Tom's Blog

Sunday, November 13, 2016

Biennial oak woodland burn at Pleasant Valley Conservancy

After a quite rainy autumn, the weather turned very favorable and we had a successful burn of our oak woodland on Thursday November 10, 2016. This has been one of the best years for doing fall burns.

We burn our North Woods every other year, usually in the fall of the year. The last time we burned it was in 2014, and details of that burn can be found on this post.

A successful burn depends on proper fuel, proper weather, and a good crew. We had all these last Thursday.

The first time we burned this oak woodland was October 1999, and we have been burning it on a biennial schedule since 2008. The predominant species is red oak, with substantial white oak and a large patch of Hill's oak in one area. Also, scattered bur oak, especially on the upper ridge.

The topography is rugged, with about 200 foot vertical drop from the upper ridge to the County highway. We have a good fire break at the top of the ridge, and always start the burn there, moving in two directions and then down the ridge to the highway. This year we extended the burn a little on the west and (especially) on the east, where there is a fine basin with many large white oaks. Parts of this latter basin had probably not been burned in 80 years, if ever.

Most of the fuel was oak leaves, which had come down over the past two weeks.

Start of the burn of the white oak woodland at the east end of the site.
The fire backburned almost all of the way down the hill.
Only a small amount of interior lighting was needed here.

The weather was quite favorable. A dry air mass had come in, promising clear skies and warm air. When lighting started at 11:30 AM the RH was 43 and the temperature about 60 F, with light wind. These conditions held all afternoon.

I did a quick measurement of the rate of fire movement through one of the white oak areas. The rate was about 3 feet per minute, which is the same rate as that given by Patrick Brose of the U.S.F.S. in his publication on burns in oak forests of eastern U.S.

After a good black line had been made over the whole periphery, a lot of interior lighting was done, to speed up the burn. When we went home at dark there were still some fire lines moving, and several smokers, but these were well inside the unit and were allowed to burn. (This is our standard practice for oak woodland and oak savanna burns.)

The next day Kathie and I did a survey of the burn coverage. Most of the areas that we expected to burn were black. In all, a succesful burn.


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