GUIDINQ PRINCIPLES IN ORDINARY THINNINGS. 473 



III. DOMINATED TREES, i. e. those about to be overtopped. 

 These are generally trees that have recently been in Class II, but, 

 owing to weaker growth, have been left behind in the race. Their 

 crowns will be already found to be more or less contracted and in 

 some of them incipient decline will be noticed. 



IV. OVERTOPPED TREES. Crowns very appreciably contracted 

 either on every side, or on one side only. In some species the 

 boughs and other large branches will be found bearing an ab- 

 normal number of short twigs grouped together in thick bunches. 

 These trees may either (a) have the clear sky above them but be 

 closely hemmed in laterally, or (7>) have only a part of their crown 

 free, the rest being completely overshadowed. Not unfrequently 

 many dead branches will be noticeable. 



V. SUPPRESSED TREES. Such individuals, if belonging to con- 

 spicuously shade-enduring species, may still have perfectly green 

 crowns ; otherwise the crowns will be found to be quite dead or in 

 a dying condition. 



It is an essential rule in making thinnings that the soil shall not 

 be uncovered to such an extent as to expose it to deteriorates and 

 that the individual trees shall not be isolated to such an extent as 

 to render them liable to get bent or broken. Hence the severity 

 of a thinning will be different according to the different prevailing 

 conditions of growth in each case. For all practical purposes, 

 however, it is sufficient to distinguish three degrees of severity as 

 follows : 



1. LIGHT THINNINGS, in which only suppressed trees are taken 

 out. Such thinnings hardly help nature at all, but serve mainly 

 to utilise stems that have practically ceased to exercise any im- 

 peding action on the growth of the rest of the crop. 



2. MODERATE THINNINGS, in which, besides suppressed indivi- 

 duals, those of category (b) of overtopped trees and a great many 

 of category (a) are also removed. This will without doubt be the 

 class of thinnings most widely used in India. 



3. HEAVY THINNINGS, in which all suppressed and overtopped 

 trees must disappear, and also perhaps a few of those that are 

 about to be overtopped. 



Which of these three kinds of thinnings to make in any given 

 case will depend on 



(a) THE AGE OF THE CROP. It is evident that the younger a 

 crop is, the greater will be the number of stems that can be safely 

 taken out as well as require to be taken out. Schuberg's experi- 

 ments in the Baden portion of the Black Forest gave the following 



