PROGRAI-I DESCRIPTION 



NETVSL is a comprehensive computer program that calculates the volume, surface 

 area, and length of tree boles from stem measurements. These measurements can be 

 obtained either from felled trees, or taken by a dendrometer from standing trees. 

 Volume units include cubic feet and board feet (Scribner and/or International 1/4" log 

 scale) . Total stem contents (including forks) and merchantable contents are calculated 

 for each of the three kinds of volume units. Merchantable contents are defined by 

 arbitrary stump heights, log lengths, and top diameter limits. Stem diameters for the 

 ends of logs are interpolated between adjacent measured stem sections. Top diameters 

 for volumes in board feet are defined by the criterion of Mesavage.^ Deductions from 

 volume in cubic feet are calculated from descriptive measurements of interior defect 

 obtained by destructive sampling of felled trees. In addition, cull in board feet 

 could be deducted by user-supplied subroutines that are called in the appropriate 

 sequence during execution of the program. 



NETVSL has been used to calculate the net volume of trees destructively sub- 

 sampled in the course of timber management inventories, and to estimate gross volume 

 through dendrometry of a subsample in lieu of using conventional volume tables. Other 

 uses would include calculation of net volume for mill-scale studies, presale cruises, 

 and local volume table construction. Because the computations produce both the board- 

 foot scale and the associated volume-surf ace- length contents, the latter system of 

 units advocated by Grosenbaugh^ can be interpreted in the widely used, but misleading, 

 units of board feet (log scale) until conversion coefficients based on mill-scale 

 studies provide a more meaningful interpretation. When presale cruises include destruc- 

 tive sampling to estimate defect deductions, this program can be used to generate the 

 tree or log data cards for subsequent expansion by sample-estimation formulae to 

 produce net volume, surface, and length for the entire sale. 



Tree data obtained by dendrometry of standing trees can be recorded in the same 

 form for processing by either NETVSL or by Grosenbaugh ' s ^ STX program with only 

 a minor difference in the coding for forked trees. This uniformity should simplify the 

 training of dendrometer operators. However, the two programs are intended for quite 

 different purposes. NETVSL is most useful when data from felled trees are being 

 augmented by additional measurements of standing trees, or when a variety of merchan- 

 tability standards must be applied to the same tree data. 



UNITS OF VOLUME ' ' 



Nine combinations of volume units and merchantability limits are possible at 

 each run. These include volumes in cubic feet or board feet (Scribner and/or Inter- 

 national 1/4" log scale). For each of the three volume units, three sets of 

 merchantability limits can be specified: total tree; fixed top diameter, and arbi- 

 trary stump height; or variable top diameter and another arbitrary stump height. 



Log lengths for board-foot volume calculations are specified at the user's 

 option. Hence, log scaling diameters, positions of minimum top diameters, and stump 

 heights are located by interpolation among the stem sections for the total tree. 

 Table 1 lists the codes identifying the various combinations of units of measure and 

 merchantability limits. These codes appear in the first column of the sample output 

 in figure 1. 



■'" Mesavage, Clement. Definition of merchantable sawtimber height. J. Forest. 63(1): 30-32. 1965. 



2 



Grosenbaugh, L. R. Some suggestions for better sample -tree measurement. Soc. Amer. Forest. 

 Proc. 1963: 36-42. 



^ Grosenbaugh, L. R. STX--FORTRAN 4 program for estimates of tree populations from 3P sample- 

 tree measurements „ U.S. Forest Serv. Res. Pap. PSW-13, 49 pp. 1964. 



