CHAP, v.] Sot! and Situation 109 



with regard to the effect of vertical elevation on the increment and the 

 shape of forest trees ' : 



A. For individual Trees. 



1. Growth in height diminishes regularly and noticeably. 



2. Growth in basal area, or sectional area of the stem at breast- 



height, does not diminish so rapidly as growth in height. 



3. Total increment diminishes gradually. 



4. The period of development is prolonged in all of the above three 



directions (i. e. the attainment of maturity is slower). 



5. The bole or stem deviates more and more from the shape of the 



cylinder and approximates towards that of the neiloid. 



6. The distribution of the increment over the various portions of 



the tree increases relatively from above downwards. 



7. The form-factor at breast-height (i. e. the proportion which the 



actual volume of the stem bears to a cylinder having the same 

 base) becomes smaller. 



8. The coronal development gradually comes lower down, nearer to 



the ground (i. e. the stems become short and stunted). 



9. The proportion of branches and brushwood increases (i.e. as the 



stems grow stunted, the coronal development increases rela- 

 tively). 



B. For whole Crops. 



1. The number of stems per acre increases, but the proportion of 



those which form the larger girth-classes diminishes. 



2. The mean average height of the crops diminishes. 



3. The total basal area at breast-height does not diminish so 



perceptibly as the average height of the crops, but it is made 

 up mostly by units belonging to the smaller classes of stems. 



4. The total quantity of wood available as timber or fuel decreases 



perceptibly ; hence the total average annual increment of the 

 mature crop becomes considerably less. 



5. The quantity of small branches and brushwood increases. 



6. There is a decided tendency towards growth of the trees in 



groups instead of being equally distributed over the whole 

 area. 



Near the polar regions, or at very high elevations, there is 

 no woodland growth. This may not be solely due to the actual 



1 S. Honda, Ueber den Einfluss der Hohenlage dcr Gebirge auf die 

 Veranderung des Zuwachses der Waldbdume, 1892, p. 27. 



