INJURY CAUSED BY FOREST FIRES 249 



which pass through, or in response to the greater mechanical 

 strains following the injury. Except on cross sections through 

 the burned part of the tree the growth will show a decrease. 

 Analyses of fire injured trees made several years after the 

 fire show, as contrasted to growth before the fire, increases 

 in rate of growth on the stump section and reduction on 

 sections above the wounds. 



(d) Injury due to forced cutting of merchantable material 

 before financial maturity. 



Where trees without present merchantable value are killed 

 it is quite evident that a sacrifice is involved which may be 

 estimated on the basis of the future value of the stand dis- 

 counted to the present time. Equally true is it that the loss 

 in the case of fire killed trees of merchantable size is not alone 

 the reduction in present value but should include the sum 

 lost by not allowing these trees to grow longer and be har- 

 vested at the time of their financial maturity. 



Injury to Forage. — Fires burn readily in dry grass and 

 other plants of forage value. In some cases fire may be of 

 temporary value in burning off a mat of dry dead vegetation 

 and enabling stock to get at the tender green shoots beneath. 

 In the final analysis fire tends to kill the roots of the plants, 

 thus reducing the density of stocking, and to replace good 

 species by those of inferior value for forage.^ Serious damage 

 to forage can be prevented by grazing so regulated that masses 

 of dry and inflammable forage do not accumulate. 



Inflammable forage is in some forests the principal fuel for 

 the rapid spread of fires. If this forage is used by stock while 

 green the fire danger is reduced. 



Injury to Stream Flow and Industry. — Under "Injury to 

 SoiV erosion was shown to be a consequence of forest fires. 

 Damage from erosion is felt not only on the lands eroded but 

 m the lower course of the stream down which the eroded 



