Looking back on biodiversity change: lessons for the road ahead

Abstract

Estimating biodiversity change across the planet in the context of widespread human modification is a critical challenge. Here, we review how biodiversity has changed in recent decades across scales and taxonomic groups, focusing on four diversity metrics: species richness, temporal turnover, spatial beta-diversity and abundance. At local scales, change across all metrics includes many examples of both increases and declines and tends to be centred around zero, but with higher prevalence of declining trends in beta-diversity (increasing similarity in composition across space or biotic homogenization) and abundance. The exception to this pattern is temporal turnover, with changes in species composition through time observed in most local assemblages. Less is known about change at regional scales, although several studies suggest that increases in richness are more prevalent than declines. Change at the global scale is the hardest to estimate accurately, but most studies suggest extinction rates are probably outpacing speciation rates, although both are elevated. Recognizing this variability is essential to accurately portray how biodiversity change is unfolding, and highlights how much remains unknown about the magnitude and direction of multiple biodiversity metrics at different scales. Reducing these blind spots is essential to allow appropriate management actions to be deployed. This article is part of the theme issue ‘Detecting and attributing the causes of biodiversity change: needs, gaps and solutions’.

A test of Conserving Nature's Stage: protecting a diversity of geophysical traits can also support a diversity of species at a landscape scale

“…It is also possible that the reason we observed lower performance for a quarter of the species inventory is that using only enduring features may have omitted essential factors that outweigh or disrupt the relationship between the abiotic environment and the distribution of the surveyed species. For example, not considering historical events or current human land use means we are not accounting for human activity that is known to impact the spatial distribution of species across multiple scales [59]. Our methodology also cannot account for the consequences of both environmental and demographic stochasticity [60].…”

Global monitoring for biodiversity: Uncertainty, risk, and power analyses to support trend change detection

“…There has never been more interest in allocating resources to reversing biodiversity loss. Human impacts have been detectable on trends in population abundances (1)(2)(3), genetic diversity (4), species diversity (5,6), and ecosystem extent, integrity, and connectivity (7). In response, the global community has agreed to the Kunming-Montreal Global Biodiversity Framework [GBF; see Conference of the Parties (COP) decision 15 /4] with ambitious targets such as preserving 30% of land and waters by 2030, halting extinctions, maintaining healthy populations, and ensuring the supply of ecosystem benefits to people.…”

“…First, there is substantial variation in the sign and magnitude of trends for different measures of biodiversity. For example, trends in abundance are variable across taxa and scales (1). Some taxa are declining rapidly in some regions (3), but other taxa are declining weakly, are stable, or are increasing in other regions.…”

Climate‐driven shifts in the diversity of plants in the Neotropical seasonally dry forest: Evaluating the effectiveness of protected areas

“…Recent studies conducted across dry biomes agree that global climate change (GCC) will cause a general decrease in the alpha diversity of plants, mammals, anurans, and birds (Dryflor et al., 2016; Hidasi‐Neto et al., 2019; Menéndez‐Guerrero et al., 2020; Prieto‐Torres et al., 2021; Strassburg et al., 2017). Further, scenarios of biotic homogenization are forecasted since naturally widely distributed species are expected to expand their distributional ranges while endemic or otherwise restricted species are expected to go locally extinct (Clavel et al., 2011; Daru et al., 2021; Dornelas et al., 2023). While these studies evidence gains and losses in SR, there are notorious gaps of information on compositional changes (beta diversity) across space and time and changes in the evolutionary history contained in different assemblages.…”