Swailing - Grassland/Forest Hazard Reduction Burning

As wildfires rage seemingly unabated throughout the western states of the U.S., we are reminded about the importance of swailing. A controlled back burn (aka swailing,) is a common annual practice in farming, woodlot/forested area, and recreational use land management. By selectively and prudently burning the dead undergrowth of grasses, leaves, weeds and fallen limbs, the risk of uncontrolled wildfires is greatly reduced. Ecologically, swailing improves the health of the woodlot by clearing away the undergrowth, reducing fungi, insect pests and invasive species of weeds and thus allowing desirable living plants a chance to grow.


Grassland and Woodlot Management via Controlled Burns

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.

(image by author)

An escaped campfire could cause a bigger forest fire which would be harder to control in the drier summer and potentially spread to homes and residential properties, causing property damage, disruptions of services, and evacuations of affected neighborhoods.

hillside after a controlled burn, called swailing

(image by author)

A Grassland and Woodlot Management Back Burn

a swailing (controlled burn-off of dead grasses) requires a back-burn trail; an area whereby burnable material is raked away the path of the fire.

(image by author)

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 eventually 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/Controlled Burning Are Required

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.

Fires in the Forest - Benefits of Swailing/Controlled Back Burns

Controlled back 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.

controlled burn site the next day

(image by author)

The taller dead grasses, weeds and tangled thickets of last summer’s vines are now gone. The tree trunks show only mild scorching. There will be less pollen and probably fewer pesky insects as a result of this action. Another successful controlled burn in this Toronto suburb has resulted.

Some Benefits of Swailing/Controlled Back Burns

Light burns actually help the soil by quickly returning some nutrients such as nitrogen and phosphorus from the burned underbrush, and swailing encourages some conifer seeds to germinate while killing undesirable insect pests, weeds and their seeds.

Soil can actually be physically damaged if the fire is too intense or concentrated on any specific area for too long, such as a burning log pile, fallen tree or piles of branch debris left over from logging operations. Burn piles such as bonfires are the example and in a controlled burn, these piles would be leveled out or removed altogether prior to the burn.

Broadcast burning (spreading the burnable material such as branches out over a larger area) has a lower overall temperature and is the most helpful and is the least damaging to the field or woodland being treated.

Coniferous forests benefit the most from controlled burns. The controlled fires help protect the trees from diseases, insect infestations and even from future fires.

A controlled burn will improve the grassland and forest for many wildlife and reduce undesirable vegetative species, allowing better undergrowth which means better grazing range for wild animals such as rabbit, deer etc. The grass is always greener and lusher after a controlled burn has cleared the way.

Insect and Snail Populations are Controlled with Swailing of Grassland/Woodlots

These snails numbers in the hundreds and probably thousands around this particular wooded grove. They are spaced within inches of each other everywhere in this woods. After the fire they are all dead. Their calcium will now quickly return to the soil and help the plants flourish.

casualties in controlled burning; many land snails perished in the fire but the calcium in their bodies will nourish the soil and animals that remain

(image by author)

The numbers of land snails that were killed here in these controlled burns will very quickly rebound. Within a month or two these woods will again host these curious snails in the familiar hoards which seem to be ever abundant in this woodlot.

Other Controlled Burn Casualties

another casualty of controlled swailing/burning of woodlot grasslands; small snakes. It appears that this snake was underground and emerged post-first, and died from exposure to smoke or hot embers. The body of the snake is not burned.

(image by author)

Nearly all the animals benefit but as with everything that is interfering in the name of helping, there are always a few casualties. Their numbers are small and while unintended and unfortunate, can be dismissed.

I found several deceased grass snakes. They seemed to have perished after the fire as if they tried to flee their underground hideaways and encountered tortuous hot spots. The grass beneath them was burned, suggesting that they had entered the area after the fire had passed through. They probably attempted to flee the relative safety of an underground hideaway and encountered misfortune. Perhaps there was too little ground-level oxygen and the snakes suffocated?

This snake (image above) was dead but not visibly scorched. The same was true with several other snakes that I discovered on my photographic hike, dead but not visibly scorched.

after the controlled burn (swailing) the hillside looks bare and dead, but soon it shall bloom with greenery anew

(image by author)

In the above image we can see the ‘white ash’ of a somewhat denser fuel-pile that burned. Here, logs or branches probably lay and burned a lot hotter and longer. I examined this controlled burn region over 24 hours after the event had ended and some of the larger ‘white ash piles’ were still giving off noticeable heat. Here, the soil was probably temporarily sterilized to a depth of several inches but it will build-back very quickly.

Slash and Burn is Uncontrolled Burning

Field burning is a technique to clear large tracts of land of unwanted crops, weed and debris. Less expensive than tilling the soil or using pesticides and therefore desirable to the farmer, field burning produces large amounts of smoke which is bothersome to residential areas and homeowners making it an unpopular option.

Some states have had bad events result from sanctioned controlled burning. In 1988 in Oregon, farmers burning grass from fields caused a smoky condition on an interstate highways which lead to a multi-vehicular pileup.

Twenty-three cars crashed on the highway due to obscured visibility. There were seven deaths and thirty-seven additional injuries as a result of the visibility-reduced conditions.

Since then, increased scrutiny and public outcries on field burning performed by farmers has resulted in proposals to ban field burning in Oregon altogether. But perhaps Oregon should not act too hastily on this proposition. The state of Florida offers a counter-view and could serve as a lesson to be learned.

About Forest Fires - WildFire Prevention by Controlled Burning

In Florida during the drought of 1998, many large wildfires spread through the everglades and damaged many homeowners’ houses and properties. I suppose that those episodes of “CSI: Miami” of a few years ago that used field shots of everglade wildfires was actual stock footage of these real fires.

Controlled burning had not been performed for a number of years leading to an ever-increasing layer of debris, leaves, mosses and dead branches. This would serve as fuel for the bigger uncontrolled fires that would eventually burn out of control and devastate the region. Had smaller, controlled burning been employed in the years prior, this uncontrolled wildfire event may have been averted or certainly been more manageable.

I think the homeowners whom lost homes due to the wildfires would agree.

I’d accept a weekend of mildly irritating wood-smoke once a year for the greater good over the increasing risk of an eventual real-estate destroying wildfire every decade or so.

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Jerry Walch
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Posted on Sep 16, 2009