Tom's Blog

Wednesday, May 8, 2019

Best year ever for spring burns at Pleasant Valley Conservancy

We have been doing burns at PVC for 22 years and we burned more acreage this year than ever.

We always have ambitious burn plans but conditions are not always cooperative. This  year things just worked out, and we burned 131 acres of the 140 acre Conservancy. These were all dormant-season burns. Because of the long period of degradation before restoration began, we are always fighting the legacy of invasive woody plants, and the best way to deal with them in our Conservancy is with fire.

The table and ArcMap summarize the burns.

Date of burn
Habitat type(s) burned
Crew size
March 21
South-facing slope; prairie and savanna
March 22
Restored prairies
March 26
Mainly savanna; Pocket Prairie; read narrative
March 27
Oak woodland & prairie
April 9
April 19
North-facing oak woods

Total acreage

Not all the wetland acres burned, since there is standing water in a number of areas. Also, the coverage in the North Woods was not 100% either, but fire passed across >90% of the area.

The March 22 and 27 burns were fairly routine, involving mostly planted prairies. The present post focuses on the March 26 burn, which was predominantly oak savannas. Although a large and complicated burn, we had a crew with lots of savanna burn experience and everything went off      quickly.

It is important to do lots of prep work for a savanna burn, especially clearing around standing dead snags to eliminate lots of time-consuming mop-up work. On a burn of this size, that takes most of a day. The work must be done ahead of the burn, but not too many days ahead.

We have two types of savannas, and both were burned the same day.
  • Ridge-top savanna, predominantly bur oak with a significant hickory component. This is the top area, on the dolomite, and mostly on both sides of the gravel service road. It includes Unit 19 and  Units 11A, B, and C.
  • Basin savanna, predominantly white oak with some hickory. This is on the sandstone, and surrounds the Pocket Prairie. It includes Unit 11D, 12A and B, Unit 18 and Units 20 A-C.

And then there is the Pocket Prairie. Although not savanna, the Pocket Prairie is always burned at the same time the Basin Savanna is burned.

Because of the steep slope and the wind, the anchor-point for the burn was where the Side Road meets the main Service Road. The long, narrow units north of the service road (Unit 19 B through E) were burned separately (crew of 4) at the same time as the big main burn (crew of 8). As soon as the Unit 19 burn was finished, that crew joined the other and did more interior lighting.

Ridge-top units 8 and 10 had already been burned during the March 21 burn and provided a solid black line uphill and downwind. Also, the Unit 7/Unit 18 boundary was secure because Unit 7 had been burned on March 21.

Running the burn Drip torches moved east and south in Unit 11A from the anchor point along the two roads. As soon as the starting area was solidly black, other drip torches moved into the burn units for interior lighting. This is essential because a savanna fire almost never backburns through a whole unit without “help”. The Unit 19 crew joined the main crew for extensive interior lighting of the Basin Savanna.

Two-way radios Each crew member had a two-way radio, and it was vital that the burn boss and line bosses monitor progress. Most crew were out of sight of each other. It is especially important to monitor for potential head fires due to wind shifts or changes in topography. As the map shows, there are several ATV trails that follow the contours of the units, which interior lighters can use as guidelines.

Mop-up There was very little mop-up. After the burn, I drove one of the UTVs through the upper trail, which gave a good view of both the ridge-top and basin savannas. There were no standing smokers, and few smokers on the ground. The latter is not surprising, since we have been burning these savannas annually for many years.

Pocket Prairie burn After the basin savanna is completely black, the Pocket Prairie is usually burned as a head fire. Given reasonable wind and R.H., it generally takes about 10-15 minutes to burn. By this time, all of the crew are out of the savanna units (which are totally black) and are watching from the road.

We started lighting at 9:57 AM and finished the Pocket Prairie at 11:39 AM. So the whole burn took 1 hour and 42 minutes (102 minutes)

Amanda ran the burn. Here she is doing crew assignments

Initial lighting

The fire has reached the corner of Unit 12B. It is now off the Ridge

Interior lighting just before the fire moves into the Basin Savanna

Waiting for the final interior lighters to finish and leave the burn

Watching the Pocket Prairie burn


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