DATA AVAILABILITY: Empirical data of population time series in the Living Planet database are available from the dedicated website maintained by the Zoological Society of London (ZSL) (http://stats.livingplanetindex.org/) and are subject to the Data Use Policy by the Indicators & Assessments Unit at the ZSL and WWF International. Simulated data to replicate the results are available from https://doi.org/10.5281/zenodo.4744533.
CODE AVAILABILITY : All simulation outputs and code (R scripts) to reproduce the results in this manuscript are available from https://doi.org/10.5281/zenodo.4744533.
EXTENDED DATA FIG. 1: The nine steps to calculating the Living Planet Index (LPI).
EXTENDED DATA FIG. 2: The Living Planet Index (LPI) for randomly fluctuating populations that are stable on average.
EXTENDED DATA FIG. 3: Starting population sizes of time series added to the Living Planet Index have declined between 1950 and 2015.
EXTENDED DATA FIG. 4: Larger population fluctuations cause less precise estimates of the Living Planet Index (LPI) in nonlinear population trajectories.
EXTENDED DATA FIG 5: Population fluctuations cause generalised additive models (GAM) to misestimate starting and ending populations when populations decrease from 100 to 40 individuals.
EXTENDED DATA FIG 6: Population fluctuations cause generalised additive models (GAM) to misestimate starting and ending populations when populations increase from 100 to 160 individuals.
EXTENDED DATA FIG 7: The reshuffling null model used to account for random population fluctuations.
EXTENDED DATA FIG. 8: Cumulative population declines can occur in the Living Planet Index even when average population declines are zero.
EXTENDED DATA FIG. 9: Cumulative population changes represent empirical trajectories more accurately than average changes as time series lengths increase.