Burn to better browse

Burn to better browse

15 April 2009

USA — “Man has come to the forest,” declared Bambi’s father as he smelled the smoke from the campfire that was to become a raging wildfire.

The vivid imagery of this Disney cartoon is the first exposure most children have to fire and wildlife. Smokey the Bear has done an excellent job of educating the public on the dangers of wildfire.

Unfortunately, the same message has usually been applied to all fires, even those that reduce the chance of wildfire and play critical roles in natural ecosystem maintenance and function. While catastrophic wildfires negatively impact people and wildlife, prescribed fires are beneficial to deer and many other native plants and animals.

Prescribed burning is fire applied by trained people in a skillful manner under particular weather conditions in a definite, confined location to achieve specific results. When thoughtfully used, prescribed fire promotes quality deer browse and increases soft mast production.

Why fire?

Fire has played a role in most North American ecosystems for thousands of years. Most parts of the United States have habitat types, which may be rare today, that require fire to maintain. Some of these habitats burned frequently, every one to three years, while other habitats burned once every decade or two.

But in every case, when fire moved through these habitats, it pushed succession a little further back, temporarily shifted dominance to the plant species adapted to fire, and started a cycle of renewal that provided a diverse selection of seedlings and sprouts for all the herbivores. The mosaic that results after a series of fires produces a diversity of plants that provide forage, mast, and escape cover for deer throughout the year.

A quick review of the literature shows that prescribed fire has been intentionally used to improve habitat all across the range of white-tailed deer. Fires for deer are typically used to top-kill thick, invasive brush in favor of tender hardwood and forb sprouts. Prescribed fires may also be set to benefit other wildlife species, improve cattle range, restore native vegetation, reduce fuel loads, control unwanted competition in forests, and prepare areas for reforestation.

Prescribed fire is most frequently seen in the Southeast, though it is becoming more and more common in the Southwest, Midwest, and even the Northeast. The areas where fire is most frequently used are the open pinelands of the South and the prairies and savannas of the Midwest.

Deteriorating aspen stands with low commercial value in the Midwest and Lake States may be enhanced by the deliberate use of fire. Fire is sometimes used to rejuvenate desirable browse plants in the West and Northwest. Prescribed fire is also used to rehabilitate some pine barrens and bog habitats, and to shift understory regeneration in low quality hardwood stands in the Northeast. Fire is used to maintain early successional components in old field habitats and as a site preparation tool prior to reforestation in many parts of the country.

Fire is not good or bad. It can improve or degrade the habitat for different animals and plants depending on how it is used. Some factors that determine the impact a fire has include the size of a burn, the reason for a burn, fuel loading, wind speed and direction, relative humidity, ignition pattern, and fire return interval. These factors interact in a complex and dynamic fashion which results in a diverse mosaic of impacts as fire moves through an area.

Most animals, especially those that live in fire-type habitats, are adapted to fire and have ways of escaping. Deer simply move in front of the fire, wander between fingers of fire, and even hop casually over low-burning fires. Fresh deer sign is frequently seen when checking fires.

The major benefit of prescribed fire for deer is an increase in forage quantity and quality. Like most other disturbances, including mowing, plowing, and herbicide treatments, there is a short-term decrease in the amount of available browse, then a longer term increase in the amount of forage and mast within “deer reach” of the ground. Not only is the amount of forage greater, but the quality is higher.

The increased forage quality is partially the result of shifts from woody browse to good weeds, including many legumes, and tender woody sprouts. The younger plants have higher nutrient concentrations, particularly proteins and phosphorus. These tender sprouts are also more palatable and digestible because they do not have as much tough lignin and fiber as older plants.

Some studies and anecdotal observations suggest that many shrubby species produce an abundance of fruit following a fire, though there is a drop in mast production the year of the fire. Many of the dwarf oaks in the South and the Lake States, though different species, respond to fire by producing more acorns two to four years following a fire. Blackberries, blueberries, and many similar soft mast producers benefit from fire and produce more mast per acre two to five years after a fire.

A secondary benefit of fire for deer and other animals is a reduced ectoparasite population. Areas that are burned frequently have lower tick, chigger (redbug), and lice populations.

How to burn

The first step in conducting a prescribed burn is to carefully consider the biological, silvicultural, legal, and social benefits and costs of burning. If fire can be used legally and safely on the property and the benefits outweigh the costs, then prescribed fire may be an option.

Most state forestry agencies are tasked with fighting wildland fires. In states where prescribed fires are typically used, they also issue permits for burning and conduct training to help people burn safely. Before burning on your property, talk with your local forestry agency and perhaps get additional advice and assistance from a biologist, forester, or other natural resource management professional.

Make sure that someone experienced with wildland fire is on the property when you burn. Take the time to develop a prescribed burning plan for each area to be burned.

The first step in developing a prescribed burn plan is to identify the fire-type areas on the property. These might be fire-adapted pines or grasses, prairies, recent clearcuts, or fallow food plots. Decide on what your average return interval will be. If it is five years, then about 1/5 of fire type habitats would be burned each year. For large properties, this usually means the fire will occur in smaller burns scattered around the property.

It is also important to identify areas to be protected from fire. Consider putting firebreaks around special mast areas, patches of escape cover, and other special places within fire-type habitats.

The two main factors to consider are control of the fire and minimizing the off-site impacts of the smoke. Weather conditions will largely determine when you can safely burn and where the smoke will go. Firebreaks should surround the area that you are going to burn. These may be plowed breaks, or they may be existing barriers, such as a waterway or a private road. When putting in new breaks, it is important to use the best management practices to reduce erosion.

Smoke management is a critical component of prescribed burning. If the atmospheric conditions are such that the smoke will impact a highway, town, hospital, or other smoke sensitive area, then another set of conditions will have to be used.

Once your breaks are prepared and weather forecasts match your prescription, get the appropriate permissions and permits for the day of the burn. After the experienced burn crew has looked at the area to be burned and reviewed the plan, the next step is to set a test fire.

If the test fire behaves as expected, then back fires are usually lit to establish backlines. In some cases, the fire is allowed to back all the way through the unit. In order to burn the area quickly so that smoke has time to dissipate, a series of spot or strip fires are often set just in front of the backfire.

Lighting all the way around the perimeter of the area to be burned often results in high intensity fires that may damage overstory and have the highest probability of trapping wildlife in the fire, so they are seldom used where wildlife is an objective. After the fire, extinguish any smoking material and danger areas along the edge of the fire with hand tools or water. Revisit the area over the next couple of days to ensure the fire is out.

While prescribed fire alone is beneficial, it is often used with other habitat management techniques. It is frequently used after thinning fire-type pines. Where wildlife is an important objective, prescribed fire is often used after an understory is treated with herbicides to improve and extend the benefits of controlling the woody understory components.

Herbicides, drum choppers, and heavy duty mower/mulchers may be used to reduce fuel loads prior to a burn. After a burn, an area may be planted with native plant or typical food plot seeds to help provide forage.

A general fire regime for deer in the Southeast is to use a cool-season fire (December to March) of variable intensity on a three to five year return interval in 25- to 200-acre blocks. Western and northern return intervals would typically be longer (five to 10 years), while the sizes of the burn units would usually increase to the west and decrease to the north.

The season of burn would shift later as you move northwards. After an area has been burned once or twice, the season of burn can also be shifted up to six or more months later to widen the burning window. Small patches may also be burned (and even fertilized and broadcast planted) just before deer season to attract deer.

Fire is one of the cheapest treatments that is used to improve wildlife habitat. Typical costs for prescribed burning range from $15 to $90 per acre. The costs of prescribed fire are increasing rapidly because of the increased time spent planning for fires, the increased cost of liability insurance, and the increased time spent mopping up after the fire. The benefits to deer following prescribed fire last from three to five years, so the annual cost of prescribed fire ranges from $3 to $18 per acre.

Man has indeed come to the forest and brought prescribed fire with him. This carefully applied tool has restored a natural disturbance to many ecosystems and improved the habitat for deer, rabbits, turkey, quail, some songbirds, and many native plant species. Blackened ash and the acrid scent of wood smoke are an assurance that tender greenery is soon to come.

24. November 2017/by GFMCadmin