BRITISH FOREST TREES 123 



to develop leading-shoots normally from about ten years of 

 age ; they attain the maximum average annual growth in 

 height on soils of the better class about the twenty-sixth to 

 thirtieth year, on average soils about the thirtieth to fortieth 

 year, and on the poorer classes of silver fir soil about the 

 fortieth year (vide tables on pages 36 to 38). 



Notwithstanding its latent energy in growth, seedlings of 

 silver fir run considerable danger from rank grasses, frost, 

 or drought, unless they are reared under the protective 

 shade of standards, and during the first two or three years 

 they are absolutely classifiable as shade-demanding like the 

 beech. When once the young crop has outgrown these three 

 dangers of the earliest period of growth, and has formed 

 thicket, it quickly develops into the pole-forest stage, and 

 continues to maintain a lively growth in height, although 

 not in general quite so energetic as in the case of the spruce. 

 It is only during the pole-forest stage of growth that silver 

 fir is much exposed to breakage from snow. 



The timber of silver fir trees grown in pure forests is not 

 so good in quality as when it has been produced in mixed 

 forests, a circumstance which offers an additional reason, if 

 one were at all necessary, for preference being given to the 

 formation of mixed rather than of pure forests. Where, 

 however, pure forests are desired, silver fir can yield more 

 satisfactory results when worked in numerous small patches 

 than when operations are strictly confined uniformly to one 

 large area during the period of reproduction and of utilisa- 

 tion of the mature crop. This method of treatment has 

 reached its highest development in the state forests of 

 Baden. The parent standards, showing wide differences in 

 age, are scattered over the whole area in groups whose 

 canopy is interrupted to a constantly varying degree, whilst 

 the younger crop is similarly scattered about in groups or 

 patches varying from ten to twenty up to fifty and sixty 



