CHAPTER X 



METHODS OF STIMULATING THE INCREMENT IN 

 TIMBER-CROPS WHEN APPROACHING MATURITY 



IT is a well-known fact that, when trees growing in close 

 canopy are thinned out, or when in the case of old crops 

 approaching maturity a partial clearance is made, the annual 

 increment on each individual stem naturally rises in con- 

 sequence of the decrease in the number of stems drawing 

 food-supplies and moisture from the soil, and engaging in the 

 unavoidable struggle for light and air. 



In the system of selecting only the largest trees for ex- 

 traction, in standards over coppice, and in standard trees 

 retained in high forest for a second period of rotation, such 

 increment in growth is certainly attained. In the following 

 cases, however, the question to be considered is mainly con- 

 nected with heavy thinnings, or a partial clearance made shortly 

 before a crop falls to the axe, in order to stimulate the remain- 

 ing trees to more energetic growth in girth before the date at 

 which the fall should take place according to the Working-Plan. 

 It is, in fact, but the continuation of the thinnings that have 

 been made as measures of tending throughout the whole life- 

 time of the crop, only it is carried out more freely on account 

 of this being the last thinning that is to be made before the 

 trees attain their full maturity. If less than one-fifth of the 

 total amount of timber on the area be removed the operation 

 may still be considered as a heavy thinning, whilst if one-fifth 



