Environment & Climate
Global tree cover expanded over 35-year period despite tropical forest declines, study finds
Satellite analysis indicates temperate, boreal, and afforested gains outpaced severe tropical canopy losses between 1982 and 2016.
The short version
- A University of Maryland study published in Nature found global tree canopy cover grew by 2.24 million square kilometers (7.1%) between 1982 and 2016.
- Canopy expansion in temperate, boreal, and polar regions—as well as afforestation in China—exceeded sharp canopy losses in tropical biomes such as the Amazon.
- Researchers emphasize that gross tree cover is not synonymous with intact natural forest, as industrial monocultures and plantations are counted as tree canopy.
- The findings contrast with traditional United Nations forestry data, highlighting differences in satellite detection methods versus national reporting definitions.
Key facts
- Satellite data analysis led by Xiao-Peng Song and Matthew Hansen found global tree cover expanded from 31 million to 33 million square kilometers between 1982 and 2016.[Hacker News]
- The greatest country-level tree cover gains occurred in Russia (+790,000 square kilometers), China (+324,000 square kilometers), and the United States (+301,000 square kilometers).[Hacker News]
- Brazil experienced the highest canopy loss of any nation, declining by 399,000 square kilometers over the 35-year study period.[Hacker News]
- Tropical dry forests suffered the highest rate of regional tree cover loss at 15 percent, alongside major reductions in tropical moist deciduous and rainforest biomes.[Hacker News]
- The study attributes 60 percent of all global land cover changes and 70 percent of tree canopy losses directly to human activities, primarily agricultural expansion.[Hacker News]
What remains uncertain
- The extent to which net tree cover gains provide the ecosystem services and biodiversity of natural forests remains uncertain, as the satellite metric includes commercial timber and oil palm plantations.[Hacker News]
- A divergence remains between the satellite-derived net gain in tree canopy and the UN Food and Agriculture Organization's reported net forest loss from 1990 to 2015 due to differing measurement methods and definitions.[Hacker News]