Ecosystems may have far less spare capacity to absorb species losses than a common conservation assumption suggests, according to a global analysis led by researchers at King’s College London and Imperial College London. The work found that most measured ecosystem functions and services continued to improve as biodiversity increased instead of reaching an early plateau.
Researchers assembled 222,829 data points from 423 published studies spanning terrestrial, freshwater, marine and estuarine environments. They evaluated 23 categories of functions and services, including pollination, water purification, carbon storage and natural pest control. The resulting database was more than twice the size of the largest earlier synthesis, according to the research team, and underpins a model intended to estimate biodiversity benefits across locations.
The result challenges a broad interpretation of “functional redundancy”: the idea that several species perform sufficiently similar roles that one can disappear without much effect. Across most categories in the analysis, benefits rose steadily as diversity increased. That pattern means losses can reduce performance even when other species remain, rather than leaving a deep reserve of substitutes.
Marine carbon storage showed the strongest positive relationship with biodiversity among the services measured. This suggests that the organisms supporting carbon movement and retention in oceans and coastal systems could be particularly important to climate strategies built around blue-carbon sinks. However, the authors stressed that this result was based on relatively few data sets. They identified marine carbon sequestration as a research gap rather than treating the large modeled response as settled evidence.
Not every service followed the general pattern. Protection from hazards such as coastal flooding and erosion was comparatively insensitive to overall biodiversity because it can depend heavily on one or two foundational species, including shrubs that stabilize dunes. The researchers say conservation planning therefore needs to protect broad diversity while also recognizing particular species whose loss cannot easily be offset.
The team also connected its database with biodiversity projections under socioeconomic pathways used by the Intergovernmental Panel on Climate Change. Its model projected that natural pest control on farms would decline more under a fossil-fuel-intensive development path than under a path with lower fossil-fuel use, with the largest losses in rapidly growing, lower-development countries.
The findings do not say that every species contributes equally to every function. They indicate that assuming abundant ecological substitutes is a poor default across many benefits people rely on. The database and forecasts have been made available for policy and planning, giving decision-makers a way to examine both general diversity and the foundational species associated with specific local services.
