SYLVICULTURAL NOTES ON OAK. 247 



must frequently be brought artificially into the ground, 

 cither by driving herds of swine through the woods, or 

 lightly hoeing the soil after the acorns have fallen. 

 The seed trees are removed quickly, generally within a 

 few years after the young crop has come up ; otherwise 

 the latter is likely to suffer from the shade of the 

 mother trees. 



i. Tending. 



Fertility of the Soil. As already stated, pure Oak high 

 forest is rarely capable of preserving the fertility of the 

 soil, hence such woods must be underplanted with shade- 

 bearing dense-crowned species. 



External dangers are on the whole not great. Young 

 Oak suffers from late frost, but such damage heals easily, 

 owing to the great reproductive power of the tree. It 

 is very storm-firm. Snow and rime only break the 

 branches, especially the lower ones. 



Cattle and game nibble Oak freely ; red deer and 

 mice to some extent peel the bark. Oak supports 

 more insects than any other tree. Kaltenbach, in an 

 incomplete list, enumerates over 500 species. The 

 acorns may be destroyed by weevils (JBalaninus) or by 

 wire-worm after planting ; the trees are frequently 

 defoliated by Tortrix viridana, Liparis monacha, and in 

 S. Europe by Cnethocampa processionea ; also by cock- 

 chafers. Many weevils eat the buds. The bark is 

 injured and sickly trees are killed by species of 

 Agrilus and by Scolytus intricatus. The timber may 

 be rendered valueless by the boring of Cossus larvse, 

 or those of Longicornia, especially in Central Europe, 

 by Ceramfyx heros. Many gall-wasps attack the Oak, 



