A study reveals the great uncertainty associated with changes in biodiversity

A new study led by Thomas F. Johnson of the University of Sheffield and involving Pol Capdevila, lecturer at the University of Barcelona and researcher at the Biodiversity Research Institute of the University of Barcelona, IRBio-UB shows the difficulty of predicting changes in biodiversity.

The study published in Nature reveals great uncertainty in the status of biodiversity change. These changes are studied through time-series abundance datasets for thousands of species at large geographic and temporal scales. The analyses show that species abundance over time is highly variable over large scales, with increases and decreases in different populations and species around the world.

The study aims to predict biodiversity change using an innovative statistical framework, analyzing ten sets of global biodiversity data and incorporating spatial, temporal and phylogenetic structures into the models.

Evidence for a global decline in wildlife abundance becomes highly uncertain when appropriate modeling techniques are used. The new statistical approach, more rigorous, considers temporal and spatial factors and the evolutionary history of the species. These new analyses reveal that changes in the abundance of wild species populations vary greatly across the planet.

Despite uncertainty in the status of biodiversity change Dr Thomas F. Johnson, lead author of the paper from the University of Sheffield says concern for biodiversity should still be high: "Accelerating climate change, rampant habitat loss and massive exploitation of wildlife provide alarming and irrefutable evidence that biodiversity is threatened, but detecting the magnitude of biodiversity loss on a global scale is difficult and a very complex challenge to tackle.”

Planet Earth is the home of millions of species that interact with each other. When the population abundances of these species are observed over time, they show constant changes and fluctuations. Environmental changes and especially those of anthropic origin, such as habitat loss, alter the dynamics of populations, but these changes do not always translate into a massive population declines, as whilst the affected species can become extinct locally, resilient and more generalist species less impacted by this anthropic change could colonize these spaces.

Dr. Johnson goes on to say: "Given this enormous complexity, it is not surprising that we cannot detect systematic declines in wildlife abundance when we average over thousands of species on a global scale. However, whilst biodiversity may appear stable, it is likely that our ecological communities are actually homogenizing, and non-generalist native species being pushed to extinction".

Conservation interventions and the creation of protected areas are critical to protecting this threatened biodiversity from extinction, but model effectiveness is limited by a lack of information on which species and locations are experiencing the greatest decline. The new statistical model proposed by this study is key to addressing this knowledge gap.

The co-author, researcher Pol Capdevila remarks: "Our study offers quantitative tools to measure biodiversity changes more accurately." This study shows that until now the modeling tools that several studies have used to measure biodiversity loss may not be statistically adequate. Instead, the methodology proposed by this study improves the accuracy of predictions of biodiversity changes at the local scale. Dr. Capdevila continues, "Whilst the average trend in biodiversity is highly uncertain, the increase in the accuracy of the models that we propose gives us hope of improving the predictions of biodiversity changes at spatial scales that are relevant to apply effective conservation policies.”

The study also emphasizes the urgent need to increase efforts in the collection of biodiversity data to identify areas that need conservation actions. Much of the world's biodiversity monitoring currently occurs in protected areas such as national parks, where populations would be more stable and thus could be biasing estimates of biodiversity trends. To see the true state of biodiversity, monitoring must capture a representative snapshot of the planet, including areas most exposed to human impact.

Dr. Capdevila concludes that: "Given the significant implications of biodiversity loss, it is crucial that we continue to develop methodologies that allow us to predict where biodiversity is changing, and why.”

 

Ref. article: Johnson et al. (2024) Revealing uncertainty in the status of biodiversity change. Nature. https://doi.org/10.1038/s41586-024-07236-z