18 THE STRUGGLE FOE EXISTENCE. 



v ; _'->roi7s, and. therefore, more promising individuals ; and so on. 



However great the care or skill exercised in felling, conversion 

 mid export operations, a certain amount of damage to the standing 

 plants cannot be avoided. The smaller and weaker individuals will 

 of course, on the whole, suffer most, but the fall of a heavy tree is 

 more likely to break and throw back for ever the larger or more 

 vigorous plants possessing a rigid, more or less unyielding stem 

 than the weaker and therefore more flexible individuals. 



(g) Climbers. Climbers kill or at least unfit trees for the strug- 

 gle for existence in six different ways 



(i) Thev may strangle the stems of their supports, narrowing 

 year after year the channel through which alone the sap, 

 taken up from the soil, can ascend. If the tree attacked 

 forms a heartwood, it must ultimately die of sheer starva- 

 tion, 



(ii) As the climber and its victim grow in diameter 3 the increas- 

 ing pressure on the bafk of the latter necessarily forces the 

 elaborated sap to descend obliquely and spirally instead of 

 vertically, and thus gradually diminishes the amount of nou.r 

 ishment conveyed to the under portion of the tree. The roo.fa 

 thereby suffer most, and their consequent debilitation and 

 contraction obviously reacts with increasing effect on the 

 crown above. 

 (Hi) Climbers also bend down by their sheer weight the stems 



and branches of their victims. 



(iv) When they get up into the crowns of their supports, tbey 

 invade and overspread those crowns, which cannot, therefore, 

 bear their full quantum of foliage, and are also {hereby im- 

 peded both in their lateral and upward development, espe- 

 cially in the latter. 

 ( v ) They distort the boles of thc-ir supports, and thus necessi- 



tato the removal of these latter by the forester, 

 (vi) When the same climber attacks two trees, the fall of one of 

 these might bring down the other or at least severely strain 

 ir. 



These various injuries will of course be greater in proportion to 

 I ho weakiK's* and low stature of the individual attacked and the size 

 :<nd weight of the climber. 



~ 



IV '. COMPLETENESS OF THE LEAF-CANOPY. It is obvious that 

 those individuals, whatever their age and size maybe, which have 

 tree space around and over them, will have every chance of growing 

 on aii'l Mirviving, while others, taller and stronger than they, but 



