When species disappear, the survivors do not always provide enough “backup” to keep ecosystems working. A global synthesis of 423 studies found that biodiversity generally supports ecosystem functions and services, and that many benefits continue to rise across observed increases in biodiversity rather than quickly leveling off. The result challenges the broad assumption that a small number of species can readily replace the rest—but it does not mean every species matters equally or every ecosystem responds the same way.
What the global analysis found
Published on 6 October 2026 in Nature Ecology & Evolution, the study combines experimental and observational evidence from terrestrial, freshwater, marine and estuarine systems. It examines 23 categories of relationships between biodiversity and ecosystem services or functions. Its central finding is that biodiversity is generally associated with stronger ecosystem performance, while the idea that many species are interchangeable substitutes is too simple as a general rule. Read the study.
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The authors analyzed 423 studies. Those studies supplied 1,959 datasets for the paper’s standardized effect-size analysis; a King’s College London announcement describes the database as containing 222,829 data points. These are different measures of the evidence base, not alternative counts of studies. King’s College London’s summary reports the data-point count.
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Why the shape of the relationship matters
A biodiversity relationship can rise steadily, flatten as additional species bring smaller gains, or follow another pattern. The analysis compared these shapes as well as estimating effect sizes. Across its 23 categories, linear and quadratic relationships were most prevalent; only two categories were best described by logarithmic models. Overall, the results suggest that a plateau often comes later than the “a few species are enough” assumption implies.
#1 Best Overall
That is not a universal rule. The relationship depends on the service measured, the biodiversity measure, ecosystem type, scale and study design. Some categories—notably freshwater decomposition—may level off at comparatively low biodiversity. The paper also reports low-to-moderate explanatory power for many relationships, so biodiversity is an important driver, not the only factor determining how much of a service an ecosystem provides.
Which benefits showed the strongest response?
Oceanic carbon sequestration had the strongest positive biodiversity response among the measured categories. The study reports a Fisher’s Z effect size of 1.48 for this relationship, using a method based on Fisher’s Z-transformed correlation coefficients. This is a standardized result from the synthesis, not an estimate of the climate benefit of a particular marine restoration project.
Rank #2
The finding comes with an important evidence limitation: the marine evidence base was small compared with the terrestrial one. The synthesis included 1,759 terrestrial datasets, 183 freshwater datasets, 153 marine datasets and 23 estuarine datasets. The study’s authors and King’s College London therefore describe ocean carbon as both a striking result and an area where more evidence is needed. It should motivate attention to marine biodiversity, not be treated as a precise forecast for any one intervention.
Why biodiversity does not protect every service in the same way
Hazard regulation, including protection from coastal flooding and erosion, was relatively insensitive to overall biodiversity in the analysis. One explanation is that this protection can depend on a small number of foundational species with distinctive roles—for example, shrubs that stabilize dunes. If a species performs a function that others cannot readily provide, the total species count may be less informative than whether that species persists.
This does not make the wider community expendable. The study emphasizes that the persistence of distinctive species is interdependent with the community around them. Conservation decisions therefore need to account for both overall diversity and species whose ecological roles are difficult to replace.
What the study projects about future pest regulation
The team used biodiversity projections linked to IPCC Shared Socioeconomic Pathways to model future biological pest regulation. The model projects that biodiversity loss may weaken this service, with the pattern varying geographically across population and development scenarios. This is a forecast from a model, not an observation of future outcomes.
One uncertainty is that projected changes in biodiversity intactness do not identify which species will be lost. If species’ vulnerability is connected to their ecological roles, the actual change in pest regulation could differ from the model’s estimate. The projection is best read as evidence that biodiversity loss can put this service at risk, not as a definitive map of future impacts.
How representative is the global picture?
The synthesis spans four broad ecosystem types, but its evidence is uneven. Terrestrial datasets greatly outnumber freshwater, marine and estuarine datasets, and the studies are geographically concentrated in developed countries. South America and Africa are among the regions underrepresented in the evidence base. As a result, the global analysis provides a broad picture, but its conclusions are better supported in some ecosystems and places than in others.
- Scope: 423 studies and 23 biodiversity–service or biodiversity–function categories.
- Uneven coverage: Terrestrial studies dominate the dataset distribution, while marine and estuarine evidence is comparatively sparse.
- Interpretation: Many measured benefits rise with biodiversity, but the size and shape of the response depend on context.
For readers, the practical message is not that every species contributes equally, or that adding species will produce the same gain everywhere. It is that assuming the remaining species will reliably compensate for losses is risky. The study supports protecting biodiversity broadly while paying particular attention to services, places and species for which the evidence indicates distinctive vulnerabilities.
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