Nearly a century of counts points to fewer earthworms in the UK
Combining more than 100 studies, the decline appeared for earthworms, especially in forests and farmland, but not for cranefly larvae.
The key idea
Nearly a century of records points to fewer earthworms, but not fewer cranefly larvae: the soil’s story differs by organism.
The study, in plain language
The team gathered data from more than 100 studies and tried to make soil-animal counts comparable, even though they used different methods, seasons, and sampling depths. They tested two ways of combining them: one gave greater weight to studies that sampled more area and the other did not. Under both approaches, the earthworm trend was downward, especially in forests and farmland.
There were fewer data on cranefly larvae, and results varied depending on how studies were combined. One model indicated stability and the other an increase. Neither suggested a general decline. Using the same reconstruction method, the two animal groups showed different signals.
What they found
- A signal of fewer earthworms appeared under both ways of combining the studies.
- The estimated decline was more pronounced in forests and farmland, although it varied by habitat.
- Cranefly larvae showed no general decline: depending on the model, they were stable or increased.
How they studied it
Researchers gathered historical counts from the UK and estimated animals per unit area, accounting for method, season, depth, and habitat type. This was not an experiment; it combined studies conducted by others.
What the study cannot show
- The compilation combines different locations and methods, with few repeat observations. Selection biases may remain; it does not identify causes or support extending the UK trend to other countries.
Something to think about
When you read that soil-dwelling creatures are disappearing, ask which organisms were counted and whether the same method was used in the same places.
The original study
Collation of a century of soil invertebrate abundance data suggests long-term declines in earthworms but not tipulids
Source under CC BY 4.0. English adaptation and explanation by PaperFlow, with AI assistance. The text has been reorganized for a general audience; it is not the complete paper and does not imply endorsement by its authors.
One study alone does not represent a field's consensus. Educational content does not replace professional advice. Report a possible error.
