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6.S. SMg^^^lCE 

 JUL 2 3 1864 

 CbRRENT S£kiAl KEUORDS 



RESEARCH NOTE LS-43 



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LAKE STATES FOREST EXPERIMENT. STATION • U.S. DEPARTMENT OF AGRICULTURE 



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P l6^r Minnesota's Timber Volume^rX. 



Minnesota's timber volume increased nearly 34 

 million cords between 1953 and 1962 to over 124 

 million cords (table 1). A wave of young trees in 

 northern Minnesota reaching merchantable size 

 in stands previously classed as "restocking" ac- 

 counts for much of the 37-percent increase in 

 timber volume. Included in the growing stock are 

 15.5 billion board feet of sawtimber (table 2). 

 This volume, expanded from 12.5 billion board feet 

 in 1953, reflects both an improved growing stock 

 and a maturing of Minnesota's second-growth for- 

 ests. Average growing stock volume per acre in- 

 creased from 5.0 to 7.3 cords; average sawtimber 

 volume per acre changed from 693 to 910 board 

 feet. 



The three northeastern survey units contain 

 almost 90 percent of the State's growing stock 

 and nearly 80 percent of its sawtimber volume. 

 In 1953 these figures were 78 percent and 67 

 percent, respectively. Southern Minnesota has had 

 a decrease in volume. Part of the loss is due to 

 timber harvest and land clearing, although differ- 

 ences in definitions between surveys account for 

 some of the loss. Definition differences had little 

 effect in the north. 



Conifers comprised 37 percent of the growing 

 stock volume and 42 percent of the sawtimber vol- 

 ume in 1962. Over nine-tenths of the conifer vol- 

 ume is in northeastern Minnesota. 



Aspen, jack pine, and paper birch, in that or- 

 der, are the most prominent species; they include 

 47 percent of Minnesota's growing stock volume. 

 Since all three are short-lived, greater harvests 

 seem warranted. Paper birch has moved from the 

 sixth most plentiful species in 1953 to the third 

 in 1962, just ahead of black spruce and balsam 



APRIL 1964 



fir. Paper birch growing stock volume has almost 

 tripled in St. Louis County and has nearly doubled 

 in Lake and Itasca Counties. 



Aspen maintains its lead in sawtimber volume. 

 Red pine, almost doubling in volume, has moved 

 ahead of jack pine as the second-ranked sawtim- 

 ber species. About 45 percent of the increase in 

 red pine sawtimber volume is in Itasca County. 



Both growing stock and sawtimber volumes 

 have accumulated rapidly since 1953 (table 3), 

 especially in the Central Pine Unit where the 

 increase exceeds 60 percent in, most counties. The 

 increase was large but less uniform in other north- 

 ern units. Volumes were reduced as much as 20 

 to 40 percent in most of the southern and western 

 counties except along the forested edge of the Red 

 River Valley. Much of this apparent reduction is 

 attributed to more rigid specifications for saw- 

 timber trees. Some poor-quality large trees classed 

 as growing stock in 1953 are now classed as culls. 



These statistics are based on results from the 

 cooperative Forest Survey conducted during 1960- 

 63 by the Lake States Forest Experiment Station, 

 the Iron Range Resources and Rehabilitation Com- 

 mission, and several other cooperators. This is the 

 second of a number of reports being prepared to 

 make forest resource statistics available to the pub- 

 lic. The first was Research Note LS-25, "Forest 

 Area Trends in Minnesota Counties," July 1963. 



Sampling error ( at one standard deviation ) is 

 estimated to be ±0.6 percent for the growing stock 

 volume in the State. This approximates ±7 per- 

 cent error per million cords or ±22 percent error 

 per 100,000 cords. The percent error figure doubles 

 as the volume is divided by 4. Sampling error is 

 somewhat lower than this in the north, where 

 sampling was more intensive than in the south. 



PAUL S. DeBALD, 

 Research Forester 



ROBERT N. STONE, 

 Research Forester 



MAINTAINED AT ST. PAUL.4, MINNESOTA, IN COOPERATION WITH THE UNIVERSITY OF MINNESOTA 



