548 Forestry Quarterly 



species. Having previously discussed the general increment prob- 

 lems {see F. Q., XIII, p. 389), he takes up the pine (Scotch) first. 



In the introductory remarks the author points out that the 

 whole problem of production consists in finding the optimum 

 number of trees per acre or, what is the same, the most satis- 

 factory standing room per tree, which each individual for its 

 unimpeded development needs and can fully utilize ; then, if 

 this refers to all the volume producing factors, diameter, height 

 and form, in the single individual, the stand also will produce its 

 best. It follows that every species, broadleaf or conifer, toler- 

 ant or intolerant, must react by increased increment to every 

 measure which improves the growth conditions, such as decrease 

 of competition in crown or root area, securing a proper 

 density, etc. 



The influence of thinnings of diflferent degree has so far been 

 most realized with tolerant species, since their dense foliage natu- 

 rally reacts to an interruption of the crown cover and increased 

 light supply more than the thinly foliaged intolerant species; 

 also, since the tolerant carry larger number per acre, root com- 

 petition is more fully reduced by removal of individual consumers. 



Another characteristic of influence in this regard is what the 

 author calls the Ausladevermogen of the species, the ability to 

 invite out, that is, to subdue and crowd out undesirable neighbors 

 in the competition for standing room. This ability lies in the 

 structure of the crown, the disposition to spread or to grow mono- 

 podially. The greatest extreme in this respect shows beech and 

 spruce, the first with the greatest ability, the latter with the 

 least ability to get rid of neighbors. Hence, also, the beech is 

 best grown under natural regeneration, the spruce most fit for 

 planting. Due to this ability and its being a broadleaf, shade- 

 enduring species, beech responds to the optimum of density 

 by the most greatly increased increment. Nevertheless, the 

 newest investigations show that pine also responds in the same 

 way and eventually all species, as well as mixed stands, will be 

 shown to react if we only learn what is in each case the optimum 

 density. 



Schwappach's yield tables of pine, 1908, brought the following 

 surprises: negative results of three degrees of thinning in the 

 subdominant, and recommendation of a moderate thinning in the 



