194 OUR FORESTS AND WOODLANDS 



these dimensions, both as to height and girth. 

 If the production of timber is the main object, 

 and not beautification of the landscape, the trees 

 should be planted in a mass, and kept close 

 together to draw them up as straight poles. 

 When once their main height has been attained 

 they can be thinned out freely at frequent in- 

 tervals, so that their strong natural demand for 

 light and large growing-space may be duly met. 

 This checking of premature branch formation is 

 more particularly necessary in the case of the 

 white willow, which will otherwise soon spread 

 itself out laterally. The wood of willows being 

 soft and porous, the pruning of large branches 

 is always attended with more than ordinary risk 

 of fungous disease in the shape of rot occa- 

 sioned by kinds of Polyporus ; and this remark 

 also applies to the poplars. 



The wood of the poplars is put to very much 

 the same uses as that of willows, only it is not so 

 tough, and is therefore not endowed with such 

 good technical qualities as the latter. To make 

 up for this, however, the poplars are even more 

 rapid in growth. They yield good marketable 

 timber at about forty to fifty years of age. The 



