152 TENDING OF YOUNG HIGH FOREST, ETC. 



different species of trees must be considered ; light-demand- 

 ing trees must have relatively more growing space than 

 shade-bearing trees. If the shade-bearing trees catch up and 

 surpass the light-demanding trees, one class or other must 

 be removed. 



Care must always be taken to preserve the required 

 mixture. 



If other considerations admit of it, remove as thinnings 

 such trees as are valuable and saleable when small, and not 

 small trees of those species which are more or less valueless. 

 It should be noted that Ash, Spanish Chestnut, and Willow 

 are valuable even when small, and are much used for split 

 hurdles, etc. Small Larch are nearly always saleable, and 

 are always useful for estate purposes. But often it would be 

 most unwise to cut these out, as they will be required as 

 mature timber. 



Finally, it may be stated that the general principles to 

 be observed in ordinary thinning operations are, speaking 

 generally, that thinnings should be so conducted that in 

 the early part of a rotation the side branches are allowed to 

 interlace and cause the death of each other, thus leaving all 

 pruning to natural agencies and, at the same time, stimulating 

 height growth ; and that in the latter part of a rotation, 

 thinnings may be more severe, but, unless underplanting takes 

 place, never so severe as to result in the disappearance of 

 humus, and the conse<fnent loss of soil moisture, and the 

 growth of rank grass and weeds. For, apart from soil 

 deterioration, a great expenditure will be incurred in clean- 

 ing the land and keeping it clean, when the time arrives for 

 the establishment of a new crop. Whereas, under correct 

 management, it should be possible to produce a new crop at 

 a minimum of expense, using seedling or quite small trees, 

 which for a year or two should be able to grow without 

 interference by weeds or rank growth. 



It is recognised by the agricultural community that 

 farming land should be kept scrupulously clean : it is equally 

 important to observe the same principle in connection with 

 land used for the growth of timber. 



