200 ELEMENTS OF SYLVICULTURE . 



trees whose timber is inferior, or at the most 

 equal, to that produced at home? Experiments in 

 naturalisation must be restricted to ornamental 

 trees, and entirely excluded from forests grown with 

 a view to production. 



Hence when it is necessary to have recourse to 

 artificial methods in order to refill blanks or restore 

 a species which has disappeared, or increase its 

 proportion in. the existing mixture, the forester must 

 confine himself to species spontaneous in the locality. 

 The same holds good in planting up large treeless 

 areas. In either case he must imitate what takes 

 place in nature. In the same district several species 

 of trees may be found, but they will not all demand 

 the same conditions of vegetation, nor will they all 

 possess the same constitution. A species which 

 to-day covers a wide area, has perhaps made its 

 appearance after, and in consequence of the pro- 

 tection of, hardier species, which have at the same 

 time improved the soil by their detritus. Here is a 

 lesson to learn from nature ; it is often absolutely 

 necessary to have recourse to plantations of the 

 Scotch or the Austrian pine* as nurses, in the very 

 home of the silver fir. In this manner the intro- 

 duction of this last tree becomes easier and surer. 

 It is advisable to operate thus even in creating a 

 new forest in the plains. If the oak requires but little 

 nursing, the trees, with which it ought to be asso- 

 ciated, cannot do without it. In this case, the 

 birch, the Scotch pine, and the cluster pine would 



* The Austrian pine in calcareous, anl the Scotch pine in sandy 

 soils. 



