The world’s mangroves

Study Number:

48

Author:

Food and Agriculture Organization of the United States

Abstract:

High population pressure in coastal areas has led to the conversion of many mangrove areas to other uses and numerous case studies describe these mangrove losses over time. Nevertheless, information on the current status and trends in the extent of mangroves at the global level is scarce. With the preparation of the present report, FAO aims to facilitate access to comprehensive information on the current and past extent of mangroves in all countries and areas in which they exist. The information provided in this report, as well as the gaps in information that it highlights, will serve as tools for mangrove managers and for policy- and decision-makers worldwide….

Some 2 900 national and subnational data sets on the extent of mangrove ecosystems have been collected during this process, permitting the compilation of an updated list of the most recent reliable estimate for each of the 124 countries and areas in which mangroves are known to exist. Regression analyses based on historical data provided revised estimates for 1980, 1990, 2000 and a forecast for 2005 for each country. Changes in definitions and methodologies over time make it difficult to compare results from different assessments, and the extrapolation to 2005 was constrained by the lack of recent information for a number of countries. This estimate is thus indicative and is likely to change when results from ongoing and future assessments become available.

The results obtained indicate that global mangrove area currently equals about 15.2 million hectares, with the largest areas found in Asia and Africa, followed by North and Central America. An alarming 20 percent, or 3.6 million hectares of mangroves, have been lost since 1980. More recently, the rate of net loss appears to have slowed down, although it is still disturbingly high. About 185 000 ha were lost every year in the 1980s; this figure dropped to some 118 500 ha per year in the 1990s and to 102 000 ha per year (–0.66 percent) during the 2000–2005 period, reflecting an increased awareness of the value of mangrove ecosystems.

Even though mangroves are often used for the collection of wood forest products and as a source of subsistence for local populations, removal of wood and non-wood forest products is rarely the main cause of the loss of mangroves. Human pressure on coastal ecosystems and the competition for land for aquaculture, agriculture, infrastructure and tourism (coastal development) are often high and are major causes of the decrease in area reported. The relatively large negative change rates that occurred in Asia, the Caribbean and Latin America during the 1980s have been caused primarily by large-scale conversion of mangrove areas to aquaculture and tourism infrastructure…

Main Results and Conclusions:

• Ecosystem goods and services provided by mangroves (5):
  • Fuel: fuel wood, charcoal
  • Construction: timber, scaffolding, heavy construction, railway sleepers, mining props, boat-building, dock pilings, beams and poles, flooring, paneling, thatch or matting, fence posts, chipboard
  • Fishing: fishing stakes, fishing boats, wood for smoking fish, tannin for nets/lines, fish-attracting shelters
  • Textile: leather, synthetic fibres (rayon), dye for cloth, tannin for leather preservation
  • Other natural products: fish, crustaceans, honey, wax, birds, mammals, reptiles, other fauna
  • Food, drugs and beverages: sugar, alcohol, cooking oil, vinegar, tea substitute, fermented drinks, dessert topping, condiments (bark), sweetmeats (propagules), vegetables (fruit/leaves)
  • Agriculture: fodder [dried hay/feed for livestock]
  • Household items: glue, hairdressing oil, tool handles, rice mortar, toys, match sticks, incense
  • Other forest products: packing boxes, wood for smoking sheet rubber, medicines
  • Paper products: paper – various

• Countries/areas from all over the world are tabulated with associated mangrove coverage (ha) and year (Table 3, 10-11).
• Indonesia has the highest area of mangrove coverage (19%), followed by Australia (10%) and Brazil and Nigeria (each with 7%). More countries are listed in Figure 3, page 12.
• Asia has experienced the greatest amount of mangrove forest change (Fig. 4, 12).
• See paper for specific regions regarding vegetation and species composition, mangrove resources: status and trends 1980–2005, main uses and threats, and mangrove conservation and management.
• Conclusions:
  • “…the current mangrove area worldwide has fallen to about 15.2 million hectares, down from 18.8 million hectares in 1980. The world has thus lost some 3.6 million hectares of mangroves over the last 25 years, or 20 percent of the extent found in 1980” (55).
  • “From about 185 000 ha lost every year in the 1980s, the net loss dropped to some 118 500 ha per year in the 1990s and to 102 000 ha per year (or a loss of 0.66 percent annually) during the 2000–2005 period, reflecting an increased awareness of the value of mangrove ecosystems” (55).
  • “Human pressure on coastal ecosystems and thus competition for land for aquaculture, agriculture, infrastructure and tourism (coastal development) are often intense and are among the major causes of the reported decrease in these forest areas over time” (55).