The day after our successful south slope burn, I walked the whole unit to determine the burn coverage. The map here (done in ArcGIS) shows the area burned. (Apologies for the small size of the map. I had to resample to make the file size suitable for the web. I'd be happy to send a larger sized version to anyone who wants one.)The area burned measured (again in ArcGIS) as 13.7 acres, small for a prairie burn, but pretty large for a burn with this complex topography.
The burn coverage was much greater than 90%. There were only a few small areas that did not burn, mainly because there was no fuel there. One unburned area had had a large clone of woodland sunflower that we mowed last August in order to set it back. The sunflower stems grow so close together that nothing could develop among them, so there was no fuel. The fire simply wrapped around this area and moved on.
The fire burned well through a number of red and black raspberry clones, which were top-killed. By mid-May there will be rosettes next to all these dead stems and we will return and kill them with Garlon 3A. Our experience has shown that spraying fire-killed resprouts is one of the best ways of eradicating brambles.
The understory of all the areas of bur oak savanna on the upper slope, visible on the map, burned very well. They burned much better than they had last year, which I attribute to the strip head fire technique that we used. The fire moving up the steep hill behaves just like a head fire, but because the strips had been laid down fairly close together, the flame height was not too high, so the trees were protected.
We've got a lot of burning yet to do, but it is satisfying that we have this complicated burn out of the way.
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