Crown Space of Western Yclloiv Pine. 335 



duction gaps caused by the death of old trees through one of 

 the above mentioned causes. In this respect, Yellow pine behaves 

 in a manner just the reverse of fruit trees which do not thrive 

 well where another tree, especially of the same species, has re- 

 cently stood. Old cut-over areas of Yellow pine frequently have 

 growing on them a fine stand of reproduction, while the sur- 

 rounding area which had never supported trees is still bare, al- 

 though the conditions for tree growth appear practically identical. 

 This has been noted frequently on small patches of timber cut 

 on the lower units of tree growth, where climatic conditions are 

 more or less severe. 



In times gone by the frequent fires killed out the patches of 

 reproduction about as soon as they occurred, but since the fires 

 have been in large measure stopped, reproduction has come in 

 very thickly in most Yellow pine forests, and its abundance points 

 to a heavier future stand than the existing stand. This abund- 

 ance is decidedly out of proportion to the comparatively small 

 number of old trees in most Yellow pine forests which make up 

 the present stand. 



Just how much the forest can be made to yield after the in- 

 juries resulting from fire, insects, and wind have been reduced 

 to a minimum, will depend on the number of dominant trees of 

 merchantable size which it will be possible to grow on an acre 

 without crowding. This number will depend on the amount of 

 space required by each tree, and for this purpose it was neces- 

 sary to find the actual average area occupied by the crowns of 

 Yellow pine of various diameters, and to add to this area the 

 proper allowance of space around the periphery of the crowns 

 which would admit the sufficient amount of side light. 



For this purpose the actual areas of the crowns of 113 Yel- 

 low pines of diameters ranging from 12 to 42 inches D. B. H. 

 were measured and the results of this study are shown in the 

 following table and curve. 



The crowns were measured by standing immediately under 

 the periphery in five or six dififerent places and measuring from 

 each place the distance in, to the center of the tree. These dis- 

 tances were then plotted on a conveniently large scale, the shape 

 of the crown drawn in, and the area determined by a planimeter. 

 These results were finally evened off on a curve. There appears 



