Dryland Forests in Plain Sight

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Photo by Adobe Stock/Fotos 593
Dryland forests, such as this one in Ecuador, support astonishing numbers of trees.

Deforestation is a major topic of conversation among conservationists today, and new research is revealing that Earth’s drylands are home to 40 percent more trees than previously thought. Roughly 1.8 million square miles of land formerly considered treeless should instead be categorized as forest, according to these new findings.

To discover these hidden forests, hundreds of students and scientists from around the world spent thousands of hours inspecting more than 200,000 images to count every visible tree and shrub. The research was warranted, because previous tree counts have proved inaccurate. Most relied on low-resolution satellite images that made it difficult to distinguish between trees, rocks, shadows, and even dirt patches, leading to an undercounting of overall trees. Thanks to newly available ultra-high-resolution photos from Google Earth in which each pixel represents a meter or less, this study has accurately identified far more trees than before.

These hidden forests are no small find. In fact, they collectively cover an area almost the size of a second Amazon rainforest and represent a 9 percent increase in estimated global forest coverage. Most are found in drylands — ecosystems with little annual rainfall that encompass close to half of the planet’s landmass. Despite their lack of international attention, dryland environments sustain close to 2 billion people, 90 percent of whom live subsistence lifestyles as small-scale farmers or herders. For these people, the forests that scientists recently “discovered” are a vital resource for sustaining their quality of life.

This research has potential for future forest preservation. A significant percentage of the world’s dryland forests have already been destroyed by deforestation, overgrazing, and desertification — processes that are expected to accelerate with climate change. This deforestation leads to land degradation that forces these communities to move to more resource-rich regions, which contributes to the international refugee crisis.

Taking measures to protect these forests will make a difference in the survival of the entire ecosystem. For instance, pilot programs of farmer-managed regeneration practices in sub-Saharan Africa have succeeded in promoting forest growth and improving soil health and water-retention rates of nearby farm fields. These practices have already significantly benefited the communities that use them, and further adoption can only continue to rectify desertification in delicate drylands everywhere.

Researchers hope this discovery of dryland forest systems will generate more awareness and propel a global push for preserving them. The study’s findings will also make it easier for scientists to estimate the amount of carbon dioxide Earth’s forests are sequestering, and how much they might be capable of sequestering in the future. Learn more about research and sustainability efforts for these unique forest ecosystems at the U.S. Geological Survey website.

Published on Aug 1, 2018