WHEN TO MAKE THE FIRST OHDINARY THINNING. 477 



soil suflSciently protected, producing the required length and 

 shape of bole, and enabling the trees to afford each other all the 

 mutual shelter and support they may be in need of. The previous 

 condition of the crop being known, the severity of a thinning 

 made in it may with accuracy be gauged by the number of stems 

 taken out and left standing. 



III. When to make the first thinning. 



So much has already been said regarding the rapidly increasing 

 growing room required by the trees composing a complete forest 

 crop, that no further evidence is necessary to prove that, in order 

 to keep up unchecked the continuous development of the trees, 

 thinnings should be undertaken as soon as the keen stage of the 

 struggle for existence has set in. In favourable soils and localities 

 the overtopping and dominant trees differentiate themselves from 

 the rest of the crop at an early age ; the moment this occurs, a 

 thinning becomes both desirable and necessary. On poor soil., al- 

 though, owing to the slow growth there, the stronger elements of the 

 crop declare themselves only after a protracted struggle, neverthe- 

 less the time for making the first thinning does not arrive the less 

 early, and the urgency of the operation is so much the greater in 

 order not only to help the struggling stems to secure an early 

 victory, but even to save them from being unnecessarily weakened 

 and perhaps permanently crippled. Thinnings must commence 

 early in all crowded crops, particularly if they have sprung up 

 from seed spontaneously or as the result of direct sowing, and if, 

 in addition, the soil is poor. In the case of crops consisting of 

 stems of more or less the same height and vigour, it would be a 

 fatal error to delay thinnings until the stems of the future have 

 declared themselves ; while waiting for such an event to occur, 

 instead of a number of individuals, sufficient to form a complete 

 crop, shooting away above the rest, in the majority of instances 

 hardly any of the trees will ever show any marked superiority 

 over their neighbours and the whole crop will be found to have 

 become crippled in its growth. So that here again early thin- 

 nings must be the rule, the stems to be preserved being chosen 

 not necessai'ily because they possess the highest vigour, but on 

 account of the regularity of their distribution. Early thinnings 

 are also required in the interests of shade-avoiding species, and in 

 places exposed to dangerous winds, where the trees have to be 

 specially encouraged to strengthen themselves as quickly as 

 possible. 



