The regular spacing in the plantation re- 

 sulted in much lower mortality than occurs 

 in most natural stands. Less than 10 percent 

 of the planted trees died between ages 24 and 

 51 years, while 76 percent were lost in the 

 natural stands. A significant differentiation 

 of crown classes was first recorded at age 29 

 when the plantation had reached a density of 

 134 square feet per acre. At this density ap- 

 proximately 24 percent of the stems were in 

 the intermediate crown class. The percentage 

 of intermediate trees was still the same at 

 age 51. 



Basal area density of living trees in the 

 plantation should culminate at about 250 

 square feet per acre. Of this stocking, how- 

 ever, only 215 square feet is expected to oc- 

 cur in trees increasing in stem diameter. The 

 remainder is in overtopped trees that are 

 not growing in diameter and will eventually 

 be lost because of suppression. 



Although the greater number of trees re- 

 sulted in higher basal area densities in the 

 plantation, the periodic diameter increment 

 has progressively been reduced to only one- 

 third that of natural stands. After age 29, 

 when the density was 134 square feet, the 

 rate of diameter increment rapidly dropped 

 below that of the natural stands. Diameter 

 growth of the 100 largest trees per acre show- 

 ed a similar reduction at the same age and 

 density, indicating that thinning should have 

 been started. 



The merchantable volume in plantations 

 at any given age will vary because of differ- 

 ences in initial spacing and survival. Planta- 

 tions established at wider spacings than ob- 



served here will tend to have higher volumes 

 at earlier ages. At age 24 the volume yield in 

 this closely spaced plantation was only 6 per- 

 cent of the natural stand volume for compar- 

 able basal area density and average stand 

 size. At 35 years of age the stand volumes 

 were nearly equal. The merchantable cubic 

 volume in the plantation at age 51, however, 

 was 51 percent greater and the cordwood vol- 

 ume 33 percent greater than in the natural 

 stands. 



Most of the plantation volume is in small 

 stems, with only 8 percent of the trees 8 

 inches or larger. Merchantable length of the 

 stem averages only 47 percent of the total 

 height, and the live crown length has been re- 

 duced to 39 percent. Quality of the wood is 

 probably lower in the plantation not only be- 

 cause the trees are smaller but also because 

 branch stubs are persisting. At a density of 

 236 square feet at 51 years of age little natur- 

 al pruning has occurred. 



The regular spacing in plantations is thus 

 associated with higher survival, a rapid in- 

 crease in basal area density to a maximum of 

 about 250 square feet per acre, and a higher 

 volume potential than normally occurs in the 

 average natural stand. An estimated 3 million 

 acres have been planted to trees in the Lake 

 States. The successful plantations now com- 

 prise perhaps as much as one-fourth of the 

 coniferous timber type, and the planted area 

 is increasing by nearly 140,000 acres each 

 year. With management to improve the size 

 and quality of the final product, they should 

 yield a large portion of the potential soft- 

 wood timber requirements of the region. 



July 1963 ff 



ft 



R. M. GODMAN, Research Forester 



( Forest Management) 

 Lake States Forest Experiment Station 

 N. F.! [SMITH, Staff Officer 



Michigan Department of Conservation 



