FNR-107
forestry & natural resources
WOODLAND MANAGEMENT 
APPRAZ—A Timber Volume Estimation Program
for the HP-41C*
by Thomas W. Beers, Department of Forestry and Natural Resources
The availability of convenient and powerful handheld programmable calculators, such as the Hewlett-Packard 41-C, promises to have a significant impact on most of the scientific community. In fact, the applicability of such calculators to the field of forestry, in general, and to forest inventory, in particular, is enormous.
This bulletin presents and describes APPRAZ—a program for the HP-41C—to show how routine forest inventories can be readily processed on this relatively inexpensive calculator instead of through laborious handwork. Although other programmable calculators are capable of forest inventory programming, the HP-41C is chosen for the sake of example and convenience.
APPRAZ is a program to calculate log volumes and to obtain, primarily, summaries by species and log grades as might be typical of a small-scale timber appraisal where individual log diameter, length, and grade are recorded in the field.
For those not familiar with the features of the HP-41C, it should be noted that its continuous memory feature and very long battery life suggest the feasibility of direct tally of tree data into the calculator therefore eliminating the pencil-paper recording operation. The system is not foolproof yet, and users are urged to apply APPRAZ to the situation where field data have been recorded on paper and an on-the-spot, or at least very timely, summary is needed. Obviously, for large forest inventories, the use of computer processing is desirable and frequently justified.
Following are five aspects involved in the use of APPRAZ—a general description; the program procedure; typical data and example; storage register assignments; and a program listing.
* This publication is the first in a series of two on the use of programmable calculators in forest management. The second is entitled, FNR-108 “CRUZ—A Timber Volume Estimation Program for the HP-41C.’
General Description
1.	Program title:	APPRAZ
2.	Calculator: HP-41C with 3 memory modules; can be used with or without
the HP-82143A printer attached.
3.	Purpose: to calculate timber volumes and summarize same by species and
log grade; additionally, numbers of trees by species and DBH class are summarized as are number of logs by species. Grand total volume, number of logs, and number of trees are also provided.
4.	Application:	to be used in timber harvest inventories, on site, or from
tally sheets where data are recorded by logs in the form
dd - LL - G
where dd = scaling diameter of log in inches
LL = log length in feet
G = log grade (5 grades possible)
5. Justification:	the primary advantage of calculator processing is that
the very time-consuming operation of sorting by grade within species is eliminated; secondarily, all calculations and sums are automated, thus avoiding table look-up or calculation errors and minimizing transcribing errors.
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA 47907