Public Release: 

When a tree lost is, or isn't, permanent deforestation: Mapping global forest loss

American Association for the Advancement of Science

Despite numerous efforts by international governments, corporations and conservationists to reduce it, the overall rate of a permanent type of forest loss known as commodity-driven forest loss has not changed since 2001, a new map-based study reports. The results of the study not only reveal the main drivers of forest loss worldwide, and where it's occurring, but also suggest that not all forests that undergo dramatic change are in fact permanently altered. Regardless, say the authors, the results indicate that zero-deforestation policies are not being implemented quickly enough to meet 2020 goals as stated by various global corporations whose work might impinge on forest landscapes. Forest loss is caused by several different factors. Some, like commodity-driven deforestation, which permanently alters a landscape's ability to produce goods as with agriculture or mining, are permanent. Others - like shifting agriculture, managed logging or wildfires, for example - are not. What's more, these latter forest loss types are often followed by forest regrowth. However, data on worldwide deforestation, such as that publicly available on the widely used Global Forest Watch platform, do not distinguish between permanent forest loss and other, temporary forms of forest disturbance. According to Phillip Curtis and colleagues, this limits the use of these datasets in identifying risk and also responsibility by corporations, of which nearly 450 have committed to achieving zero-deforestation in their supply chains by 2020. To address the need to contextualize tree cover loss, Curtis et al. developed a model to characterize and map global forest disturbances using high-resolution Google Earth satellite imagery between 2001 and 2015. Their results indicate that approximately 27% of global forest loss can be attributed to commodity-driven deforestation. What's more, the authors found that the rate of commodity-driven deforestation, about 5 million hectares per year, remained steady across the 15-year period. Other drivers of loss were attributed to forestry (26%), shifting agriculture (24%), wildfire (23%) and urbanization (0.6%). The researchers have made their underlying forestry data publicly available here: The data can be viewed on Global Forest Watch when the embargo lifts.


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