20 



BULLETIN 285, U. S. DEPARTMENT OF AGRICULTURE. 



Table 9. — Growth in volume {cubic) of northern hardwoods and hemlock in the Lake 



States. 1 





Average growth. 



Maximum growth. 



Minimum growth. 



Age. 



ft 



a 



GO 



o 



pq 



M 



o 



M 

 o 

 o 



8 



a 



H 



o 

 o 



1 

 pq 



a 



m 



§ 



o 



| 



M 



o 

 o 



o 

 1 



m 



pq 



1 



a 



02 



o 



pq 



p 



IS 



o 



o 

 o 



a 



© 



o 



1 



pq 



Years. 

 20 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cu.ft. 



Cw./if. 



30 





















2.1 

 6.4 

 13.0 



22.0 

 .33.0 

 46.0 

 59.0 

 73.0 



87.0 

 101.0 

 115.0 

 130.0 

 145.0 



161.0 

 177.0 

 193.0 

 210.0 

 228.0 



247.0 

 267.0 



335.0 













40 











1.5 



4.8 



9.2 

 15.5 

 23.0 

 32.0 

 41.0 



51.0 

 61.0 

 72.0 

 82.0 

 93.0 



104.0 

 115.0 

 126.0 

 138.0 

 151.0 



165.0 

 178.0 







2.4 

 5.0 



8.1 

 12.1 

 17.2 

 24.0 

 31.0 



40.0 

 49.0 

 60.0 

 71.0 

 82.0 



93.0 

 106.0 

 119.0 

 133.0 

 147.0 



161.0 

 176.0 



205. 



2.2 

 6.6 



12.4 

 20.0 

 29.0 

 39.0 

 50.0 



64.0 

 78.0 

 94.0 

 112.0 

 131.0 



152.0 

 174.0 













50 











2.5 



5.6 



9.5 



14.7 



21.0 



29.0 



37.0 

 47.0 

 58.0 

 69.0 

 81.0 



93.0 

 107.0 

 121.0 

 136.0 

 151.0 



168.0 

 184.0 



1.8 



3.6 



5.9 



8.7 



12.1 



16.5 



21.0 

 27.0 

 34.0 

 40.0 



47.0 



55.0 

 62.0 

 71.0 

 79.0 

 89.0 



98.0 

 109.0 











0.8 

 2 2 



60 





1.0 

 2.2 

 3.7 

 5.5 



7.8 



10.5 

 13.8 

 17.6 

 22.0 

 27.0 



32.0 

 38.0 

 44.0 

 50.0 

 56.0 



63.0 

 71.0 



1.0 

 2.4 

 4.3 

 6.8 

 10.0 



13.8 

 18.3 

 24.0 

 30.0 

 37.0 



44.0 

 53.0 

 61.0 

 70.0 

 79.0 



88.0 

 98.0 



"i'.h' 



3.6 

 5.9 



9.2 

 12.5 

 17.1 

 22.0 



28.0 



34.0 

 40.0 

 47.0 

 54.0 

 61.0 











70 



80 



1.5 

 3.0 

 5.0 

 7.3 



10.3 

 14.0 

 18.3 

 23.0 

 29.0 



35.0 

 42.0 

 49.0 

 57.0 

 66.0 



75.0 

 84.0 

 94.0 

 104.0 

 115.0 











4.5 



7 5 



90 



" i.T 



2.3 

 3.6 



5.1 



7.0 



9.0 



11.3 



14.1 



17.3 

 21.0 



35.0 



1.1 



2.4 



3.8 

 5.3 

 7.0 

 9.0 

 11.5 



14.3 

 18.6 

 21.0 

 25.0 

 30.0 



36.0 

 42.0 



61.0 







11 4 



100 



110 



120 



130 



140 



150 



160 



170 



180 ..... 



190 



200-.. . 



210 



220 



230 



240 



250 



1.5 

 3.0 

 4.8 

 6.8 

 9.3 



12.3 

 16.0 

 20.0 

 25.0 

 30.0 



35.0 

 40.0 



52.0 

 58.0 



"i'.b' 



1.8 

 2.6 

 3.4 

 4.6 

 5.9 



16.3 



22.0 

 28.0 

 35.0 

 42.0 

 49.0 



57.0 

 65.0 

 73.0 

 81.0 

 90.0 



99.0 

 109.0 



130.0 

 141.0 



i Based on same data as Table 7. 



SECOND GROWTH. 



Before lumbering began young growth of the intensive species was 

 practically confined to individuals and groups of various ages within 

 the virgin forest. Fires, windfall, and other accidents to the stand 

 undoubtedly resulted in some even-aged reproduction over small 

 areas, but only a small amount as compared with the reproduction 

 of the extensive species. In 1825, for example, fires denuded an area 

 in New Brunswick and northern Maine estimated at more than 

 5,000,000 acres, over the greater part of which aspen and paper- 

 birch thickets sprang up. In the shade of these the more intensive 

 species came in irregularly, producing relatively uneven-aged stands. 



As a result of widespread logging operations and the fires which 

 have followed them, even-aged second-growth stands of the intensive 

 species have become fairly numerous, especially in the rough eastern 

 part of the northern hardwood region, where more of the land has 

 been allowed to revert to forest. It is common for these stands to 

 be of mixed species, one or two of which predominate over the others 

 in number and size. Over small areas a single species may grow in 

 almost pure stands. Yellow birch is the most frequent example 



