SHORTLEAF PINE : IMPORTANCE AND MANAGEMENT. 33 



precede or follow the age of greatest annual growth, depending upon 

 demand and market prices. 



Yield and growth tables show the relation between age, size of 

 trees, and total yields. They form the basis, therefore, for deciding 

 when to cut in order to obtain any desired quality and size of timber. 

 For example, on Quality II sites the maximum mean annual yield 

 per acre of saw timber in North Carolina for trees 6 inches and over 

 in diameter (scaled by the Scribner log rule) occurs at about 90 

 years (Table 15, note) , with an average yield of about 420 board feet 

 per year. Fully stocked stands in Arkansas for average Quality II 

 sites appear to reach a culmination of yield of 570 board feet pro- 

 duced annually at the age of about 100 years (Table 17, note). 

 Measurements of similar unthinned stands in Virginia x show the 

 culmination of annual yield in saw timber at about 57 years, and 

 those of a few pure stands in New Jersey indicate a maximum annual 

 yield there at 45 to 50 years. The age of culmination in annual 

 volume production is thus increasingly later as the region of growth 

 is better. 



The production of cubic volume or cordwood without regard to 

 size or quality appears to culminate about 20 to 30 years earlier 

 than the production of saw timber. The maximum mean annual 

 yield in cubic volume for unthinned well-stocked stands in North 

 Carolina is obtained on the best sites at about 50 to 60 years, on 

 medium or second-quality sites at about 65 to 75 years, and on the 

 poorest or third-quality sites at an estimated age of about 85 years. 

 At 80 years, stands on third quality sites were found not yet to 

 have passed their maximum in volume production. The more rapid 

 growth of thinned stands hastens the date of their financial ma- 

 turity by from 15 to 30 years. 



If the aim is to raise saw timber, a rotation of from 80 years on the 

 better sites to 100 years on the poorer sites will apparently give the 

 greatest yield in the shortest time; for cordwood the age of highest 

 production lies mostly between 60 and 80 years. 2 In practice stands 

 will more likely be cut in shorter rotations, or before they reach their 

 maximum rate of growth. Pine is extensively cut for ties at 12 inches 

 breasthigh diameter. This size is reached at 65 years in North Caro- 

 lina, and the tree is then 70 feet high. Such a tree will make two to 

 four tics, according to the size of the tie desired. The disadvantage 

 of holding charges at compound interest tends strongly to reduce the 

 rotation. 



: \V. \V. Ashf, ' ' S'i,<,rllc;ir I'irur in Virginia " |». 28), published by the Virginia Depari 

 menl <>f Agriculture and Immigration. 

 • Scrub and pitch pines are extensively used for Qrewood and are usually removed from 

 : tand with Bbortleaf because <>r their Inferiority for saw timber. 



8497 Bull. 808 -15 5 



