Temporal Trends in Biodiversity Intactness Vary with Baseline Levels Across Regions and Climates

Exploring the relationship between the magnitude and temporal trend of the Biodiversity Intactness Index (BII) is critical to assessing current and future changes in biodiversity intactness. However, investigations into the relationship between BII magnitude and trends worldwide have been limited. Using annual BII time series data from 2000 to 2020, we assess the global spatial patterns of BII magnitude and trend, as well as their relationship. Our findings reveal four key insights: First, the global mean BII magnitude exhibits pronounced latitudinal and climatic heterogeneity, with higher values observed in less human-impacted regions. Second, biodiversity trends display contrasting trajectories between areas of differing baseline intactness—regions with initially low biodiversity (BII < 0.50) show recovery potential (−0.007 ± 0.021 decade−1), while high-biodiversity areas (BII > 0.90) face accelerated declines (0.002 ± 0.012 decade−1). Third, continental and climatic disparities are striking: Europe and temperate zones demonstrate stabilizing trends, whereas tropical and polar regions experience marked deterioration. Fourth, climate variables, particularly precipitation seasonality (BIO15) and mean temperature of the coldest quarter (BIO11), show strong negative correlations with the BII trend, indicating climate-linked declines while exhibiting minimal influence on baseline BII magnitude. This study has the potential to help develop more efficient sustainable practices and behaviors to mitigate biodiversity disparities and achieve sustainable development goals.