Nearly 6 million trees disappeared from farmlands in three years, says satellite mapping study

India tree loss: 11% of fully grown trees seen via satellite in 2010-2011 were no longer visible when reviewed from 2018 to 2022

In a mere three years, from 2019 to 2022, India may have lost close to 5.8 million full-grown trees in agricultural lands, says a satellite-imagery based analysis by researchers at the University of Copenhagen, Denmark, and published this week in the peer-reviewed journal Nature Sustainability.

Additionally, 11% of such trees detected via satellite during 2010-2011 were no longer visible when reviewed from 2018 to 2022, leading the researchers to conclude that these trees had “disappeared.”

However, this doesn’t necessarily imply that India’s overall tree cover, or trees outside forest, is declining as the analysis was specific to only large trees above a certain size.

The Forest Survey of India (FSI) conducts regular surveys of tree cover – both inside and outside forests – but only publishes data on the changes in acreage and not individual trees. The latest FSI report says that India’s tree cover has increased in 2021 over 2019.

The present analysis however focusses on Indian farmland and tracks individual trees, albeit only big ones, relying on maps from multiple ‘micro-satellites’, and machine learning analysis to estimate trends, beginning 2010.

About 56% of India is covered by farmland and 22% by forest. With the largest agricultural area in the world, changes in tree cover here, while critical, have been largely “overlooked,” the authors say.

For their analysis, the researchers combined satellite-imagery from two repositories – RapidEye and PlanetScope – to estimate changes in tree number from 2010 to 2022. These have resolutions of three to five metres, meaning that the satellite can “see” large trees, three to five metre apart, as individual trees. The FSI relies on data from the Sentinel satellite that has a coarser resolution of 10 metre – implying that they can tell apart blocks of trees but not individual ones.