Thermal thinning and the art of fire

Every now and then I run across a wildland fire term that is new to me. For example, “pyrodiversity“, from a few months ago, or allowing fire to “visit” an area, from about 10 years ago.

Well, here’s another one, “thermal thinning”, from an article about prescribed fire on the South Carolina Department of Natural Resources web site. An excerpt:

According to [Johnny] Stowe, prescribed fire can also be used in more sophisticated ways—for example, to prune and thin stands of longleaf pine. The ability of fire to kill or topkill (which inhibits growth) of hardwoods such as red maple, sweetgum, water oak and other species that are generally undesirable in longleaf woodlands and savannas, is well known. Less well-known is the artful use of fire to prune the lower limbs of young longleaf pines; to reduce the number of trees in longleaf stands that are too dense; and to remove other pine species, particularly loblolly, from these stands.

I like the fact that they referred to “the artful use of fire”. And it’s true. Planning and igniting a prescribed fire is as much an art as it is a science, and you can’t become expert in the art of fire from books, classes, or four or five seasons of work as a firefighter. In prescribed fire, you are sometimes dealing with the micro-aspect of fire–the flame length, flame height, residence time, temperature, and how those and other factors will affect the vegetation over the short and long term. And these fire effects and fire behavior on a micro-scale can’t always be predicted using computer programs such as BEHAVE. And if you think of fire as a “dragon”, you will never become artful in using it as a tool.

Fire suppression, in my mind, is less about the micro-aspect of fire. It is a lot more about the science than the art of fire. In suppression, you are using science (whether you know it or not), aided by your experience and the “slides” in your memory bank, to predict what the fire will do and where it will be at a particular time, while you select the most appropriate tool you have available to remove or cool the fuel adjacent to or ahead of the fire.

Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire. Google+