18 



BULLETIN 139, IT. S. DEPARTMENT OF AGRICULTURE. 



Table 6. — Minimum, average, and maximum growth in diameter, Bayfield County, 



Wis., on basis of age. 



[Based on 139 stumps from 108 to 202 years old.] 





Diameter breast-high (inches). 





Diameter breast-high (inches). 



Age 

 (years). 





Age 

 (years). 



















Minimum. 



Average. 



Maximum. 





Minimum. 



Average. 



Maximum. 



10 



0.2 



0.6 



1.3 



110 



9.3 



17.9 



25.2 



20 



1.0 



2.8 



5.4 



120 



10.3 



18.9 



26.2 



30 



1.9 



5.7 



10.3 



130 



11.3 



19.8 



27.1 



40 



2.7. 



8.0 



13.8 



140 



12.4 



20.8 



28.0 



50 



3.7 



9.9 



16.6 



150 



13.5 



21.7 



28.7 



60 



4.6 



11.7 



18.8 



160 



14.6 



22.7 



29.5 



70 



0.0 



13.2 



20.5 



170 



15.7 



23.7 



30.3 



80 



6.5 



14.6 



21.9 



180 



16.9 



24.6 



30.9 



90 



7.4 



15.9 



23.1 



190 



18.0 



25.5 



31.7 



100 



8.3 



16.9 



24.2 



200 



19.2 . 



26.5 



32.4 



Table 7 shows the diameter growth of trees which are now occu- 

 pying a dominant position in the stand. Figures in the column 

 headed "Maximum" are for trees which have grown practically in 

 the open for their entire life. The column headed "Average" shows 

 trees which have been somewhat crowded, but which from the start 

 have dominated the remaining timber in height growth. The "mini- 

 mum" is for trees which have been suppressed by jack pine. The 

 growth in both diameter and height of such Norway pines is stunted. 

 In 80 years the trees have reached a diameter of but 4.3 inches, as 

 contrasted with 19.2 inches in the case of open-grown trees. At 

 this age jack pine dies out, and by 100 years has entirely disappeared 

 from these even-aged stands. The surviving Norway pines, freed 

 from competition and with plenty of crown space, develop good 

 crowns and take the position of intermediate or dominant trees. 

 Only their record of diameter growth remains to show the former 

 existence of the jack pine in mixture. Had these trees grown in 

 pure stands, they would have been killed in competition. 



Table 7. — Minimum, average, and maximum diameter growth of dominant trees on basis 

 of age, Cass and Itasca Counties, Minn. 



[Based on 739 stumps from 27 to 303 years old.] 



Age 

 (years). 



Diameter breast-high (inches). 



Age 



(years). 



Diameter breast-high (inches). 



Minimum. 



Average. 



Maximum. 



Minimum. 



Average. 



Maximum. 



10 



20 

 30 

 40 

 50 

 60 

 70 

 80 

 90 

 100 





0.8 

 2.8 

 4.9 

 6.6 

 8.2 

 9.6 

 10.9 

 12.0 

 13.0 

 13.9 



2.7 

 6.8 

 10.1 

 12.6 

 14.6 

 16.4 

 17.9 

 19.2 

 20.3 

 21.3 



110 

 120 

 130 

 140 

 150 

 160 

 170 

 180 

 190 

 200 



6.8 

 7.6 

 8.4 

 9.1 

 9.8 

 10.4 

 10.9 

 11.3 

 11.8 

 12.1 



14.7 

 15.5 

 16.1 

 16.7 

 17.3 

 17.8 

 18.4 

 18.9 

 19.5 

 20.0 



22.1 

 22.8 

 23.5 

 24.1 

 24.7 

 25.2 

 25.7 

 26.3 

 26.7 

 27.2 



0.4 

 .8 

 1.3 

 2.0 

 2.7 

 3.5 

 4.3 

 5.2 

 6.0 



