BRITISH FOREST TREES 193 



killed by Rosellinia querdna. Red-rot in the timber is due 

 to Polyporus sulphureus, Thelephora perdix, and Stereum 

 hirsutum, white-rot to Polyporus dryadeus and tgniarius, and 

 Hydnum diversidens, the diseases often gaining foothold 

 where branches have been broken off, or where trees have 

 been trimmed with the saw without the sawn surfaces being 

 tarred. A better-known parasite is the mistletoe ( Viscum 

 albnni), though it is of rather rare occurrence on the 

 branches, and does not practically do any damage to the 

 timber of the bole. 



The oak suffers less than any other forest tree from the 

 effects of accumulations of snow and ice on the branches, 

 and, owing to its rugged bark, does not get scorched or sun- 

 burnt. Rank growth of grass on the soil is only prejudicial 

 to its growth at the youngest stages in so far as it increases 

 the danger from frost. Owing to the rapid development of a 

 tap-root, long-sustained drought also occasions it little damage. 

 The astringent properties of the young shoots and foliage 

 protect them from being browsed on by cattle to any very 

 great extent. Serious damage may, however, be done in 

 plantations of fifteen to twenty years of age by deer stripping 

 the bark in spring and summer where strong herds of red- 

 deer are maintained. 



Sylvicultural Treatment of Oak. As a light-loving species 

 soon becoming interrupted in canopy and having, moreover, 

 foliage which does not yield good humus on decomposition, 

 oak is not under ordinary average circumstances naturally 

 suited for growth in pure high timber forest. It is not well 

 endowed with a capacity for retaining and conserving the 

 quality of the soil, which sometimes deteriorates so much 

 with long periods of rotation that, unless improved by under- 

 planting, it would hardly be possible to produce future crops 

 of oak until after some soil-improving species had first been 

 grown in order to recuperate the productive capacity of the 







