Prescribed Burning Guidelines
in the Northern Great Plains
Methods of spreading fire in grasslands
Basic way to conduct a burn
Assuming that all fire control actions, equipment, and people are complete and ready, we recommend starting all grassland fires in the following manner:
- Determine the onsite wind direction by holding up a light cloth or by
watching the smoke and fire behavior from a small (less than 2 sq m) test
fire (Fig 21).
- Put out the test fire, then plot the wind direction as an arrow on your
burn unit map. The point where the arrow strikes your farthest downwind
firebreak or fire containment line is the baseline where you start the fire.
- At the baseline, again go over the basic burning plan and procedures with
your crew, explain alternate courses of action on the map (Fig 22) should
the wind shift or should the fire breach a fire control line. (Examples
of burning plans are found in appendices A, B, and C.) Inform the crew where
you, the fire boss (Fig 23), will be during the sequence of the burn and
how to keep in constant communication with you. Also provide contingency
fire control plans for 90-, 180-, 270-, and 360-degree wind shifts.
- If your crew has only one person setting fire and the wind is blowing perpendicularly toward a baseline firebreak, then start the backing fire at one end of the baseline. If the wind is blowing diagonally across a burn unit, start the backing fire at a corner or bend in the baseline.
If only one person is setting fire and starting at a corner, the fire should be set in a series. First set 100 m or less of fireline on one side and then about the same length on the other until a backing fire has been established along about a fourth of the perimeter length.
If your crew has two people setting fire and the wind is blowing perpendicularly to your baseline, start the fire at the midpoint of the baseline with fire setters moving in opposite directions from the midpoint (Fig 24). When the wind is blowing diagonally across your burn unit, start at the downwind corner with the people setting fire moving away from each other.
It is much easier to start a fire at a corner with two fire setters than with one. Corners and points are higher risk areas to burn than gradual curves, so when possible bend your fire containment lines around corners and obstacles rather than using sharp angles.
After setting the fireline along the full length of the baseline and rechecking fire containment measures along the baseline, monitor the backing fire until it has burned a buffer strip 30 m (100 ft) wide. Increase the buffer strip to 60 m (200 ft) in width if winds are stronger (more than 13 km/h, or 8 mph) (Fig 25).
The baseline should not be considered secure until this buffer strip has been burned. Then and only then, can the fire boss prescribe action to complete the rest of the burn.
Steps 1 through 4 as presented above are recommended for any grassland fire. At the end of step 4, the rest of the burn can be completed with whatever burning pattern that fits your objectives, equipment, and fire crew size and experience.
For example, if your prescription requires a backing fire pattern, at the end of step 4 you set no new fireline and the old fireline is monitored constantly by the fire crew until the backing fire reaches the fire containment line or consumes all of the fuel.
If your prescription requires a surround pattern, then at the end of step 4 the fire setter(s) continue setting fire, taking care to skip no perimeter segments, until the total perimeter of the fire unit area is burning. If you choose to use another pattern of burning, such as strip-head fires, spotfires, or chevron techniques, we suggest you follow the guidelines of Mobley et al (1977).
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