CHAP, vii.] Treatment of Mixed Woods 147 



B. Concerning Mixed Crops of Shade-bearing and 

 Light-demanding Species. 



Common Spruce as ruling Species or Matrix. 



During the youthful period of development all light-demand- 

 ing kinds of trees are of quicker growth than the Spruce, 

 and damage the latter by injuring the tender leading-shoots 

 when it begins to catch them up in growth. Later on, most 

 of the light-demanding species are overtaken by the Spruce ; 

 and unless it is intended to utilize them by removal during 

 the periodical thinnings, the former require special tending 

 and protection against the latter. 



Spruce with Oak, Ash, Maple, Sycamore, or Elm as sub- 

 ordinate Species. All these species are overtaken in growth 

 by Spruce between the fifteenth to twenty-fifth year as a rule, 

 although on very good soils they retain their advantage some- 

 what longer, especially when they also predominate numerically. 

 For the most part, however, these valuable species should be 

 grown in admixture with the Beech. Even when Oak has an 

 advantage in growth up to about twenty years, it is still usually 

 liable to be caught up when the Spruce gets to about fifty years 

 of age ; and then it is either suppressed, or else hindered in 

 afterwards attaining its normal girth as mature timber. Expe- 

 rience shows that a mixture of Oak with Spruce should only 

 take place when once the former has advanced considerably 

 towards maturity. This can best be effected by cultivating 

 the Oak in pure forest first of all, and then, about the sixtieth 

 to seventieth year, making a strong thinning or partial clear- 

 ance, with simultaneous sowing or planting of the Spruce. 

 The whole crop is then harvested as one mature crop about 

 eighty to a hundred years later on. 



Spruce and Birch. Of all the subordinate species of trees 

 which are at first of quicker growth than the Spruce, the Birch 

 does most damage, owing to the extent to which the whip-like 

 twigs scour and injure the leading-shoots. Thus, although 



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