DIAMETER GROWTH. 131 
DIAMETER GROWTH OF SOME MINNESOTA TREES. 
Cottonwood GAs asintt anced eer eeaeneneeas I inch in 1.4 years 
Norway SDPrices az ice deace iain cels weuneces I inch in 2.5 years 
Silver ‘Maple: .2axa4 sce ade veseds dees hess ol INCh im 2-7 veats 
White: Wolo we: shes eeran, sincie sees osha hie, be 1 inch in 2.8 years 
BASSWOOGL .cuseacaciy scadtnun nuh ease ernenated I inch in 4.5 years 
Supare Maples yavir cy sumeavactan ane auene ys 1 inch in 6.6 years 
Witte lity eats 4g os ste sce Rare eat eet 1 inch in 6.8 years 
Bure Oak si icanaa sce catsunns akon niece 1 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. 
