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PART 1: GLOBAL OVERVIEW

INTRODUCTION

Mangroves are commonly found along sheltered coastlines in the tropics and sub-tropics where they fulfil important socio-economic and environmental functions. These include the provision of a large variety of wood and non-wood forest products; coastal protection against the effects of wind, waves and water currents; conservation of biological diversity – including a number of endangered mammals, reptiles, amphibians and birds; protection of coral reefs, sea grass beds and shipping lanes against siltation; and provision of habitat, spawning grounds and nutrients for a variety of fish and shellfish, including many commercial species.

High population pressure in coastal areas has, however, led to the conversion of many mangrove areas to other uses, including infrastructure, aquaculture, rice and salt production. Numerous case studies describe mangrove losses over time, but information on the status and trends of mangrove area extent at the global level is scarce.

The first attempt at estimating the total mangrove area in the world was undertaken as part of the FAO/UNEP Tropical Forest Resources Assessment in 1980, where the world total was estimated as 15.6 million hectares. More recent estimates range from 12 to 20 million ha (refer to Table 1 below). For many of these studies, countries with small areas of mangroves were excluded due to lack of information and because their combined area of mangroves would not significantly affect the world total.

Table 1. Previous estimates of global extent of mangroves.

 

Reference

Reference year1

Number of countries included

Estimated total area (ha)

 
 

FAO, UNEP, 1981

1980

51

15 642 673

 
 

Saenger et al., 1983

1983

65

16 221 000

 
 

FAO, 1994

1980-1985

56

16 500 000

 
 

Groombridge, 1992

1992

87

19 847 861

 
 

ITTO/ISME2, 1993

1993

54

12 429 115

 
 

Fisher and Spalding, 1993

1993

91

19 881 800

 
 

Spalding et al., 1997

1997

112

18 100 077

 
 

Aizpuru et al., 2000

2000

1123

17 075 600

 
           

A recent FAO initiative aims at facilitating access by policy makers, planners and mangrove managers worldwide to comprehensive information on the current and past extent of mangroves in all countries and areas in which they exist. This document presents the preliminary results, which include an updated list of the most recent, reliable mangrove area estimate by country along with revised estimates for 1980 and 1990 and an extrapolated estimate for 2000 for each country.

All national level estimates for each country are presented along with a short description of the mangrove vegetation and graphs illustrating the trend in mangrove area changes over time.

MATERIALS AND METHODS

This study builds on the earlier FAO/UNEP assessment of the global mangrove area and on the recent FAO Global Forest Resources Assessment 2000 (FRA 2000), where all countries were asked to provide information on current forest area according to forest types, using their own classification system. Most of the countries that have mangroves provided specific information on their extent.

An extensive literature search and requests for information sent to mangrove networks and individual specialists worldwide yielded additional information. In addition to the past assessments listed in Table 1, the main bibliographical sources consulted include proceedings of conferences and other technical reports available in FAO’s libraries, the Aquatic Sciences and Fisheries Abstracts (ASFA) database and the CABI abstracts as well as information available on the internet.

Attention focused, in the first instance, on references with recent and reliable national level information on the extent of mangroves in a given country. A search was also made for past estimates in order to facilitate an analysis of area changes over time in each country. Sub-national level data (region/province/extended forest) were also included where available. In some cases, these sub-national level figures were used to create a composite national estimate. They were also very valuable for the trend analyses.

More than 2800 national and sub-national datasets were collected, covering 121 countries and areas where mangroves are known to exist, with the earliest estimates dating back to 1918. Crosschecking of data was done wherever possible and the information in the database has been analysed with the assistance of mangrove specialists throughout the world. (Refer to Annex 3 for a list of people contacted.)

One of the results of this analysis is an updated list of the most recent, reliable estimate for each country, mostly based on inventories or analysis of remote sensing imagery.

An initial screening of results included weeding out duplicates, discarding rough “guesstimates” and selecting just one estimate for those years where more than one was available for the country trend analyses. This was followed by regression analyses (best fit of linear, polynomial, logarithmic and power curves) of existing reliable data over time for each country, which provided estimates for 1990 and 1980, and an extrapolated estimate for 2000.

Where insufficient information was available, i.e. only one estimate within the last 30 years (representing around 0.1 percent of the total mangrove area), the area was assumed to have remained constant unless qualitative information indicated otherwise.

Where recent information was unavailable (about 3.5 percent of the total mangrove area), the extrapolation to year 2000 was based on the annual forest change rate for all forest types in the country for the period 1990 to 2000 applied to the latest reliable estimate. These change rates were reported in the Global Forest Resources Assessment 2000 (FAO, 2001).

All estimates and a review of all references consulted were entered in the Forestry Information System (FORIS), developed by FAO’s Forest Resources Assessment Programme. FORIS includes a relational database that enables the users to connect geographic units with references, data context and subject classification.

For details on reference sources and the estimates and regression used for individual countries refer to Part 2 and to FAO, in press. All primary datasets and reference reviews are accessible at the following website: http://www.fao.org/forestry/mangroves.

RESULTS

A total of 121 countries and areas were identified as containing one or more species of true mangroves (sensu Tomlinson, 1986). Table 2 below presents an overview of the main results of the analysis of the status and trends in mangrove area extent in the form of regional and world totals. The year given for the most recent, reliable estimate is the area-weighted average.

The most recent, reliable estimate for each country/area is shown in Table 3. A table with country level estimates for 1980, 1990 and 2000, based on trend analyses, can be found in Annex 1, while detailed information for each country/area is presented in Part 2.

Table 2. Status and trends in mangrove area extent by region.

 

Region

Most recent
reliable estimate

1980

1990

Annual change
1980-1990

2000

Annual change
1990-2000

 
   

000 ha

Ref year

000 ha

000 ha

000 ha

%

000 ha

000 ha

%

 
 

Africa

3 390

1993

3 659

3 470

-19

-0.5

3 351

-12

-0.3

 
 

Asia

6 662

1991

7 857

6 689

-117

-1.6

5 833

-86

-1.4

 
 

Oceania

1 578

1995

1 850

1 704

-15

-0.8

1 527

-18

-1.1

 
 

N & C America

2 103

1994

2 641

2 296

-34

-1.4

1 968

-33

-1.5

 
 

South America

2 030

1992

3 802

2 202

-160

-5.3

1 974

-23

-1.1

 
 

World Total

15 763

1992

19 809

16 361

-345

-1.9

14 653

-171

-1.1

 

As can be seen from Table 2, the most extensive area of mangroves is found in Asia, followed by Africa and South America. Four countries (Indonesia, Brazil, Nigeria and Australia) account for about 41 percent of all mangroves and 60 percent of the total mangrove area is found in just ten countries. Refer to Figures 1, 2 and Table 3, which are all based on the most recent, reliable estimate identified for each country.

The results of the trend analyses indicate that the current mangrove area worldwide has now fallen below 15 million hectares, down from 19.8 million ha in 1980. The world has thus lost 5 million ha of mangroves over the last twenty years, or 25 percent of the extent found in 1980. As is also evident from Table 2, mangrove deforestation continues, albeit at a slightly lower rate in the 1990s (1.1 percent per annum) than in the 1980s (1.9 percent per annum).

The figures presented in Annex 1 suggest that, in absolute terms, the highest rates of deforestation in the 1980s were found in Brazil, Indonesia, Pakistan, Australia and Mexico. The same countries (except for Pakistan which has been replaced by Papua New Guinea) top the list of countries with the largest losses of mangroves in the 1990s, although the rates have diminished substantially in most of these.

Figure 1. Mangrove extent per country (hectares).

In relative terms, countries with high deforestation rates include Singapore, Benin, Dominica, Brazil and Côte d’Ivoire in the 1980s and Côte d’Ivoire, Honduras, China, Congo and Barbados in the 1990s. Conversely, a number of countries have registered a positive change over time, including Bangladesh, where the largest mangrove area (The Sundarbans Reserved Forest) is well protected and substantive and successful efforts have been made in coastal afforestation, particularly on land formed by accretion. Kuwait also registers a positive trend, as mangroves have been planted as an introduced species. For other countries, an apparent positive or negative trend may be due to changes in methodology or definition – or due to the discovery of new mangroves areas not previously included (e.g. United Arab Emirates).

Figure 2. Mangrove extent per country (percentage).

Table 3. Most recent, reliable mangrove area estimates.

AFRICA

 

ASIA

 

OCEANIA

Country/
Area

ha

Year

 

Country/
Area

ha

Year

 

Country/
Area

ha

Year

Angola

60 700

1992

 

Bahrain

100

1992

 

American
Samoa

52

1976

Benin

1 700

1989

 

Bangladesh

622 482

1996

 

Australia

955 277

1997

Cameroon

227 500

2000

 

Brunei
Darussalam

17 100

1992

 

Fiji

42 464

1991

Comoros

2 600

1976

 

Cambodia

72 835

1997

 

Guam

70

1993

Congo

12 000

1995

 

China

36 882

1994

 

Kiribati

258

1995

Côte d'Ivoire

15 000

1995

 

India

487 100

1997

 

Marshall
Islands

n.a.

n.a.

Dem. Rep. of
Congo

22 600

1995

 

Indonesia

3 493 110

1988

 

Micronesia

8 564

1983

Djibouti

1 000

1985

 

Islam. Rep. Of
Iran

20 700

1994

 

Nauru

1

1993

Egypt

482

1998

 

Japan

400

1980

 

New Caledonia

20 250

1987

Equatorial
Guinea

25 700

1995

 

Kuwait

2

2000

 

New Zealand

22 200

1996

Eritrea

6 400

1997

 

Malaysia

587 269

1995

 

Niue

3 000

1981

Gabon

115 000

2000

 

Maldives

n.a.

n.a.

 

Northern Mariana Islands

7

1984

Gambia

59 600

1993

 

Myanmar

452 492

1996

 

Palau

4 708

1985

Ghana

10 000

1995

 

Oman

2 000

1992

 

Papua New
Guinea

464 000

1993

Guinea

296 300

1995

 

Pakistan

207 000

1990

 

Samoa

752

1993

Guinea-Bissau

248 400

1990

 

Philippines

127 610

1990

 

Solomon
Islands

52 500

1995

Kenya

52 980

1995

 

Qatar

500

1992

 

Tokelau

n.a.

n.a.

Liberia

19 000

1995

 

Saudi Arabia

20 400

1985

 

Tonga

1 305

1990

Madagascar

325 560

1987

 

Singapore

500

1990

 

Tuvalu

40

1993

Mauritania

104

1993

 

Sri Lanka

8 688

1992

 

Vanuatu

2 519

1993

Mauritius

7

1991

 

Thailand

244 085

2000

 

Wallis and Futuna Islands

n.a.

n.a.

Mayotte

668

1989

 

Timor Leste

3 035

2000

       

Mozambique

392 749

1997

 

United Arab
Emirates

4 000

1999

       

Nigeria

997 700

1995

 

Viet Nam

252 500

1983

       

Sao Tome and
Principe

n.a.

n.a.

 

Yemen

927

1993

       

Senegal

182 400

1985

               

Seychelles

2 000

1995

               

Sierra Leone

156 500

1986

               

Somalia

10 000

1975

               

South Africa

673

1991

               

Sudan

500

1995

               

United Rep. of
Tanzania

143 284

1987

               

Togo

1 000

1999

               

Total Africa

3 390 107

1993

 

Total Asia

6 661 717

1991

 

Total Oceania

1 577 967

1995

Table 3 cont.

NORTH AND CENTRAL AMERICA

 

SOUTH AMERICA

Country/Area

ha

Year

 

Country/Area

ha

Year

Anguilla

90

1991

 

Brazil

1 012 376

1991

Antigua and Barbuda

1 175

1991

 

Colombia

379 954

1996

Aruba

420

1986

 

Ecuador

149 688

1999

Bahamas

141 957

1991

 

French Guiana

55 000

1980

Barbados

14

1991

 

Guyana

80 400

1994

Belize

65 767

1995

 

Peru

4 791

1992

Bermuda

16

1992

 

Suriname

98 121

1998

British Virgin Islands

587

2001

 

Venezuela

250 000

1986

Cayman Islands

7 268

1991

       

Costa Rica

41 330

1992

       

Cuba

529 700

1992

       

Dominica

10

1991

       

Dominican Republic

21 215

1998

       

El Salvador

26 800

1994

       

Grenada

255

1992

       

Guadeloupe

2 325

1997

       

Guatemala

17 727

1998

       

Haiti

15 000

1990

       

Honduras

54 300

1995

       

Jamaica

9 731

1997

       

Martinique

1 840

1998

       

Mexico

488 000

1994

       

Montserrat

5

1991

       

Netherlands Antilles

1 138

1980

       

Nicaragua

282 000

1992

       

Panama

158 100

2000

       

Puerto Rico

6 410

2001

       

Saint Kitts and Nevis

79

1991

       

Saint Lucia

200

2002

       

Saint Vincent and
Grenadines

51

1991

       

Trinidad and Tobago

7 150

1991

       

Turks and Caicos Islands

23 600

1991

       

United States

197 648

2001

       

United States Virgin Islands

978

1991

       
             

Total North and Central America

2 102 886

1994

 

Total South America

2 030 330

1992

The relatively large mangrove deforestation rates in Asia, the Caribbean and Latin America in the 1980s reflect large scale conversion of mangroves for aquaculture and tourism infrastructure. Most countries have now banned the conversion of mangroves for aquaculture purposes and require environmental impact assessments prior to large-scale conversion of mangroves areas for other uses.

The study did not provide information on the rate of mangrove degradation or fragmentation.

DISCUSSION

As with all analyses, the reliability of the results depends on the quality of the inputs. In this particular case, lack of comprehensive information and changes in definitions and methodologies between different assessments make it difficult to compare results over time and establish reliable trends. For some countries, the most recent estimate is a composite of sub-national figures due to lack of recent national figures and for others, the borders have changed or additional mangrove areas have been discovered recently, making trend analyses very challenging.

The discussion below focuses on overall data availability and quality and on specific issues related to the determination of the most recent, reliable estimate and the trend analyses.

Overall data availability

FAO’s database on mangrove area estimates currently includes 2814 datasets sorted by the 121 countries and areas identified by this study as having mangroves. The total number of different references is 497. Of these, 43 are references providing information on mangrove areas at the global or regional level while the remaining 454 are country-specific references. An illustration of the information availability per country (number of country-specific references and number of national and sub-national level datasets) is given in the Figures below.

A total of 1010 datasets provide national level estimates (including those with breakdown to sub-national units), while 1804 datasets only provide sub-national figures, covering regions, provinces or important mangrove areas within a given country. Some of the entries are secondary sources repeating past estimates. The total number of different national level estimates is 756 - equalling an average of six different estimates over time per country.

Despite concerted efforts, no quantitative information was identified on the extent of the mangroves found in 5 countries/areas, i.e. Maldives, Marshall Islands, Sao Tome and Principe, Tokelau and Wallis and Futuna Islands. For ten countries, only a single estimate was identified. Conversely, more than ten different national level estimates over time were identified for 28 countries. For seven of these, more than 100 datasets (national and sub-national level) were identified.

Figure 3. World data availability map.

Figure 4. Data availability. Africa.

Figure 5. Data availability. Asia.

Figure 6. Data availability. Oceania.

Figure 7. Data availability. North and Central America.

Figure 8. Data availability. South America.

Data quality

The general quality of the data is illustrated in Table 4 below, which shows the methodology used for generating national level mangrove area estimates. The percentages given for the different methodologies refer to the number of national estimates, not the percentage of the mangrove area covered by this methodology.

Table 4. Data quality.

   

All national level estimates

 

Most recent, reliable estimate

 
   

Ground survey

Remote sensing/ Mapping

Expert estimate

Not known

 

GS

RS

EE

NK

 
 

Region

No.

No.

%

No.

%

No.

%

No.

%

 

No.

%

No.

%

No.

%

No.

%

 

Africa

191

3

1

68

36

22

11

98

51

 

1

3

14

44

5

16

12

37

Asia

248

8

3

65

26

32

13

143

58

 

2

8

11

46

4

17

7

29

Oceania

60

2

3

19

32

6

10

33

55

 

2

11

9

50

0

0

7

39

N. & C. America

191

16

8

58

30

36

19

81

42

 

12

32

9

26

5

15

8

23

South America

66

0

0

31

47

6

9

29

44

 

0

0

3

37

2

25

3

37

    World

756

29

4

241

32

102

13

384

51

 

17

15

46

40

16

14

37

32

Around 36 percent of all national level estimates were based on ground surveys or remote sensing and mapping. It is noteworthy that none of the national level estimates for countries in South America were based on ground surveys – probably due to the costs involved in conducting large scale inventories.

The high level of estimates without a known methodology is worrying. Where this is due to reliance on secondary sources attempts will be made to obtain copies of the original sources of information. However, the study also highlighted that there is a need to pay further attention to the description of the methodology used when reporting new figures.

As it is evident from the right hand side of the table, the selection of the most recent, reliable national level estimate gave priority to those estimates derived from ground surveys and/or remote sensing, where possible. More than half of the estimates selected are thus based on the use of these methodologies.

Definitions

In the present study, mangroves were broadly defined as areas containing one or more true mangroves according to Tomlinson, 1986. No attempt was made to re-classify areas defined as mangroves in the original sources; however waterways and other vegetation types existing within the larger mangrove area and areas of freshwater swamp substracted from the total area, when reported. All definitions used by the original sources have been inserted into the database. Given that mangroves are a relatively distinct and, in most cases, easily demarcated forest type, the problem of different definitions used over time is deemed to be less significant than the problems caused by the use of different methodologies and sampling intensities over time and possible interpretation errors.

Most recent, reliable estimate

Recent estimates, dating from 1995 or later, were identified for 45 countries (or 44 percent of all countries and areas) with estimates from an additional 48 countries dating from 1990 to 1994. Together, these two groups of countries account for 69 percent of the mangrove are in the world.

Conversely, for 23 countries and areas the most recent, reliable figure was dating from before 1990, and for five countries no estimate was identified at all. The majority of countries and areas where the most, recent reliable estimate dates from 1985 or earlier, are arid zone countries or Small Island Developing States (SIDS) i.e. countries with relatively small areas of mangroves.

The combined area of four countries (Indonesia, Brazil, Nigeria and Australia) has a strong influence on the global total, as these countries together account for an estimated 6.5 million ha or 41 percent of the total mangrove area in the world.

Despite the very high number of sub-national and national level estimates available, estimating the area of mangroves for Indonesia proved particularly difficulties due to the large area and the lack of recent information covering the whole country. Sub-regional estimates for eight main groupings of islands (Bali, Irian Jaya, Java, Kalimantan, Maluku, Nusa Tenggara, Sulawesi and Sumatra) were thus used to generate a composite national level estimate as well as for the trend analysis. However, no recent estimate was identified for Irian Jaya which contains one of the largest mangrove areas. As a result, the area weighted average year of the composite estimate from Indonesia is 1988 (Refer to Part 2, Box 2 for details). For Brazil, the most recent, reliable estimate identified dates from 1991; for Nigeria, the most recent estimate is from 1995 and for Australia it is 1997.

Table 5 lists the countries and areas according to the date of the most recent, reliable estimate.

Table 5. Countries sorted by year of most recent, reliable estimates.

No quantitative information

y<1980

1980=y<1985

1985=y<1990

1990=y<1995

1995=y=2002

Maldives

American
Samoa

French Guiana

Aruba

Angola

Australia

Marshall Isl.

Comoros

Japan

Benin

Anguilla

Bangladesh

Sao Tome and
Principe

Somalia

Micronesia

Djibouti

Antigua and Barbuda

Belize

Tokelau

 

Netherlands Antilles

Indonesia

Bahamas

British Virgin Islands

Wallis and
Futuna Isl.

 

Niue

Madagascar

Bahrain

Cambodia

   

Northern Mariana Isl.

Mayotte

Barbados

Cameroon

   

Viet Nam

New Caledonia

Bermuda

Colombia

     

Palau

Brazil

Congo

     

Saudi Arabia

Brunei Darussalam

Côte d'Ivoire

     

Senegal

Cayman Islands

Dem. Rep. of Congo

     

Sierra Leone

China

Dominican Republic

     

United Rep. of
Tanzania

Costa Rica

East Timor

     

Venezuela

Cuba

Ecuador

       

Dominica

Egypt

       

El Salvador

Equatorial Guinea

       

Fiji

Eritrea

       

Gambia

Gabon

       

Grenada

Ghana

       

Guam

Guadeloupe

       

Guinea-Bissau

Guatemala

       

Guyana

Guinea

       

Haiti

Honduras

       

Islam. Rep. Of Iran

India

       

Mauritania

Jamaica

       

Mauritius

Kenya

       

Mexico

Kiribati

       

Montserrat

Kuwait

       

Nauru

Liberia

       

Nicaragua

Malaysia

       

Oman

Martinique

       

Pakistan

Mozambique

       

Papua New Guinea

Myanmar

       

Peru

New Zealand

       

Philippines

Nigeria

       

Qatar

Panama

       

St Kitts and Nevis

Puerto Rico

       

St Vincent and
Grenadines

Saint Lucia

       

Samoa

Seychelles

       

Singapore

Solomon Isl.

       

South Africa

Sudan

       

Sri Lanka

Suriname

       

Tonga

Thailand

       

Trinidad and Tobago

Togo

       

Turks and Caicos
Islands

United Arab Emirates

       

Tuvalu

United States

       

US Virgin Islands.

 
       

Vanuatu

 
       

Yemen

 

Total number of countries per class

5

3

7

13

48

45

Percentage of total mangrove area per class

n.a.

0.1 %

2%

29%

25%

44%

Trends over time

The literature search covered a period of more than 80 years with the earliest assessments analysed dating back to 1918 (Philippines), 1921 (Madagascar) and 1928 (Singapore) and the most recent ones dating from 2002 (Saint Lucia).

Part 2 provides the list of all the national level estimates by country - including the full references as well as information related to the methodology and whether the estimate was used for the trend analysis. The results of the individual trend analyses for each country and area can also be found in Part 2. The complete lists of both national and sub national level estimates and references entered in the database are included in FAO (in press).

The trend analyses were hampered by three main problems: lack of comprehensive data over time, differences in definition over time and differences in assessment methodologies over time. The use of different methodologies over time is the largest problem in the current study. The apparent, fairly large mangrove deforestation rate in Australia, for example, may, at least partly, be due to the use of different methodologies over time. Although preference was given to estimates based on field level inventories and remote sensing when selecting estimates for the trend analysis, it was not always possible to exclude estimates where the methodology was unknown.

Even when the same method was used over time, different scales and sampling intensities may have been used.

Comparison with previous studies

Table 6 below presents an overview of the results of this study compared with previous global estimates.

Table 6. Comparison with previous studies.

 

Extent (ha)

 
 

Region

Ibid,

1980

Ibid,

1990

Ibid,
2000

Spalding et al. 1997

ISME/ ITTO 1993

Fisher & Spalding, 1993

Ibid

1992

Groombridge 1992

Saenger et al. 1983

FAO, UNEP 1981

 
 

Africa

3 659 322

3 469 844

3 350 813

3 738 304

2 945 367

5 566 354

3 390 107

5 549 780

3 258 800

3 607 000

 
 

Asia

7 856 500

6 689 280

5 832 737

7 580 932

5 091 913

7 719 081

6 661 717

7 682 335

5 179 600

5 581 651

 
 

Oceania

1 850 067

1 703 949

1 526 934

1 878 894

38 543

1 514 457

1 577 967

1 492 157

1 698 002

553 000

 
 

N. & C. America

2 641 289

2 296 402

1 968 407

2 479 425

1 931 650

3 314 940

2 102 886

3 309 940

2 012 400

2 151 700

 
 

South America

3 801 600

2 202 000

1 974 300

2 457 900

2 459 546

1 813 823

2 030 330

1 813 823

4 072 200

3 749 322

 
 

World Total

19 808 778

16 361 475

14 653 191

18 128 005

12 467 019

19 928 655

15 763 007

19 848 035

16 221 002

15 642 673

 

The present figures are obtained by adding all the country figures for each region

In summary, and keeping the caveats cited in the previous sections in mind, the results indicate that previous estimates of the total mangrove area made in the early 1980s were too low (primarily due to the limited number of countries included), whereas those made in the 1990s were too high. It should be noted that, while the new estimates provided by this study for 1980 and 1990 and the most recent, reliable estimate (area weighted average year: 1992) are presumed to be the best available and fairly reliable in that they are primarily based on information from inventories and aerial surveys, the extrapolation to year 2000 is, by nature, less reliable - particularly where few or no recent assessment results were available. This estimate is thus only indicative and is likely to change as and when results from on-going and future assessments become available.

CONCLUSIONS

Mangroves fulfil many extremely important productive, protective and social functions. Yet, increased population pressures in coastal areas and lack of awareness have lead to large scale conversion of mangroves to other uses. Numerous case studies and anecdotal evidence exist describing mangrove losses over time. However, access to comprehensive information on the status and trends of mangrove areas at the global level has been limited.

The initiative by the FAO described in this paper aims at facilitating access to comprehensive information on the current and past extent of mangroves in all countries and areas in which they exist.

More than 2800 national and sub-national data sets have, so far, been collected, covering 121 countries and areas where mangroves are known to exist, with the earliest estimates dating back to 1918. An updated list of the most recent, reliable estimate for each country has been compiled. Regression analyses based on earlier data provided revised estimates for 1990 and 1980 and an extrapolated estimate for 2000 for each country.

The results of the analysis of the most recent, reliable estimate identified for each country and area show that the area of mangroves vary from a few hectares to more than a million hectare in individual countries and that four countries (Indonesia, Brazil, Nigeria and Australia) account for about 41 percent of all mangroves and 60 percent of the total mangrove area is found in just ten countries.

The study illustrated the problems associated with generating reliable trends due to differences in methodology used over time as well as the lack of recent, reliable and comprehensive information. The estimate for 2000 is thus indicative only and is likely to change when results from on-going and future assessments become available.

Nevertheless, the trend analyses indicate that the current mangrove area worldwide has now fallen below 15 million hectares, down from 19.8 million ha in 1980. The world has thus lost 5 million ha of mangroves over the last twenty years, or 25 percent of the extent found in 1980.

The study also indicates that mangrove deforestation continues, albeit at a slightly lower rate in the 1990s (1.1 percent per annum) than in the 1980s (1.9 percent per annum), reflecting the fact that most countries have now banned the conversion of mangroves for aquaculture purposes and require environmental impact assessments prior to large-scale conversion of mangroves for other uses.

In addition to providing access to all primary data and thus facilitating the analysis of these by others, the database also gives an indication of where information is lacking and efforts should be made to obtain more recent and reliable area estimates.

Better information on both the extent and the condition of mangroves is needed as an aid to policy and decision making aimed at the conservation, management and sustainable use of the world’s remaining mangrove ecosystems.

Readers are thus strongly encouraged to provide feedback and additional information to help update and improve this database for the benefit of all those who may have an interest in mangroves.

BIBLIOGRAPHY

Aizpuru, M., Achard, F., and Blasco, F. 2000. Global assessment of cover change of the mangrove forests using satellite imagery at medium to high resolution. In: EEC Research project n 15017-1999-05 FIED ISP FR – Joint Research Centre, Ispra.

Clough, B.F. 1993. The Economic and environmental values of mangrove forests and their present state of conservation in the South-East Asia/Pacific Region. Mangrove Ecosystems Technical Reports vol.3 ITTO/ISME/JIAM Project PD71/89. Rev. 1(F) Okinawa, Japan, ISME. 202 pp.

Diop, E.S. 1993. Conservation and sustainable utilization of mangrove forests in Latin America and Africa regions, Part II – Africa. Mangrove Ecosystems Technical Reports vol.3 ITTO/ISME Project PD114/90. Okinawa, Japan, ISME. 262 pp.

FAO. in press. FAO’s database on mangrove area estimates. By Wilkie, M.L., Fortuna, S. and Souksavat, O. Forest Resources Assessment Working Paper No. 62. Forest Resources Division. FAO, Rome. (Unpublished)

FAO. 2001. Global Forest Resources Assessment 2000: Main report. FAO Forestry Paper 140. Rome. www.fao.org/forestry/fo/fra/main/index.jsp

FAO. 1994. Mangrove forest management guidelines. FAO Forestry Paper 117. Rome, 319 pp.

FAO, UNEP. 1981a. Los Recursos Forestales de la America Tropical Proyecto de Evaluación de los Recursos Forestales Tropicales (en el marco de SINUVIMA) FAO, UNEP, Rome. 349 pp.

FAO, UNEP. 1981b. Tropical Forest Resources Assessment Project, Forest Resources of Tropical Africa. Part II: Country Briefs FAO, UNEP, Rome. 586 pp.

FAO, UNEP. 1981c. Tropical Forest Resourcess Assesment Project, Forest Resources of Tropical Asia. FAO, UNEP, Rome. 475 pp.

Fisher, P. and Spalding, M.D. 1993. Protected areas with mangrove habitat. Draft Report World Conservation Centre, Cambridge, UK. 60pp.

Groombridge, B. 1992. Global biodiversity: status of the earth's living resources. WCMC / The National History Museum / IUCN / UNEP / WWF / WRI. Chapman & Hall, London. 594 pp

Lacerda, L.D. 1993. Conservation and sustainable utilization of mangrove forests in Latin America and Africa regions. Vol. 2 Part I- Latin America. Mangrove Ecosystems technical reports ITTO/ISME Project PD114/90 (F). Okinawa, Japan. 272 pp.

Saenger, P., Hegerl E.J. and J.D.S., Davie. 1983. Global status of mangrove ecosystems. Commission on Ecology Papers No.3. IUCN. Gland, Switzerland. 88 pp.

Spalding, M.D., Blasco, F. and Field, C.D., eds. 1997. World Mangrove Atlas. The International Society for Mangrove Ecosystems, Okinawa, Japan. 178 pp.

Tomlinson, P.B. 1986. The botany of mangroves. Cambridge University Press, Cambridge, UK. 419 pp.


1 Except for FAO, UNEP 1981 and Aizpuru et al., 2000, the reference year is the year of the publications in which the estimate is cited, not the weighted average of all the national area estimates.

2 Combined figure from 3 publications by Clough, 1993; Diop, 1993 and Lacerda 1993.

3 New estimates were provided for 21 countries, for the remaining countries the study relied on Spalding et al., 1997.

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