54 CIRCULAR 791, U. S. DEPARTMENT OF AGRICULTURE 



160 years on poor sites. As a result of the exceedingly large numbers 

 of trees in fully stocked stands, pnlpwoocl production is fairly good 

 despite the slow growth of the individual trees. Fully stocked stands 

 on average sites grow at the rate of about one-fourth cord per acre per 

 year. Upland trees become infected with butt rot and succumb to 

 breakage or uprooting at around 80 to 90 years. 



It is recommended that thrifty swamp stands be given a series of 

 periodic light partial cuttings leading to the creation of all-aged 

 forests adapted to the selection system. The initial cut should pref- 

 erably remove not over one-third of the merchantable volume. Such 

 cuts should eventually result in increasing the growth by one-third 

 to one-half. Winclthrow has been found to be less of a risk than 

 formerly supposed. 



Badly decadent overmature swamp stands must be clear cut. Al- 

 though reproduction usually is reasonably adequate, it can be im- 

 proved by slash-disposal measures such as piling that cause exposure 

 of more of the soil surface. Prevention of logging damage to advance 

 reproduction also helps to maintain satisfactory stocking. 



Nearly pure types on uplands and the fringes of swamp borders 

 should be clear cut when they become mature or show signs of opening 

 up due to wind damage. Keproduction on uplands is likely to include 

 such species as quaking aspen, paper birch, jack pine, and balsam fir. 

 although black spruce will continue as a more or less important ele- 

 ment that can be encouraged by release cuttings or in connection with 

 commercial thinnings. 



LITERATURE CITED 



(1) Amidon, G. B., and LeBarron, R. K. 



1944. TO WHAT TOP DIAMETER CAN SPRUCE PULP WOOD BE CUT PROFITABLY? 



Pulp and Paper Mag., Canada. September 1944. 



(2) Averell, J. L., and McGrew, P. C. 



1929. the reaction of savamp 'forests to DRAINAGE IN NORTHERN MINNE- 

 SOTA. Minn. State Dept. Drain, and Waters, 66 pp., illus. 



(3) Bellefeuille, R. 



1935. LA REPRODUCTION DES PEUPLEMEXTS D'EPENNETTE NOIRE DANS LES 



forets du norde-quebec. Forestry Chron. 11 : 323-340, illus. 



(4) Bowman, A. B. 



1944. GROWTH AND OCCURRENCE OF SPRUCE AND FIR ON PULPWOOD LANDS IN 



northern Michigan. Mich. Agr. Expt. Sta. Tech. Bul. 188, 82 pp., 

 illus. 



(5) Brown, A. W. A. 



1941. foliage insects of spruce in Canada. Canada Dept. Agr. Tech Bul. 



31, 29 pp., illus. 



(6) Brown, R. M. and Gevorkiantz, S. R. 



1934. VOLUME. YIELD, AND STAND TABLES FOR TREE SPECIES IN THE LAKE 



states." Minn. Agr. Expt. Sta. Tech. Bul. 39, 208 pp., illus. 

 (Revised.) 



(7) Cheyney, E. G. 



1942. American silvics and silviculture. The University of Minnesota 



Press, 472 pp., illus. 



(8) Cooper, W. S. 



1911. reproduction by layering among conifers. Bot. Gaz. 52 : 369-379, 

 illus. 



(9) ■ 



1913. THE CLIMAX FOREST OF ISLE ROYALE, LAKE SUPERIOR, AND ITS DEVEL- 

 OPMENT. Bot. Gaz. 55; 1-45, 115-140, 189-235, illus. 

 (10) Day, M. W. 



1944. FOREST MANAGEMENT FOR THE EASTERN PART OF THE UPPER PENINSULA 



of Michigan. Mich. Agr. Expt. Sta., Cir. Bul. 190, 22 pp., illus. 



