74 



MISC. PUBLICATION 11, U. S. DEPT. OF AGRICULTUKE 



If full data were available, it would probably be found that a different rota- 

 tion ought, theoretically, to be adopted for each type. Full data are not avail- 

 able, but average relationships between age and d. b. h., without differentiation 

 of types, have been determined from a limited number of stump analyses. 

 The trees selected for measurement were not picked for good crown development, 

 but were taken at random as found in the woods after a felling crew. Further- 

 more, comparatively few trees were used in each determination. For the 

 present it is safe to assume that tie-sized trees mil be produced in 140 years 

 in all types ; and that period will be considered as the rotation. 



Within all types in the virgin stand there is a good representation of all 

 diameter classes. Accordingly when the mature trees are removed from the 

 virgin stand in the first cut there is left a large number of small trees per 

 acre. For stand tables, giving the average number of trees left per acre after 

 cutting see Tables 5, 6, and 7 of the " Growth and yield " report. 



After the removal of the larger trees from the virgin stand the remaining 

 trees are able to get more light and moisture, and their rate of growth is stimu- 

 lated. For detailed figures giving rate of gTowth per decade after cutting 

 and in the virgin stand refer to Tables 19, 20, and 21 of that report. 



By applying the rate of growth per decade to the number of trees per acre in 

 each diameter class one is able to predict the number of trees in each diameter 

 class at stated intervals following cutting. 



By applying a volume table to the trees in each class the total volume of 

 the stand per average acre at different periods following the cut can be 

 predicted. 



. The table given below shows the yield per acre for each type for three decades 

 following cutting of the original stand : 



Table 1. — Yield per acre for each of three types 



TEN YEARS AFTER CUTTING VIRGIN STAND 





Pine type 



Douglas 



fir type 



Spruce type 



10 vears after first cut 



Board ft. 



3,025 



2,266 



759 



Ties 

 87.38 

 69.42 

 17.96 



Board ft. 



2,795 



2,035 



760 



Ties 

 69.64 

 49.59 

 20.05 



Board ft. 

 4,985 

 2,915 

 2,070 



Ties 

 44.11 

 18.97 

 25.14 



Sly Sties'^ 

 163. 10 



Left after first cut 



95 40 



Available to cut 



67.70 







TWENTY YEARS AFTER CUTTING VIRGIN STAND 



20 years after first cut 



Left after first cut 



Available to cut 



4,011 



106. 75 



3,801 



2,266 



69.42 



2,035 



1,745 



37.33 



1,766 



7,664 



86.84 



2,915 



18.97 



4,749 



67.87 



244. 52 

 95.40 

 149. 12 



THIRTY YEARS AFTER CUTTING VIRGIN STAND 



i 



30 years after first cut. 



Left after first cut 



Available to cut 



5,208 



132. 64 



5,169 



129. 84 



11,059 



141. 67 



2,266 



69.42 



2,035 



49.59 



2,915 



18.79 



2,942 



63.22 



3,134 



80.25 



8,144 



122. 88 



342. 85 



95.40 



247. 45 



1 Ties of this size are not now marketable. The figures indicate the possible cut of mine props or of oth er 

 small material, if a market is found. 



(e) Summarized tatles. — 



Table 2. — Area classification of Rio Puehlo watershed 



Acres 



Gross — 110,385 



Alienated : 



Disputed strip 19. 754 



Homestead-entry surveys 190 



Santa Barbara grant 25, 784 



Total alienated 45, 728 



Net 64,657 



