46 THE THEORY AND PRACTICE OF WORKING PLANS 



The prevailing local storm direction is entered (where it is 

 not known already it must be determined; in a mountainous 

 region the storms often follow the direction of the main drain- 

 age) by means of long dotted arrows (see Fig. i). 



The next step is to obtain the areas of the various divisions, 

 types, alienations, etc. This is most easily done by means of a 

 planimeter. One decimal place usually suffices. The larger 

 areas are always measured first — e.g., the blocks before the com- 

 partments — the sum of the smaller divisions, e.g., of compart- 

 ments, should check with the area of the larger unit (block) 

 containing them. Minor errors can be proportioned. Roads, 

 streams, boundary lines which have been cut through, etc., are 

 seldom calculated as separate areas unless they are excessively 

 wide, e.g., more than 20 feet. 



Tables are now drawn up to contain these and other data 

 which can be summarized. These may be: 



(a) Stand Table. — A tabular enumeration showing separately 

 for each diameter class and species, the number of trees on a 

 given unit of area, usually an average acre. The corresponding 

 volume may or may not be given. 



Obviously, this form of table is most useful in the uneven- 

 aged forest. The following example of such a table is taken 

 from Bulletin 11 of the N. Y. State Conservation Commis- 

 sion,* based on virgin stands of hardwoods in the Catskill 

 Mountains. 



(&) Stock Table. — A tabular enumeration s"iiowing separately 

 for each diameter class and species, the volume of timber upon 

 a given unit of area, usually an average acre. 



This form of table is best adapted to the uneven-aged forest. 

 It serves as an excellent basis for computing the estimates, 

 by simply multiplying the values given in the table by the 

 total acreage. The following example of such a table is taken 

 from Bulletin 11 of the N. Y. State Conservation Commission. f 



* Bulletin 11, " Forest Survey of a Parcel of State Land," Albany, N. Y. 



1915- 



t Ibid. 



