While man is responsible for a many-fold increase in the occurrence of forest fires, lightning as a natural cause has operated with a frequency that places fire among the determining ecological factors that influenced development, modification, and survival of species, especially of pines. In dry hot climates lightning fires occurred at intervals so short that pines became modified in order to survive as seedlings or saplings. In cooler northern climates fires tended to destroy most of the stand, and adaptations took the form of protecting seed sources. To successfully reproduce and grow pines we must adapt silvicultural measures to the inherent habits of each species of pine, as determined for it by the environment in which it has developed the adaptations. This is difficult with some northern species such as white pine (P. strobus) and jack pine (P. divaricata). The reasons for these difficulties are chiefly the fact that clear cuttings, even with seed sources, do not usually duplicate natural conditions under which these pines originate, hence special skill and often considerable expense is involved. With southern pines, the duplication of natural conditions is extremely practical and inexpensive, consisting of the use of prescribed controlled fire at intervals dependent on the species; 3 years for longleaf pine (P. palustris), 5-6 years for slash pine (P. caribea), and 8-10 years for loblolly pine (P. taeda). This practice not only insures abundant reproduction during seed years but fireproofs the forest against almost certain destruction as the result of excluding fire and building up an unnatural fire hazard of brush and dead grass. The extension of the use of prescribed fire to the shortleaf (P. echinata) and pitch pine (P. rigida) types in New Jersey is an outgrowth of the practices found successful and officially adopted by the Forest Service in the southern pines.