more than twice as much per acre to estabhsh 

 a new stand on 10-acre blocks as on 80-acre 

 blocks. 



Similarly, the way one management task is 

 carried out can affect subsequent management 

 actions. A minimum job of site preparation 

 may be low in cost, but it can result in higher 

 planting costs. The amount of debris on the 

 ground after site preparation may even affect 

 the cost of thinning. It is important, therefore, 

 that costs used in financial calculations be 

 realistic in terms of the quality of the work 

 done and the interrelationships between the 

 actions planned. 



VALUE YIELD ESTIMATES 

 MUST BE CONSISTENT 



The problem in estimating yields is to pre- 

 dict how crops of trees will develop over time 

 and how value yields will be affected by 

 management. Also, it is necessary to estimate 

 future wood prices. 



Procedures for predicting how stands will 

 develop under different assumptions of man- 

 agement are still rather crude. Computer pro- 

 grams have been developed for projecting 

 stands when growth and mortality data are 

 available, but as yet these are crude in them- 

 selves and more often than not the growth 

 and mortality data available are inadequate. 



Where stand projection programs are lacking 

 it may be necessary to fall back on normal 



yield tables. These are thought to give reason- 

 able estimates of the capacity of the land to 

 produce wood. For example, table 3 shows the 

 volume of wood that might be expected from 

 fully stocked stands on white pine land for a 

 range of ages and site classes. 



Yield tables can be used for making stand 

 projections. To illustrate, figure 2 shows the 

 development of the average wild fully stocked 

 stand on land in site class 60 in terms of 

 volume in trees of different sizes. From this, 

 some approximations can be made of the 

 influence of stocking control. For example, 

 assuming it is reasonable with thinning to 

 grow stands in which all trees will be 1 2 inches 

 and larger in diameter at 90 years, then AB = 

 the volume gain at that point attributable to 

 thinning if 12 inches (diameter) is the mini- 

 mum merchantable tree size. If a series of 

 commercial thinnings is planned, it is essential 

 to estimate also how these are expected to 

 influence yield. 



To illustrate further, according to yield 

 tables a fully stocked stand of western larch 

 on site 70 land in the Northern Region should 

 contain dominant and codominant trees aver- 

 aging 70 feet in height at 50 years of age, and 

 the stand should have a total volume of 4,682 

 cubic feet of wood. If the stand approaches 

 "normal" in stocking and tree size distribu- 

 tion, 78 percent of the volume should be in 

 trees 5.0 inches d.b.h. and larger and about 47 

 percent in trees 8 inches and larger. The 

 Northern Region anticipates that with thin- 



Table 2. — Cost of selected tinnber growing 

 activities by size of area 



Size 



Activity 





of 



Slashing 



Prescribed 



Planting 



Total 



area 



burning 





Acres 



10 



20 



40 



80 



41.00 

 30.50 

 20.00 

 12.50 



- Dollars per acre 

 26.00 

 23.50 

 19.00 

 13.50 



49.50 

 35.00 

 29.00 

 25.00 



116.50 

 89.00 

 68.00 

 51.00 



9 



