Navigating methodological decisions: Balancing rigor and data volume of the Canadian Living Planet Index

Abstract

The Living Planet Index -- a biodiversity indicator that assesses the relative change of aggregate vertebrate abundance data -- is an indicator used in global and national biodiversity monitoring frameworks. In Canada, the LPI has been modified (C-LPI) -- adopting differing methodological choices relative to the global LPI. However, there is no clear consensus on the most appropriate analytical methods, particularly as they pertain to the treatment of zeros, confidence intervals and uncertainty, time series length and number of data points required, modelling of short time series, removal of outliers, weighting species, and the impact of baseline year selection. Our analysis transparently explores multiple methodological options and the consequent C-LPI output for each of these decision points. Our research does not evaluate the superiority of a single approach but rather provides transparency and accountability in C-LPI reporting. We hope that this will further strengthen the utility of the C-LPI and provide decision makers with the necessary information to appropriately interpret patterns, evaluate progress towards biodiversity targets, and inform conservation action.