200 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



quite useless to underplant a crop of the light-crowned species 

 unless the following conditions exist : — 



1. The species of which the crop consists must yield timber 

 of high commercial value, which increases with the girth of 

 the trees. 



2. The trees must be of good shape, so that they may, when 

 felling time arrives, cut up well. 



3. The trees must be sound, and they must be young enough 

 to be capable of further vigorous development under the treat- 

 ment applied. 



To underplant a crop which does not fulfil these conditions 

 is a mere waste of time and of money. It will not be benefited 

 to a remunerative extent, while the development of the crop 

 established beneath it will be impeded by it. Unpromising 

 crops, even of valuable species, which have no future, should 

 be removed as soon as other circumstances may permit, and 

 the ground should then be restocked. 



If a species be susceptible in youth to frost or drought, 

 shelter for it can be provided in other and better ways than 

 by planting it under the shade of a valuable over-crop, which 

 must stand over it, to its detriment, much longer than is 

 necessary for its protection. But a crop which does not fulfil 

 the above conditions may be used as a temporary shelter- 

 wood for tender species, the old trees being removed as soon 

 as the new crop no longer needs their shelter. 



