Fire Effects

The frequency, intensity, and season of fire is second only to precipitation in terms of vegetation response. In other words, if it does not rain, nothing will grow whether it was burned or not. The amount of time since a fire is the most important factor of a fire’s impact on vegetation structure and composition. Time of year (season) has minimal impact on the native plant community.

Fire Effects on Major Trees and Shrubs

Non-sprouting: These are woody plants fire will kill if the above ground portion is heated sufficiently (i.e. all the growing points are killed or the cambium is killed).

Eastern Redcedar (Juniperus virginiana)
Mountain Cedar/Ash Juniper (J. Ashei)
Cottonwood (Populus deltoides) mature trees when exposed to extreme heat (i.e. understory of eastern redcedar that burns)
Loblolly Pine (Pinus taeda) trees less than 12 feet tall or less than 4 inches dbh
Mockernut Hickory (Carya tomentosa)

Sprouting: These are woody plants top killed by fire, but come back from stump or root sprouts. Fire will normally reduce plant height, percent canopy cover and volume. Stem density usually increases after fire. Some of these plants are vigorous resprouters and will
recover to pre-fire status in three years or less. Others are slower to return, such as sand plum, but they will recover. Depending upon objectives, a three year or less fire return interval is recommended for most woody plant species to maintain at appropriate levels.

Blackberry (Rubus oklahomus)
Black Locust (Robinia pseudoacacia)
Bois d’Arc/Osage Orange (Maclura pomifera)
Honey Locust (Gleditsia triacanthos)
Mesquite (Prosopis glandulosa)
Oaks (Quercus spp.)
Persimmon (Diospyros virginiana)
Rough-Leaf Dogwood (Cornus drummondii)
Salt Cedar (Tamarix chinensis)
Sand Plum (Prunus angustifolia)
Sand Sagebrush (Artemisia filifolia)
Shinnery Oak (Quercus havardii)
Shortleaf Pine (Pinus echinata) seedlings and saplings
Sumac (Rhus copallinum, R. glabra)
Winged Elm (Ulmus alata)

Fire Effects Information

For more information see:
Fire Effects in Native Plant Communities NREM-2877 at:
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2703/NREM-2877webW-survey.pdf and The Effects of Fire Video VT-1139 available at: http://nrem.okstate.edu

OSU NREM Fire Ecology (http://fireecology.okstate.edu)

Fire Effects Information System (http://www.fs.fed.us/database/feis)

Fire Frequency

Fire frequency is the key to managing woody plants. Fire is not a one-time tool, it is a management program. One year of fire will not change years of fire suppression. With the appropriate fire frequency (based on objectives), the native plant community can be maintained as a forest, a woodland, a savannah, a shubland, or a grassland. Thus, depending on the objectives (such as wildlife, brush control, forage production for livestock, etc.) land can be molded to meet landowner goals.

Fire frequency is the key to land management. Examples are for the past 20 years in Oak-Pine forest of SE Oklahoma.

Fire Frequency A

No burn

Fire Frequency B

3 yr burn frequency

Fire Frequency C

2 year burn frequency

Fire Frequency D

1 year burn frequency

Fire Effects on Wildlife

White-tailed Deer
White-tailed deer have a diverse diet and occur in many different habitats. However, they are primarily browsers that consume shrubs and young woody vegetation, vines, forbs, and a limited amount of grass. Acorns and soft mast (fruit) are seasonally important.
To be accessible, these plants must be at or near ground level (<6 feet). Many of the desired plants for deer need ample sunlight to grow. Thus, closed canopy forest and redcedar dominated rangelands
provide little forage or browse for deer. Fire can be used to open up forest canopy and to stimulate growth of desirable plants for deer. A fire frequency of 4 years or less will accomplish this on many sites in Oklahoma. Longer fire frequencies may be appropriate, as long as redcedar does not dominate (usually after 7 years). The size of a burn unit can be quite large for deer as their home ranges usually cover several miles. Thus, burns up to a section (640 acres) in size are appropriate, although larger burns may be warranted under some conditions. For more information see White-tailed Deer Habitat Evaluation and Management Guide E-979 at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2971/E-979websurvey2011.pdf

Forested Area

This forested area is burned every 4 years and provides good habitat for white-tailed deer. Notice the abundant available browse.

Wild Turkey
Wild turkey require varied habitat depending on the season of the year. In the spring, they seek out areas with abundant forbs and insects to feed. These same areas are important for poults after hatching. A recently burned area will provide this type of vegetation. A portion of the property should be burned annually to provide for the brood cover needed for turkey. Up to half of the area would be appropriate on most properties, as long as adequate cover is available for that year. Turkeys will use brood habitat throughout
the summer. As fall approaches and mast begins to drop, turkeys use forest edges more and will gradually flock up in hardwood draws for the winter. They will use many species of trees for winter roosting, as
long as the understory is not occupied by redcedar. Thus, riparian draws should be periodically burned to keep redcedar from encroaching (at least every 7 years). For more information see Management of Wild Turkey in Oklahoma NREM-8700 at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2707/NREM-8700.pdf

Post Fire Response of Legumes

Immediately following a
fire, there will be a response of forbs and legumes, such as this showy partridge pea, that are beneficial to wild turkey. Many of these beneficial plants decrease over time in the absence of fire.

Bobwhite Quail
Quail, like turkey, require a diverse habitat that contains forbs, grasses, and some woody thickets. During the spring, quail seek out areas with last years grass cover for nesting. Thus, having some areas not burned that year is beneficial for nesting quail. However, once the chicks hatch, they need a forb rich area to find insects and cover. This vegetation should be open at ground level with limited litter as to not impede chick movement. Recently burned areas provide this
type of habitat. On sandier soils in western Oklahoma, this type of vegetation persists for many years following fires, but in the eastern portion of the state grass and litter cover builds quickly. Thus, fire frequency should be shorter as you move east. In fact, fire frequency of two to three years is appropriate in eastern Oklahoma, while fire once every seven years may maintain habitat conditions in the far western portions of the state. Woody cover (thickets) must be main
tained. Many woody plants resprout quickly following fire. But in areas with very frequent fires (such as two years), protecting some of the woody cover is beneficial to quail. The size of a burn unit for quail should match their home range, which is generally small. Burns of 25 to 100 acres would be ideal, although this may not always be possible for safety and cost reasons. Note: it is more important to burn quail habitat, even if you must burn large areas, to keep redcedar to a minimum. Once redcedar becomes dominant, quail numbers decline. For more information see Bobwhite Quail Habitat Evaluation and Management Guide E-904 at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2698/E-904%20-%202013.pdf

6 Months Post Fire

An example of a diverse plant community maintained by fire. Note the cedar skeletons and abundant forbs 6 months after the burn. This is excellent quail habitat.

Fire and Food Plots
Many landowners spend considerable effort and money on food plots to attract wildlife. However, as noted above, fire promotes plants that wildlife prefer for food. Thus, a burned plot of any size is a food
plot. Strategic placement of burned areas can provide excellent hunting for deer, turkey, and quail. Additionally, a late summer fire can produce a September dove field. These growing season fires are often dominated by plants highly preferred by dove. Using fire to produce food plots is not only cost effective, but also meets other land management goals. For more information see A Practical Guide to Food Plots in the Southern Great Plains E-1032 at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-8840/E-1032%20food-plot-guide-online.pdf

Fire Effects on Erosion

Research has shown that soil loss following fire are insignificant and should not be a concern.

Fire and Grazing

Selecting the proper stocking rate is the most important consideration in grazing management. Some land managers believe that higher stocking rates are better, but research and ranch budgets have shown that maximum net return per acre occurs at a moderate to light stocking rate. Land managers should ask the question is grass
fuel, forage, or habitat? If thought of as forage only, there will not be enough fuel to burn. Deferment of grazing before conducting prescribed burns is not necessary if a proper stocking rate is used. If you don’t have enough fuel to burn, you are overstocked and losing income on your livestock enterprise.

Additionally, with the proper stocking rate there is no need to withhold livestock from burned pastures. Cattle will graze on the new high quality forage following a prescribed fire until a newer burned area is available. Thus, the land manager should be burning some portion of the grazed land every year, and move cattle around on the property and providing rest on the unburned portions of the land for fuel accumulation.

This is called patch burning and it is an effective way to manage forage for cattle, fuel for fire, and habitat for wildlife. To learn more about this concept see E-998 Patch Burning: Integrating Fire and Grazing to Promote Heterogeneity at: E-998 http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-4677/E-998survey2013.pdf

Eastern Redcedar and Fire

Forage/Fuel Loss
Cedar severely limits forage/fuel production beneath its canopy. It has been shown that 250 large trees per acre will cut forage/fuel production by half. If fire is suppressed from a site for several years
(usually 7 to 10 years) cedars become tall and dense enough that fire alone may not kill them. The following are general guidelines on the effectiveness of fire to remove redcedar. For more information about cedar control see Cedar Control by Individual Scorched-
tree Ignition Following Fire NREM-5053 at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-7936/NREM-5053.pdf and Eastern Redcedar Control and Management – Best Management Practices to Restore Oklahoma’s Ecosystems NREM-2876
at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2550/NREM-2876web2013.pdf

Trees less than1 foot tall = 100 percent control with 2,000 lbs/acre of fine fuel

Trees 1 foot to 5 feet tall = 95 percent control with 4,000 lbs/acre of fine fuel, only 60 percent control with 2,000 lbs/acre of fine fuel