( 18 ) 
In addition to the operations described above for 
the conservation and improvement of soils, others 
which are connected with the trees and their yields, 
such as density of planting and thinning out, have 
to be considered. 
Density of On land which has not been completely 
Plantation. cleared of jungle timber and stumps, 
120 — 140 trees per ^,cre should be 
planted in order to allow for losses by root diseases. 
Where clean clearing has been adopted, and in the 
case of lalang land free from timber and stumps, 
the stand may be reduced to 100 per acre. It has 
recently been suggested that when budded stock is 
used, considerably wider planting may be adopted. 
This is, however, considered to be a distinctly risky 
proceeding in the present stage of ignorance of 
variation among such stock. 
Thinning Disease and accidents may be expected 
Out. to reduce the stand of trees on un- 
cleared land at the end of the fourth 
year to 100 per acre; following this will come the 
removal of obvious wasters (undersized bark-bound 
trees). This should give sufficient space for the 
next two years ; at the end of this period, a certain 
number of consistently poor yielders will have been 
identified and removed, the stand thus being reduced 
to about 85 trees per acre by the end of the 6th 
year. Thereafter — if not earlier — disease should be 
the chief factor in thinning out and every precaution 
should be taken lest healthy trees which happened 
to be of moderate development and yield are removed, 
while diseased trees of better temporary yield and 
appearance are left, to die later, when every loss is 
serious. The ideal would seem to be 50 trees per 
