FOREST AND RANGE RESOURCES OF UTAH 69 



ditions for any unit, it has been found essential that a well-thought- 

 out and carefully prepared plan of management be written for each 

 unit. Such a management plan is the guide which tells how, where, 

 and how much timber is to be cut each year. Generally, a manage- 

 ment plan is prepared for what is called a " working circle," which 

 may be described as the timber-producing area tributary to one 

 point of manufacture or to one community. The boundaries ^ are 

 usually determined by relief or lay of the land. The working circle 

 is divided into compartments, usually small watersheds within the 

 working circle, which are in turn further divided into subcompart- 

 ments, which are natural- logging units. These divisions are usually 

 necessary in order to build up a really usable management plan. 



The following are the main data essential for the preparation of 

 a plan: 



A statement of the amount of each kind of timber ready for cutting on each 

 subcompartment. 



A table showing, for each kind of timber and age class, the average number 

 of trees, and volume of timber to be left per acre after cutting. 



Data showing at what size or age trees of the various kinds cease to make 

 satisfactory growth and the rate of growth until this time arrives. 



Maps showing the distribution of the timber by kind and age for the entire 

 working circle. . 



Besides these data, an intimate knowledge of such things as eco- 

 nomic conditions, available markets, accessibility of the timber to 

 market, and other related factors, is necessary to the making of a 

 plan. The rotation (age or size at which timber will be cut), and 

 how often the area is to be cut over, must also be decided. 



If the area is not clear-cut the first time, it is possible to take the 

 trees which are left as fast as they mature in sufficient volume to 

 make it worth while. The period between cuttings, once determined, 

 is called a " cutting cycle." Generally the oftener an area is cut 

 over, taking out only such trees as are ripe or defective, the greater 

 will be the growth per acre. For this reason it is best to come back 

 as often as the volume of timber per acre of such timber is sufficient 

 to pay to do it. 



The next step is the determination of how much can be cut each 

 year on a sustained-yield basis. There are many ways of determin- 

 ing this, most of which are too complicated to be dealt with here. 

 Suppose that by using the table mentioned above as an essential 

 of a management plan, showing the number of trees of each kind 

 and size left per acre, along with the rate of growth, it is found that 

 an average acre will add 150 board feet of wood through growth 

 each year. Then suppose the working circle consists of 100,000 acres 

 of timber-producing land. It is obvious that 15,000,000 board feet 

 could safely be cut each year and that this cut could be continued 

 forever. 



The next thing to answer is where to cut first and in what order 

 to proceed. The logical place to cut first is on the subcompartment 

 where the percentage of overmature timber is heaviest, other things 

 being equal. 



The question of how to cut is covered by what are called marking 

 rules. These rules are simply instructions as to what kind of trees 

 to cut and what to leave under different conditions. They are based 

 on experience in Forest Service cuttings, and on research. 



