Center for Theoretical Study, Charles University & Czech Academy of Sciences, CZ-110 00, Prague, Czech Republic.
Department of Ecology, Faculty of Science, Charles University, CZ-128 44, Prague, Czech Republic.
Nat Commun. 2024 Jun 21;15(1):5295. doi: 10.1038/s41467-024-49070-x.
The Living Planet Index (LPI) measures the average change in population size of vertebrate species over recent decades and has been repeatedly used to assess the changing state of nature. The LPI indicates that vertebrate populations have decreased by almost 70% over the last 50 years. This is in striking contrast with current studies based on the same population time series data that show that increasing and decreasing populations are balanced on average. Here, we examine the methodological pipeline of calculating the LPI to search for the source of this discrepancy. We find that the calculation of the LPI is biased by several mathematical issues which impose an imbalance between detected increasing and decreasing trends and overestimate population declines. Rather than indicating that vertebrate populations do not substantially change, our findings imply that we need better measures for providing a balanced picture of current biodiversity changes. We also show some modifications to improve the reliability of the LPI.
生命星球指数（LPI）衡量了近几十年来脊椎动物物种数量的平均变化，并且已经被反复用于评估自然的变化状态。LPI 表明，在过去的 50 年中，脊椎动物的数量减少了近 70%。这与基于相同种群时间序列数据的当前研究形成鲜明对比，后者表明，增加和减少的种群平均来说是平衡的。在这里，我们检查了计算 LPI 的方法学流程，以寻找这种差异的来源。我们发现，LPI 的计算受到几个数学问题的影响，这些问题在检测到的增加和减少趋势之间造成了不平衡，并高估了种群的减少。我们的研究结果并不是表明脊椎动物种群没有实质性的变化，而是意味着我们需要更好的措施来提供当前生物多样性变化的平衡图景。我们还展示了一些改进措施，可以提高 LPI 的可靠性。
