Vertebrate populations decline and the Living Planet Report

The Living Planet Index represents the largest effort to understand wildlife status worldwide. In the 2020 report, the Living Planet Index suggested that, the 20,811 monitored vertebrate populations declined by 68% on average between 1970 and 2016 – an alarming number, calling for better commitment to reduce human impacts on nature.

In November 2020, Leung and colleagues claimed that Living Planet Index is sensitive to extremely declining populations. To demonstrate this, they removed only 2.1% of the extremely declining populations to show no net trends in the remaining global vertebrate populations. Their study, published in the journal Nature, found that these drastically declining populations are restricted to some world regions (e.g., Asia and Indo-Pacific).

In a Matters Arising article published in the latest issue, we show that the sensitivity of the Living Planet Index to the declining population is overstated by Leung et al. as they did not properly account for the effects of extremely increasing populations in their analyses.

When we removed extremely increasing and extremely declining populations in an equal manner, we found the results are very similar to the Living Planet Report (compare the black and yellow lines below).

Further, we also show that the sampled populations in the Living Planet Report may even be better off than most: they tend to reside in protected areas much more than expected by chance. Therefore, the actual status of most wildlife could be worse than the 68% decline suggested by the Living Planet Index, highlighting the need for greater population monitoring.