642 PROTECTION AGAINST FOREST FIRES. 



Phius rigida, Mill., in the Gotten forest near Bonn, in 

 March, 1893, produced shoots from dormant buds, after a fire, 

 but not a complete crop. The plants, 7-10 years old, were 

 cut back, after the fire, and produced 9 or 10 shoots each, 

 38 c.m. high. 



Amongst broadleaved species, rough-barked trees, such as 

 oak and elm, withstand fires better than smooth-barked trees, 

 such as the beech, ash or sycamore. 



Fires are evidently more frequent and dangerous in High 

 Forests than in coppices. 



c. Age of Trees. 



Young woods up to thirty years old are most exposed to fire, 

 at first owing to the presence of weeds, later on, as the struggle 

 for existence is strongest, and there is usually most dead wood 

 at this period. 



Well-stocked woods between 30 60 years of age withstand 

 fires best of all, as middle-aged coniferous woods after the 

 earlier thinnings contain least combustible material, such as 

 dead wood, grass or heather undergrowth. 



Woods over 60 years of age, where grasses and other weeds 

 spring up, again become more endangered. 



The following average figures, taken from a list of forest 

 fires in Hanover between 1864 84, support the above con- 

 clusions. Out of 1,000 acres of forest, there were burned 

 annually during these twenty years : 



Age. Acres. 



Broadleaved woods . . , . . '170 



(1 SOyrs. 1-107 



Coniferous woods . . .3060 0'262 



I over 60 0'354 



Mixed coniferous and broadleaved I n-464 

 forest * . - -; -.. I 

 d. Locality. 



Forests in plains, on account of the greater dryness of the 

 air, and frequently of the soil, suffer more than mountain- 

 forests. On sunny aspects fires spread much more rapidly 

 than on cool northerly slopes. A dry sandy soil increases the 



