firebreak -
An area cleared of all flammable material to prevent a fire from spreading across it.
Wikipedia
A firebreak (also called a fireroad, fire line or fuel break) is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebreak may occur naturally where there is a lack of vegetation or "fuel", such as a river, lake or canyon. Firebreaks may also be man-made, and many of these also serve as roads, such as a logging road, jeep trail, secondary road, or a highway.
