Short answers, pulled from the story.
The Forest Landscape Integrity Index measures how much human activity has altered forest ecosystems by treating integrity as the opposite of cumulative modification across a landscape. It generates a continuous score from 0 to 10 for each 300-meter pixel using mapped pressures, modeled indirect effects, and changes in connectivity.
In the study's global map for early 2019, 40.5 percent of forest area was classified as high integrity covering about 17.4 million square kilometers across the planet. The index uses data from 2000 to establish a stable baseline while subtracting tree-cover loss from 2001 to 2018.
High-integrity forests were concentrated in boreal regions of Russia and Canada which together contained about half of the global high-integrity forest area. Nations such as Canada and Russia dominate the upper rankings with vast boreal reserves compared to countries like Brazil and Indonesia that appear lower on the list.
The Forest Landscape Integrity Index is referenced under Target 2 of the Kunming-Montreal Global Biodiversity Framework for monitoring ecological integrity. It serves as an indicator for tracking progress toward global goals in the 2023 Forest Declaration Assessment and helps identify forests qualifying for funding through High Integrity Forest methodology.
Forest modification prior to the year 2000 may not be reflected in the underlying global datasets used for calculation because some pressures are difficult to map consistently at a global scale. Climate change impacts and invasive species remain outside the current model scope while finer-scale infrastructure often escapes detection.