922 



A NATIONAL PLAN FOR AMERICAN FORESTRY 



In addition to the old-growth stands and the young stands that 

 have developed following lumbering operations, there are in the Doug- 

 las fir region considerable stands of timber 40 to 150 years old which 

 originated after fires. Stands that^have reached an age of about 100 

 years can be cut in a manner similar to that recommended for old 

 stands with about the same results except for two factors : The material 

 removed will not yield much clear lumber, but will be uniformly sound, 

 and will be excellent for structural timber; and, the residual stand 

 will consist very largely of Douglas fir and will be in better condition 

 to make rapid growth. Figure 5 and table 7 represent the conditions 

 in a stand varying from 80 to 120 years of age (17). A few old veterans 

 and a few groups of young trees are present in this stand, and cutting 

 will be to a slightly lower diameter limit. About 30,000 board feet 

 per acre will be removed and about 30,000 board feet left. Some 

 groups will be cut clear to permit Douglas fir reproduction ; the remain- 



8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 SMALL MEDIUM LARGER 



DIAMETER BREAST HIGH (INCHES) v 



TIMBER GROUP TOTALS 



FIGURE 5. Distribution of cubic volume by diameter classes on average acre, 80- to 120- year-old Douglas 

 fir with a few old veterans (48- and 50-inch classes) and a subordinate stand of western hemlock and 

 western red cedar. 



ing stand will be managed for from 40 to 60 years longer, with cuttings 

 about every 20 years. 



Spruce-hemlock forests occur in a limited area known as the "fog 

 belt " along the Oregon and Washington coasts. As Douglas fir, also, 

 occurs to some extent in this belt, the area is considered part of the 

 Douglas fir region. These particular forests present a remarkable 

 example of two forest stands, of widely separated age classes, growing 

 on the same area. The first constituent is the old spruce, ranging to 

 110 inches in diameter and probably 600 to 800 years old. This 

 undoubtedly had a high percentage of even-aged hemlock associated 

 with it at the start. As hemlock usually does not live to more than 

 300 years of age the hemlock stand has gradually changed to all-aged 

 form, and now exists and develops almost independently of the pres- 

 ence of the few remaining spruce trees. The spruce stand includes 

 most of the immediate realization values. 



Figure 6 shows cubic-volume distribution by diameter classes on 

 average acres for two closely adjacent areas in the lower Columbia 



