The mud banks and coastal plains are composed of fine clay sediments originated mainly from the Amazon River, which flows into the Atlantic Ocean about a 1000 km south-east of the Corentyne River (Reyne, 1961). The rivers of Guyana carry a relatively low quantity of silt into the coastal areas, perhaps, because the watershed of these rivers is under forest cover and erosion negligible.

The mud banks move along the coast at a rate of about 1.3 km a year, in a series of waves commonly known as micro-ripples. A trough or crest passes a given point on the coast about once in 30 years (Reyne, 1961). When a trough is adjacent to a part of the coastline, its capacity for erosion may be greatly increased due to the refraction and concentration of wave energy through the trough (ODA, 1980). This may often result in serious erosion concentrated in small areas and in cases, breaches of the sea walls causing extensive damage to agricultural land and habitation behind the wall (ODA,

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1980). However, erosion does not always takes place under the above mentioned circumstances as mud slings, a highly viscous fluid comprising of clay particles in suspension, when present in the sea water near the coast, play a role in locally protecting the coast. Since the mud slings are in a fluid state, they participate in any wave motion and much of the energy of the waves is consumed in agitating this high density layer resulting in the reduction of the effectiveness of wave action on coastal areas. As a result, it is difficult to predict the location of erosion. Swayne (1986), noted that the severity of eroding action is often concentrated to small areas. He reported that in West Demerara (Region 3) there are only three places where intensive erosion is threatening the sea defence. In Orangestein about 120 m can be regarded as very critical while at farm and La JeLouse about 200 m can be regarded to be in the same category. The local experience is that the severity of erosion lasts between a year to 3 years at one place before the action moves on to a new site which can be anywhere along coastal Guyana.

Figure 1: Shoreline covered by mud flat with mangrove seedlings (A. germinans).

On the coast of Guyana, there is small variation in mean daily temperature, ranging from 240 C to 300 C. The heat in the coastal areas is greatly modified by the cool sea breeze. Trade winds prevail from the north-east throughout the year. Annual rainfall in the coastal region varies from 2000 to 2500 mm, and occurs throughout the year with two peaks in May-June and December-January (Figure 2). The highest amount of rainfall normally falls in June. However, this pattern sometimes changes, and some months may have more rain than normally expected as was the case of December 1943 and August 1954 when the coastal region received 1006 mm and 643.5 mm rainfall respectively (Abernethy, 1980).

Storms, hurricanes and cyclones do not occur in Guyana. However, there are innumerable instances of floods occurring as a result of high rainfall and exceptionally high spring tides, presenting concern for breaches of the sea defence system. Hence, mud banks are unable to absorb wave energy, and sluices are unable to rapidly drain behind the sea walls.

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R A I N F A L L M O N T H L Y A V E R A G E F O R 4 6 Y E A R S O N C O A S T A L G U Y A N A ( 1 9 4 0 - 1 9 4 6 )

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

J A N F E B M A R A P R M A Y J U N J U L A U G S E P T O C T N O V D E C

M O N T H S

RA

INFA

LL (M

M)

Figure 1: Monthly average rainfall on the coastal belt of Guyana (1940-1996) (Timehri Meteorological Station, 1996) 3. MANGROVES AS A POSSIBLE SOLUTION

The restoration of mangroves along coastal Guyana is a possible solution to the problem of flooding. This is so because (a) mangroves influences the development of coastal and estuarine areas by land building through soil accretion, absorption of wave energy, protection of the sea walls, and provision of other resources (forest and non-forest) and values (economical, social and ecological), and (b) the need to evaluate the cause(s) of decline of mangroves in Guyana and considering conditions required for restoration.

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CHAPTER TWO - MANGROVES 1. MANGROVE VEGETATION (a) GENERAL DESCRIPTION OF MANGROVES

Mangrove vegetation primarily comprises of trees and shrubs, with limited number of palms and lianas. Accordingly, a report on the global status of mangrove ecosystems made by IUCN in 1983 identified 61 species. The major mangrove species belong to less than 15 families but the most frequently occurring mangroves belong to the Rhizophoraceae, Combretaceae, Sonneratiaceae and Avicenniacease (Hussain, 1995).

In the Guianas of South America there are a limited number of mangrove species. Traditionally, three species were noted, Rhizophora mangle, Avicennia germinans and Laguncularia racemosa (Tomlinson, 1986).

R. mangle is the most common species of this genus in the region. The tree grows up to about 25 m in height and up to 40 cm diameter at breast height. It has stilt or prop roots and germinates viviparously. A single seed germinates inside the conical fruit forming a long narrow first root (radicle) which is green except for the brown enlarged and pointed end up to 1.25 cm in diameter. It can grow up to 100 cms in length before it gets detached from the parent tree and fall (Tomlinson, 1986). The species is extensively present and normally grows in soft muddy soils along sheltered river banks and estuarine margins, and can be utilised for any planting activities. Flowering and fruiting takes place all around the year, and as a result planting materials are also available throughout the year. The wood of R. mangle can be used as posts, poles, firewood and can be converted into good quality charcoal. The bark produces a high quality tannin of the phlobaphene yielding catechol group which is not broken down by ferments (Pearman, 1956) and is thus very suitable for leather work. According to Pearman (1956) 227,272 kg of Rhizophora bark were extracted annually in Guyana for tanning hides and fishing nets.

A. germinans predominates along the shoreline of Guyana. This tree grows in the form of isolated groups or woodland formation, which may be fairly large, and may grow up to 20-25 m in height. The wood can be used as fuel wood, poles and fish traps and the seeds can be eaten when cooked. The flower produces a clean high quality honey and apiaries have been established in some areas for the extraction of honey. The species bear pneumatophores or breathing roots which can also act as a silt trap.

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Figure 3: A. germinans predominating the shoreline of Guyana. (i) PHYSICAL ENVIRONMENT OF MANGROVES

The general distribution of mangroves corresponds to that of the tropical forest, but is restricted to conditions for optimum growth and development. These conditions are: regions having no frosts between 25o N and 25o S of the equator, although conditions may permit mangroves as far as 32o N (Thuraiaja, 1994), gently sloping shores that are subjected to high and low tides, sheltered sites, shallow brackish saltwater, an abundant inflow of fresh water containing high levels of minerals and organic matter, high annual rainfall of 1000 mm that will keep the water salinity below 60 per thousand (Clarke and Allaway, 1993) and a uniform hot and humid climate, which more or less correspond to coastal areas.

Mangroves can also occur in semi-arid (Mauritania, Angola, South-eastern Madagascar, the Egyptian shore of the Red Sea) and temperature environments (eastern South African coast) (IUCN, 1983), but are generally less extensive, less dense and have fewer varieties of flora. (ii) DISTRIBUTION OF THE MANGROVE SPECIES

There is no data available on the total land area of mangrove forests in Guyana. However, Pastakia (1991) observed during his studies in Guyana and Suriname that the geographical distribution of mangrove species is different along the coast of South America, when compared to the normal distribution in the Caribbean. The development of mangroves in the Caribbean follows a pattern of pioneering colonisation by Rhizophora spp. with increasing stablisation. Avicennia spp. invade and dominate the Rhizophora with a higher, denser canopy: with Laguncularia spp. forming the main part of the higher, inward areas of the mangal (Campbell, 1978).

In Guyana, large areas of the coast have become monoculture stands of A. germinans. There is no evidence that pioneering R. mangle is present along parts of the coast. This is the main pattern of mangrove development along the Atlantic coast from the Corentyne to the Essequibo rivers. In the developing sand banks in Region 6, L. racemosa and A. germinans are found as poineering species within the mudflats.

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Chapman (1976), reported the presence of Rhizophora harrisonii in Guyana, but the presence of this particular species cannot be ascertained. The Jonah Boyan herbarium at the University of Guyana and the Guyana Forestry Commission herbarium do not have any record of collection and or identification of this particular species.

From the Essequibo to the Pomeroon Rivers there is a change in the general pattern of the coastal mangrove. In Pomeroon, the dominant species is R. mangle. Avicennia and Laguncularia spp. are found, but as dominant species inland.

The pattern of coastal Avicennia dominance changes along the river banks and the coasts adjacent to the mouths of the river, creeks and canals. R. mangle does not normally occur in abundance in areas exposed directly to the ocean but is found dominating in sheltered areas of Barima-Waini, Essequibo, Demerara and Corentyne rivers, and canal banks. The length of R. mangle spread along the coast is apparently dependent on the size of the river. This pattern of riverine distribution is also reported from the San Juan River estuary and its adjacent coast in Venezuela (Pannier and Ramcharan, 1983).

This distribution of mangroves in Guyana is similar to that of the entire coast of the Guianas, and a number of theories have been advanced to explain why A. germinans rather than R. mangle is the pioneering species of the coast. Augustinus (1978) discussed these theories, and proposed his own: that the sling mud conditions along the coast of the Guianas is so little consolidated that it can be fluidised by wave action to a certain depth, thus preventing the settlement of hypocotyls of R. mangle. A. germinans embryos are able to become established in this regime, and so Avicennia spp. become the single pioneering species. (iii) MANGROVE ECOLOGY AND COMPOSITION

The mangrove forest of Guyana is a complex ecosystem because it represents an inter-phase between two contrasting types of communities: terrestrial, as represented by shrubs, grasses and agricultural crops; and marine, as represented by sea grass. There is an abrupt transition from mangal to marine communities, while transitions to terrestrial communities, such as fresh-water swamps, are gradual in some places. (Pastakia, 1991).

There are two principal mangrove species occurring in Guyana, Avicennia germinans and Rhizophora mangle commonly known as black and red mangrove, respectively. A distinction is made between the environment of R. mangle dominated mangal, and that dominated by A. germinans. The large, dense crowns and high aerial roots of R. mangle provides an open, clear woodland in its understorey, whilst Avicennia germinans, described by some as Avicennia nitida (Rambajan, 1989) dominated woodland has a more congested understorey. A. germanins occurs extensively on the exposed coastal mud flats outside the sea defence, as well as mixed with R. mangle and other species inland and on sheltered places. A. germinans is the most important and dominant mangrove species in Guyana.

A. germinans can be found almost as a pure crop with an occasional presence of L. racemosa or C. erectus (Buttonwood mangrove), while in sheltered areas like river banks R. mangle predominates with some A. germinans, C. erectus and L. racemosa.

According to Chapman (1976), newly formed land in the coastal area is first colonised by a grass known as Spartina braziliensis. The presence of this grass provides an indication that the land is ready for mangrove establishment. One major shrub that can be found in association with A. germinans is Batis maritima. As described by

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Chapman (1976), its profuse growth can be seen in areas under A. germinans as well as areas around it including those where the trees have died out.

The sandy beaches, which are on higher grounds than the mud flats are covered in places with Machaerium lunatum, Fimbristylis spathacea (Masala grass) and Ipomea biloba. In some places, Stenotaphrum secundatum and bushy Cnidoscolus urens (Cow itch) can be seen.

In inland areas, L. racemosa is dominant. In many areas, an understorey of B. maritima is found. The fern, Acrostichum danaeifolium is common as an understorey plant in the denser mangrove forests. Other species recorded include Achyranthes aspera, Belchnum brownei, Corida marcrostachya and Cynodon dactylon. In more open areas Sesiuium portulacastum and Brachypteris ovata can be found.

Information on the fauna in mangrove environments in Guyana is not as comprehensive as that on the flora. Most accounts of the fauna deal only with a list of species and localities without much discussion on the interaction with flora. However, Pastakia (1991) observed many animal species utilising mangroves as their habitats in the mangrove forest of Guyana. Many of the species found are either vulnerable or endangered species, or have high commercial values. Some animals are temporary visitors, whereas others are part of the permanent population. He stated that these animals appear to have six major habitats: (1) the terrestrial tree canopy, occupied mainly by birds ( Eudocimus ruber, Egretta alba and Ardea cocoi), mammals and insects which come from nearby habitats; (2) rot-holes in branches and water in the cleft between trunk and branches, usually occupied by mosquito larvae; (3) the soil and soil surface occupied by several crustaceans ( Paeneus subtilis, P. braziliensis and Xyphopaenus kroyeri), molluscs and migrating turtles such as the leatherback (Dermochelys coriacea), Olive-Ridley (Lepidochelys olivacea) and hawksbill (Eretmochelys imbricata); (4) aerating roots and portions of trunks in the intertidal zones occupied by molluscs; (5) permanent and semi-permanent pools inhabited by crabs ( Uca rapax, U. vocator and U. maraconai), mosquito larvae and frogs; and (6) channels with fishes and reptiles. The microfauna in the mangrove forest is an important ecosystem, especially for fisheries species. (b) NATURAL COMMUNITY STRUCTURE AND DYNAMICS 1. NATURAL SUCCESSION (i) REGENERATION AND ESTABLISHMENT OF MANGROVES

The structure of a mangrove forest is relatively simple with only one strata compared to other forest types. This is accounted to the combined effects of salinity stress and the need for light that prohibits development of understorey vegetation. But for areas with relatively abundant rainfall, a complex stand characterised by full canopies and high basal areas are conspicuous (Smith, 1992).

The most significant site conditions that influence regeneration and succession are the nature of the substrate, wave action of the sea, age of the forest, inundation class, salinity and the presence of canals, streams and rivers (Hamilton, 1984).

Seed dispersal, establishment and development in mangrove ecosystems are regulated by both inter-specific and extra-specific factors (Rambajan, 1989). Inter-specific refers to species’ individual physical, chemical and morphological make-up. Whilst, extra-specific factors refers to the environmental factors affecting the plant.

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Phenological studies are important to determine the success in regeneration. Hussain (1995), categorised mangrove seeds into crypto-viviparous and viviparous. Crypto-viviparity occurs in species of Laguncularia, Pelliciera and Avicennia, where their embryos develop within the fruit, but does not enlarge sufficiently to rupture the pericarp. In contrast, seeds of Rhizophora, Ceriops, Bruguiera and Nypa develop into seedlings while they are still attached to the mother tree. This phenomenon is known as vivipary where the embryo ruptures the pericarp and grows beyond it. Mangrove seeds retain their viability for a long period while still in the saline environment, but lose viability soon after they are removed from that environment (Hussain, 1995). Tomlinson (1986) observed Pelliciera spp having seeds 8 cm long that weigh 60 to 90 g while R. mangle has seedlings 20 to 25 cm long that weigh about 15 g.

Studies revealed that flowering and fruiting of R. mangle and A. germinans are not similar. However, both species develop their flower buds into mature propagules for about 10 months (Pastakia, 1991). Maturity of R. mangle and Bruguiera gymnorrhiza with fruit having an extended hypocotyl were 3.5 and 0.7 years, respectively (DENR, 1994). In Pagbilao, Philippines, Rhizophora starts to flower at the age 4 years and continue to bear flowers regularly. R. apiculata and R. mucronata requires 3 to 6 months, respectively for full fruit development (PCARRD, 1991). Baldevorana (1992) in his study revealed that Rhizophora species could successfully be established with a 94.28 % survival rate.

Propagules, which are too heavy or long are dispersed from the mother tree to a shorter distance. Likewise, propagules, which are dispersed longer distances fail to establish in areas which are frequently inundated. Several researchers revealed that large seeds cannot invade higher grounds where water depth is insufficient. This is validated in the study of Chan and Husin (1985), where 74 % of the propagules that were dispersed became stranded resulting in 30 % establishment only. A single 3-year old Rhizophora tree within the forest by a river bank dispersed 30 propagules concentrated underneath its canopy within 5 metre radius whilst zero propagules were found at 30 to 65 metre radius making regeneration insufficient (Clarke and Myerscough, 1993).

Seedling establishment is critical in the life of all seed plants and considered as difficult for mangrove owing to the unstable, variable substrates and tidal influence within mangroves (Tomlinson, 1986). The range of germination types shows a correlation with seed size. A study of the effects of propagule size on the growth of Rhizophora seedlings revealed that seedling performance was directly proportional to its propagule size. It was observed that a propagule size of greater than 40 cm has the highest mean leaf per plant, mean area per leaf and mean diameter of the stem at first inter-node as compared to those propagules with a length less than 40 cm (Qureshi, 1990). Variability in seed size may also affect dispersal and the ability to emerge from different depths of substrate and thus, potentially, may affect seedling establishment.

In some areas of coastal Guyana, there seem to be a problem of establishment despite regular seeding of mangrove species. This is attributed to seed and seedling bouyancy in sea-water for several tidal cycles, and many becoming stranded close to parent trees. Thus, the lack of low numbers of newly established seedlings is as a result of dispersal ability as affected by tidal inundation and hydrodynamics in mangrove forests (Pastakia, 1991). However, in Regions 1 and 5 (Appendix 2), there are areas where natural reforestation of A. germinans has been taking place after the mangrove vegetation was completely destroyed (Figure 4). This was observed by Pastakia (1986) and Rambajan (1989) at Waini, Dundee and Mon Choisi near the estuary of Berbice River.

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Figure 4: Regeneration of a stand of A. germinans (ii) TOLERANCE TO SHADE

Mangrove species have high light requirement for regeneration and growth (Smith, 1992). In contrast, B. gymnorrhiza is considered as the most shade tolerant mangrove species. Hence, regeneration of this species under shade tend to be poor. Clarke and Allaway (1993) found in the Philippines, the average seedling density of A. marina, both in gaps and under canopies, was 7.8 / m2, whereas, the sapling density (plant > 50 cm high) was 2.37 / m2 in gaps and 0.002 / m2 under canopies. Seedlings of A. marina are shade tolerant at least until the cotyledonary stage and thereafter, show some shade tolerance for up to 6 years (Smith, 1992). (iii) PREDATION

Natural stands of mangrove species are rarely severely affected by pests and diseases. However, disruption in the existing ecological balance could create conditions that favour infestation.

Although mangrove propagules are tough, bouyant, and readily water-dispersed, they are preyed upon by small macro-invertebrates such as graspid crabs, lepidopteran larvae and burrowing bettle larvae (Coleoptera) once they have abscised (Farnsworth and Ellison, 1997).

Post-dispersal propagule predation is a significant factor structuring mangrove communities throughout the world. However, post-dispersal surveys on fallen mature propagules may underestimate the number of propagules damaged or aborted owing to heavy predation levels on the parent tree (Smith, 1992).

Pre-dispersal predation has received less attention in mangrove studies. However, burrowing insects commonly destroy aerenchyma and vascular tissues in the developing hypocotyls of mangrove species in the Rhizophoraceae, and in the cotyledons of Avicennia species (Farnsworth and Ellison, 1997). Although the organisms do not always kill the propagule outright, the magnitude of the damage, and implications for subsequent seedling establishment are significant.

In the Caribbean and South American regions, mangrove species are often attacked by borer beetles (Poecilips fallax) and fiddle crabs (Uca species) (Farnsworth and Ellison, 1997) (Figure 5). The borer bettles leave small, pin-sized holes on the

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portion of the propagules not submerged in water. The affected parts reveal a series of tunnels with the larvae of the beetle. The larvae feeds on the living bark, thereby, killing the tree while the woody portion is left unharmed. The fiddler crabs commonly attack newly planted and succulent mangrove propagules. They dig into the soil, girdle the root collar and eat the fleshy cambium of the propagules that eventually die. Hence, the potential of natural regeneration is minimised.

Figure 5: Indication of fiddler crabs (Uca species) on mud flat. 2. ZONATION IN MANGROVES AND DIFFERENCES AMONG SPECIES (i) ZONATION PATTERNS

Zonation of mangrove species in a community is spatial phenomenon, and species

zonation patterns is commonly observed in typical mangrove forests (Smith, 1992). In the Guianas, there is a distinct pattern of zonation that categorises species into zones. These are the seaward, landward and riverine fringes zones (Figure 6). The zonation patterns dictate, which species will grow abundantly. In Suriname, seedlings of R. apiculata and R. mangle are highest along riverine edges with the average values of 605 and 2,163 seedlings per hectare, respectively, and tend to decline in inland areas. On the other hand, Avicennia seedlings cover the seaward areas with values of 1270 seedlings per hectare, whereas, L. racemosa and C. erectus show low densities on seaward areas but high densities at the landward side of approximately 320 and 282 seedlings per hectare, respectively (Augustinus, 1978). In Quezon, Phlippines, four distinct zonation patterns are found, seaward, middle, landward and riverine. Clarke and Myerscough (1993) found an average density of 24 A. marina seedlings per square metre in the upper edge of the seaward mangrove zone while no seedlings were found in the saltmarsh zone. Ceriops and Lumnitzera showed high densities at landward side with their values of 1,033 and 128 seedlings per hectare, respectively.

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Zonation Pattern

Description Species

Seaward Zone

Portion of swamps daily affected by tidal inundation including neap tides. Species found are called front liners and are of true mangroves; soil type range from sandy to sandy loam and mud flat.

A. germinans, A. marina

Landward Zone

The back portion of mangrove swamps which remains unaffected by tidal inundation, except during spring tide. Soil is generally clayey to silty clay. Vegetation is diverse (vines and epiphytes).

L. racemosa, C. erectus

Riverine Zone

Portions of swamps along or indenting the river system, and mouths of rivers and canals.

R. mangle, R. harrisonii, R racemosa, R. apiculata

Figure 6: Zonation patterns of mangrove in the Guianas (Augustinus, 1978). (ii) SALINITY TOLERANCE OF CERTAIN SPECIES

Mangroves grow in conditions where few other plant species can survive. They are considered as facultative halophytes due to their ability to withstand and often survive in areas with high concentrations of salts. They are categorised as salt accumulators (euhalophytes), salt excretors (crynohalophytes) and those which salt is localised in specialised structures (Melana, 1994). In Northern Australia, seedlings of B. exaristata, Rhizophora stylosa, A. marina and Avicennia officinalis were found growing in soils with salinities over 65 % whilst, Avicennia tonduzii and R. racemosa thrived in less than 40 % (Smith, 1992). 2. GLOBAL IMPORTANCE OF MANGROVES

Mangrove forests are among the richest and the most productive ecosystems, and form the foundation of the food chain for coastal fisheries. Commercial and traditional products range from construction timbers to charcoal, fuel wood and pulpwood for paper, from tannin and medicines to honey, and many other utility products (Appendix 4) (Hamilton and Snedaker, 1984). They provide an excellent protection against erosion of coastal shoreline as their root systems trap eroded soil particles and other pollutants especially during heavy rains; serve as land builders of coastal areas through soil accretion, and minimise water pollution. Melana (1992) suggested they serve as habitats, breeding and nursery grounds for marine fishes, crustaceans, and other fauna. They provide nutrient enrichment in nearshore areas for both aquatic and terrestrial flora and fauna. Litter fall from the forest is mechanically and biochemically broken down by animals that feed on it, mainly crabs. This is the first step in nutrient cycling. Micro-organisms further digest fragmented vegetative matter and animal excreta, while filter feeders and phytoplankton use fine organic matter and dissolved nutrients (Sin, 1990). Sin (1990) estimated biomass productivity of mangrove ecosystems in Kampuchea as 2000 g m-2 year -1, as compared to 730 g m-2 year-1 on land and 155 g m-2

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year-1 at sea. In addition, mangrove forests provide aesthetic, scientific and educational benefits because of the uniqueness of the ecosystem (Choong et al., 1990). 3. THE ROLE OF MANGROVES IN COASTAL PROTECTION IN GUYANA

In Guyana, mangrove vegetation can play an indirect but very important role in coastal protection.

Mangrove forests do not form an impervious layer like the masonry wall or earthen embankments. Consequently, a mangrove vegetation of any width is incapable of arresting the intrusion of the ocean water into agricultural fields. However, mangrove vegetation when fully established, does neutralise, depending on the width of the strip, much of the wave action. This kind of vegetation, therefore, can play a very important role in the protection of the sea wall or embankment (Figure 7). Furthermore, mangrove vegetation helps in the acceleration of the process of deposition of soil particles suspended in tidal water, thereby raising the level of the coastal land in the inter-tidal zone and creation of new accretions beyond. In calm waters, sediments are deposited in quantities as high as 20 to 200 metres per year (Bohorquez, 1985).

However, in areas where concentrated wave action keeps eroding the coast, the defensive role of mangrove vegetation may be questionable particularly when the width of the mangrove belt is narrow.

It will not be easy to establish any mangrove vegetation in areas where severe erosion is currently taking place because the force of wave action in such areas is so strong that it will wash away seedlings, and damage or destroy the sea walls. Under such a condition the scope of vegetation establishment is almost nil. Similarly, in areas where there are unsuitable land for mangrove reforestation, it may not be possible to use mangrove vegetation as a protective shield against wave action. Mangrove vegetation, therefore, cannot be used as a protective option in areas where there is excessive erosion because it is extremely difficult to establish any mangrove vegetation in hostile conditions and even if it becomes possible to establish such vegetation in such areas, it will not be before 5-7 years, depending on their growth and development before a vegetation is established well enough to be able to provide any form of protection to the sea defence system.

Figure 7: The protection of the sea wall by mangrove vegetation.

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CHAPTER THREE - CURRENT STATUS OF MANGROVE VEGETATION IN GUYANA 1. CURRENT STATUS OF MANGROVE VEGETATION IN GUYANA

The distribution of mangroves in Guyana has declined substantially, especially in the last few decades. Very little documented information is available on mangrove vegetation and management in Guyana. However, it is known that historically almost the entire coast of Guyana was covered with mangrove formations. According to Dalton (1855) the entire Guyana coast was under mangrove vegetation at the time of colonisation. There has been a very serious depletion of mangrove vegetation particularly in Regions 3, 4 and parts of 2 and 5 (Appendix 2). From the information gathered locally, a large portion of the coastal belt was under mangrove formation even 20-30 years ago. However, various causes have been identified for the decline in mangrove vegetation along coastal Guyana. (a) CAUSES OF DECLINE OF MANGROVE VEGETATION

Erosion and wave action are thought to be important causes of the decline of

mangrove vegetation in Guyana. Rambajan (1989) provided evidence to show what has been happening at Phoenix in Region 5 where mangrove formations were being destroyed systematically by sea waves. Trees were uprooted and washed away to be deposited later near the facade embankments in piles. Uprooting of trees by wave action is common in most other countries (Rambajan, 1989), however, in Guyana it seems that the magnitude is much higher than what is experienced elsewhere.

The blocking of drainage canals is another cause for the decline in mangrove vegetation. In Region 5, which comes under the jurisdiction of the Mahaica- Mahaicony-Abary Agricultural Development Authority (MMA / ADA). Pastakia (1986) reported that all the channels for discharge of fresh water into the ocean were blocked, and a 25 miles long facade drain that runs parallel to the coastal embankment / wall has been excavated. A large number of sluice gates that were in operation previously have now been blocked and taken out of operation. Mangrove vegetation, is tolerant of salinity, the degree of tolerance varying with species. What could have happened in this area (MMA / ADA) is that with the substantial decrease in the flow of fresh water, the sweet-salt water balance was upset resulting in the weakening and death of mangrove trees. At Phoenix in Region 5, Rambajan (1989) observed that the leaves of some trees had lost their natural colour before they were uprooted. He noted that such change in colour was not due to the erosive process and was definitely linked with the physiological process. This, however, needs more detailed investigation.

In some cases, excessive salinity may be responsible for the decline in mangrove vegetation. In Onverwagt in Region 5, there has been large-scale death of mangrove vegetation. One preliminary study by Ramsammy of the University of Guyana indicated that the salinity in water within Onverwagt area was almost twice as concentrated as it was in the ocean, which was above the tolerance level of R. mangle. This high salt concentration may have rendered the area toxic to tree growth. Similarly, in Dundee excessive salinity due to geomorphic processes contributed to large-scale death of mangrove vegetation. This area had become saucer shaped as a result of soil deposition on the seaward side and the presence of embankments on the landward side (Rambajan,

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1989). During spring tides, saline water would enter this saucer shaped body. The evaporation of saline water has resulted in a higher salinity concentration in the absence of any supply of fresh water. This could have made the habitat condition toxic to tree growth and caused large scale death to trees in the area. Salinity levels in mangrove forests typically undergo daily fluctuations. High salinities are normally experienced during high tide (37.0 parts x 103) and relatively low salinities during low tides (2.0 parts x 103) (Augustinus and Mees, 1984).

However, questions may arise at this point in one’s mind about why this destruction has been accelerated in recent years as most of the coastal regions were vegetated until recent times. 2. GENERAL PERCEPTION OF THE MANGROVE FOREST

In Guyana, mangrove forests are generally perceived as a liability and have never been taken seriously as an asset. As a result, the forest was destroyed to control mosquitoes, used unsustainably for fuel wood, and bark collection for tannins, and there is a lack of political recognition.

Most people are ignorant of the values of mangrove forests, and consider them primarily as the source of mosquito menace. Mangrove formation in some areas especially close to urban localities, have reportedly been destroyed in order to eliminate the habitat for mosquito breeding. However, how much mangrove formation has been destroyed for this purpose is not known.

The mangrove forest is used unsustainably for fuel wood and bark collection for tannins. Historic clearance of mangroves coupled to erosion have meant that the mangrove areas of the coast are generally thin. Only along the Barima-Waini and Pomeroon coast are mangrove forests of any size found today, together with isolated areas such as Crab Island in the Berbice estuary (Pastakia, 1991). However such mangrove areas provide fuel wood for domestic cooking to a section of the coastal population. Even at present, a few rural communities are dependent on mangrove vegetation for the supply of fuel wood. The practice is not supervised, and the forests become badly damaged in the processes, so sustainable forestry is not possible.

Small-scale fishermen may also cause damage. In some areas, the fishermen may pull their boats up on the mudflats and beaches, create paths through the mangrove stands, or the trees for mooring of boats and laying of fish nets in rivers.

Mangrove bark, particularly that of R. mangle has been extensively exploited for the extraction of tannin. Half a million pounds of bark were extracted annually during the colonial days (Pearman, 1956). According to the Guyana Forestry Commission Production Statement for 1996, 381,617 pounds (173,462 kg) of bark were extracted during 1988 to 1996.

There is a lack of political recognition of the mangrove forest in Guyana. It is not classified as state forest, the Guyana Forestry commission has little or no control, and it is not included in the national forestry action plan.

The mangrove vegetation in Guyana, even though located on state land does not form a part of the State Forest (Appendix 5). As a result, the Forests Act, Chapter 67:01 of the Laws of Guyana 1953 and the amended regulations of 1972 and 1996 do not apply to these formations. There are no set guidelines for mangrove outlined in the Forests Act (Pastakia, 1986). As far as it could be ascertained these forests have never been subjected to any scientific management. The coastal zone is under the authority of the Regional Administrative Councils. Control over coastal forests has been exercised

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by Regional Officers and Regional Rangers who have tried to supervise and regulate felling and extraction. The effectiveness of their control has been limited because of a shortage of manpower, lack of training in forestry practices, and a lack of guidelines based on silvicultural or management practices for sustainable utilisation of the mangrove tree resources. Moreover, no comprehensive assessment or inventory of the resources exists.

The Guyana Forestry Commission has limited representation along the coast with personnel stationed only at New Amsterdam, Skeldon and Parika. The manpower is grossly inadequate to impose any effective control over the exploitation of mangrove vegetation.

A National Forestry Action Plan was prepared for Guyana in 1989, but the plan does not consider the mangrove vegetation as a component of the national forest resources. Therefore, no intervention for mangrove vegetation was included in the formulation of the plan. Most recently, the Guyana National Forest Policy document was passed in Parliament (October, 1997) giving the Guyana Forestry Commission the authority or governing body of only the coastal forest, but the current legislation was not reviewed or amended to facilitate legal implications of the coastal forest, nor has it been declared State Forests. 3. SPECIFIC VALUES OF COASTAL GUYANA

The Guyana coast consists of an alluvial plain formed through the course of ages by the deposition of clay of which a greater part is considered to have originated from affluent of the Amazon River. The coastal plain is narrow, extending to about 60 km inland, and forms the most important region of Guyana (Appendix 3). (a) Economically

The coastal belt provides the ecosystem for mangrove forests where small quantities of forest products and aquatic resources are derived. The major forest products from the mangroves include poles for fish nets and firewood for a small number of rural communities. Minor products include honey, which is an exportable commodity (Pearman, 1956; Chapman, 1976 and Hussain, 1990), and tannin extracts which generates income for coastal dwellers. The Guyana Forestry Commission (1996) reported 10,886 kg of mangrove bark were extracted for tannin to be used by the local tannery industry in 1996.

Several important aquatic resources such as fishes including fry and fingerlings of different species, molluscs, crabs, shrimp and other crustacean species thrive in the mangrove ecosystems (Hussain, 1990). In Cienaga Grande de Santa Marta, Colombia, 99 % of P. occidentalis, white shrimp, was harvested from the mangrove swamps in 1984 (Bohorquez, 1985). In Trinidad and Tobago mangrove swamps, fishery products harvested in 1974 was valued at US $ 120.00/ha/yr (Dixon et al., 1989).

Agriculturally, the area is the most important, as all agricultural products including sugarcane and rice, which are the major export commodities are grown on the coastal plain. In addition, the coastal belt is the major fishery and livestock production area. (b) Socially

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More than 90 % of Guyana’s population lives on the coastal belt. All major industries, commercial centres, cities including the capital Georgetown are located on the coastal plain, and most export earnings are generated from this region.

A few rural communities depend on the mangrove resources for subsistence food and income (honey, fish and crab). In addition, new uses for mangroves, through tourism development are becoming increasingly valuable. The mangrove forest at Shell beach, Region 1 has become a major tourist attraction site. This is attributed to the mangrove forest providing the home for the scarlet ibis bird, and the sandy beaches a nesting ground for the leatherback and hawksbill sea turtles. (c) Ecologically

The mangrove forests along the coastal belt play a significant role in the ecological stability of their ecosystem and other outlying ecosystems. They serve as buffer against the north-east trade winds and tidal waves (Hussain, 1990 and Pastakia, 1991).

Hence, the values of the coastal belt contribute significantly to Guyana’s economy. 4. THE NEED FOR RESTORATION OF MANGROVE FORESTS

The mangrove forest is the only motivation related to the protection of the sea defence system in Guyana. Mangrove forests are known to be effective barriers to coastal erosion by tidal wave actions and cyclonic storms. The Sundarbans of Bangladesh Bangladesh have been planted to assist in flood prevention (Lugo et al., 1990) and reports from Monsterrat and Jamaica have shown that boats sheltering within the mangroves survived hurricane Hugo in 1989, whilst boats in harbours and open water were destroyed (Spanns and Baal, 1990).

With human development so close to the shore in most areas, the reliance on the sea defence system is considerable. The Guyana coast is protected by a number of sea defences, about 69 km are protected by masonry sea walls, 169 km by earthen embankments (or the bunds of facade drains), and about another 78 km have been reported to be protected by natural sandbanks. The Ministry of Works, Department of Hydraulics has considered another 123 km of masonry walls for construction which would require international consultancy, funding and technical assistance (Pastakia, 1991). In Suriname, where human development has tended to be more inland, although the empoldering and drainage systems are similar, Suriname has relatively few sea walls, and allows a strip of land (seaward of development) to be considered as ‘sacrificial’ land for natural erosion (Pastakia, 1991).

To reduce the budget for sea defence construction and maintenance, consideration should be given to mangrove management in Guyana. Mangroves traditionally have been considered as suitable for coastal protection in certain areas, and form the main vegetation of the Surinamese ‘sacrificial’ strip.

Without any system for sea defence, the rate of erosion would increase along the coastal plain due to tidal inflows. But the sea walls and earthen embankments, as currently built are vulnerable to erosion and destruction from the force of wave action. To assist in controlling the problem, a system of reclamation of land and mangrove reforestation as a component of the existing sea defence system is recommended as the most feasible and cost effective option. Otherwise, the highly populated and most important agricultural sections of Guyana coastland will be seriously devasted, and

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“may be completely submerged as part of the ocean within the middle of the 21st century” (Rambajan, 1989) if no action is taken immediately to establish a fast and successful programme.

With the existing pressures on the remaining mangroves by erosion and indiscriminate logging, natural regeneration is not sufficient to replenish the mangrove resource. Natural regeneration needs to be supplemented by artificial regeneration and plantation establishment. In logged stands with sufficient numbers of seed trees, the profuse flowering and fruiting of mangrove should facilitate natural regeneration. In instances where few seed trees and seedlings remain planting is recommended.

Reforestation though labour intensive, poses advantages over natural regeneration and the construction of sea walls. The advantages of reforestation includes, relatively faster re-establishment of the denuded mangrove, freedom to regulate spacing and density, uniformity in restocking sites, uniformity in stand structure, ease in cultural management practices, and is applicable on repeated occasions to ensure success on difficult sites. In contrast to natural regeneration, competition of seedlings may restrict diameter and height growth, establishment is often slow and irregular, and management operation is difficult. In addition, the process of natural regeneration may have to be reinforced by planting so as to avoid the risk of failure, to correct deficiencies in stocking, or to shorten the duration of individual management operations. Moreover, reforestation is less costly than construction and maintenance of masonry and earthen walls.

Finally, the Guyana Forestry Commission, Environmental Protection Agency, Regional Administrative Democratic Councils, Ministry of Agriculture and University of Guyana are in place to support the restoration of mangrove forests along the coastal belt.

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CHAPTER FOUR - ACTION PLAN FOR RESTORATION OF MANGROVES

Mangroves are now being managed sustainably in many countries based on sound

silvicultural and forest management principles. In Bangladesh and India for example, mangrove forests have been silviculturally managed for more than a century on a sustainable basis (Hamilton and Snedaker, 1984). Through the years, several silvicultural systems have been applied to different mangroves in different countries with the primary aim of obtaining adequate natural regeneration. Unfortunately, reports on the effects of different silvicultural practices on seedling or sapling regeneration are lacking. Further knowledge on this would give a strong basis in determining a more viable management system.

In 1995, Siddiqui described the regeneration status of mangroves by country. In Indonesia and Kampauchea, Modified Selective Cutting and Replanting System is the usual method practised; this involves retention of 40 evenly-spaced trees per hectare in the area (Nugroho, 1992). However, a clear-felling system is also used in easily flooded areas with cutting cycles of 30 years. In Venezuela and Costa Rica, a strip clear-felling system has been found to allow adequate natural regeneration. The strips vary in width from 20-50 metres and may be at right angles to the waterways. In India, management techniques and felling cycles vary from 20 to 100 years depending upon the species under the selection system employed. The selection system with 20 years felling cycle of the Sundarbans in Bangladesh, natural mangrove forests regeneration density per hectare is as high as 53,350 seedlings (<1.3 m) (Siddiqui, 1995). Malaysia claims that they have a long history of systematic management of mangrove forests applying their usual practice of strip clear-felling and seed tree plus planting (Thurairaja, 1994). To ensure adequate and uniform distribution of growing stock, loggers are required to leave 100 young mother trees as a source of regeneration shortly after clear-felling operations. In like manner, Thailand uses clear-felling in alternate strips with a rotation of 30 years. In the Philippines, shelterwood and various selection methods are used including prescribed harvesting methods, the number of seed trees to be left, the annual allowable cut, the rotation period and planting is recommended (PCARRD, 1991). In spite of that, other countries such as Colombia, Cameroon and Nigeria are practising their own way trying to find a more sustainable practice for mangrove management. In most cases, studies are geared towards artificial regeneration or plantation establishment.

It is time that the mangrove forests in Guyana be inventorised and brought under intensive management practices based on scientific principles. This will give guidelines towards the formulation and implementation of appropriate silvicultural prescriptions and immediate treatments. Scientific management of mangrove forests should not be too difficult in Guyana because only a limited number of species are involved. Moreover, the same species exist in other South and Central American, and Caribbean countries. Some of the species are also present in West African countries. Many of these countries have already been exercising scientific management practices in mangrove forest. Experience from these countries could be greatly helpful in formulating a suitable management regime for mangrove forests in Guyana.

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1. SITE SELECTION (a) INDENTIFICATION OF APPROPRIATE SITES

Guyana is divided into ten Administrative Regions with Regions 1, 2, 3, 4, 5 and 6

occupying parts of the coastal belt (Appendix 2). The Atlantic coastline in Guyana extends over 400 km from the Barima-Waini River on the Venezuela border in the west to the Corentyne River on the Suriname border in the east. The coastal belt is broken in places by major rivers such as the Pomeroon, Essequibo, Demerara, Mahaica, Mahaicony, Abary and Berbice.

The erosional nature of the coast of Guyana is one where there is considerable undercutting of the foreshore resulting in a rapid loss of foreshore areas. The species of mangrove, A. germinans along the eroding coast provides no protection to this form of erosion. Tomlinson (1986) noted that the general accepted conclusion of the role of mangroves in coastal protection is that they do so only in regions that would undergo sedimentation even in the absence of shoreline vegetation. This view has been supported by Hussain (1990). According to Pastakia (1986) the only natural stabilisation is the development of beaches and sand bars, and the formation of these could provide some of natural coastal protection. However, the mangroves do have a potential role in coastal protection in Guyana, by raising the foreshore areas through increased sedimentation and being a component of the existing sea defences and groynes.

Because it is almost impossible to forecast where erosion will take place next along coastal Guyana, it may be important that a protective mangrove belt be created all along as much of the coast as possible. This, in turn, is dependent on the width of the inter-tidal zone. Mangrove vegetation will thrive only in areas which are inundated regularly but that do not remain under water for long period of time, and are clayey or silty, are ideal for mangrove afforestation. The supply of fresh water is a necessity for healthy growth of mangroves. Thus, areas where the fresh water supply has been cut off will not be ideal for mangrove reforestation. However, in areas where concentrated wave action keeps eroding the coast, the defensive role of mangrove vegetation may be questionable particularly when the width of the mangrove belt is narrow.

NEDELO (1972) and Hussain (1990) have identified and reported on a number of areas along the coastal belt that can be targeted for mangrove reforestation sites, but this does not necessarily mean that these areas may be suitable for plantation establishment due to changes in the environment, erosive processes, sedimentation, and human activities that are currently undergoing.

Several areas of coastal Guyana are targeted for mangrove plantation. One indication that the land may be ready for mangrove plantation is the presence of colonising grasses and shrubs such as, Spartina braziliensis and Batis maritima or a few seedlings of mangrove species scattered over such land. However, NEDELO and Hussain suggested the following sites: (i) Region 3 (East Essequibo and West Demerara)

The East Essequibo and West Demerara areas in Region 3 (Appendix 2) have limited lands that are suitable for mangrove plantation. Some suitable areas, are however, available at Ruimzeigt and Winsor Forest where plantation work can be undertaken. The predominant species in the existing mangrove forests is A. germinans and as such, this will be the only suitable species for the area as reported by Hussain

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(1990). This is because A. germinans is the pioneering mangrove species of the coast, it establishes well and is better adapted to seaward conditions than the riverine and inland species, R. mangle and L. racemosa, respectively. (ii) Region 4 (Demerara - Georgetown - Mahaica)

The shoreline along Georgetown is very much disturbed and will be extremely difficult to establish any plantation. However, a long stretch of land that is suitable for mangrove plantation establishment has been identified by NEDELO (1972) and is available from the east of Kingston to Bel Air, Georgetown (Appendix 2). Some natural mangrove vegetation exists along this stretch of land and A. germinans can be planted. (iii) Regions 5 (Mahaicony - West Berbice)

The western part of Region 5 from Mahaica to Profit has a mangrove forest stretching over 20-25 km. This area needs management and protection. This formation can also serve as a major source of planting stock for planting areas in both Regions 5 and 6 as well as neighbouring Regions.

In the central part of the Region consisting of Phoenix, Trafalgar, Onverwagt, Yeoville and Mon Chosi in the east, large-scale death of mangrove trees has been occurring in recent years. At Yeoville and Mon Chosi, re-colonisation by mangrove species has already started. This process of re-establishment of mangroves can be enhanced through planting of suitable species, such as A. germinans, which is in this area. (iv) Region 6 (East Berbice - Corentyne)

Region 6 strecthing between Berbice and Corentyne has good mangrove vegetation along the coast. In the western portion of the Region the belt is wide and in places extends up to 2-3 km. The central portion of the Region has been depleted of vegetation. Suitable land is available in most places and plantation activities can be taken up mainly by Avicennia germinans. At New Amsterdam and Skeldon, a major breach has occurred in the embankment, and the main road inshore has been eroded. Skeldon has land outside the sea defence system, which is suitable for mangrove plantation. At Skeldon, R. mangle will do better than A. germinans as R. mangle is not directly exposed to the ocean. (b) RECONNAISSANCE AND GROUND VERIFICATION SURVEY

The first step in restoring A. germinans and R. mangle along the coastal belt of

Guyana should be the identification and assessment of suitable land available for planting. Then it will be necessary to prioritise areas in order of the necessity of both short and long-term interventions, so that scarce resources available for restoration efforts are most effectively used. The assessment of the actual area available can be made from recent aerial photographs of the coastal areas taken at high and low tides associated with ground truthing or through physical inspection of the coastal regions. Proposed sites should be delineated on a map (latest map as possible with a scale of 1:10,000) where political and administrative boundaries, and location points are well defined. Information concerning accessibility, and travel time should be included.

A verification team can be dispatched consisting of at least a Forester, an Environmentalist, a Civil Engineer, two Regional Administrative Officers, and a Sworn Land Surveyor. The verification team should be able to conduct an assessment of the areas or proposed sites considering the accessibility of the sites, site conditions, quantitative vegetation description, acceptability from affected coastal communities

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about the programme, and prepare a report on the validation or ground verification activities with its recommendations before reforestation begins. 2. SPECIES SELECTION AND NURSERY CONSIDERATIONS (a) SELECTION OF SPECIES

A.germinans and R. mangle have distinguishing characteristics and are highly recommended as good reforestation species in Guyana (Hussain, 1990 and Pastakia, 1991). It appears as though the choice of species for reforestation of mangroves in Guyana is quite simple and straightforward. In areas exposed directly to the ocean, the only species that will be able to withstand the actual condition is A. germinans. A. germinans forms the single dominant species in the existing mangrove vegetation along the shoreline. A. germinans is more tolerant to high saline conditions than any other tree species found growing in a wide range of saline habitat conditions in Guyana ( Pastakia, 1991). As it is the most versatile mangrove species in Guyana, A. germinans can play a major role in any plantation or mangrove reforestation programme in the country. The species flowers and fruits all year and germination is viviparous in nature and as a result, the germinated propagules or seedlings can be planted directly in the plantation sites; it is not necessary to establish nurseries. A. germinans coppices well and can be managed under a coppice system.

R. mangle is the next species in order of importance. It can be planted in areas, which are not directly exposed to the ocean. R. mangle is extensively present on river banks and can be utilised for planting activities along river banks and other sheltered areas.

A. germinans and R. mangle, a mixture of the two species can form an ideal species combination for any planting in areas that are not directly exposed to the ocean. According to Hussain (1990) ideal sites for such a planting exercise can be in Region 5 (Phoenix, Yeoville and Onverwagt) where some mangrove vegetation already exists, and additional suitable areas are found where the process of afforestation can be quickened through artificial planting.

L. racemosa and C. erectus are both members of the family Combretaceae and can be found in limited numbers in different mangrove formations. These species are of smaller sizes and less economic importance, and may not be expected to play any significant role in a plantation programme in Guyana. (b) PLANTING STOCK

For reforestation purposes, good quality planting stock can be defined as those trees having attributes necessary for seedlings to survive and grow after outplanting (Hussain, 1995) or the degree to which planting stock realises the objectives of management. Burdett (1983) has identified nine morphological and physiological characteristics that define high quality planting stock. These include (1) the ability to rapidly produce new roots, (2) the ability to quickly resume photosynthesis and continue growth, (3) sun adapted foliage, (4) balanced root to shoot ratio, (5) good carbohydrate reserves, (6) an optimum mineral nutrient content, and, (7) tolerance to stress.

Both A. germinans and R. mangle are viviparous in germination, that is, their seeds germinate while they are still attached to the mother tree. Once they are mature, the germinated seeds or propagules fall into the water and float until such time when

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they have either been able to reach shoreline and initiate rooting or then rot in the sea-water.

Generally, viability of the propagules or germinated seeds is quite long once they are in a saline environment. However, once they are removed from such an environment and stored in a dry condition, the viability is shortened, primarily because of dehydration of the germinated seeds. Under such conditions the propagules may not retain their viability for more than 3-5 days (Hussain, 1990). The viability in such conditions can be enhanced somewhat by sprinkling saline water on the propagules or keeping them soaked.

As the seeds germinate readily and germinated seedlings are available, it may not be necessary particularly in the coastal condition of Guyana, where both the species flower and fruit all year round to raise planting stock in nurseries as it can somewhat increase the planting cost while not providing any additional benefits. (c) COLLECTION OF PLANTING STOCK

Ideally, propagules should be collected directly from parent trees for planting. When mature and germination has set in or is about to set in, A. germinans seeds turn a darker greenish brown from its original green colour making germinated seeds easily observed. In case of R. mangle, the hypocotyl of mature propagules have reddish brown tips, could be as long as 25-30 cm and weigh about 15g (Tomlinson, 1986).

Collection can be done directly from the trees during the middle or towards the end of the peak fruiting season of each species. This, however, will be more intensive than collecting them from the ground as they fall from the trees or as they are washed ashore. The collection from trees will ensure collection of good quality planting stock as it is desirable that healthy parent trees be selected in advance for the collection of propagules. Hussain (1995) noted that in cases where propagules for collection are not fully developed, can be stored in a humid room for a couple of days where the propagules can be kept continuously soaked in saline water. This will perhaps help in the completion of the developmental process of the propagule seedlings.

As mentioned earlier, propagules and seeds can be found in most coastal regions (Appendix 3). In Region 5, there is a large stand of good quality A. germinans west of Profit and east of the Mahaica River. This stand is located close to the main road passing along the coast can provide sufficient propagules for planting activities in Regions 2 to 5. In Ruimzeigt in West Coast Demerara there is a good stand of A. germinans and propagules or seeds of R. mangle can be collected from the rivers such as the Demerara and Abary.

The planting materials should be handled properly during transport to prevent any part of the propagule from injury. The propagules can be tied in bundles using gummy sacks or the same as cover to protect them from drying up (PCARRD, 1991) or can be placed in jute bags soaked in saline water.

Selection of healthy, mature and large trees for collection of seeds or propagules should be made as far as practicable, because there is a substantial variation in growth among trees of the same species growing in some localities (Hussain, 1990). 3. PLANTING AND MAINTENANCE PROGRAMME (a) PLANTING PROCEDURE

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The plantation sites for mangrove vegetation should be located in inter-tidal zones. Planting will have to be done only during low tides. Pastakia (1991) noted that 4 to 6 hours are available depending on the location of planting sites for planting each day. Because of the short time available for planting each day, the adverse working conditions in the soft mud and short working hours because of the tides. Hussain (1990) suggested that 8-10 man days of labour may be required to plant a unit of land, one hectare than it would have been necessary otherwise. This, however, does not include propagule or seedling collection and transportation.

A number of different spacings have been used in different countries for planting of mangrove species. In the Philippines, the ideal spacing is 1.5 m x 1.5 m and in Costa Rica it is 1 m x 1 m. However, a spacing of 1.5 m x 2 m or 2 m x 2 m seems to be adequate. This means that between 2500 to 2857 seedlings could be planted per hectare. These spacings, which are quite close can be prescribed because of the quite hostile habitat condition, and to reduce labour cost in planting. In order to locate the exact positions where planting should be done, a rope with knots at 1.5 m intervals and another rope 2 m long can be used. The ropes can be aligned and stretched out in the planting area and the propagules or seedlings be planted at each knot.

No special site preparation may be necessary, as planting will be done on soft mud flats. The roots of the propagules can be gently pushed into the soft mud making sure that the roots are not curled or twisted into ringlets. In cases where the soil may be too clayey, holes can be dug large enough to freely accommodate the ball of earth and roots of the seedlings. The depth of planting should consider the length of the propagules. Planting depth could be 1/3 to 2/5 of the total length of propagules. A. germinans require 5-7 days to take root in mangrove soils whereas, R. mangle need 11-15 days to become rooted (Smith, 1992). Propagules of Avicennia require 3-5 weeks to establish and after 4 weeks 62 % of the propagules should become successfully rooted (Clarke and Myerscough, 1993).

According to Pastakia (1986 and 1991) and Hussain (1990), it appears that the ocean in the coastal region is at its roughest between November and February, and most gentle on a relative scale between April and July. Hence, it may be important that all planting activities be completed during the neap tide between April and July.

(b) MAINTENANCE PROGRAMME

One reason for failure in reforestation of mangrove vegetation is due to the high mortality of seedlings. To attain high survival rates of mangrove species planted, a maintenance programme is essential. In so doing the following is suggested:

1. Since, seedlings will be subjected to varying degree of wave action, it may be necessary to undertake some replanting activities within 3 weeks to 1 month after the initial planting. The seedlings which may have either died or washed away can be replaced in such operations. Some amount of replanting may also be necessary about 1 year from the time of the original planting. It may be difficult to make any reasonable estimate about how many seedlings may survive. So, it may be necessary to make an assessment about 3 years after planting to see how dense the crop may have become.

2. Prescribe pruning and thinning can be carried out if presumed to be necessary. This can improve the quality of main stems. The pruned branches and thinned stems can be used for firewood by coastal dwellers.

3. A temporary fence or stakes should be maintained on the periphery of the plantation sites or compartments. This will protect the young plants from trespassers while providing them the guide on which way to take especially during high tides.

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4. There should be regular visits to newly established sites during low tides to remove debris (coconut branches, banana stems and leaves, and others) brought into the area by tidal inundation. This will minimise injury to the seedlings as the tide rises and recedes.

5. Seedlings infected by P. fallax should be regularly collected and disposed. These should be brought inland and burn to avoid the occurrence of borer bettles. Application of insecticide is not recommended due to its possible effect on marine organisms such as plankton, fishes and other crustaceans.

6. Accurate records of the planting date, area, density and growth of surviving seedlings and other activities should be kept.

4. CONSIDERATIONS FOR IMPLEMENTATION There is urgent need for the restoration of mangrove forests along the coastal belt.

The restoration programme will require considerable natural, human and financial resources to co-ordinate and execute all activities. It is, therefore, imperative that the following be considered for the successful immediate and long-term implementation of the programme: (a) education and training, (b) studies and investigation, (c) establishment of model plots, and (d) review and revision of current legislation and policies. (a) EDUCATION AND TRAINING 1. It will be necessary to launch an intensive programme about educating people about the usefulness and many benefits of the mangrove forest. For the successful restoration of the mangrove forests, people’s cognigence of many benefits of mangrove forests and their co-operation and support will have to be a basic pre-requisite. This will require extensive extension activities at the community level in coastal areas provided by the Regional Democratic Councils and the Guyana Forestry Commission. This can be supported by television and radio broadcast, and documentaries. 2. Forest managers in Guyana have never been exposed to the management of mangrove forest nor the establishment of mangrove plantations. Experience acquired in the management of tropical rainforest cannot be readily applied or utilised in mangrove ecosystems. It is, therefore, imperative that some training programme in both management of natural mangrove forest and the establishment of plantations is organised for forestry personnel who will be involved with the execution of such a programme. A short training programme can be organised locally where an expatriate resource person with the experience in mangrove forests management and plantation establishment can impart the training. As an alternative, foresters can be sent to countries such as Bangladesh, Venezuela, Philippines, Malaysia, Indonesia or Costa Rica for about 6-12 months where mangrove forest management and plantation activities can be observed. On return to Guyana, such personnel (s) can arrange training for other colleagues. (b) STUDIES AND INVESTIGATION

The depletion and destruction of the mangrove forests in different localities is not

well explained. It is quite possible that in some localities destruction is just not a straight forward result of erosion resulting mainly from strong wave action, as has been discussed earlier in this paper.

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There is no strong support for mangrove research studies in Guyana. That is why, until now, and if the trend remains the same, in the advent of technological innovations where decision support systems and sophisticated software are used for managing mangrove forest, Guyana will not be able to do anything and will be left behind. The reason for this lies on the dearth and many gaps of knowledge concerning management systems of mangroves. Similarly, there is a lack of continued support when it comes to Government’s thrust towards mangrove research and development projects. This may be exemplified by a shift in concern depending upon the thrust of the authority as a result to a change in Government and programmes.

It is, therefore, recommended that multi-disciplinary studies and investigations be conducted in mangrove areas that would provide valuable information, and increase the forestry and environmental database of the country. These studies should be considered by the relevant authorities or departments in Guyana, together (where possible) with the University of Guyana, to devise programmes to execute these tasks. The studies are as follows: (1) to determine the actual composition and extent of mangrove forest between the Barima-Waini and Pomeroon Rivers, in order to provide a natural baseline for A. germinans and R. mangle in Guyana, (2) to inventorise the flora and fauna of the mangrove forest, and to estimate populations of any endangered species, (3) the establishment of planted areas of mangroves and the comparison of these areas with naturally regenerating areas, to develop a local technology for re-plantation, (4) to investigate the extent and causes of mangrove decline, and (5) a study of the accretion / erosion process in specific areas along the coast, in particular the mechanism for beach formation, and its relation to the sand / shell sediments carried by the major rivers, and their transport properties along the coast. (c) MODEL PLOTS

Once an assessment of available sites has been made and priorities have been set,

the establishment of about 50 hectares of mangrove plantation can be undertaken as a model. These plantations should be monitored and evaluated closely for a year or so, since a critical evaluation of the performance will have to be done before a full-scale plantation programme can be undertaken. Once the performance of the plantations at the end of the first or second year has been carried out successfully, and some of the problems that may have arise have been sorted out, a long-term reforestation programme can be taken up with a target that is feasible from management, financial, logistic, manpower and technological considerations. In addition, a small-scale experimental plantation programme can be set up in an area under severe erosion. (d) REVIEW AND REVISION OF CURRENT LEGISLATION

The current legislation under which the Guyana forests are managed are colonial

and outdated, and does not account for mangrove formations along the coast nor riverian areas. Moreover, the coastal belt on which the mangrove forests are located falls under State Land and not State Forest of which there are two differing legislations (State Land and State Forests). The authorities governing coastal lands are the Ministry of Agriculture, Department of Hydraulics (sea defence system) and Department of land Surveys (awarding agricultural and developmental lands), the Regional Democratic Administrative Councils and the MMA / ADA (agricultural drainage and irrigation projects). Therefore, it is very important at this point in time to review and revise the

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existing legislation (the Forests Act, Chapter 67:01) to incorporate mangrove activities, and declare all coastal mangrove forests as State forest. This can be done without much difficulty, since the Minister in charge of Forests is empowered under section 3 (1) of the Forests Act, “to declare any area of State Land to be State Forests and may, from time to time, vary or revoke such order” (Government of Guyana, 1953). As the coastal land is state owned, an order by the Honourable Minister of Agriculture who is now responsible for forestry can be helpful. This will give the Guyana Forestry Commission who has been recently named as the governing body of the mangrove vegetation under the National Forestry Policy (1997) a more authoritative role. Moreover, this could enable the Guyana Forestry Commission in collaboration with the Ministry of Agriculture, MMA / ADA and the Regional Democratic Administrative Councils to formulate, co-ordinate and execute projects for the effective management of mangrove formations at the ecosystem level for the sustainable development and utilisation of its forestry and non forestry resources in the future. To assist in such processes it may be important that the future practices be related to the actual conditions within the country, and the alternative courses of actions offered by these conditions. In addition, policies for preservation, protection and coastal zone management of mangrove areas be developed with responsibilities for protection from human activities clearly defined. This will require management both in terms of policy and field monitoring by the relevant authorities.

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CHAPTER 5 - DISCUSSION AND CONCLUSION

DISCUSSION Mangrove vegetation can play an important role in a long-term programme for the

protection of the coastal area from saline water. Once the newly accreted land has become stabilised, the vegetation belt can probably be extended gradually, and if the process is continued, a reasonably wide belt of mangrove vegetation will come into existence outside the sea wall in a few years. The establishment of this belt of mangrove vegetation will not only provide protection to the coastal defence system, but will help in the extension of the shoreline into the sea. In addition, it will provide engineers with more time for consolidating the sea defence in places where a breach may be likely to occur.

The mangrove ecosystem plays a very important role in the economy of the coastal regions. Because of breaches in the sea defence system resulting in flooding of the coastal areas, it may increasingly become more difficult to cultivate rice, sugarcane, vegetables and ground provision (cassava, eddoe, dasheen, sweet potato and yam) which are the principal crops of the coastal belt and the country as a whole. So, in most cases the development of mangrove forest is capable of generating economic activities of far reaching consequences.

A number of interests overlap when considering the value and management/ administration of the mangrove coast of Guyana. The first stage in the future management and administration of the mangrove zone must be to determine the policy towards the foreshore. This seems to be a complex problem, as it involves conflicts of interest from many government and private sector bodies. The illegal harvesting of mangroves for fuel wood, harvesting of mangrove bark by coastal dwellers, small-scale fishermen creating unwanted paths through the swamps, mangrove clearance for irrigation canals by MMA/ADA and the tourism sector often competes for the same resource on the same land. It may not be as simple as to pass on the administrative aspects to any department, without consultation with other interest groups, and consideration of the impacts and uses of the coastal zone. Therefore, it is important (in the future) for the interests of sea defence, forestry, conservation, fisheries and human heritage to be integrated into a policy for the management and administration of the coastal zone.

Plantation activities in the coastal mud flats is labour intensive as all activities that are associated with establishment of plantations will have to be done manually. It is envisaged that planting of seedling or propagules in knee to waist deep mud will be slow and cumbersome. However, the use of a mud sledge (catmarang) by fishermen in the coastal mud flats could be useful.

Guyana has a low population and the availability of adequate manpower for planting activities could be a limiting factor in implementing any plantation programme. In areas that are predominantly agricultural, the availability of labour may not be too difficult but it may be necessary to pay higher wages of between $2,500.00 - 3,000.00 (Guyana) per day per person, which is about twice the minimum wages for unskilled labour in the country. However, in areas close to the major urban centres, this could become a major problem. It is therefore, suggested that the development of any plantation programme in the coastal areas close to urban centres should be preceded by an assessment of the availability of manpower willing to undertake plantation work.

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The limitation of mangrove species in Guyana is of concern to environmentalists and foresters. In neighbouring Suriname, the species R. apiculata and A. marina are found in abundance in addition to R. mangle, A. germinans and L. racemosa found in Guyana. It is suggested that provenance and trial plots be established with the aim of introducing R. apiculata and A. marina into Guyana taking into account their tolerance, survival and adaptability to the local environment. This would facilitate the establishment of basic data in the understanding of the ecology and functions of the exotic species. If successful, the new species can be introduced to increase the diversity of mangrove species in Guyana.

Because of the nature of activities to be performed, the Guyana Forestry Commission could be a logical choice for executing any plantation programme or managing any natural mangrove forest given its recent mandate, in collaboration with the Ministry of Agriculture, Hydraulics Division and the Regional Democratic Administrative Councils. But the Guyana Forestry Commission is severely handicapped by an acute shortage of trained manpower, although administrative and financial resources are in place. An infrastructure for the execution of any mangrove project with adequately trained personnel will have to be put in place before undertaking any plantation programme. Services of expatriate experts in mangrove forest management and plantation establishment may also be necessary in the early phases of the execution of mangrove programmes.

In spite of the fact that a major portion of the mangrove vegetation along the Guyana coast has already disappeared due to erosion and cutting, it is very important that whatever remains today is properly protected and managed. It will be necessary to ensure that no further indiscriminate felling of mangrove trees take place which would require monitoring, and plans for the management and development are taken up without any further delay.

Mangrove forests have existed all along the coast when the sea defence system was constructed (Pastakia, 1991). In some areas like the MMA / ADA project area, almost all the outlets of fresh water into the mangrove swamps have been blocked as was reported. This kind of action did cause adverse effects on the mangrove vegetation. A clear understanding of the effect of different types of sea defence structures on mangrove vegetation is very important, and this can only be achieved through a detailed study of the effect of sea defence system on mangrove vegetation. Such a study can be combined with a study of the contribution of biotic factors particularly man to the depletion of mangrove vegetation. It may be interested to note, that in future, all protective measures involving engineering structures along coastal Guyana should be preceded by an environment impact analysis.

CONCLUSION

In concluding, the following points can be highlighted:

1. A programme of mangrove development in Guyana is of paramount importance. Implementation of reforestation programmes is needed especially in the view of the poor state of the economy to afford the rehabilitation and construction of levees and sea walls, the problem of their high maintenance cost and the shortage of professional and technical skills in sea defence systems. It is, therefore, important that a proper management regime be instituted for both tree resources and other resources that may be present in the mangrove environment. The resources of the mangrove forest should be

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managed at an ecosystem level, taking into consideration that all its components are managed on a sustainable basis. 2. A detailed study by competent scientists who understand the dynamics of a mangrove ecosystem some of the reasons for the decline in mangrove vegetation along the coast can be identified. It is important that such a study be commissioned by the Guyana authority as soon as possible. 3. It will be necessary to undertake studies on the effect of biotic factors and sea defence system on mangrove vegetation. 4. An intensive programme for educating coastal communities as well as government officials both at policy and execution levels about the importance and many benefits of mangrove vegetation will have to be undertaken. The coastal communities should also be made to understand that the protection of the properties and agricultural lands are not the responsibility of the Guyana Government alone. These communities do have an important role to play in the protection of the coastal environment. 5. The coastal belt where mangrove formation is either in existence or can be developed should be declared State Forest and the relevant legislation be reviewed, amended or revised in the shortest possible time. 6. An infrastructure with adequately trained manpower and other logistic support will have to be established for the management of the mangrove forests. The installation of a proper management and protection mechanism for the existing mangrove vegetation is extremely important and should be taken up without further delay. 7. Mangrove forests will not form an impermeable structure like the sea wall and as such may not be able to arrest the penetration or intrusion of the sea-water into agricultural fields. However, the vegetation will play a meaningful role in the protection of the sea walls or embankments.

Therefore, an all out effort should be made for the establishment of a continuous belt of mangrove vegetation as far as possible outside the existing sea defence system by raising plantations in localities without vegetation and properly managing the existing vegetation in other areas.

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Hussain, M. 1990. The Mangrove Belt in Guyana. Technical Paper No. 1 TCP / Guy 18953. FAO, Rome. Hussain, M. 1995. Silviculture of Mangroves. Unasylva. 181 (6): 36-42. IUCN. 1983. Global Status of Mangrove Ecosystems. Commission on Ecology Paper No. 3. Gland, Switzerland. Lugo, A. E., M. Brinson and S. Brown. 1990. Ecosyatems of the World 15. Forested Wetlands. Elsevier Science Publishers B.V. The Netherlands. Melana, D. 1994. Survival and Early growth of Rhizophora species Seedlings of Selected Provenances as Affected by Salinity. PhD Dissertation. UPLB-CF. College Laguna, Philippines. Pp 188. NEDELO. 1972. Report on Sea Defence Studies. Prepared for the Ministry of Works, Hydraulics and Supply, Guyana. Netherlands Engineering Consultants. The Hague. Nugroho, J. 1992. Mangrove Forest Management and Utilisation in Indonesia. A Paper Presented and Discussed in SFI 299 under Prof. V. T. Manarpaac. UPLB-CF. Pp 1- 17. Overseas Development Administration. 1980. Sea Coast Defences, Essequibo Districts - Design Study for Alternative Forms of Construction. ODA, London. Pannier, F. and E. Ramcharan. 1983. Conservation and Management of Mangroves in Venezuela, Trinidad and Tobago. Report for Sierra Club / UNEP. Pastakia, C. M. 1986. Investigation into Dead Mangrove - Courida. Occasional Report No. 2 MMA / ADA. Abary Drainage and Irrigation Project, Guyana. Pastakia, C. M. 1991. A Preliminary Study of the Mangroves of Guyana. Article B 946/89, No. 8912. Aquatic Biological Consultancy Services Limited. Pearman, R. W. 1956. Tanning Material of the British Commonwealth. In Colonial Plant and Animal Products. R. H. Kirby Publishers. Philippine Council for Agriculture, Forestry and Natural Resources Research Development. 1988. Reforesting Denuded Mangroves. PCARRD Farm Primer No. 1- DENR. Philippine Council for Agriculture, Forestry and Natural Resources Research Development. 1991. The Philippines Recommends for Mangrove Production and Harvesting. Philippines Recommends Series No. 74. PCARRD - DENR. Qureshi, T. M. 1990. Experimental Plantation for Rehabilitation of Mangrove Forests in Pakistan. Mangrove Ecosystems. Occasional Papers No. 4 . UNDP / UNESCO Regional Mangroves Project RAS/86/120. Rambajan, I. 1990. Mangrove. A National System of Sea Defence. Guyana National Printers Limited. Public Road, La’Pentience, Georgetown. Reyne, A. 1961. On the Contribution of the Amazon River to Accretion of the Coast of the Guianas. Geologie en mijnbouw. Siddiqui, N. A. 1995. A Review on the Regeneration Problems of the Mangroves with Particular Reference to Bangladesh Mangroves. International Society of Mangrove Ecosystems. Newsletter No. 16. Pp 2-8. Sin, M. S. 1990. Mangroves in Kampuchea. Forest Ecology and Management. 33/34: 59-62. Smith, T. J. 1992. Forest Structure. Coastal and Estuarine Studies. Tropical Mangrove Ecosystems. Americas Geophysical Union. Washington, DC. Pp 101-136. Spaans, A. L. and F. l. Baal. 1990. The Estuarine Zone of Suriname: Towards a Symbiosis Between Conservation and Development of a Coastal Wetland area.

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Fiselier, World Wildlife Fund, Netherlands. Swayne, C. S. 1986. West Demerara Sea Defence- Vulnerability Report. P.V. Sanasi and Associates. Thuraiaja, V. 1994. Coastal Resources Development Options in South-east Asia and the Pacific Regions: Economic Valuation, Methodologies and Applications in Mangrove Development. Maritime Studies. 79: 1-13. Timehri Meteorological Station, Guyana. 1996. “46 Years of Weather Forecasting”. Newsletter No. 22. Ministry of Agriculture, Georgetown, Guyana. Tomlinson, P. B. 1986. The Botany of Mangroves. Cambridge University Press.