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Recovered tree cover did not bring periodical cicadas back

In Iowa, present-day cicada populations were better predicted by 1930 forest cover than by today’s habitat, and a relocation of more than 20,000 adults failed.

Evidence
Peer-reviewed
Geography
Johnson County, Iowa, USA
System
Temperate deciduous forest and regrown woodland

WHAT THE EVIDENCE SAYS

Researchers compared historical and contemporary tree cover with 2024 periodical cicada distributions and found breeding populations were better predicted by forest cover in 1930 than by current cover. Many reforested areas remained unoccupied despite decades of habitat recovery, and an experimental relocation of 20,126 adult cicadas to apparently suitable restored forest failed to establish a chorusing population.

WHY IT MATTERS / OUR READ

The counter-signal is that habitat recovery is not necessarily population recovery. For species with extreme dispersal constraints and long generation times, historical fragmentation can create a recovery debt lasting many decades or centuries even when the vegetation metric looks repaired.

CAVEATS / UNCERTAINTY

Periodical cicadas have unusually long life cycles and limited dispersal, so the result should not be generalized to all species or forest restorations. Much of the empirical work is from one Iowa landscape, and the relocation result is one experiment shaped by strong predator aggregation.

SOURCE

Ecology · Original evidence
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