PROFITABLE TIMBER TREES 85 



recently cleared of Scots fir or other conifers. Where this 

 occurs on a large scale, as in extensive fir woods where the 

 soil and herbage are adapted for natural regeneration, this 

 may sometimes be a disadvantage, as the birch effectually 

 prevents the growth of pine seedlings on the same area. 

 But in districts where birch poles can be easily disposed of, 

 and where moderate clearings of Scots fir are made, a self- 

 sown crop of birch which will cover the ground for twenty 

 or thirty years is not to be despised. It is often difficult 

 to replant Scots fir successfully for several years after the old 

 crop has been removed, owing to the attacks of weevils, 

 beetles, and other vermin, while the thick layer of peaty 

 debris, which invariably collects under Scots fir, is very 

 unsuitable material for planting young trees of any kind in. 

 A few years under birch or any other hardwood allows this 

 peaty layer to decay and an ordinary humus layer to take its 

 place, and renders the soil much more suitable for ordinary 

 planting than when first cleared of pine. 



The value of such crops can be greatly increased by 

 mixing them lightly with larch when the birch is about a 

 foot or so high. The former will grow into useful poles in 

 any case, and should the soil happen to be one suited to the 

 larch, a plantation of that tree may eventually result by 

 reversing the usual order of things and treating the hardwood 

 as a " nurse," which can be cut away from time to time as 

 necessary. By netting in the area so treated, or by using 

 larch plants able to take care of themselves where rabbits 

 are scarce, a crop of larch can thus be raised at one-third 

 the cost of ordinary planting, although it can only be con- 

 sidered a profitable proceeding where a thick crop of birch 

 and a ready sale for the poles exist. 



THE ALDER (Alnus glutinosa). 



The alder was at one time of considerable importance 

 in connection with the manufacture of gunpowder, and its 

 cultivation for that purpose was an important feature in 

 English forestry of the sixteenth and seventeenth centuries. 

 In early references to English woodlands, particularly in 



