BRITISH FOREST TREES 315 



reproduction of poplars usually takes place, by means of 

 slips or rooted stoles. 



Poplars are gifted with very considerable reproductive 

 power. Those of them which, like the aspen, do not throw 

 out many shoots from the stool, send out all the more stoles 

 or suckers from the roots. Wounds on the bark, or where 

 branches have been broken off, heal quickly and completely, 

 without leaving callus marks or diseased spots in the wood. 

 Shallow, loose soil stimulates to rich production of root- 

 suckers on the parent stem being felled, as is most notably 

 the case with the aspen, and the reproductive power of the 

 root-system can remain quiescent for many years till circum- 

 stances afford the sunshine and warmth necessary to call 

 the dormant energy into activity. Areas over which clear 

 fellings of other forest trees have been made, thus suddenly 

 become covered with large-leaved aspen brood, though no 

 trees of that species were among the mature crop just 

 removed from the soil. There hardly ever exists any 

 necessity for artificial reproduction of the aspen, for it only 

 too often occurs in much greater quantity than is at all 

 desirable ; on the contrary, as in the case of birch, measures 

 have often to be taken against it as a weed interfering with 

 the development of young growth of other more remunera- 

 tive species. 



Liability to Suffer from External Dangers. With regard 

 to late and early frosts, the aspen is hardy, and therefore 

 often asserts itself in damp hollows liable to frost, where 

 better species get killed off. Light-foliaged, and generally 

 growing in sheltered localities, it is not much exposed to 

 danger from windfall, although its shallow root-system is 

 but little calculated to offer much resistance to violent 

 storms ; where it shoots up quickly as a stole from half- 

 rotten roots, it can also have little hold on the soil. When 

 grown in the open, however, the poplars develop a good 



