640 PROTECTION AGAINST FOREST FIRES. 



of the trees. A dense coating of lichens on the trees increases 

 the danger of the occurrence of crown-fires. 



(I. Fires in Stems. 



Green trees seldom catch tire even from lightning,* and 

 when a whole stem is burned, there is generally some decay 

 present, and the trunk or branches of the tree are hollow. 



3. Damage dune, 

 a. General Account. 



Forest fires do direct damage by destroying whole woods, 

 and especially young growth. Reproduction may be stopped 

 for the year by the destruction of blossom or fruit, while, 

 owing 4o repeated fires, broadleaved trees which are not killed 

 become misshapen and weakl3\ Game may be killed in 

 extensive* fires. By heath fires in Hannover many hives of 

 bees are burned. 



Indirect damage consists in the burning of the dead leaves 

 or needles on the ground, which prevents the accumulation of 

 humus and the improvement of the soil, and renders it poor, 

 hard and unsuitable for reproduction. Henry states (" Eev. d. 

 E. etF.," June 1st, 1902) that high forest produces the following 

 quantity of dead leaves in 6 years per acre : — 



Beech 10,500 lbs. 



Spruce 13,500 „ 



Scots pine .... 18,000 „ 

 Coppice-with-standards . . 4,000 ,, 



There is about If lbs. of nitrogen in 100 lbs. of dead leaves, 

 worth about Id. a pound. The value of the nitrogen destroyed 

 in the dead leaves is 14s. per acre for coppice-with-standards, 

 and three to four times as' much for high forest. 



A proper sequence of age-classes may be interrupted. The 

 annual burning of the soil-covering on hill-sides may cause 



* Von Tubeuf, in 1892, observed that lightning had set fire to a growing 

 spruce tree, and the fire spread to neighbouring trees. 



In the years 1877 — IS8H, tliere were 'M) fires in the Bavarian State forests, 

 which arose as follows: l' from ground-fires; 416 (82 percent.), surface-fires; 

 To (40 per cent.), combined surface and crown-fires ; 15 (3 per cent.), combined 

 surface and stem-fires ; G (1 per cent.), stem-fires. 



