FOREST AND RANGE RESOURCES OF UTAH 



63 



Some forests are entirely of one class, but those of Utah must be 

 handled with both main purposes in mind. 



The first step in handling forests for continuous yield of timber 

 is a general stock taking or an extensive cruise. This is made by 

 cruisers who, working alone, pace a compass line through each forty 

 (^e -section) and at intervals of 10 chains, measure the timber 

 on 14-acre sample plots. On each plot the cruiser records by species 

 the sizes of trees suitable to cut and to leave. He also maps the 

 streams and ridges and the boundaries of the various kinds and age 



Figure 33. — The latest method in lumber manufacture — a modern band mill 



classes of timber. When passing through immature timber he 

 makes special note of the age and rate of growth so as to be able to 

 determine when these young stands will reach merchantable size. 

 The age and rate of growth of standing trees are determined by 

 cutting out a core from the bark to the heart with a hollow auger 

 (called an increment borer), counting the annual rings, and measur- 

 ing the growth. (Fig. 34.) The results of this cruise are worked 

 into a management plan for handling the timber stand. According 

 to this plan the forest is divided into units of continuous timber pro- 



