20 



When the formation of height classes is necessary, the form No. 1 

 may be modified as follows: 



Form No. 2. — Diameter ineasurements. 





1 

 Oak. Hard maple. 



i 



[ 



Hickory. Ash. 



Black wal- 

 nut. 



Si 

 '2. 



Height, 

 Class I. 



Height, Height, 

 Class II. Class I. 



1 



Height, 

 Class II. 



Height, 

 Class I. 



Height, 

 Class U. 







1 





'1. 





11 









ill 





111 

 III 





'1. 



t^ 'O u 



\ 'h ® ^ 





:1^ 



In. 



8 

 9 

 10 



































Form No. 2 would be applicable should the oak, the hard maple, and 

 the hickory of our hard- wood grove differ in height so as to necessitate 

 the formation of two height classes for each of these species. Each 

 height class then will have to be treated like a separate species. Of 

 course only the species of economic value are measured. In the example 

 represented by Form No. 1, five species were- supposed to form the 

 stand. Ill measuring, fractions of less than one-half of an inch are 

 disregarded while those over half an inch are counted as full inches. 

 Each tree calipered is scored in the appropriate species column on its 

 proper diameter line by a mark, each fifth score crossing the four pre- 

 ceding, so that groups of five scores are made for more convenient 

 addition. The measuring can be done more expeditiously if two or more 

 persons divide the labor of scoring, calipering, and marking the calip- 

 ered trees so as to avoid repetition in measuring; one scorer following 

 two measurers who call out species and measured diameter, and mark 

 the measured trees, or else one or two assistants blaze the trees to keep 

 the work in line, preventing repetition as well as omission of trees. 



When all the trees have been scored, the volume of each species may 

 be determined either (1) by felling and measuring in detail a samj)le 

 tree representing the average of all the trees of the species, or (2) by 

 felling and measuring a number of sample trees, each representing the 

 average of a diameter class, or (3) for the greatest accuracy, by felling 

 and measuring a proportionate number of sample trees for each diame- 

 ter, the proportion felled being a fixed percentage of the number of 

 trees of each diameter. 



DETERMINATION OF VOLUME BY MEANS OF AN AVERAGE SAMPLE 



TREE. 



This method requires for each species {a) a calculation to determine 

 the diameter of the average sample tree; (b) the selection of the sample 

 tree in the forest and its measurement; and, finally (c) the calculation 

 of the total volume of the species. 



