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GFC warns that control burns kill, too The burning of pine forests in the South is an accepted practice as a management tool. One of the most widely used burning techniques is the backing burn. These gentle burns are easier to manage and used mainly to reduce the ground litter which reduces fire danger/risk and at the same time promotes a healthier forest. The past few years, however, we have observed cases where gentle backing burns have led to insect problems later. So, where's the problem? On pine forest floors, an organic layer of duff (humus) exists just below the fresh fallen layer of pine needles. These duff layers can range from deep to non-existent and generally are deepest around the trunk of the pine. The feeder roots of pines grow up into this duff layer to retrieve water and nutrients. When this area is burned with a slow gentle backing fire, under normal conditions the duff layer smolders at temperatures well above the killing zone of the trees feeder roots. The killing temperatures can last up to 8 hours after the burn is over with. These gentle burns are killing the feeder roots and in extreme cases, the lateral roots. This leads to stress or death of the tree and bug activity. So, what's the fix? Before burning, check the moisture in the duff layer. If it is dry, don't burn. The duff layer needs to be moist to offer protection to the feeder roots. The use of backing fires is better with a moist duff layer. Don't burn the same area year after year. Repeated burns destroys the duff layer to the point where it is completely eliminated, offering no protection for feeder roots. A happy medium needs to be found between how much duff is needed for soil protection or too much for increased wildfire risk. A second alternative for a solution is to change the burning technique. The use of strip heading or spot heading firing techniques has proved to be more effective in eliminating the concentration of smoldering heat in the duff layer. However, these techniques require more of a professional approach. For more information contact your local Georgia Forestry Commission office, call 1-800 GATREES or visit our web site at www.gatrees.org.
John Godwin is the chief ranger with the Georgia Forestry Commission.
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