inches, blank spaces are provided to specify the correct 

 2-inch diameter class, such as 18, 20, 22, or 24. When a 

 tree has been completed, summarize the dot counts in 

 the space provided. Total all columns and rows and 

 enter this figure under heading TOTAL (T). Also enter 

 the grand total segment count in the header information. 



Definitions 



DRC— The diameter to the nearest 0.1 inch of a tree 

 at just above the root collar or ground line. DRC is 

 measured at the ground Hne for single-stem trees with 

 uniform stem taper. If a tree forks near or below the 

 ground line, a DRC of each stem is measured and an 

 equivalent DRC (EDRC) is computed and recorded in 

 place of DRC: 



EDRC = ^/ I DRC.2 



V i = l ' 



where 



n = number of stems 



DRC; = diameter of the ith stem. 

 Although a tree must have at least one stem 3 inches 

 DRC or larger to be segmented, the EDRC computation 

 may include stems less than 3 inches DRC if these 

 stems support qualifying segments. Space is provided 

 for recording multiple diameters for later calculation and 

 for checking the data. 



Situations often occur that require judgment in deter- 

 mining the point of diameter measurement. DRC or 

 EDRC is used to compute the basal area of stems sup- 

 porting the total stem and branch volume of a tree. 

 Thus, DRC or EDRC should be measured at the lowest 

 point on a tree where it best represents the basal area 

 supporting that tree. In other words, the measurements 

 should be taken at the lowest point consistent with the 

 taper of the stem(s) in a tree. Do not include butt swell 

 or other abnormalities that will increase the diameter 

 over that taken at the base of a stem(s) with uniform 

 taper. Move the measurement point up the tree as 

 needed to obtain a reasonable measurement. 



When a tree forks near the base, EDRC should be 

 computed from the stems above the fork if a single 

 measurement near the base would obviously inflate the 

 value. A tree forking just above the ground could often 

 be measured at the base as a single-stem tree, but space 

 between the stems will usually inflate the measurement. 

 On the other hand, moving too far up a tree to measure 

 stems above a fork could give an unreasonably small 

 measurement to represent the base of that tree. See fig- 

 ure 9 for examples of DRC and EDRC measurement 

 points. 



No. stems.— A count of the number of basal stems 

 used for DRC or EDRC measurements. Stems, as com- 

 pared to branches, provide structural support for a 

 major portion of a tree. 



Qualifying segment.— A piece of wood at least 1 foot 

 long and at least 1.5 inches in diameter (outside bark) at 

 the small end. 



Total ht.— The total height of a tree measured perpen- 

 dicular to the ground line to the nearest 1 foot. For 

 multiple-stem trees, the height of the tallest stem is 

 measured. 



Measure at ground line when Measure above buti swell, 



reasonable. 



Measure DRC at base when represen- Measure individual stems when DRC 



tative of total basal area. excessive. Compute EDRC. 



EDRC. line. Compute EDRC. 



Figure 9.— Examples of DRC and EDRC 

 measurements. 



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