Original title: More than 75 percent decline over 27 years in total flying insect biomass in protected areas
Researchers used Malaise traps, which catch flying insects, in 63 protected areas in Germany over 27 years. They weighed the insects caught to measure total biomassThe combined weight of all the organisms being measured.: the combined weight of the insects, not just how many there were or which species appeared. Seasonal biomass fell by 76%, and the mid-summer figure fell by 82%. The decline appeared across habitat types, but the measured weather, land-use, and habitat changes did not explain it.
Imagine weighing everything in a pantry to see how much food is left. The number of items can stay high even as the total weight drops, and a few shelves may not show what is happening across the whole pantry. In this paper, the pantry is a protected area, the food is flying insects, and weighing the catch reveals how much insect life is present overall.
Flying insects feed animals and support ecosystem functions, so losing much of their total biomass may affect species that depend on them. The decline occurred across habitat types in protected areas, and the measured changes in weather, land use, and habitat characteristics did not explain it.
The measurements come from 63 protected areas in Germany and cover 96 unique location-year combinations, so the abstract does not establish the same trend everywhere. The analysis finds that measured weather, land-use, and habitat changes do not explain the decline, but it does not identify what caused it.
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More than 75 percent decline over 27 years in total flying insect biomass in protected areas — Caspar A. Hallmann, Martin Sorg, Eelke Jongejans et al. — PLoS ONE — doi:10.1371/journal.pone.0185809
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.