97 



Pennsylvania storm, where Carya ranked first in resistance. 

 Ulmus, Betula and Fraxiniis which rank second, third and fourth 

 respectively in Illick's list do not appear among our first ten at all. 



Among the factors which make for resistance to ice storm 

 injury the following appear to be of considerable importance. 



I. Small surface exposure. Trees with few stout twigs fared 

 better, on the whole, than those with many fine twigs. The 

 first place held by Catalpa was due largely to this factor. 



Shagbark Hickory. Typical of conditions in farm woodlcts 



2. Shortness of limb. The longer the branch, the greater the 

 leverage which the weight of ice could bring to bear on the part. 

 A comparison of column 12 with columns 8 and 4 shows that 

 almost invariably small trees were damaged less than larger ones 

 of the same species. While other factors are involved here, 

 shortness of limb played a strong part. 



3. Horizontal branching. The accumulations of ice on the 

 horizontal branches of the spruce, etc., soon changed frcm a 

 bending load to a pulling load, and this was easily carried so long 

 as the weight was symmetrically distributed. The elms and 



