Good point. It's almost like the word system in ecosystem is important. Haha.
Your comment makes me want to learn more about beavers. I'm interested but don't know much.
This is the key and overlooked part of it all. Plus they can move upstream or downstream as situations dictate.
I think most dams (small low head dams, often abandoned) have those same properties.
3 years vs 30 years. And you usually regulate the river around the dam so it can't meander, beaver dams make the river meander around them. So after 30 years you maybe return to status quo with a small, abandoned human dam. In that time you would have 10 different riverbed changes with beavers and all that area is now marsh.