82 PRUXIXG 



being impeded. The remedy adopted is to make longitudinal 

 incisions in the bark, without removing any tissues. This is 

 believed to relieve the bark pressure, being followed by a natural 

 increase in thickness of the affected stem. 



Ring-barking, or Ringing. These are terms applied to the 

 removal of a strip of bark, varying in breadth from a few inches to 

 as much as two feet, according to the size of the tree, from near 

 the base of trees which it is desired to kill by starvation. It is 

 commonly adopted in some countries for killing large or other 

 trees which would be costly to cut down. To be quite successful 

 it must be performed during the period of greatest cambial activity, 

 i.e., when the sap is up, as it is popularly called, the bark being 

 then most easily separated from the wood ; the excised bark must 

 be cut sufficiently deep to expose the cambium, that is, the bast 

 layer or inner bark must be removed, otherwise the operation will 

 be ineffectual. The chief effect of this is to cut off the downward 

 flow of sap and food material between the leaves and the roots. 

 Where the trees are required for their timber, the process of 

 killing by ring- barking is considered to improve the quality of the 

 latter. A form of ringing is sometimes adopted to hasten the 

 ripening of fruits, and, as a last resource, to render unfruitful trees 

 productive. The principle is also employed in different methods 

 of propagation, as a means of inducing the formation of a callus on 

 cuttings or layers. 



Pollarding or coppicing is a necessary process in the culti- 

 vation of certain tropical products, more particularly of Cinnamon 

 and Cinchona. In effect it is also applied to Tea, Coffee, Camphor, 

 etc., since it consists of cutting back the main stem and branches so 

 as to keep the trees dwarf, and induce productive young growth. 



