FORESTRY COMMISSIONER. 125 



largest possible sustained yield must be secured. With a suitable composition of 

 the growing stock and a careful application of sylvicultural principles, that object 

 may be obtained under an average rotation of 120 years. 



As regards tho sylvicultural treatment, and especially the regeneration of the 

 woods, two different classes of forest or growing stock (corresponding with two 

 qualities of locality) stand out prominently. 



First: Forest of spruce with a strong admixture of silver fir (the latter occa- 

 sionally predominating) more or less frequently interspersed with beech and more 

 rarely with Scotch pine. 



Secondly: Forest in which spruce prodominates with a slight admixture of sil- 

 ver fir and here and there of Scotch pine, but devoid of beech. 



The first class of forest occurs in the granite area and on those parts of the Bun- 

 ter Sandstein (clay sandstone), which have deep, easily decomposed soils fit to be 

 classed as good. The characteristic features of this class of forest are the occur- 

 rence of beech and deep soils, rarely covered with boulders or debris, lying mostly 

 at the lower elevations; natural regeneration can here be successfully effected in a 

 comparatively short period of time. 



The second class of forest occupies the stony slopes of the Bunter Sandstein 

 area, and in exceptional cases the quartzite parts of the granite area. Here the 

 soil is generally covered with loose boulders and rock debries of varying size. 

 These areas are nearly all found at the middle to upper elevations. The condi- 

 tions described demand the maintenance of an uninterrupted canopy up to the 

 age of maturity, and a careful execution of the regeneration cuttings spread over a 

 prolonged period of time, or else weeds will spring up, which make regeneration 

 very difficult, and at any rate expensive. 



On the whole, however, careful management is sure to be successful in securing 

 natural regeneration in all the areas pertaining to this group; for this purpose, as 

 well as for the production of valuable timber, a rotation of 120 years on an average 

 is considered of sufficient length. The length of the regeneration period differs 

 considerably in the different parts, varying on the whole from 30 to 50 years. 



b. The second group consists of woods growing on soils, which, even under 

 the most careful management, cannot be expected to produce trees of first or even 

 second quality. The trees here produced are of such limited height growth, that 

 the production of valuable timber is out of the question. The woods are found in 

 the upper, and here and there in the lower part of the Bunter Sandstein area, 

 where the soil is covered with large masses of the debris of gravelly sandstone, 

 which is not easily decomposed, and where the slightest interruption of the canopy 

 overhead is followed by the appearance of a dense growth of bilberry and heather. 



Nevertheless, these areas are capable of yielding timber of the inferior classes, 

 as well as firewood, and the returns which may reasonably be expected from them, 

 justify the application of a method of treatment which, while avoiding any inter- 

 ruption in the canopy and all expensive cultural operations, facilitates natural re- 

 generation; in other words the treatment under the selection system by removing 

 all trees which are deteriorating or incapable of increasing in value. It is difficult 

 to fix any definite rotation, but it is estimated that the trees will take about 150 

 years to reach maturity. 



The lowest quality limit for this group has been fixed at 7 cubic feet increment 

 per acre and year, while the upper limit is, as already indicated, 43 cubic feet. 

 The area comprised in this group amounts to 12 per cent of the total area. 



