Using satellite technology to map Mangroves

Dec 06, 2010

Mangroves are among the most biologically important ecosystems on the planet, and a common feature of tropical and sub-tropical coastlines. But ground-based evidence suggests these vital coastal forests have been strained in many regions because of harvesting for food, fuel, and medicine. Now, scientists have used satellite images to compile the most comprehensive map of mangroves worldwide, which should help in future efforts in monitoring and conservation.

Mangrove forests are typically made up of trees, shrubs, and palms that have adapted to the harsh conditions of high salinity, warm air and water temperatures, extreme tides, muddy, sediment-laden waters, and oxygen-depleted soils. They are fertile nurseries for many marine species, and also serve as a first line of defense against hurricanes and tsunamis by dissipating wave and wind energy.

These maps show the location and relative density of mangroves, which cover roughly 137,760 square kilometers (53,190 square miles) of Earth’s surface. The forests can be found in 118 different countries and territories, though nearly 75 percent of their area occurs in just 15 countries.

They are most often found straddling the equator between 25º North and South latitude. About 42 percent of the world’s mangroves are found in Asia, with 21 percent in Africa, 15 percent in North and Central America, 12 percent in Australia and the islands of Oceania, and 11 percent in South America.

The effort to create the maps was led by Chandra Giri of the U.S. Geological Survey and published recently in the journal Global Ecology and Biogeography. Using digital image classification techniques, the research team compiled and analyzed more than 1,000 scenes from the Landsat series of satellites.

Giri and colleagues found 12.3 percent less area covered by mangroves than previously estimated by the United Nations Food and Agriculture Organization. The current extent of mangroves is probably half of what once existed. Only 6.9 percent of mangrove forests are protected by law.

Indonesia (center of the lower map) includes as many as 17,000 islands and nearly a quarter of the world's mangroves. Yet those forests have been cut in half in the past three decades, shrinking from 4.2 million hectares in 1982 to 2 million in 2000. Of the remaining forests, nearly 70 percent are "in critical condition and seriously damaged," reported Fadel Muhammad, Indonesia's minister of fisheries and marine affairs.

Nearly a fifth of the coast of Australia (the north coast is shown above) is surrounded by mangrove-lined coast. Australia has the third largest area of in the world after Indonesia and Brazil, and approximately 6.4% of the world’s total mangrove area.

Explore further: Study urges 15-year plan for low-carbon growth

More information: Giri, C., et al. (2010) Status and distribution of mangrove forests of the world using earth observation satellite data. Global Ecology and Biogeography, DOI: 10.1111/j.1466-8238.2010.00584.x

add to favorites email to friend print save as pdf

Related Stories

Mangroves Save Lives In Storms

Apr 14, 2009

(PhysOrg.com) -- A new study of storm-related deaths from a super cyclone that hit the eastern coast of India in 1999 finds that villages shielded from the storm surge by mangrove forests experienced significantly ...

Mangrove-dependent animals globally threatened

Jul 01, 2009

More than 40 percent of a sample of amphibians, reptiles, mammals, and birds that are restricted to mangrove ecosystems are globally threatened with extinction, according to an assessment published in the July/August issue ...

Mangroves importance and decline studied

Feb 27, 2006

Scientists say mangroves, the backbone of tropical ocean coastlines, are far more important to the global ocean's biosphere than previously thought.

Recommended for you

Dutch unveil big plan to fight rising tides

3 hours ago

The Netherlands on Tuesday unveiled a multi-billion-euro, multi-decade plan to counter the biggest environmental threat to the low-lying European nation: surging seawater caused by global climate change.

Drought hits Brazil coffee harvest

6 hours ago

Coffee output in Brazil, the world's chief exporter, will slide this year after the worst drought in decades, agricultural agency Conab said Tuesday.

Landmark fracking study finds no water pollution

7 hours ago

The final report from a landmark federal study on hydraulic fracturing, or fracking, has found no evidence that chemicals or brine water from the gas drilling process moved upward to contaminate drinking water at one site ...

Politics divide coastal residents' views of environment

9 hours ago

From the salmon-rich waters of Southeast Alaska to the white sand beaches of Florida's Gulf Coast to Downeast Maine's lobster, lumber and tourist towns, coastal residents around the U.S. share a common characteristic: ...

User comments : 0