DIAMETER GROWTH. 131 



DIAMETER GROWTH OF SOME MINNESOTA TREES. 



Cottonwood . . . 

 Norway Spruce 

 Silver Maple . . 

 White Willow . 



Basswood 



Sugar Maple . . 

 White Elm .... 

 Bur Oak . 



inch in 1.4 years 

 inch in 2.5 years 

 inch in 2.7 years 

 inch in 2.8 years 

 inch in 4.5 years 

 inch in 6.6 years 

 inch in 6.8 years 

 inch in 8.5 years 



The height growth of Silver Maple and White Willow is 

 about two feet per year, Norway Spruce one foot per year. Bur 

 Oak averaging thirty feet in height makes an average growth of 

 about .55 feet per year, while the rate of height growth of the 

 first twenty feet of marketable cordwood is about one foot in 1.5 

 years. The height growth of Cottonwood varies from two to 

 eight feet per year. A fifteen-year-old Cottonwood will often 

 grow in height three feet per year. Black Spruce has shown a 

 diameter growth of one inch in 14.7 years, and a height growth 

 of one foot in 2.3 years. 



