Using Prescribed Fire in Loblolly Pine Stands

Prescribed Fire March 27, 2013 Print Friendly and PDF

An even aged loblolly pine stand that is managed with periodic fire. Note the absence of a hardwood midstory due to the frequent fire.

 

Loblolly pine is widely distributed across the southeastern U.S. and is an important commercial tree species. It also provides a host of other values including wildlife habitat, aesthetic value, and erosion control. Prescribed fire is an important practice in managing loblolly pine stands. However, care must be taken to minimize tree damage by setting the appropriate fire prescriptions.

Minimizing mortality

In general, loblolly less than 5 years in age will be damaged by prescribed fire. Therefore, if commercial timber production is a goal, prescribed fire should be withheld until trees are well established. Trees that are at least 3 - 4 inches ground diameter or about 15 feet in total height are generally not damaged by low-intensity fire. Consider using a backfire and burning during the dormant season when ambient temperature is less than 60 degrees F. Good atmospheric lift and moderate wind speeds (>10-15 mph) also favor dissipation of heat from the canopy. Even larger pines can be damaged by crown scorch if atmospheric conditions do not favor lift. Generally, crown scorch of less than 50% will cause minimal mortality but may impact growth rates for a couple of years.

Litter moisture is also important. If the duff layer is consumed, root damage is likely to occur, which can lead to tree mortality. Additional care should be taken to remove large woody debris from the base of trees to ensure the cambium layer is not damaged by the residual heat from these long-burning heavy fuels.

Hardwood control

Hardwood species compete heavily with young pines and can limit growth of pines. Herbicide applications, such as Arsenal AC (24 oz/ac) or Chopper (32 oz/ac), are often used to minimize hardwood competition. Once the pines are large enough, prescribed fire every 2-5 years will limit hardwood competition and encourage herbaceous groundcover.

 

This diverse herbaceous understory resulted following a dormant season fire in this young pine stand.

Agroforestry

Livestock grazing is very compatible in open pine woodlands and savannahs that have adequate grass forage. Total biomass of grass forage will increase as basal area of pine decreases. Therefore, landowners must consider the appropriate balance between timber production and livestock production, which may vary depending on current commodity prices and other landowner objectives. Regardless, prescribed fire should be used in these agroforestry systems to limit hardwood encroachment and increase the palatability of the grass forage for livestock. Additionally, by burning portions of the pine stand, livestock can be rotated without fencing (patch-burning) as they will quickly move to the recent burns to forage on the grass regrowth. This is beneficial as it will allow grass fuel to accumulate on the unburned (and ungrazed areas) and will minimize fencing needs, which will make tree harvest easier. If hardwood encroachment becomes problematic, growing-season fire (August-September) or headfires during the dormant season can be used to better control hardwoods, assuming the pine stand is of sufficient age to survive increased fire intensity. Livestock stocking rates should be low to moderate for young pine (<5 yr of age) to minimize pine mortality. 

Wildlife management

Many species of wildlife may use loblolly pine stands, especially those with open canopies managed with prescribed fire. White-tailed deer, wild turkey, and northern bobwhite are focal species for most landowners. Prescribed fire can be used to manage vegetation composition and structure for these species. Generally, a fire frequency of 3-7 years, 2-5 years, and 1-3 years for white-tailed deer, wild turkey, and northern bobwhite, respectively, is appropriate in loblolly stands.

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USDA / NIFA

This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.