14 BULLETIN 154, U. S. DEPARTMENT OF AGRICULTURE. 



EFFECT OF FIRE. 



Fire has been one of the most important agencies in the reproduc- 

 tion of loclgepole pine. Its effect is fourfold: (1) B} t softening the 

 resin and drying out the cone scales it opens the sealed cones and 

 makes available the accumulated seed production of many years; 

 (2) by reducing the density of the ground cover it admits plenty of 

 light; (3) by exposing the mineral soil and removing the ground 

 cover it prepares a favorable seedbed; (4) by killing and driving away 

 for a time the rodents and birds it saves the seed from being eaten, 

 Thus aided by fire, lodgepole has been able to replace to a consider- 

 able extent all the species within its range, since these usually pro- 

 duce seed in abundance only once in several years and discharge it 

 immediately. Most of the extensive lodgepole stands now in existence 

 have come in as a result of fire. On the other hand, areas former ry 

 covered with lodgepole have been made barren by " double burns," 

 where stands of young growth which followed the first fire have been 

 destroyed by a second one before they were old enough to produce 

 seed. Areas of this kind on which all of the trees have been killed 

 will not reforest naturally for many years, since the only way repro- 

 duction can take place is by seeding from the sides. 



Fire in a mature stand is usually followed by too dense a reproduc- 

 tion to permit the most satisfactory development of the young trees. 

 Sample plots on the Gallatin Xational Forest, Mont., show repro- 

 duction after the fires of 1910 with a maximum density of about 

 300,000 one-year-old sedlings per acre. On the Deerlodge Xational 

 Forest stands following fire have been found which, at the age of S 

 years, had a maximum density of about 175,000 live seedlings per 

 acre, averaging about 2 feet high. Ten small sample plots on the 

 Arapaho Xational Forest, Colo., in a 22-year-old stand, showed an 

 average of nearly 44,000 trees per acre. These figures, of course, rep- 

 resent maximum densities on small areas, but as extreme illustrations 

 they show that severe overstocking is more than likely to follow fire. 



The effect of fire on cut-over areas may be very different. Where 

 all the trees have been felled and the brush piled in windrows — a 

 practice in many private operations — a fire in the slash may be fol- 

 lowed by reproduction of moderate density. Such a fire usually de- 

 stroys all the seeds in the windrows, the locations of which are marked 

 by the absence of reproduction, while a moderately dense stand starts 

 in the intervening spaces from cones which did not get into the 

 windrows and thus escaped destruction. 



On unburned, cut-over areas reproduction is apt to be much less 

 dense, and therefore more satisfactory than irf the case of burned- 

 over uncut stands. Throughout the Rocky Mountains are thousands 

 of acres of old cuttings, untouched by fire, upon which the repro- 

 duction is decidedly satisfactory. This is especially true of the Deer- 

 lodge Forest, near Butte, Mont., where it is unusual to find an old 



