162 y. y. Kotze 



stomach of a tree lie in its crown, hence it must be seen to that 

 the crowns of those individuals intended for the main crop are 

 properly developed and not allowed to deteriorate. Every species 

 has its own individuality of habit which must be taken into account 

 when thinning. Furthermore its habit varies according to 

 situation and age and whether it is growing pure or in mixture with 



other kinds An error of judgment in the conducting of 



thinnings may not be eradicated throughout the rotation of a crop.'* 



Further on in his Bulletin, again discussing thinning, he says: 

 *' It has been pointed out that after establishing 'forest conditions', 

 the next consideration is to maintain a * normal stand * throughout 

 the rotation of the crop by means of periodic thiimings. Also that 

 the degree and frequency of these thinnings must be regulated 

 according to the species, situation, variation of seasons, and the 

 class of material it is desired to produce. The first thinning is 

 usually called a cleaning when the material removed is too 

 small or inferior to yield a monetary return. As a rule the cost 

 of cleaning is very small. In the vicinity of markets the sale of 

 material from subsequent thinnings should more than cover the 

 cost of the operation to an ever increasing extent, thus bringing 

 in a gradually growing interest on the capital outlay before the 

 final crop is felled. 



It is safer to thin lightly and frequently than too heavily at one 

 time, but undue delay may result in serious loss of growth and 

 injury to the final crop ". 



A word or two may be added. In the case of plantations of 

 conifers all that is required for a good many years is the removal 

 of dead, suppressed, badly shaped or sickly trees. With Euca- 

 lypts, however, thinning at a comparatively early stage (after 

 say 5 years) is often necessary as their rate of growth is in early 

 youth so very much more rapid. 



If the struggle for existence be not interfered with it will con- 

 tinue until height growth lasts. The trees become so drawn up 

 and lanky that they are unable to stand upright if deprived of 

 tiie support of their neighbours and are liable to whip and be 

 laid low by wind. Moreover, all their vitality has gone into height 



