[Blueflag]

A limnologist calls this natural process eutrophication.

Gee, what if the grassy areas can be shown to harbor protected species???? They'll be so conflicted.

[RonF]

It's not natural if it was introduced by humans. And it probably hasn't been there long enough to become habitat for any rare species that didn't already have habitat there.

[HairOfTheDog]

Human beings introducing a foriegn invasive plant that takes over is a real problem. stronger invasives may push out better native food or cover plants.

Sometimes they are quite harmful, sometimes they aren't....