Lesson 12: Prescribed Burns - Fighting Fire with Fire
Background Control Burn What the Indians here used to do, was to burn out the brush every year, in the woods, up the gorges, keeping the oak and the pine stands tall and clear with grasses and kitkitdizze under them, never enough fuel there that a fire could crown. Now manzanita, (a fine bush in its right) crowds up under the new trees mixed up with logging slash and a fire can wipe out all. Fire is an old story, I would like, with a sense of helpful order, with respect for laws of nature, to help my land with a burn, a hot clean burn (manzanita seeds will only open after a fire passes over or once passed through a bear) And then it would be more like, when it belongs to the Indians Before. by Gary Snyder	American Indians have understood the beneficial and natural role fire plays in ecosystems for thousands of years. After learning our lesson from the consequences of years of fire supppression, we understand that some ecosystems need to burn for their health and survival. In today's society, fires cannot be indiscriminately set, nor can they be allowed to burn unchecked. Fire management uses fire, in the form of prescribed burns, as a tool to bring about change in an ecosystem that mimics the effects of wildfire. Prescribed burns, or controlled burns, are small fires that are purposely set under highly regulated conditions and allowed to burn within a planned, geographic area. Special care is taken to consider the safety of people and property. They are planned in advance to achieve a specific objective in a specific area under appropriate weather conditions and at the right time of year. Fire equipment and fire crews are used to keep the fire under control. During the broadcast, you will be witnessing a prescribed burn. Its purpose will be to remove the slash, or the branches, twigs, and other woody debris left on the forest floor after a time harvest, or logging operation. Study the "9 Steps to a Successful Prescribed Burn" outline and the "Anatomy of a Prescribed Burn" diagram to familiarize your class with the procedure. Prescribed Burn Uses and Benefits improve wildlife habitat enhance native plant communities reduce fuel loads that contribute to wildlife hazards prepare seedbeds for fire-resistant species such as jack pine and red pine remove woody debris left on the forest floor following logging operations discourage the growth of exotic species or other undesirable species These are all natural consequences of wildfires that humans can duplicate with controlled fire. Or can they? The very fact that the fire has to be controlled is contrary to nature. However, with today's increasingly complex integration of civilization and natural wilderness, it may be as close as we'll ever get.
9 Steps to a Successful Prescribed Burn
Choose the Site Identify a site with a natural firebreak such as a creek or a road. Create a map of the site that includes fences, gates, power poles and lines, streams, wetlands, roads, trails, nearby buildings, and other important features. Also note the types of vegetation on the site. Season Choose the time of year to conduct your burn. Early spring and late fall are the best time to do prescribed burns in northern Minnesota. Prepare the Site Before the burn, clear the area of anything that should not be burned. Create firebreaks where natural ones such as streams or roads do not exist, so the entire site is contained within firebreaks. Firebreaks can be created by mowing, plowing, or bulldozing a line around the edge of a site. Gather Crews and Equipment The number of people needed for a fire crew depends on the size of the fire. People are needed for the ignition of the fireline, for the control of the fireline to ensure it doesn't escape or jump the line and get out of control, and people are needed to mop up. Assemble drip torches for ignition, backpack sprayers, shovels, and rakes for control, and axes and chainsaws for mop up. Be sure to have a pumper truck with a high pressure hose on hand in case the fire gets out of control. Two-way radios, first aid kits, fireproof clothing, hard-hats, and drinking water are also important. Safety is as important at a prescribed burn as it is at a wildfire. Every prescribed burn runs the risk of getting out of control. Permits and Notification You cannot perform a prescribed burn without a permit from your state Department of Natural Resources, Forestry Office, or the town fire chief. Notify the DNR, local fire departments, law enforcement officials, and neighbors that you will be conducting the burn. Weather Conditions Weather is the most important factor in conducting a prescribed burn. The wind speed, relative humidity, and temperature will together determine whether your fire will be safe and controlled, or wild and dangerous. In general, weather conditions should fall under these guidelines: wind speed–less than 15 miles per hour relative humidity–more than 25 percent temperature–lower than 80 degrees Fahrenheit Even if the weather conditions are right on a particular day, you need to consider the conditions leading up to that day as well. If it has just rained, the fuel my be too wet to burn efficiently. If it has been dry for several days, the fire will burn hotter and faster, and may be more difficult to control. Foresters take measurements of fuel moisture content to determine how efficiently the area will burn. Wind speed should also be considered, because it will determine which area of the site will be burned first, and it will also determine where the smoke will end up. If the smoke is near buildings and houses, your neighbors will appreciate your efforts if you avoid doing burns when their houses are in the path of the smoke. Conducting the Burn Recheck the weather conditions constantly on the day of the burn. Reschedule the burn if weather conditions change. Assemble the crew and go over the plan. See the "Anatomy of a Prescribed Burn" diagram on the next page for the procedure. Mop–up Make sure all burning debris is extinguished before leaving the site. This may require hours of tedious work, but it's better than starting a wildfire. Recheck the site daily for a few days for persistent burning embers. Evaluation After the burn, inspect the site. Was it successful? Did you accomplish your objective? Was it safe and efficient? Were the firebreaks effective?
Anatomy of a Prescribed Burn
Lesson 12: Prescribed Burn - Fighting Fire with Fire
Journal Entry: Using the weather section from your local newspaper, keep track of the weather conditions in your area and make notes about which days would be appropriate for burning and which days would not. What would happen if you conducted a burn on a day when the humidity was too low? What would happen if the wind speeds were too high? What if the temperature was too high? Classroom Activity: Fuel Moisture Content Objective: To identify the significance of fuel moisture content in determining the potential success of a prescribed burn. Materials: candle matches paper cup water Safety Equipment: fire extinguisher hot pads eye goggles Procedure: Pour a small amount of water into the paper cup. Light the candle. Hold the paper cup over the candle flame. The water inside the cup absorbs the heat from the flame, preventing the cup from becoming hot enough to burn. The heat being absorbed by the water causes it to evaporate. Once all of the water in the cup has evaporated, the cup will become hot enough to burn.	Discussion: Moisture inside trees and other vegetation performs the same function. Just after it rains, fuel moisture content is high. After a long period without rain, the sun will have evaporated much of the excess moisture from the fuel, causing it to be very dry. How does fuel moisture content affect a fire? If the fuel moisture content is low, will the fire burn quickly or slowly? Apply this same concept to moisture in the air. Under which conditions will a fire burn more easily – low relative humidity or high relative humidity? Often times, when it rains or snows on a raging forest fire, the rain or snow never reaches the ground. Use the analogy of the water in the cup activity to explain why. (The heat from the intense fire causes the precipitation to evaporate before reaching the ground.) Extensions: Discuss the term relative humidity. Relative humidity is the amount of water in the air compared to the amount of water the air can hold at that given temperature. So if the relative humidity is 50%, the air is holding half of the water that it is capable of holding at that given temperature. The higher the temperature, the more water the air is capable of holding. This is why winters tend to be dry and summers tend to be humid. Experiment with the burning efficiency of different types of fuels – 1) green branches, leaves, and twigs; 2) dead and dry branches, leaves, and twigs; 3) dead and dry branches, leaves, and twigs that have been "rained on" (sprayed with water); 4) branches and pieces of wood of large diameter and mass; 5) partially burned wood from a fireplace or campsite. Which ones burn easily? Which ones do not? Why? Where and under what conditions can each fuel type be found in nature?