To encourage healthy re-growth in grassy undergrowth and leafy wooded areas, a controlled burn operation is undertaken in the spring when it is still cool and before saplings have begun to bud. In forestry and land management, this helps to reduce fungal disease, insect infestations, clear old thatch and keep invasive weeds under control.
Parks & Recreation here in Toronto have been doing their annual prescribed burning around the residential neighborhoods. This is a part of planned forest management to maintain a healthier forested area and also is a hazard reduction tool. By burning-off in a controlled manner the dead grasses and small fallen limbs and branches that have accumulated over the previous summer and winter, the likelihood of a more serious uncontrolled fire later in the season is reduced. An escaped campfire for instance could cause a bigger forest fire which would be harder to control in the drier summer and potentially involve homes and residential properties.
A Back-Burn Trail
Here you can see the control region where the undergrowth was raked back before the ‘back-burn’ was started. There was insufficient fuel for the fire to progress across this trail so the fire spread up the hill back towards the main fire approaching from the other side. Where these two fires meet they run out of fuel and expire.
Notice in the above image that the branches are distributed on the burned area. They were cut and broadcast to limit the fire’s intensity in any one spot for too long.
Permits for swailing, the ‘hazard reduction burning’ must be obtained in advance. Local neighborhoods are advised of the impending event a few weeks in advance with posters, handbills and other notifications. The weather conditions must be perfect. The prescribed day can be postponed if the weather conditions are not ideal. It must be cool outside with no winds and preferably with rain in the forecast. Humidity at the onset would be a asset too as this would limit the intensity of the burn. The organization that performs the controlled burn requires licensing to do controlled burns but still may not be freed from liability should the fire get out of control and cause damage to personal property of home owners. There is always risk involved with controlled burning of woodlot areas but it is managed risk.
Benefits of Controlled Burning
Controlled burns are part of sensible forest management, prairie restoration programs and oddly enough, there are even greenhouse gas abatement issues at stake. A light controlled burn will prevent a larger wildfire later on which will cause more extensive damage and release far more carbon during the months when temperature inversions could trap the smoke closer to the ground, creating ’smog’ pollution. Even if the light burning is not complete or is performed in a ‘mosaic’ pattern’ over larger tracts of land, it still greatly limits the potential damage that a subsequently larger and uncontrolled wildfire can do.