60 TREE WOUNDS AND DISEASES 



single trees dotted over a gorse-covered common 

 are usually killed when a conflagration of the 

 undergrowth takes place. Probably sparks 

 emitted by railway engines are responsible 

 for most of the fires in rural districts, and 

 particularly where railway lines traverse planta- 

 tions that are mainly composed of coniferous 

 trees. Negligence, and fires due to incendiar- 

 ism, come next in number. 



Scorched trees, particularly when the bark 

 peels off, rarely recover their wonted vigour ; 

 and even when the damage done by fire 

 appears at the time insufficient to necessitate 

 the removal of the crop, the rapid attack of 

 insect pests soon makes the felling of the 

 injured trees a necessity. There is little doubt 

 that the heat generated in the soil over which 

 a fire has raged has as much to answer for in 

 the damage to the health of the trees as the 

 scorching of the stems by the flames. On 

 several estates known to the writer, where 

 large areas of heath-covered, gravelly land are 

 covered with the Scotch pine, fires are of almost 

 annual occurrence. This is mainly attributable 

 to the carelessness of visitors, who, in one case 



