288 TENDING OF CROWDED WOODS AFTER EARLY YOUTH. 



provided tlie living tissue of the tree is not injured durinp; the 

 operation. 



According to R. Hartig pruning green branches while the 

 tree is in sap causes a somewhat rapid decomposition of the 

 wood near the wound. For this reason also pruning in tlie 

 first lialf of winter is recommended. 



Section III. — Thinning. 

 1. General. 



One of the most important objects in the formation of a 

 wood is to stock the area sufficiently, so that a complete cover 

 overhead may be established as early as possible. This is 

 desirable, not only for the preservation of the soil, but also for 

 a i)roper development of the trees. In order t) ensure quick 

 closing overhead it is necessary to bring on to the ground a 

 much larger number of plants than can find room on it for 

 any prolonged period. Soon after a complete leaf canopy has 

 been "established, the trees commence pressing one against the 

 other, there is not enough growing space for all, and then a 

 stri(;/(ile for existe)ice sets in. A portion of the trees outgrow 

 the rest, and they rear their heads up to the full enjoyment 

 of the light. Between and below them are the rest of the 

 trees ; some of these still enjoy with their leading shoots light 

 from above, though they are already dominated trees ; others 

 have been already left behind to such an extent that they are 

 actually dei)rived of the direct enjoyment of light, in other words 

 they are suppressed ; they live on for a shorter or longer period 

 according to species and other circumstances, and then die. 



Thus there are four classes of trees, namely : — 



(1.) Dominating trees. 



(2.) Dominated trees. 



(3.) Suppressed trees. 



(4.) Dead and dying trees. 



This struggle, if not interfered with, continues whilst height 

 growth lasts, and it gradually reduces the growing space of 

 each dominating tree to such an extent, that the hitter cannot 



