YIELD TABLES FOR PLANTATIONS 



Yield estimates for plantations were produced assuming 

 that there was no natural regeneration. On most sites in 

 the Inland Empire, some natural regeneration can be ex- 

 pected. Therefore, the yields in these tables will apply only 

 to stands in which early and repeated thinnings remove 

 the natural regeneration. Simulation of the combined 

 yields from planted as well as naturally regenerated trees 

 would also be possible with the Prognosis Model. 



Douglas-fir 



Expected yields for plantations with 500 Douglas-fir 

 trees per acre at 5 years are listed in tables 2 through 6 

 and figures 7 through 9 for the five management regimes. 

 In comparison to the yields estimated for natural stands, 

 Douglas-fir plantations are estimated to produce higher 

 volumes at the early and middle ages because the height 



growth is faster at the early ages. This difference in height 

 growth can be seen by comparing top heights at early ages 

 for the same site index (table 2). 



Variation of yields between simulations for the same site 

 index is less than for the natural-stand yields because 

 initial stocking is uniformly 500 trees per acre at 5 years 

 (figs. 10, 11). 



Treatment effects on mean d.b.h. are shown in figures 12 

 through 16. As expected, thinning from below produces 

 the largest diameters, but response is slight on the lower 

 site qualities. 



Effects of thinning regimes on standing volume are com- 

 pared in figures 17 through 22 for total cubic and mer- 

 chantable board foot volumes. Effects of thinning regimes 

 on total yield are compared in figures 23 through 28. To- 

 tal yield was nearly constant for site index 90. For site 

 indices 50 and 70, however, none of the thinning regimes 

 matched the total yield of the un thinned plantations. 



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