Common species can decline while local biodiversity looks surprisingly stable
WHAT THE EVIDENCE SAYS
Researchers synthesized population trends from 129 studies spanning 4,748 sites. Formerly common species declined more strongly than rare species in terrestrial and marine assemblages; freshwater assemblages showed no clear directional pattern. Rare species present at the start also declined, while colonizing species partly compensated within the rarest abundance class.
WHY IT MATTERS / OUR READ
Stable local species richness can coexist with substantial community reorganization and loss of numerically dominant species. Because common species often carry a large share of biomass and ecosystem function, conservation dashboards that emphasize richness alone can miss meaningful functional erosion.
CAVEATS / UNCERTAINTY
The synthesis pools heterogeneous monitoring programs, taxa and time series. Abundance rank is relative within assemblages, and the study does not imply that rare species are secure; many rare species also declined.
SOURCE
Nature Communications · Original evidence
View original evidence ↗
A synthesis across 4,748 sites finds formerly common species declining more strongly than rare species in terrestrial and marine assemblages, exposing a blind spot in aggregate richness metrics.
Read the Wild Lands assessment →