Controlled Burn South of Campus

This semester I have been auditing a class in prescribed fire taught in the Forestry Department. It is an undergraduate class with no graduate section. I learned a lot, and I encourage landscape architecture students, and any student interested in landscape ecology, fire ecology, or fire effects, to take the class. This class gives the student an opportunity to examine how climate, weather, physiography, and forest types interact, not just in general (as in an ecology class), but in terms of a specific disturbance pattern: fire. I found that I was able to focus much more intently on weather processes when viewing them with a specific application in mind rather than for the sake of the processes themselves. In order to effectively burn a unit of land, that is, to burn it in order to achieve specific management goals, a certain set of conditions must be met. Fuels can't be too wet, but they can't be too dry either. Air has to be stable - high winds can spread the fire out of control - but not TOO stable: stratified air won't allow the smoke to rise.

The second half of the course involves developing a burn plan for a specific parcel. The burn must have a goal. The effects, especially smoke effects (since smoke is mobile) on neighboring areas must be considered. Everything needs to be mapped: the site itself, and the site in the context of the landscape matrix. In this way, the class is much like a landscape architecture studio course but with a twist: a lot more attention is paid to weather and the design intervention amounts to a human-produced imitation of a natural disturbance.

Part of the class involves participation in a prescribed burn. All semester the conditions were not good, but finally, on the last week of class, the MSU forest supervisor was able to plan and get a permit to burn a 40 acre unit in the John W. Starr Memorial Forest. Students were notified the day before by email and were told to arrive at the classroom at noon with hardhats, boots, and safety glasses.

We arrived at the unit about half past twelve. The temperature was about 71 degrees Fahrenheit with relative humidity about 34%. Wind was from the west at about 4 miles per hour. The purpose of the unit is production of saw timber. The purpose of the burn was to reduce hazard fuels. The hazard fuels were understory trees and vines. From my observation walking through this consisted mainly of maple, sweetgum, hickory, and a lot of smilax (greenbriar) and vitis (muscadine or scuppernong grape, I can't tell them apart).

So here are the photos. As always, if you want more detail, click on them and they get bigger.

This road is the east boundary of the unit. The view is southwest. The unit is a square quarter of a quarter section. The backing fire was set first along this east boundary, about an hour before we arrived. A backing fire moves slowly into the wind.

 This is the fire lane that was plowed along the north boundary.

 

Our professor showing us the disc that was used to plow the fire lanes. Since the unit is bounded on three sides by roads, only the north side needed a plowed lane. The crew had added an extra lane running east-west in the center of the unit.

 We walked along the north boundary and observed the backing fire. There wasn't much to see. Flame height was about a foot and it was advancing slowly. The above is a three-photo panorama hastily snapped and stitched of the students and some of the fire crew on the north side watching the backing fire. Smoke is blowing away from us to the east.

The burn crew gave us a drip torch and we all entered the forest about fifty feet beyond the front of the backing fire to set a strip head fire. The professor carried a compass to ensure that we stayed on a due-south line. The flaming front of the strip head fire moves with the wind to meet the back fire. Even though the wind was very light (imperceptible to me in the forest interior), the strip head fire behaved quite differently than the backing fire. Flames were much higher and it moved faster. Going was rough in the interior: lots of smilax, vitis, and small hardwoods.

The strip head fire consumed a lot of the smilax and  vitis and the needles draped among the vines. Where these fuels were thick, the fire actually roared and hissed.

We paused in the fire lane at the halfway point to watch the strip head fire approach the backing fire. This is another hastily snapped and stitched three photos of the strip head fire we just set.We then continued south setting fire to the woods. The underbrush here was even thicker than before.

A student with the drip torch.

Here is one of the more dramatic shots of the strip head fire. After we emerged on the south boundary, we lit up the rest of that, then moved north along the west boundary, setting it alight as the final head fire of the day.

It looked to my inexperienced eyes like a fairly successful understory burn. We observed that not all of the duff was consumed, just the top layer. The soil was undamaged. But most of the smaller maples, sweetgum and understory trees were top-killed by heat girdling. Many of these will resprout from the roots, but their above-ground mass is gone for now. Better browsing for deer.

Again, I encourage landscape architecture students to take a prescribed burn class because it brings out the details of the natural environment in dynamic interaction. Also, "certified burn boss" looks good on a resume. At least it does to me.