But the rock-bottom Poppies put up a real fight before accepting the inevitability of demotion from non-League football's top flight.
Carl Shutt's side actually started the better of the two and went close through a Mark Haran header and Wayne Diuk who dribbled through only for his final shot to drift wide.
But, as so often this season, the hosts found themselves trailing as Forest Green broke the deadlock from virtually their first attack as Steve Cowe's looping header flat footed Willie Gourlay.
Forest Green should then have put the game to bed with Alex Meechan and Darren Jones both guilty of wasteful finishing.
And the visitors were made to pay for that profligacy seven minutes before the break when Craig Norman was held down contesting a corner and dusted himself down before despatching the resulting penalty.
Within four minutes of the restart, however, Forest Green went back in front as Cowe's pot shot from the edge of the box took a kind deflection off an opposing boot and looped up over the helpless Gourlay.
And they virtually wrapped up the points in the 58th minute with Meechan netting a spot kick following an infringement by Lee Clarke in the box.
Deep into stoppage time the Poppies managed to pull one back when substitute Niall Inman's low shot was deflected in off Martin Foster.
But the result was already decided in front of the lowest Rockingham Road League crowd for many seasons of just 422.