296 BRITISH FOREST TREES 



reproductive power, become reduced in proportion. Under 

 normal circumstances, however, it has a considerable 

 power both of shooting from the stool and of sending out 

 root-suckers, in which latter respect it has some advantage 

 over the common alder. The shoots are of rapid growth 

 for about the first ten to fifteen years, but then decrease 

 considerably in their rate of annual increment. 



The capacity for reproduction from the stool also 

 diminishes much more rapidly than in the case of the 

 common alder, but, with failing power in this respect, the 

 tendency towards increased development of root-suckers 

 becomes distinctly apparent. Deep felling of the timber 

 and coppicing close down to the ground also stimulate the 

 formation of suckers. As regards the production of seed,- 

 it closely resembles the common alder ; the seed, however, 

 is lighter in colour, and has not the same tendency to 

 scatter quickly before it can be conveniently harvested. The 

 seed is somewhat smaller than that of the common alder. 



Liability to Suffer from External Dangers. Grown 

 usually in sheltered localities, the white alder is little 

 exposed to danger from heavy storms, against which its 

 root-system is little fitted to offer strong or effective re- 

 sistance. Against hard frosts in winter it is somewhat 

 hardier than the common alder, the reproductive power of 

 the stools being less liable to be damaged by ice. Like the 

 other species, however, it is not exempt from being killed 

 outright, or being interfered with in growth, by having its 

 roots exposed when a rapid thaw suddenly succeeds a 

 sudden frost, a danger that increases in proportion to the 

 amount of soil-moisture. Inundation of the stools after 

 felling is on the other hand more injurious to the white 

 than to the common alder. 



Like nearly all deciduous broad-leaved trees, it is liable 

 to the cankerous fungoid attacks of Nectria ditissima on the 



