FIRE AS A TOOL IN SOUTHERN PINE

ARTHUR W. HARTMAN.

For three centuries people in the South have practiced woods burning. The custom began in the Coastal Plain flatwoods, where groups of settlers had to clear ground for farming and then for their livestock. They soon learned that late winter was a critical period for their stock the ground had a cover of dead grass, needles, and litter, and the animals fared badly. But on a fresh winter burn new and succulent grass would spring up to tide their stock over until spring. They set fires also to clear the woods of varmints.

The settlers, observing some beneficial effects, came to believe the whole practice beneficial and, with the passage of time, the population developed customs and community procedures for burning the Coastal Plain pinelands about every second or third winter. When the people migrated inland to the rolling uplands of the Piedmont and the Appalachian, Arkansas, and Missouri Mountains, they carried with them the custom of "light burning." It became universal across the South. They had no way of knowing the extent to which the custom had grown away from beneficial application and become seriously detrimental to the then abundant timber stands.

When trained foresters carefully observed the results they concluded that light burning had been detrimental to the health, growth, and yielding capacity of the stands affected; that it was the limiting factor to good forestry practice in the Coastal Plains; and that eventually it would destroy the hardwoods and less fire-resistant pine stands of the uplands. Three figures show the magnitude of the problem in 11 Southern States: In 1947, there were 158,425 fires that burned over 21,005,581 acres in the total forest area of 185,416,000 acres.

One must not assume that a major part of a population knowingly and maliciously practices or tolerates for a long time a custom detrimental to the community. Rather, one must understand that generations of observation by the people point to some solid reasons for burning, even though application sometimes drifted into extremes.

A few early foresters investigated and concluded that all use of fire was not evil and that fire correctly used under specific conditions and for predetermined results could, in fact, be beneficial. Furthermore, they developed the thesis that the long-established and deeply ingrained custom would be broken only after foresters themselves had clearly identified and separated the helpful from the harmful application of fire and then proved the identity of the two.

Progress toward the identification of the effects to be had from fire has been under way for many years. Here and there observant landowners worked out and applied some uses of fire on their own lands. The work of such men as H. M. Wilson and William Ottmeier produced valuable lines of approach.

As far as the records reveal, the investigations of H. H. Chapman were the first attempts to identify scientifically and define woods conditions that might be bettered by fire, to measure results from actual use, to create guide lines for proper fire intensities, and to measure the influences of climatic conditions on fire behavior.

The Southern Forest Experiment Station twenty years ago began a series of studies to determine some phases of fire effects in longleaf pine stands. The studies progressed until, by 1940, there was evidence that net benefits were obtainable from fire under certain specific sets of conditions. In the meantime, pilot studies were conducted on longleaf pine lands in national forests. The sum of the evidence disclosed a need for burns to be carried out over a large area and under varied conditions.

In considering the program undertaken, certain facts and principles must be kept in view:

1. The term "prescribed burning" is meant to describe and apply only when on-the-ground examination and analysis has revealed some unsatisfactory condition that can be bettered if fire (of a specified intensity and under prescribed conditions of season, fuel moisture, wind direction and velocity) is applied at the proper time and only to the designated area.

2. Timbered land should be protected from wildfire at all times.

3. The burden of proof is on the land manager each time he uses fire as a tool. Use of fire on timber stands must be viewed as akin to surgery on a human being. It is justified only after competent diagnosis of an unsatisfactory condition indicates that opportunity for gain will be in excess of losses and cost and must presuppose acceptable skill in execution.

4. Generalizations, such as "southern pines," must be avoided; in all cases reference must be made to the tree species involved on any one area considered for treatment by fire.

5. In evolving prescribed-burning practices, it is equally as essential to determine where and when use of fire is detrimental as it is to clarify when it can be beneficial.

WHEN THE PROGRAM of prescribed burning was started, available information indicated that it should be tested for its value in meeting the following situations :

1. Preparation of seedbed. Longleaf pine yields a good seed crop at intervals of 5 to 8 years. Characteristic ground cover in this timber type, 2 years or more after being burned, is a mat of dead grass and pine needles so dense that it prevents all but a small part of the seed fall from reaching mineral soil and becoming established.

2. Sanitation burning to eradicate brown spot needle disease from longleaf pine seedlings in the grass stage. Where the disease is prevalent and not cleaned off, either on the natural or planted seedlings, infected plants fail to make growth, gradually lose health and vigor, and in 5 to 8 years may suffer 90 to 100 percent mortality.

3. Subjection of healthy longleaf grass-stage seedlings to a smothering cover of grasses and overstory of brushy plants. Root competition for food and moisture, coupled with shading from sunlight, starve a seedling from starting height growth for as much as 12 years. Fire can remove the shade and reduce competition.

4. Encroachment of any undesirable growth. Edges of ponds, bays, swamps, and streams support growths of titi, gallberry, myrtle, and other commercially worthless species. Under complete fire exclusion, this growth encroaches and occupies good pine sites with thickets so dense as to exclude pine reproduction. In Florida such encroachments have taken over as much as 25 percent of the best pine sites. On the drier longleaf sites, volunteer loblolly can become an undesirable species. Fire can reclaim such areas for establishment of productive growth.

5. Protective burning. This phase of burning is full of divergent interpretations and misunderstanding and controversy. The basic idea in the investigation has nothing to do with the periodic light burning of woods as a substitute for full protection against fire. The simple fact that over Coastal Plain pinelands a wildfire will again burn rapidly within 6 months or a year after having been burned would render any such protection scheme futile.

Opportunities for protective burning are typified by the Osceola National Forest in Florida. There the ground cover is such that an intensive fire-protection organization would fail frequently and to the extent that the sum of fire losses could equal the increment of the area over a rotation period.

Fire exclusion was practiced there for 15 years. It is an area of lush and prolific growth. Longleaf and slash pine seedlings came in profusely following wildfires just previous to establishment of fire protection. Dense stands resulted, understoried by rank growths of the tolerant palmetto, gall-berry, and grasses. Pine needle cast, which lasts many years without appreciable decay, drapes over the lower pine branches, bushes, and grass accumulations and creates a floor of man-high fuel heaps. By measurement, there were 25 tons of flash fuel per acre.

As the fuel accumulated, the danger of fire increased constantly. During the long dry periods in late spring and early summer, the stands reached almost explosive conditions. Whether a fire was caused by man or lightning, a moderate wind could fan it into a fast-running crown fire before a man could reach it. Then the only chance of breaking the head lay in backfiring a road that might be several miles away. Burns of thousands of acres were in prospect, particularly because the highest incidence of incendiarism in the country is found in parts of this vulnerable region.

The manager of such a forest land must calculate carefully his risks. On the one hand, can he burn out the fuel at a cost of about 15 cents an acre and the equivalent of one-half of a year's growth of his stand when a killing accumulation of fuel develops? On the other hand, should he take a chance that wildfire will not get into his stand when it is worth upwards of $20 an acre? The factors he must take into account are frequency of incendiary fires, the amount of local sentiment against having range go back to timber, the probability of accidental fires, the size and location of his investment with regard to constant surveillance, and the degree of certainty to which local fire forces can be relied upon to hold incendiary settings of fire to small size. He might also have to consider the chances of fire that exist when a plantation or an equally valuable stand of natural young growth is located in an area of high risk near a settlement, railroad, sawmill, or a frequented fishing site.

6. Scrub oak control. Following heavy cutting on longleaf ridges, scrub oaks tend to take over the sites, producing a closed canopy that excludes pine reproduction. Some observers believe that fire can be used to thin out or even remove these scrub oak thickets.

7. Planting preparation. Burning just before planting removes the "rough," or mat of dead grasses and leaves, and facilitates planting operations. Brown spot disease is removed from whatever volunteer seedlings are present, and infection in planted stock is reduced. Also, it insures the costly plantation from destruction by wildfire during its most vulnerable period.

8. Wildlife burns. In many areas under complete fire protection, the food supply of deer, turkey, quail, and other wildlife decreases seriously and game birds lose nesting places. There is evidence that fire can be used to increase game foods and keep nesting areas open and sanitary. Sites burned for such purposes are an insignificant fraction of wooded areas, and the desired effects may often be provided by burns carried out for other purposes. However, for the guidance of those land managers who choose to practice multiple use and make some sacrifice of timber production to favor wildlife, a program of prescribed burning is obligated to test and assess methods and scope of fire use for such a purpose.

9. Exploration in the loblolly and shortleaf pine types. Indications are that fire can have a favorable effect under certain limited conditions.