61 



ICE STORMS AND TREES 



Walter E. Rogers 



Several papers, particularly those of Harshberger^ and Illick^, 

 have given accounts of ice storms and some of their effects on 

 trees. Both of the studies cited were conducted in Pennsylvania 

 and apparently little data on this subject has heretofore been 

 collected outside the Atlantic coastal territory. It is thought 

 that data from a different climatic district will be of some interest. 



Opportunity for study of ice storms in their relation to trees 

 in the Middle West was afforded by the visit in 1922 of two of 

 these storms to central Wisconsin. The first occurred late in 

 February and was heavily destructive; the second came late in 

 March, was much less severe and was easily withstood by the 

 trees. 



The first storm began on February 21, with a light rain 

 falling and with the thermometer registering slightly below 

 freezing. The rain froze immediately wherever it fell. By the 

 following morning ice had accumulated in considerable quantities 

 on all trees. Twigs of Acer saccharum examined at the time 

 showed marked increases in diameter and weight. Meteorolog- 

 ical conditions remained practically constant for many hours 

 more. Following the storm a period of cold weather made it 

 possible to study the accumulations of ice on various plants. 



Increase in Twig Size 



Most of the measurements of twigs were made in the field. 

 Readings were made directly from a millimeter scale which 

 was held against the stems. The great majority of stems had 

 accumulated thicker ice layers on the windward side and measure- 

 ments of the greater and lesser diameters were necessary. These 

 were made, in each case, at the same point on the twig. The 

 results appear in the following table. 



' Harshberger, John W. : The Relation of Ice Storms to Trees. Contrib. 

 Bot. Lab. Univ. of Penna., II: 345-349, 1904. 



^ Illick, J. S.: A Destructive Snow and Ice Storm. Forest Leaves, XV, 

 103-107, Feb. 1916. 



