Comment by andy99
https://en.m.wikipedia.org/wiki/Invasive_earthworms_of_North...
Also learning about this today. Apparently they're bad for ecosystems that had evolved with slowly decaying organic matter (because they eat it all quickly). In particular forests.
At least in my education they have always been framed as a vital component of the ecosystem and a sign of healthy soil. It's interesting to learn that's not true.
To some extent it's a matter of definition, and whether being caused by humanity means it's bad. After all, the native earthworms would eventually have migrated north and caused similar changes.
Is it bad that redwoods are doing very well in the UK?