An important body of research mapped the changes in forests of the Earth. The work showed areas of forest loss and gain over the entire globe as mapped by Landsat satellites between 2000-2012. Each pixel of a Landsat image covers 30×30 meters, about the size of a baseball diamond. That makes the level of resolution quite good. The researchers analyzed 143 billion pixels in 654,000 Landsat images to compile the maps. Scientists from the University of Maryland, Google, the State University of New York, Woods Hole Research Center, the U.S. Geological Survey (USGS) and South Dakota State University were part of the research team. Abstract in the November 15 issue of the journal Science.
Deforestation is a growing and very significant problem world wide. The biomass in our forests is huge. They contribute enormously to the processing of carbon dioxide to oxygen. Previous country to country comparisons have been difficult. Some countries allow limited or no access to certain regions. Countries have different criteria when asked to self-report. This Landsat analysis uses a uniformly applied set of standards over a long time period. Here is an example of a map showing loss and gain in a region of Sumatra. Red indicates cleared forest and blue is new growth. Purple shows areas of trees both cut down and re-grown. Green is forest cover that has not been disturbed. Indonesia’s deforestation rate has doubled from levels in 2000-2003.
Here is an example from the southeastern United States near Jacksonville, Florida. In it we see a fine patchwork of purple. Landowners harvest trees and quickly replant. Trees are treated as a crop. About 30% of the forests were regrown or lost during this 12 yr. period. That is an intensive use of the resource. It explains the purple color showing both loss and gain over the period.
Public Access to the Data
You may be wondering if you can see the region where you live in this Landsat data. The answer is yes. There is an excellent online tool constructed with the cooperation of Google Earth which compiles the global data into a form that allows you to search for a location and zoom into your house and neighborhood. I added four arrows to the home page of the tool Global Forest Change from the U. of Maryland Dept. of Geographical Sciences. They are part of a navigation tutorial I will present below. Go ahead and click on the GFC link in the previous sentence to open this new window or tab in your browser. Then, come back here for some simple instructions.
In the lower left is the zoom tool. Upper left shows a search box for locations. Upper right points to Map and is where you can change to Satellite view later. At the right is a slider to make the overlay of the forest map be less or more transparent. Here is what I want you to do in your new window or tab.
• In the upper left search box type Alto Paraíso – Rondônia, Brazil. Hit return to see a bigger version of this image.
• Move the transparency slider all the way left. You are in the right place. But the map doesn’t show much is there.
• Change the Map in the upper right to Satellite. Now you can see the actual surface details.
• Move the slider back and forth to notice the locations of the red deforested areas. You can zoom in for greater detail. Notice the farms or ranches. These rectangular plots are areas cleared of forest mainly for agribusiness. Bolivia, Paraguay and Argentina are under intensive pressure from agroindustrial development. Paraguay’s Chaco woodlands within the western half of the country are experiencing rapid deforestation in the development of cattle ranches. The result is the highest rate of deforestation in the world. Brazil has reduced their rate of deforestation. But, remote areas like this are hard to manage.
Explore some preset example locations with the drop down menu at the lower right of the window. One I suggest is the first about the Alabama tornado. Once you select it, then below it click zoom to area. Don’t forget to move the transparency slider and change the zoom.
Check Your Neighborhood
Or, search for a location you remember hearing about in the news that had forest fires a few years ago. The fires this year won’t show on this map.
Landsat was first launched 41 years ago. Several others have been added over the years. The most recent is Landsat 8 launched in February 2013. Image analysis has improved as computers have become more powerful. The USGS made the data freely available on the Internet in 2008. That has allowed research projects such as this one to be done adding to our awareness of Earth’s systems and the issue of deforestation in particular.