From the text (p.193-194) ... 'In the southern pine belt, the pines were perpetuated by the recurrence of tornadoes, and by the constant repetitions of naturally caused forest fires. Destruction of longleaf pine as a type was caused by: (1) hog grazing, (2) clearcutting over wide areas, (3) annual instead of periodic fires at two to five year intervals, and finally, later (4) by total exclusion of fire.... If fire is kept out, the whole character of the longleaf forest undergoes a complete change. There are plenty of examples of this, even where the pine has not been cut. With longleaf pine, either keeping out fire altogether or burning every year are violations of the rule of excluding man's influence.... The same argument holds good for loblolly pine, slash pine, and shortleaf pine. Natural areas not changed in character by extensive logging are few, but the effect of natural fires in keeping down worthless hardwoods and encouraging pine growth is the basis for our efforts to grow pine instead of hardwoods in the loblolly and shortleaf types.... If foresters are to succeed in growing the species most useful to man by any other means than forcible reforestation, the lessons learned for any commercial species can only be gleaned by insistent and persistent study of natural requirements and natural methods for these species. For these reasons, we should do our best to secure as much as possible of available areas on which these natural agencies of destruction and reforestation still have free play. These areas should cover as great a variety of types and species as possible.' © by the Ecological Society of America. Abstract reproduced by permission.