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New Mapping Tool Tracks Global Forest Gain And Loss

November 15, 2013
Image Credit: Google Earth Engine

Ranjini Raghunath for redOrbit.com – Your Universe Online

A team of researchers from the University of Maryland, Google and the US government has put together the first comprehensive, high-resolution map of changes in global forest cover over the last 12 years.

The study, published online on November 14, in the journal Science, shows that the world lost nearly 900,000 square miles of forest cover and gained less than half that number between 2000 and 2012.

The map was developed using more than 650,000 satellite images dating back to 1999, and takes into account all forest “disturbances” in the last decade – from forest fires and storms to illicit deforestation, climate change and diseases.

[ Watch the Video: When Trees Fall, Landsat Maps Them ]

Data obtained using the mapping tool showed that sub-tropical forests, such as those in the southeastern United States, showed greater “disturbances” (i.e. loss or gain) – four times more than those in South America. In the last decade, 31 percent of the southeastern US forest cover alone was either lost or re-grown, the paper said.

“This is the first map of forest change that is globally consistent and locally relevant,” said Matthew Hansen, Geological Sciences professor at the University of Maryland, in a release. Hansen is also the team leader and corresponding author of the Science paper.

The map also pointed out positive changes that have happened in the last decade, such as the reduction in deforestation in Brazil. Brazil, which has long been criticized for its deforestation activities, has stepped up its efforts to preserve its rainforests. The country has now cut down its forest loss by half, the report said.

But not all regions have been as lucky. Some African and Asian countries, such as Malaysia, Zambia and Angola, have lost a major portion of their forest cover in the last decade. Indonesia, for example, reportedly more than doubled its loss of forest cover during the study period, despite increased regulation of logging licenses in the last few years.

The map shows a clear picture of dynamics and variables at both global and local scales at a very high resolution, and could contribute greatly to the existing knowledge of forest cover changes, the paper reported.

Earlier, such data was put together using information collected by individual countries. But different countries followed different protocols and had their own regulations and definitions of forest gain and loss. As a result, there was no consistent set of data showing forest loss or gain over the world as a whole.

“There has not been a way to get detailed, accurate, satellite-based and readily available data on forest cover change from local to global scales,” Hansen said.

this new resource will contribute greatly to our understanding of how forest cover changes over time, both from natural and man-made causes, and how this will affect the environment and human society, the researchers believe.

The map could also prove to be a useful tool for shaping public policy regarding deforestation, according to the researchers. Brazil has already demonstrated that to a certain extent by using the satellite data to make changes in its forestry policies and sharing their results with other countries.

“Now, with our global mapping of forest changes every nation has access to this kind of information, for their own country and the rest of the world,” Hansen said, in the release.

Deforestation can have far-reaching effects on many segments of the ecosystem such as weather patterns, rainfall, water supply and biodiversity. Studying these effects has been hampered by the lack of detailed and accurate real-time data covering the world as a whole, Hansen pointed out.

Which is why he, along with other researchers at the University of Maryland, developed the mapping tool with data acquired from the United States Geological Survey’s center for Earth Resources Observation and Science (EROS).

Researchers from Google Earth Engine pitched in, developing models to help analyze and decode the satellite data. Google Earth Engine is an extremely valuable resource that helped speed up the analysis, quickly processing large amounts of data and images, cutting down years of work to merely days.

The map could help scientists and policy makers understand how and why the ecosystem could be affected by these changes, the researchers believe, by providing a “transparent, sound and consistent basis” to understanding critical environmental issues, according to Hansen.

The study was also supported by the Gordon and Betty Moore Foundation and NASA, and the United States Agency for International Development through its CARPE program. A web link to the map is also available at:

http://earthenginepartners.appspot.com/science-2013-global-forest




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