If a Ravage is prevented <i>(by, e.g., A Year of Perfect Stillness or Choke the Land with Green)</i> do the Dahan still fight back?

If a Ravage is prevented (by, e.g., A Year of Perfect Stillness or Choke the Land with Green) do the Dahan still fight back?

No. See 'Ravage' on p. 9 of the rulebook.
There are many other ways the Ravage can be prevented entirely. Note that Defense by itself does not prevent the Ravage, just reduces the damage.