Periodical Literature 501 



a more solid, stronger wood is formed than in neighboring portions. 

 Metzger and Schwarz claim that tree trunks are built as, or 

 at least closely resemble, beams or columns of equal resistances. 



Such dynamic responses explain the greater taper of trees grown 

 in the open, and other form development, hence this knowledge is 

 of importance to the forester. The mathematical theory and law, 

 after Metzger, under which the tree trunk assumes its general 

 form is developed by the author. 



If we follow on the basis of this theory, the development of a 

 tree in the open, i. e., a tree with a crown which remains at equal 

 distance from the ground, the following relations will be found: 

 In the branchless portion the ring width will increase towards the 

 base; in the branched portion it will remain constant. In close 

 stand, on the contrary, the reverse will hold as far as the branchless 

 bole is concerned; the ring width decreases toward the base. By 

 freeing such a tree (if the crown is still alive) the area exposed to 

 wind pressiure is increased; an increased increment "due to light" 

 takes place which can be approximately calculated. The stem 

 becomes more tapering as corresponds to experience and theory. 

 In some cases, with the increase of ring width toward the base a 

 reduction in the upper portions of the stem takes place. 



Green pruning has the opposite effect; the crown is curtailed, 

 the wind pressure reduced; dimensions are changed, and often the 

 annual ring up to a certain height fails to form for some years. If 

 the annual height growth rate is known, the point up to which 

 this will occur can be approximately calculated. The stem thereby 

 becomes less tapering. Theory and experience also support the 

 rule that the form factor in close stand increases with age and 

 height in trees with equal opportunity, but predominant stems have 

 a more tapering form than the lower ones because they are more 

 subjected to wind pressure. 



In the branchless portion relations do not change if cross-sections 

 are compared which are equi-distant from the resultant of forces 

 working on the cross-section. 



If the crown approaches conical shape in trees in the open, annual 

 ring width increases from top to root collar ; in trees in close stand, 

 on the other hand, the ring width experiences a maximum at the 

 point where the crown starts. 



In trees with crowns of a shape narrower than a cone, theoreti- 

 cally, if grown in the open the ring width at the base of the crown 



