FROST EFFECT ON FOREST TREES. 

 By W. K. Eberly. 



Although late spring frosts have been quite common in 

 eastern Nebraska for a number of years, only general notes 

 have appeared as to the effects on forest trees. In the future, 

 it is planned to keep a definite record of such injury, as detailed 

 information is needed from both practical and scientific stand- 

 points. It is thought that variable weather conditions following 

 frost damage may have a cumulative injurious effect in some 

 cases and a compensating effect in others. 



LATE SPRING FROST OF 1910. 



From April 23 to April 25, 1910, an area of high atmos- 

 pheric pressure and low temperature extended over the plains 

 region east of the Rocky Mountains from Dodge City, Kan- 

 sas to northern Minnesota. The pressure ranged from 30.1 

 to 30.2 inches. At Lincoln, Nebraska, the sky was clear and the 

 temperature fell to 15 degrees Fahrenheit on April 23, reaching 

 30 to 32 degrees on the following days. The wind came di- 

 rectly from the north and had an average velocity of 20 miles 

 per hour with a minimum of 11 miles. On May 3, ten days 

 later, another heavy frost occured which extended from Con- 

 cordia, Kansas, north through Nebraska, eastern Wyoming, 

 western Dakotas, Minnesota and east through Iowa. At Lin- 

 coln, the weather was again clear, with a northeast wind that 

 had an average velocity of only 7.2 miles per hour. The tem- 

 perature fell to the freezing point; the pressure and relative 

 humidity were high. 



The combination of these climatic factors resulted in se- 

 vere killing frosts. The damage was very great, all growth 

 was far advanced as a result of the season being six weeks 

 earlier than normal. Many forest trees occuring as individual 

 shade trees or in park-like formation were badly injured. The 

 trees which had leafed out earliest were the ones which usually 

 suffered the most. 



Only deciduous species were affected. Not a single injured 

 conifer was observed, probably on account of their greater 

 frost resistance. The injury was generally greatest on the north 

 side of affected trees. Recently transplanted trees and pollarded 

 trees suffered more than those grown in place or those which 

 had not been disturbed for some time. The character and 



