Monday, November 14, 2011

Missoula Forest Fire 2011

Wild land fire east of Missoula, Montana

Forest fires near Missoula, Montana area are not uncommon. The forest in this area is subject to forest fires as many years there is a distinct dry period when the forest becomes fire susceptible. The forest is very similar to forest areas of eastern Washington; however, the recurrence of fires may be more frequent in Montana as lightning strikes are more common in this area.

The picture above shows that a forest fire does not mean that the entire forest is killed. Large areas of trees from this burn survived as the fire was limited to the understory and most of the trees would likely survive. In the picture above the fire was burning down hill, into a very light wind, the air temperature was not too hot as it was late in the day, trees are well spaced, and the understory was not thick. Other areas in this fire were burned more intensely - places with thicker forest, places where the fire burned when the air was hotter, and places where wind and topography drove the flames higher.

Having inspected burned areas in the past as well as this fire, I have learned to take reported acres burned in a bit different perspective. A 50,000 acre fire does not mean all the trees within the 50,000 acres were burned. Fire is an important part of forest landscapes and land management, And political sometimes a hot issue (pun sort of intended). Post fire impacts to geomorphic processes are an interesting subject that has been gaining attention with studies of post fire run off and sediment loads in stream systems. It turns out that the intensity of the fire makes a big difference in post fire rain water infiltration. Very intensely burned areas not only kill all the trees but also are subject to higher flood risk due not only the loss of tree canopy but can also be at risk due to soil alteration from the heat.

Clark and his dog with fire on the slope above the Clark Fork


Anonymous said...

Flying into Missoula summer before last, I was struck by the number of dead trees standing in the Bitteroots. The pine bark beetle epidemic is devastating those forests and setting up a tremendous conflagration for sometime ahead. Probably worse than the big fire a hundred years ago.

Dan McShane said...

Just a note on fire in forests that have been hit hard by the bugs. I was in Colorado the summer before last and a fire there within one of the damaged areas burned less intensely in part because the the tree canopies were so much thinner.