Quantcast
Popular
Hansen/UMD/Google/USGS/NASA tree cover data displayed on Global Forest Watch. Green pixels represent tree cover with greater than 20 percent canopy density but do not count trees outside of these pixels. Note, coarse pixels as shown above may be more efficient for rapidly detecting large scales of deforestation, while individual mapping techniques as described below may be more effective for monitoring land restoration and degradation.

Scientists Use Google Earth and Crowdsourcing to Map Uncharted Forests

By Katie Fletcher, Tesfay Woldemariam and Fred Stolle

No single person could ever hope to count the world's trees. But a crowd of them just counted the world's drylands forests—and, in the process, charted forests never before mapped, cumulatively adding up to an area equivalent in size to the Amazon rainforest.

Current technology enables computers to automatically detect forest area through satellite data in order to adequately map most of the world's forests. But drylands, where trees are fewer and farther apart, stymied these modern methods. To measure the extent of forests in drylands, which make up more than 40 percent of land surface on Earth, researchers from UN Food and Agriculture Organization, World Resources Institute and several universities and organizations had to come up with unconventional techniques. Foremost among these was turning to residents, who contributed their expertise through local map-a-thons.


Technical Challenges, Human Solutions

Traditional remote sensing algorithms detect tree cover in a pixel rather than capturing individual trees in a landscape. That means the method can miss trees in less-dense forests or individual trees in farm fields or grasslands, which is most often the nature of dryland areas.

Google Earth collects satellite data from several satellites with a variety of resolutions and technical capacities. The dryland satellite imagery collection compiled by Google from various providers, including Digital Globe, is of particularly high quality, as desert areas have little cloud cover to obstruct the views. So while difficult for algorithms to detect non-dominant land cover, the human eye has no problem distinguishing trees in the landscapes. Using this advantage, the scientists decided to visually count trees in hundreds of thousands of high-resolution images to determine overall dryland tree cover.

Local knowledge helped researchers ground-truth desert forest tracking. World Resources Institute

Local Map-a-thons Using Collect Earth

Armed with the quality images from Google that allowed researchers to see objects as small as half a meter (about 20 inches) across, the team divided the global dryland images into 12 regions, each with a regional partner to lead the counting assessment. The regional partners in turn recruited local residents with practical knowledge of the landscape to identify content in the sample imagery. These volunteers would come together in participatory mapping workshops, known colloquially as "map-a-thons."

To lay the groundwork for the local map-a-thon events the team identified both an entry point, usually a university, that could help recruit participants, as well as a facility with the capacity and internet to host the map-a-thon. Once trained, any given analyst could identify 80 to 100 plots per day.

Example of Collect Earth grid set for data collection.

Quality control was carried out afterwards by comparing the identified land cover with the number of trees counted. For example, if a local participant identified an image as having just three trees but later identified the same image as forest, the researchers knew there was human error and further review was required.

The Collect Earth tool allows users to navigate between multiple windows and select the best imagery for each particular data point.

These map-a-thons were designed so that people with first-hand knowledge of local landscapes could participate. No knowledge of remote sensing or any technology beyond internet literacy was required. The expertise needed was the understanding of regional landscape and land use. This practical knowledge of the region was critical as the participants were not only able to count individual trees but also identify the type of land use and trees they saw on the Google Earth images.

This research only "discovered" new forest in the sense that Columbus "discovered" the New World. The drylands forest was always there, and the people who live in the area always knew it was there. In fact, they were the only ones who had the background knowledge to identify subtleties like whether an image of a plant in their region was a shrub or actually a young tree, or if what appeared to be a tree was just a perennial plant. A few common perennial crops, including coffee and banana, looked like shrubs in the satellite images, but local participants had no problem identifying them correctly as perennial crops instead of shrubs, a distinction that would have been impossible with satellite imagery analysis alone.

Collect Earth Map-a-thon Event in Gatsibo, Rwanda.

This human identification component, along with the ability to zoom into sub-meter resolution with cheap and available technology, has helped achieve the breakthrough result of forest cover identification 9 percent higher than previously reported.

Local Ownership of the Map and the Land

Utilizing local landscape knowledge not only improved the map quality but also created a sense of ownership within each region. The map-a-thon participants have access to the open source tools and can now use these data and results to better engage around land use changes in their communities. Local experts, including forestry offices, can also use this easily accessible application to continue monitoring in the future.

Global Forest Watch uses medium resolution satellites (30 meters or about 89 feet) and sophisticated algorithms to detect near-real time deforestation in densely forested area. The dryland tree cover maps complement Global Forest Watch by providing the capability to monitor non-dominant tree cover and small-scale, slower-moving events like degradation and restoration. Mapping forest change at this level of detail is critical both for guiding land decisions and enabling government and business actors to demonstrate their pledges are being fulfilled, even over short periods of time.

The data documented by local participants will enable scientists to do many more analyses on both natural and man-made land changes including settlements, erosion features and roads. Mapping the tree cover in drylands is just the beginning.

Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Energy
Mackinac Bridge from Straits of Mackinac. Gregory Varnum / Wikimedia Commons

Michigan Gov. Signs Bill to Keep Line 5 Pipeline Flowing

Michigan's outgoing Gov. Rick Snyder signed legislation on Wednesday that creates a new government authority to oversee a proposed oil tunnel in the Straits of Mackinac to effectively allow Canadian oil to keep flowing through the Great Lakes.

The controversial tunnel will encase a replacement segment for Enbridge Energy's aging Line 5 pipelines that run along the bottom of the Straits, a narrow waterway that connects Lakes Huron and Michigan.

Keep reading... Show less
Popular
The illegal La Pampa gold mine, seen here in 2017, has devastated the Peruvian Amazon and spread poisonous mercury. Planet Labs

Unprecedented New Map Unveils Illegal Mining Destroying Amazon

A first-of-its-kind map has unveiled widespread environmental damage and contamination of the Amazon rainforest caused by the rise illegal mining.

The survey, released Monday by the Amazon Socio-Environmental Geo-Referenced Information Project (RAISG), identifies at least 2,312 sites and 245 areas of prospecting or extraction of minerals such as gold, diamonds and coltan in six Amazonian countries—Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela. It also identified 30 rivers affected by mining and related activities.

Keep reading... Show less
Animals
Mako sharks killed at the South Jersey Shark Tournament in June 2017. Lewis Pugh

Shark Fishing Tournaments Devalue Ocean Wildlife and Harm Marine Conservation Efforts

By Rick Stafford

Just over three years ago, I was clinging to a rock in 20 meters of water, trying to stop the current from pulling me out to sea. I peered out into the gloom of the Pacific. Suddenly, three big dark shapes came into view, moving in a jerky, yet somehow smooth and majestic manner. I looked directly into the left eyes of hammerhead sharks as they swam past, maybe 10 meters from me. I could see the gill slits, the brown skin. But most of all, what struck me was just how big these animals are—far from the biggest sharks in the seas, but incredibly powerfully built and solid. These are truly magnificent creatures.

Keep reading... Show less
Politics
Sen. Joe Manchin and United Mine Workers of America President Cecil Roberts held a press conference on Oct. 3, 2017. Bill Clark / CQ Roll Call

Coal-Friendly Manchin Named Top Dem on Senate Energy Panel

After weeks of discord over the potential appointment, Sen. Joe Manchin, the pro-coal Democrat of West Virginia, was named the ranking member of the Senate Committee on Energy and Natural Resources, Sen. Chuck Schumer announced Tuesday.

Many Democrats and environmental groups were adamantly opposed to Manchin serving as the top Democrat on the committee that oversees policies on climate change, public lands and fossil fuel production.

Keep reading... Show less
Sponsored
Insights/Opinion
Hikers on the Mt. Hollywood Trail in Griffin Park, Calif. while a brush fire burned in the Angeles National Forest on Aug. 26, 2009. Mel Melcon / Los Angeles Times via Getty Images

Major Health Study Shows Benefits of Combating Climate Change

During the holiday season, people often drink toasts to health. There's something more we can do to ensure that we and others will enjoy good health now and into the future: combat climate change.

Keep reading... Show less
Energy
Employees of Rural Renewable Energy Alliance working together with students and faculty of Leech Lake Tribal Collage to construct solar panels, 2017. Ryan James White

A Tribe in Northern Minnesota Shows the Country How to Do Community Solar

By Susan Cosier

Last summer on a reservation in northern Minnesota, students from Leech Lake Tribal College earned their solar installation licenses while they dug, drilled and connected five photovoltaic arrays. The panels shine blue on the plain, reflecting the sky as they generate roughly 235 megawatts of electricity a year, enough to help 100 families pay their energy bills. This is community solar in action.

Keep reading... Show less
Sponsored
Energy
Arches National Park. Chris Dodds / Flickr / CC BY-SA 2.0

Trump Auctions Off 150,000 Acres of Public Lands for Fracking Near Utah National Parks

On Tuesday the Trump administration offered more than 150,000 acres of public lands for fossil-fuel extraction near some of Utah's most iconic landscapes, including Arches and Canyonlands national parks.

Keep reading... Show less
Climate
The Vanderford glacier in East Antarctica is one of four that is beginning to melt, according to NASA. Angela Wylie / Fairfax Media / Fairfax Media via Getty Images

Melting Discovered in East Antarctic Region Holding Ice 'Equivalent to Four Greenlands'

Ice sheets in Greenland and West Antarctica have been melting at alarming rates in recent years, but at least the glaciers of East Antarctica were believed to be relatively stable. Until now. National Aeronautics and Space Administration (NASA) scientists have discovered that glaciers covering one-eighth of Antarctica's eastern coast have lost ice in the past 10 years. If the region keeps melting, it has enough ice in its drainage basins to add 28 meters (approximately 92 feet) to global sea level rise, BBC News reported.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!