56 Studies in Forestry [CHAP. in. 



exposures and misty regions, as compared with warmer southern 

 aspects and localities where the crowns can revel in the undis- 

 turbed possession of genial sunlight and warmth. 



The relative powers of the various species of trees to bear 

 shade under any given conditions as to soil and situation are 

 of great, and indeed vital, importance in practical sylviculture. 

 For on these are mainly dependent the measures that may 

 seem prudent with regard to the selection of species of trees 

 for woodland crops, the extent to which admixture of species 

 may be advisable, the best method of treatment and tending 

 to be accorded to the woods, the most advantageous time for 

 harvesting the mature crops and reproducing them, &c. In fact, 

 without a due consideration of their individual characteristics 

 in this respect, it is impossible to accord rational scientific and 

 practical treatment to woodland crops. 



IV. Normal Shape and Development of the Stem 

 and Crown. 



The essential characteristic of a tree as compared with 

 a shrub is its habit of developing a bole or stem before be- 

 ginning to ramify and form a crown of foliage-bearing branches. 

 Some kinds of forest trees have a greater tendency to ramifi- 

 cation than others, as, for instance, the broad-leaved trees 

 generally in comparison with conifers ; but the individual 

 tendencies of each kind with regard to the length and straight- 

 ness of the bole are often to a very considerable extent de- 

 pendent on (i) the growing-space allotted to if, (2) the age of the 

 crop, (3) the nature and quality of the soil and situation. 



Douglas Fir, Spruces, Silver Firs, Larch, and Weymouth Pine, then 

 Scots Pine, sessile Oak, and Alder have naturally a strong tendency 

 towards the formation of a good bole or stem ; whilst Hornbeam, pedun- 

 culate Oak, and Willow are prone to branching growth. 



The other species of woodland trees occupy an intermediate 

 position between these two classes. But the natural tendency 



