Crews were called to the reserve, on Natures Way, Hampton, on Tuesday (August 25) at 3.48pm.
Cambridgeshire Fire and Rescue Service said crews responded from Dogsthorpe, Yaxley, Stanground, Huntingdon, March, Chatteris, Gamlingay, St Neots and Peterborough Volunteer Fire Brigade, along with a specialist 4x4 vehicle.
The service said teams were assisted by a farmer, who supplied a water bowser, to tackle the fire, which affected grass and trees in the reserve.
Motorists were also warned about smoke on the near-by Fletton Parkway.
A spokesperson for Cambridgeshire Fire and Rescue said the fire was under control by 7.30pm.
Peterborough Telegraph reader Geoff Dixon sent us these pictures of the incident.
1. Hampton
The blaze came after the status of a major fire an Holme Fen Nature Reserve was downgraded Photo: Geoff
3. Hampton Nature Reserve Fire
Motorists were warned of smoke crossing the parkway Photo: Geoff
4. Fire at Hampton Nature Reserve
Crews were assisted by a farmer to fight the flames Photo: CFRS