PURE CHOP OF MIXED AGES. 27 



in nearly every case on the side of the larger individual. This state- 

 ment requires no explanation as regards the effect produced by the 

 mere violence of the rushing flood-waters and the covering of silt 

 brought in by them. As regards the injury which plants may 

 sustain from submersion, it is evident that the younger and, there- 

 fore, the smaller from among them will be completely submerged 

 during the most ordinary floods, and that the extent of damage will 

 increase in geometrical ratio with the length of time the floods last. 

 Thus is accounted for, to a very great extent, the small proportion 

 of young individuals, even of species inhabiting only flooded lands, 

 in tracts subject to frequent inundations. As regards the excess 

 of moisture in the soil accompanying a flood, it is evident that the 

 younger individuals, if the species is a denizen of marshy land, will 

 suffer more than their older neighbours, from being unable to trans-* 

 pire as rapidly, and also from having their root-system comprised 

 within the upper layers of the soil, /. e. the layers most affected by 

 the flood-waters. This latter reason also explains why the larger 



A */ O 



trees resist the effects of saline deposits longest. 



(f) Action of man. : Here also little can be added to the re- 

 marks made under this head in the First Case. It is durino- the 



O 



period preceding the sapling stage that plants possess their maxi- 

 mum power of recovering from injuries caused by felling, conver- 

 sion and export operations, because it is during this time that they 

 are most flexible and elastic, and shoot up in the most vigorous man- 

 ner from below any point at which they may be broken or badly 

 damaged. After this period they rapidly lose their flexibility, and, 

 but in a less degree, also their elasticity, and, if they get broken, 

 they have a tendency to develop a tuft or brush of shoots instead 

 of at once throwing out a strong leader. Moreover, the larger the 

 size of the injured tree is, the larger will be the wound and the quick- 

 er will be the progress, and the more weakening the nature, of 

 the consequent decomposition, 



(g) Climbers. The action of climbers has been pretty fully 

 explained in the First Case. In the present Case attention need be 

 drawn only to one additional point. As a rule, climbers can get 

 up much more easily into young trees owing to their thin stems and 

 low branches than into the lofty crowns of their older thick-boled 

 well-grown neighbours, and once a young tree has been invaded, it is 

 hopelessly doomed, not only as a potential piece of timber, but also 

 as one of the strugglers in the race for life. Nevertheless, if a climber 

 can, by means of neighbouring small individuals, get up into the 

 crown of a large overtopping tree, it will maintain all or nearly all 



