12 CIRCULAR 791, U. S. DEPARTMENT OF AGRICULTURE 



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F-290076 



Figure 9. — Nearly pure stand of 65-year-old black spruce growing on upland in 

 northeastern Minnesota. This stand contained 25 cords per acre in trees over 

 5.5 inches d. b. h. 



TRENDS IN FOREST SUCCESSION 



Considerable information has been gained concerning the possibil- 

 ities of black spruce for forest management by studying its develop- 

 ment under natural conditions and its responses to destructive agents, 

 such as fire and logging. Some factors aid its perpetuation and others 

 definitely retard it. 



