United States

Department of

Agriculture

Forest Service

Southern 

Research Station

General Technical 

Report SRS–138

Southern Forest 

Inventory and Analysis 

Volume Equation User’s Guide

Christopher M. Oswalt and Roger C. Conner
June 2011

Southern Research Station 

200 W.T. Weaver Blvd. 

Asheville, NC 28804

Authors 

Christopher M. Oswalt, Research Forester, and Roger C. Conner, 

Research Forester, U.S. Forest Service, Southern Research Station, 

Forest Inventory and Analysis, Knoxville, TN 37919. 

Cover photo: Logging on an upland hardwood site in Hot Spring 

County, Arkansas. (photo by Tony G. Johnson)
Southern Forest Inventory and Analysis 

Volume Equation User’s Guide

Christopher M. Oswalt and Roger C. Conner

iii

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Using the Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Variable Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Description of Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Definition of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Page

Southern Forest Inventory and Analysis 

Volume Equation User’s Guide

Christopher M. Oswalt and Roger C. Conner

Abstract

Reliable volume estimation procedures are fundamental to the mission of 

the Forest Inventory and Analysis (FIA) program. Moreover, public access 

to FIA program procedures is imperative. Here we present the volume 

estimation procedures used by the southern FIA program of the U.S. 

Department of Agriculture Forest Service, Southern Research Station. The 

guide presented includes a description of the relevant variables populated 

in the public FIA database, a description of the set of equations used to 

estimate tree volume in the south, the volume equations, definition of 

terms, species-specific (or species group) coefficients for each equation, 

and examples of estimating individual tree volume.

Keywords: Biomass, FIA, volume, volume equation, volume estimation.

Introduction

The Forest Inventory and Analysis (FIA) program of the 

U.S. Department of Agriculture Forest Service, Southern 

Research Station (SRS) is charged with producing Statelevel estimates of various forest resource values, levels, and 

trends for 13 Southern States, the Commonwealth of Puerto 

Rico, and the U.S. Virgin Islands territory. Sound estimation 

procedures are desideratum to generating credible population estimates in order to evaluate the status and trends 

in resource conditions. As such, volume estimation is an 

integral component of forest resource analysis and reporting. 

Reliable volume estimation procedures are fundamental 

to FIA’s mission. Copious data have been collected and 

used to estimate species-specific parameters. Currently, 

the SRS FIA utilizes inside bark volume estimators of the 

conventional linear regression model form:

where

dbh = bole diameter at breast height

Ht = tree height

α and β are species-specific (or species-group-specific) 

coefficients (Spurr 1952) 

to derive volume estimates (Zarnoch and others 2003). 

The SRS FIA program along with other SRS scientists 

began destructive sampling of southern tree species more 

than 50 years ago (sensu Cost (1978) modified for felled 

trees) with the objective of building volume equations. 

That undertaking resulted in the development of volume 

equations that have long been in use as one of the 

foundational elements of the SRS FIA program. However, 

those equations and associated species-specific coefficients 

currently used by the SRS FIA program are not readily 

available in the published literature. 

Recently, FIA adopted a nationally consistent method for 

estimating individual tree component biomass (Components 

Ratio Method (CRM) – Heath and others 2009) that is 

dependent upon estimates of sound volume. Those interested 

in replicating SRS FIA biomass estimation procedures 

require access to SRS FIA volume equations. This makes 

it imperative that the volume estimation procedures be 

publicly available. This publication facilitates such access in 

a comprehensive and transparent manner. 

Using the Guide

This user’s guide presents the set of inside bark equations 

and coefficients the SRS FIA program currently uses to 

populate seven individual tree volume variables in the 

public FIA database (FIADB currently version 4.0). In 

addition, we explain how to implement the SRS FIA volume 

estimation procedures. 

There are six components to this guide: 1) a description 

of the relevant variables populated in the FIADB, 2) a 

description of the set of equations used to estimate tree 

volume in the South, 3) the volume equations, 4) definition 

of terms, 5) species-specific (or species group) coefficients 

for each equation, and 6) examples of estimating individual 

tree volume using this guide. 

+= βα ( ) + ε 2 V h Htdb
2

Variable Descriptions

Seven primary volume variables are populated in the 

FIADB (table 1). Each of the seven primary volume 

variables describes a unique portion of an individual stem 

(fig. 1). While SRS FIA has developed equations for total 

stem volume, not all estimates are used to populate variables 

in FIADB. 

Descriptions of populated variables are provided as background information to help explain how each variable is 

calculated and used to derive various volume estimates. 

Detailed descriptions of all FIADB variables can be found 

in the FIA Database Description and Users Manual Version 

4.0 for Phase 2 accessed online at http://www.fia.fs.fed.us/

library/database-documentation. 

Table 1—Volume variables populated in FIADB 4.0

Variable Tree form Populated in FIADB when: Estimated volume accounts for: Units

VOLCFGRS Timber Live, dead, or cut tree, DBH ≥ 5" Central stem, 1' stump to 4" top DOB ft3

Woodland Live, dead, or cut tree, EDRC ≥ 5" DRC measurement point to 1.5" top DOB ft3

VOLCFNET Timber Live, dead, or cut tree, DBH ≥ 5" Central stem, 1' stump to 4" top DOB less rotten 

and missing cull

ft3

Woodland Live, dead, or cut tree, EDRC ≥ 5" DRC measurement point to 1.5" top DOB less 

rotten and missing cull (For SRS FIA, VOLCFNET, 

and VOLCFSND report the same volume)

ft3

VOLCFSND Timber Live or dead tree, DBH ≥ 5" Central stem, 1' stump to 4" top DOB less rotten 

and missing cull

ft3

Woodland Live or dead tree, EDRC ≥ 5" DRC measurement point to 1.5" top DOB less 

rotten and missing cull ft3

VOLCSGRS Timber Live tree, DBH ≥ 9" (softwoods)

≥ 11" (hardwoods), Tree Class = 

Growing Stock

Saw-log portion, 1' stump to 7" (softwoods) or

9" (hardwoods) top DOB

ft3

Woodland Not populated

VOLCSNET Timber Live tree, DBH ≥ 9" (softwoods)

≥ 11" (hardwoods), Tree Class = 

Growing Stock

Saw-log portion, 1' stump to 7" (softwoods) or 

9" (hardwoods) top DOB less rotten and missing 

cull

ft3

Woodland Not populated

VOLBFGRS Timber Live tree, DBH ≥ 9" (softwoods)

≥ 11" (hardwoods), Tree Class = 

Growing Stock

Saw-log portion, 1' stump to 7" (softwoods) or 

9" (hardwoods) top DOB

board 

feet

Woodland Not populated

VOLBFNET Timber Live tree, DBH ≥ 9" (softwoods)

≥ 11" (hardwoods), Tree Class = 

Growing Stock

Saw-log portion, 1' stump to 7" (softwoods) or 

9" (hardwoods) top DOB less rotten and missing 

cull and cull volume removed due to poor forma

.

board 

feet

Woodland Not populated

FIADB = Forest Inventory and Analysis Database; VOLCFGRS = gross cubic-foot volume; VOLCFNET = net cubic volume; VOLCFSND = 

sound cubic foot volume; VOLCSGRS = gross cubic-foot volume in the saw-log portion; VOLCSNET = net cubic-foot volume in the saw-log 

portion; VOLBFGRS = gross board-foot volume in the saw-log portion; VOLBFNET = net board-foot volume in the saw-log portion; DBH = 

diameter at breast height; DOB = diameter outside bark; EDRC = equivalent diameter at root collar; DRC = diameter at root collar.

a

 Cull volume due to poor form was accounted for in the development of the board-foot equations. Form cull is not measured in the field by 

SRS FIA.
3

VOLCFNET Net cubic-foot volume. For timber species 

(trees where the diameter is measured 

at breast height [d.b.h.]), this is the net 

volume of wood in the central stem of a 

sample tree ≥5.0 inches diameter, from 

a 1-foot stump to a minimum 4-inch top 

diameter outside bark (d.o.b.), or to where 

the central stem breaks into limbs all of 

which are <4.0 inches d.o.b. For woodland 

species (trees where the diameter is 

measured at root collar [d.r.c.]), this is 

the net volume of wood from the d.r.c. 

measurement point(s) to a minimum 

1.5-inch top. This is a per tree value and 

must be multiplied by TPA_UNADJ to 

obtain per acre information. This attribute 

is blank (null) for trees with DIA <5.0 

inches. All trees measured after 1998 

with DIA ≥5.0 inches (including dead 

and cut trees) will have entries in this 

field. Does not include rotten and missing 

cull (volume loss due to rotten and 

missing cull defect has been deducted). 

Note—VOLCFNET in other FIA regions 

accounts for additional deductions for 

form cull.

Cull volume 

removed 

(missing/rotten)

FIA reported 

volume

Cull volume 

removed

(form)

Stump volume

(not included)

1-foot stump

9-inch top

7-inch top

4-inch top

Tip

VOLCFGRS VOLCFNET

VOLCSGRS/VOLBFGRS

Hardwood Softwood Hardwood Softwood Hardwood Softwood

VOLCSNET VOLBFNET

VOLCFSND

Figure 1—Graphical illustration of the primary volume variables* populated in FIADB 4.0.

* See table 1 for variable definitions.
4

VOLCFGRS Gross cubic-foot volume. For timber 

species, this is the total volume of wood 

in the central stem of sample trees ≥5.0 

inches d.b.h., from a 1-foot stump to a 

minimum 4-inch top d.o.b., or to where 

the central stem breaks into limbs all of 

which are <4.0 inches d.o.b. For woodland 

species, this is the total volume of wood 

from the d.r.c. measurement point(s) 

to a minimum 1.5-inch top. This is a 

per tree value and must be multiplied 

by TPA_UNADJ to obtain per acre 

information. This attribute is blank (null) 

for trees with DIA <5.0 inches. All trees 

measured after 1998 with DIA ≥5.0 

inches (including dead and cut trees) 

have entries in this field. Includes rotten, 

missing and form cull (volume loss due to 

rotten, missing, and form cull defect has 

not been deducted).

VOLCSNET Net cubic-foot volume in the saw-log 

portion. The net volume of wood in the 

central stem of a sample commercial 

species tree of sawtimber size (9.0 inches 

d.b.h. minimum for softwoods, 11.0 inches 

d.b.h. minimum for hardwoods), from 

a 1-foot stump to a minimum top d.o.b. 

(7.0 inches for softwoods, 9.0 inches for 

hardwoods), or to where the central stem 

breaks into limbs, all of which are less 

than the minimum top d.o.b. This is a 

per tree value and must be multiplied 

by TPA_UNADJ to obtain per acre 

information. This attribute is blank (null) 

for softwood trees with DIA <9.0 inches 

(11.0 inches for hardwoods). All larger 

trees have entries in this field if they are 

growing-stock trees (TREECLCD = 2 and 

STATUSCD = 1). All rough and rotten 

trees (TREECLCD = 3 or 4) and dead and 

cut trees (STATUSCD = 2 or 3) are blank 

(null) in this field. 

VOLCSGRS Gross cubic-foot volume in the saw-log 

portion. This is the total volume of 

wood in the central stem of a sample 

commercial species tree of sawtimber 

size (9.0 inches d.b.h. minimum for 

softwoods, 11.0 inches d.b.h. minimum 

for hardwoods), from a 1-foot stump 

to a minimum top d.o.b. (7.0 inches for 

softwoods, 9.0 inches for hardwoods), 

or to where the central stem breaks into 

limbs, all of which are less than the 

minimum top d.o.b. This is a per tree 

value and must be multiplied by TPA_

UNADJ to obtain per acre information. 

This attribute is blank (null) for softwood 

trees with DIA <9.0 inches (11.0 inches 

for hardwoods). All larger trees have 

entries in this field if they are growingstock trees (TREECLCD = 2 and 

STATUSCD = 1). All rough and rotten 

trees (TREECLCD = 3 or 4) and dead and 

cut trees (STATUSCD = 2 or 3) are blank 

(null) in this field.

VOLBFNET Net board-foot volume in the saw-log 

portion. This is the net volume 

(International 1⁄4-inch rule) of wood in 

the central stem of a sample commercial 

species tree of sawtimber size (9.0 inches 

d.b.h. minimum for softwoods, 11.0 inches 

d.b.h. minimum for hardwoods), from 

a 1-foot stump to a minimum top d.o.b. 

(7.0 inches for softwoods, 9.0 inches 

for hardwoods), or to where the central 

stem breaks into limbs all of which are 

less than the minimum top d.o.b. This is 

a per tree value and must be multiplied 

by TPA_UNADJ to obtain per unit area 

information. Trees with DIA <9.0 inches 

(11.0 inches for hardwoods) have zero 

in this field. All larger trees should have 

entries in this field if they are growingstock trees (TREECLCD = 2 and 

STATUSCD = 1). All rough and rotten 

trees (TREECLCD = 3 or 4) and dead and 

cut trees (STATUSCD = 2 or 3) are blank 

(null) in this field.

VOLBFGRS Gross board-foot volume in the sawlog portion. This is the total volume 

(International 1⁄4-inch rule) of wood in 

the central stem of a sample commercial 

species tree of sawtimber size (9.0 inches 

d.b.h. minimum for softwoods, 11.0 inches 

d.b.h. minimum for hardwoods), from 

a 1-foot stump to a minimum top d.o.b. 
5

(7.0 inches for softwoods, 9.0 inches for 

hardwoods), or to where the central 

stem breaks into limbs all of which are 

less than the minimum top d.o.b. This is 

a per tree value and must be multiplied 

by TPA_UNADJ to obtain per unit area 

information. Trees with DIA <9.0 inches 

(11.0 inches for hardwoods) have zero 

in this field. All larger trees should have 

entries in this field if they are growingstock trees (TREECLCD = 2 and 

STATUSCD = 1). All rough and rotten 

trees (TREECLCD = 3 or 4) and dead and 

cut trees (STATUSCD = 2 or 3) are blank 

(null) in this field.

VOLCFSND Sound cubic-foot volume. For timber 

species, the volume of sound wood in the 

central stem of a sample tree ≥5.0 inches 

d.b.h. from a 1-foot stump to a minimum 

4-inch top d.o.b. or to where the central 

stem breaks into limbs all of which are 

<4.0 inches d.o.b. For woodland species, 

this is the net volume of wood from the 

d.r.c. measurement point(s) to a minimum 

1.5-inch top. This is a per tree value and 

must be multiplied by TPA_UNADJ to 

obtain per acre information. This attribute 

is blank (null) for trees with DIA <5.0 

inches. All trees with DIA ≥5.0 inches 

(including dead trees) have entries in this 

field. Does not include rotten and missing 

cull (volume loss due to rotten and 

missing cull defect has been deducted).

DIA Current diameter. This is the current 

diameter (in inches) of the sample tree at 

the point of diameter measurement. For 

additional information about where the 

tree diameter is measured, see DIAHTCD 

or HTDMP in the FIADB manual version 

4.0. DIA for live trees contains the 

measured value. DIA for cut and dead 

trees presents problems associated with 

uncertainty of when the tree was cut or 

died as well as structural deterioration of 

dead trees. Consult individual FIA units 

for explanations of how DIA is collected 

for dead and cut trees.

For tree species in which d.r.c. is 

collected, equivalent diameter (EDRC) 

(Chojnacky 1994) is calculated for use in 

volume equations. 

EDRC =

where

n = number of stems measured for drc

on individual woodland species 

drc = diameter root collar

HT Total height. (core phase 2: ≥5.0-inch 

d.b.h./d.r.c. live trees; core optional 

phase 2: ≥1.0-inch d.b.h./d.r.c. live trees 

and ≥5.0-inch d.b.h./d.r.c. standing dead 

trees. Core phase 3: ≥1.0-inch d.b.h./

d.r.c. live trees; core optional phase 3: 

≥1.0-inch d.b.h./d.r.c. live trees and 

≥5.0-inch d.b.h./d.r.c. standing dead 

trees.) The total length (height) of a 

sample tree (in feet) measured from the 

ground to the tip of the apical meristem. 

The total length of a tree is not always its 

actual length. If the main stem is broken, 

the actual length is measured or estimated 

and the missing piece is added to the 

actual length to estimate total length. The 

amount added is determined by measuring 

the broken piece if it can be located on 

the ground; otherwise it is estimated. The 

minimum height for timber species is 

5 feet and for woodland species is 1 foot.

ACTUALHT Actual height. (core phase 2: live and 

standing dead trees with broken or 

missing tops, ≥5.0-inch d.b.h./d.r.c.; core 

optional phase 2: live trees ≥1.0-inch 

d.b.h./d.r.c. and ≥5.0-inch d.b.h./d.r.c. 

standing dead trees [with broken or 

missing tops]; core phase 3:live trees 

≥1.0-inch d.b.h./d.r.c. (with broken or 

missing tops and standing dead trees 

≥5.0-inch d.b.h./d.r.c. [with broken or 

missing tops]). The length (height) of the 

tree to the nearest foot from ground level 

to the highest remaining portion of the 

n

i =1

drc2

i
6

tree still present and attached to the bole. 

If ACTUALHT = HT, then the tree does 

not have a broken top. If ACTUALHT is 

<HT, then the tree does have a broken 

or missing top. The minimum height for 

timber species is 5 feet and for woodland 

species is 1 foot.

CULL Rotten and missing cull. The percent of 

the cubic-foot volume in a live or dead 

tally tree that is rotten or missing. This 

is a calculated value that includes fieldrecorded cull (CULL_FLD) and any 

additional cull due to broken top. 

CULL_FLD Rotten/missing cull. (core: ≥5.0-inch 

live trees; core optional: ≥5.0-inch 

live trees and standing dead). The 

percentage rotten or missing cubic-foot 

cull volume, estimated to the nearest 

1 percent. This estimate does not include 

any cull estimate above actual length; 

therefore volume lost from a broken top 

is not included (see CULL for percent 

cull including cull from broken top). 

When field crews estimate volume loss 

(tree cull), they only consider the cull 

on the merchantable bole/portion of the 

tree, from a 1-foot stump to a 4-inch top 

d.o.b.. For western woodland species, the 

merchantable portion is between the point 

of d.r.c. measurement to a 1.5-inch top 

d.o.b.

At times, separate coefficients exist for saplings, poles, and 

sawtimber. The specifications for each are:

Saplings— Softwood (SPCD or SPN <300) = d.b.h. 

≥1 inch and <5 inches

Hardwood (SPCD or SPN >299) = d.b.h. 

≥1 inch and <5 inches

Poles— Softwood = d.b.h. ≥5 inch and <9 inches

Hardwood = d.b.h. ≥5 inch and <11 inches

Sawtimber— Softwood = d.b.h. ≥9 inches and tree class = 2

Hardwood = d.b.h. ≥11 inches and tree class 

= 2

Additionally, coefficients have been fit for planted slash 

pine and planted loblolly pine for some equations. While 

ACTUALHT is used as an explanatory variable of volume, 

each net cubic-foot volume variable accounts for deductions 

for missing tops (see broken-top cubic-foot cull), missing 

volume (see missing cubic-foot cull) and rotten wood 

(see rotten cubic-foot cull). In the case of estimated net 

board-foot volume, the estimates account for deductions 

for missing tops, missing volume, rotten wood and poorly 

formed wood (for example, sweep and crook, see percent 

board-foot cull). Note—In the South cull is reported 

as CULL_FLD and CULL in the FIADB. CULL_FLD 

represents cubic-foot cull, CULL represents CULL_FLD 

with the addition of broken-top cull.

Description of Equations

Cubic and board-foot (inside bark) volumes are calculated 

for softwood and hardwood stems on forest land. 

International 1⁄4-inch log rule is used for board-foot 

equations. Multiple volumes are estimated by utilizing a 

combination of species- or species-group-specific simple 

linear equations and ratio-based conversion factors. 

All total stem volumes are calculated on all trees in the 

inventory that are >1.0-inch (2.5 cm) d.b.h. However, treelevel volume variables in the FIADB are only populated for 

trees >5-inch (12.5 cm) d.b.h.

All other volumes (gross, net growing-stock, and sawtimber 

volumes) are calculated on the merchantable stem. Gross 

volume is generally the first output from volume equations 

and has not been adjusted for the presence of cull (rot and 

defect). Net volume is gross volume minus an estimate of 

volume lost due to rot, physical defect, and/or other damage.

SRS FIA volume is most often reported as gross board-foot 

volume, gross cubic-foot volume, net board-foot volume, 

or net cubic-foot volume. Volume is generally reported for 

populations of growing-stock (see Definition of Terms) 

or all-live trees. Each metric and population is defined by 

individual specifications.

Board-foot volume is referred to as sawtimber (or saw-log) 

volume; for softwoods it is the volume of a tree from a 

1-foot stump to a 7-inch top, calculated for softwood species 

≥9-inch (22.5 cm) d.b.h.; and for hardwoods, it is the 

volume of a tree from a 1-foot stump to a 9-inch top, 

calculated for hardwood species ≥11-inch (27.5 cm) d.b.h. 

(table 2).
7

Table 2—Description of the types of volume calculated with SRS FIA equations, tree specifications, equation variable name, 

the FIADB equivalent variable name, equation number, and variables used to perform calculations for each type of volume 

calculated

Type of volume Tree specifications

Variable 

name

FIADB 

equivalent Equation Function

- - - - inches - - - -

All softwoods and hardwoods

Volume of the total stem, ground to tip ≥ 1 (2.5 cm)

Volume from ground level to the tip ≥ 1 and < 5 (12.5 cm) TCU CU000068 (TF, CV4)

Volume from 1' stump to 4" top d.o.b. ≥ 5 CV4 VOLCFGRS CU000067 (SPCD_EQ, DBH, HT)

Softwood saw-log volume

Volume from 1' stump to 6" top d.o.b. ≥ 9 (22.5 cm) CUSAW VOLCSGRSa CU000069 (RCUSAW' CV4)

Hardwood saw-log volume

Volume from 1' stump to 8" top d.o.b. ≥ 11 (27.5 cm) CUSAW VOLCSGRSa CU000069 (RCUSAW' CV4)

Softwood saw-log volume (board foot)

Volume from 1' stump to 6" top d.o.b. ≥ 9 BD VOLBFGRSa BD00049 (RBD' CV4)

Hardwood saw-log volume (board foot)

Volume from 1' stump to 8" top d.o.b. ≥ 11 BD VOLBFGRSa BD00049 (RBD' CV4)

SRS FIA= Southern Research Station, Forest Inventory and Analysis; FIADB = Forest Inventory and Analysis Database; TCU = total cubic-foot 

volume from ground level to tip; TF = total cubic-foot volume from ground level to tip; CV4 = cubic-foot volume; SPCD_EQ = FIA species code and 

associated equation number; DBH = diameter at breast height; HT = total height; VOLCFGRS = gross cubic-foot volume; CUSAW = cubic-foot volume 

of the saw-log portion; RCUSAW = ratio of cubic-foot volume of the saw-log portion; VOLCSGRS = gross cubic-foot volume in the saw-log portion; BD 

= board-foot volume; VOLBFGRS = gross board-foot volume in the saw-log portion; RBD = ratio board-foot volume. a Not populated for tree class 3 (rough cull) or 4 (rotten cull).

Equations

Equation Form CU000067 = CV4

The following equations compute total cubic-foot volume for 

saplings and planted saplings:

CV4Sapling = A1 + A2 * (DBH2 * HT)

CV4Planted Sapling = B1 + B2 * (DBH2 * HT)

The following equations compute cubic-foot volume from a 

1-foot stump to a 4-inch top d.o.b. for poles and sawtimber: 

CV4Pole = C1 + C2 * (DBH2 * HT)

CV4Sawtimber = D1 + D2 * (DBH2 * HT)

Equation Form CU000068 = TCU

The following equations compute total cubic-foot volume 

from ground level to tip:

TFPole = E1 + E2 * ( )

2

 1

DBH – 3

TCU = TF * CV4

Equation Form CU000069 = CUSAW

The following equation converts cubic-foot volume from a 

1-foot stump to a 4-inch top d.o.b. to cubic-foot volume of 

the saw-log portion of the tree:

Ratio is limited to between 0.60 and 0.99

CUSAW = R * CV4

TFSawtimber = F1 + F2 * ( )

2 1

DBH – 3

TFPlanted Sawtimber = G1 + G2 * ( )

2 1

DBH – 3

R = H1 + H2 * ( )

2

 1

DBH – 5

TFPlanted Pole = G1 + G2 * ( )

2

 1

DBH – 3
8

Acknowledgments

The authors would especially like to thank Jeffery Turner 

for his tremendous support querying NIMS SQL packages 

to identify, in explicit terms, various procedures long hidden 

from view and the numerous discussions that helped bring 

these procedures to print. We would also like to thank Jason 

McHan, Helen Beresford, and Ted Ridley for numerous 

discussions and allowing multiple interruptions, all of 

which led to a more thorough product. Thanks are also due 

to Ray Sheffield, Larry Royer, Nathaniel Osborne, John 

Lhotka, and Ray Souter for reviewing this manuscript. This 

work was supported by the U.S. Forest Service, Southern 

Research Station, Forest Inventory and Analysis program. 

Literature Cited

Chojnacky, D.C. 1988. Juniper, pinyon, oak, and mesquite volume 

equations for Arizona. Rs. Pap. INT–391. Ogden, UT: U.S. Department 

of Agriculture Forest Service, Intermountain Research Station. 11 p.

Chojnacky, D.C. 1994. Volume equations for New Mexico’s pinyon-juniper 

dryland forests. Res. Pap. INT–471. Ogden, UT: U.S. Department of 

Agriculture Forest Service, Intermountain Research Station. 10 p.

Cost, N.D. 1978. Multiresource inventories—a technique for measuring 

volumes in standing trees. Res. Pap. SE–196. Asheville, NC: U.S. 

Department of Agriculture Forest Service, Southeastern Forest 

Experiment Station. 18 p.

Hann, D.W.; Bare, B.B. 1978. Comprehensive tree volume equations 

for major species of New Mexico and Arizona: I. Results and 

Methodology. Res. Pap. INT–209. Ogden, UT: U.S. Department 

of Agriculture Forest Service, Intermountain Forest and Range 

Experiment Station. 43 p.

Heath, L.S.; Hansen, M.; Smith, J.E. [and others]. 2009. Investigation 

into calculating tree biomass and carbon in the FIADB using a 

biomass expansion factor approach. In: McWilliams, W.; Moisen, 

G.; Czaplewski, R., comps. Forest Inventory and Analysis (FIA) 

Symposium 2008. Proc. RMRS–P–56CD. Fort Collins, CO: U.S. 

Department of Agriculture Forest Service, Rocky Mountain Research 

Station. 26 p.

Spurr, S.H. 1952. Forest inventory. New York: Ronald Press Co. 476 p.

Zarnoch, S.J.; Clark, A.; Souter, R.A. 2003. Comparison of past, present, 

and future volume estimation methods for Tennessee. Res. Note 

SRS–12. Asheville, NC: U.S. Department of Agriculture Forest 

Service, Southeastern Forest Experiment Station. 6 p.

Equation Form BD000049 = BD

The following equation converts cubic-foot volume from a 

1-foot stump to a 4-inch top d.o.b. to board-foot volume:

BD = R * CV4

Board-Foot Cull Defect Equation

Only used in processing for broken-top trees.

where 

DEFECTBF = percent board-foot cull

Note—Currently DEFECTBF = DEFECTCF for SRS FIA 

processing

Cubic-Foot Cull Defect Equations

Calculated for all net cubic-foot variables (VOLCFNET, 

VOLCSNET and VOLCFSND).

where 

DEFECTCF = percent cubic-foot cull + missing top cull

NIMS–SRS Implementation

VOLCFGRS = CV4

VOLCFNET = CV4 – cubic-foot cull defect

VOLCFSND = CV4 – cubic-foot cull defect

VOLCSGRS = CUSAW except 0 if tree class = 3 or 4

VOLCSNET = CUSAW – cubic-foot cull defect

VOLBFGRS = CV4 * board-foot conversion ratio 

VOLBFNET = CV4 * board-foot conversion ratio – cubicfoot cull defect

VOLBFNET = VOLBFGRS – (VOLBFGRS * ) 

DEFECTBF

100

R = I1 + I2 * (1 – 1

DBH)

VOLCFNET = VOLCFGRS – (VOLCFGRS * ) DEFECTCF

100

VOLCSNET = VOLCSGRS – (VOLCSGRS * ) DEFECTCF 

100

VOLCFSND = VOLCSGRS – (VOLCSGRS * ) DEFECTCF 

100
9

Definition of Terms

The following definitions are taken from the Forest 

Inventory and Analysis glossary (available from the SRS 

FIA program). Additional information and definitions 

are available from the Forest Inventory and Analysis 

National Core Field Guide, Volume 1: Field Data Collection 

Procedures for Phase 2 Plots. SRS Version 3.0. October 

2005. (http://srsfia2.fs.fed.us/data_acquisition/manual.

shtml).

Cull—Portions of a tree that are unusable for industrial 

wood products because of rot, form, or other defect. Cull is 

further categorized as the following:

Broken-top cubic-foot cull—The broken-top proportion 

of a timber species tree’s merchantable portion from 

the break to the actual or projected 4-inch top diameter 

outside bark, or to where the central stem forks, where 

all forks are <4.0 inches diameter. For trees 1.0–4.9 

inches diameter this is the proportion of the main stem 

missing due to a broken top.

Missing cubic-foot cull—The proportion of a tree’s 

merchantable portion that is missing. Does not include 

any cull deductions above actual length for broken-top 

timber trees. Does include cull deductions above actual 

length for broken-top woodland species. Trees with 

d.b.h./d.r.c. <5.0 inches have a null value in this field.

Rotten cubic-foot cull—The proportion of a tree’s 

merchantable portion that is in a decayed state. Does 

not include any cull deductions above actual length for 

broken-top timber trees. Does include cull deductions 

above actual length for broken-top woodland species. 

Trees <5.0 inches d.b.h. have a null value in this field.

Rotten/missing cull—The part of the tree’s 

merchantable portion that is decayed and/or missing 

due to other factors.

Diameter at breast height (d.b.h.)—The diameter for tree 

stem, located at 4.5 feet above the ground (breast height) on 

the uphill side of a tree. The point of diameter measurement 

may vary on abnormally formed trees.

Diameter at root collar (d.r.c.)—The diameter of a tree 

(usually a woodland species), measured outside of the bark 

at the ground line or stem root collar.

Forest land—Land that is at least 10 percent stocked by 

forest trees of any size, or land formerly having such tree 

cover, and is not currently developed for a nonforest use. 

The minimum area for classification as forest land is 1 acre. 

Roadside, streamside, and shelterbelt strips of timber must 

have a crown width at least 120 feet wide to qualify as forest 

land. Unimproved roads and trails, streams and other bodies 

of water, or natural clearings in forested areas shall be 

classified as forest, if <120 feet in width or 1.0 acre in size. 

Forest land is divided into timberland, reserved forest land, 

and other forest land (such as woodland). 

Growing-stock trees—Live large-diameter timber species 

(excludes nonsaw-log species) trees with one-third or more 

of the gross board-foot volume in the entire saw-log portion 

meeting grade, soundness, and size requirements or the 

potential to do so for medium-diameter and small-diameter 

trees. A growing-stock tree must have one 12-foot log or 

two noncontiguous 8-foot merchantable logs, now (largediameter) or prospectively (medium-diameter and smalldiameter), to qualify as growing stock.

Log—Eight foot (2.4 m) or longer tree segment suitable for 

processing into lumber, veneer, or other wood products.

Merchantable portion—The portion of the main stem of 

a timber species tree from a 1-foot stump to a minimum 

4-inch top diameter inside or outside bark depending on 

species. The portion of a woodland species tree from the 

d.r.c. measurement to the 1.5-inch diameters of all the 

qualifying stems.

Poletimber-sized tree (i.e., poles)—Softwood timber 

species 5.0 to 8.9 inches d.b.h. and hardwood timber species 

5.0 to 10.9 inches d.b.h. Often referred to as mediumdiameter trees.

Sapling—Live trees 1.0 to 4.9 inches d.b.h./d.r.c. 

Saw-log portion—That portion of the main stem of a timber 

species tree of large-diameter size from a 1-foot stump to 

a minimum top d.o.b. 7.0 inches for softwoods, 9.0 inches 

for hardwoods (equivalent 6.0 inches diameter inside bark 

(d.i.b.) for softwoods, 8.0 inches d.i.b. for hardwoods).

Sawtimber-sized trees—Softwood timber species ≥9.0 

inches d.b.h., and hardwood timber species ≥11.0 inches 

d.b.h. Often referred to as large-diameter trees.

Seedling—Live trees <1.0-inch d.b.h./d.r.c. that are 

≥6 inches in height for softwoods and ≥12 inches in height 

for hardwoods and >0.5-inch d.b.h./d.r.c. at ground level for 

longleaf pine.

Species group—A collection of species used for reporting 

purposes.
10

Total length—The total length of the tree, recorded to the 

nearest 1.0 foot from ground level to the tip of the apical 

meristem. Trees growing on a slope are measured on the 

uphill side of the tree. If the tree has a broken or missing 

top, the total length is estimated to what the length would 

be if there were no missing or broken top. Forked trees are 

treated the same as unforked trees.

Tree—A woody perennial plant, typically large, with a 

single well-defined stem carrying a more or less definite 

crown; sometimes defined as attaining a minimum diameter 

of 3 inches and a minimum height of 15 feet at maturity. For 

FIA, any plant on the tree list in the current field manual is 

measured as a tree.

Tree class—An indication of the general quality of the 

tree. In the annual inventory, this is the tree class for both 

live and dead trees at the time of current measurement. In 

the historical periodic inventory, for cut and dead trees, this 

is the tree class of the tree at the time it died or was cut. 

Therefore, cut and dead trees collected in periodic inventory 

can be growing stock.

Cull species—Species measured at d.r.c. and timber 

species (measured at d.b.h.) that would not produce saw 

logs.

Growing stock—Live large-diameter timber species 

(excludes nonsaw-log species) trees with one-third 

or more of the gross board-foot volume in the entire 

saw-log portion meeting grade, soundness, and size 

requirements or the potential to do so for mediumdiameter trees. A growing-stock tree must have one 

12-foot log or two noncontiguous 8-foot merchantable 

logs, now (large diameter) or prospectively (medium 

diameter), to qualify as growing stock.

Rough cull—Trees that do not contain at least one 

12-foot saw log or two 8-foot logs now or prospectively, 

primarily because of roughness or poor form. Less than 

one-third of its gross board-foot volume meets size, 

soundness, and grade requirements and less than onehalf of the cubic-foot cull is rotten or unsound.

Rotten cull—Trees that do not contain at least one 

12-foot saw log or two 8-foot logs now or prospectively 

and/or do not meet grade specifications for percent 

sound primarily because of rot. All species not having 

one-third or more of its gross board-foot volume 

meeting size, soundness, and grade requirements, and 

over one-half of the cubic-foot cull is rotten or unsound.

Volume—A measure of the solid content of the tree stem 

used to measure wood quantity.

Gross board-foot volume—Total board-foot volume of 

wood inside bark without deductions for total boardfoot cull.

Gross cubic-foot volume—Total cubic-foot volume 

of wood inside bark without deductions for rotten, 

missing, or broken-top cull.

Net board-foot volume—Gross board-foot volume 

minus deductions for total board-foot cull.

Net cubic-foot volume—Gross cubic-foot volume minus 

deductions for rotten, missing, and broken-top cull.

Metric Equivalents

1 acre = 4,046.86 m2 or 0.404687 ha

1 cubic foot = 0.028317 m3

1 inch = 2.54 cm or 0.0254 m

Breast height (4.5 feet) = 1.4 m above the ground

1 square foot = 929.03 cm2

 or 0.0929 m2

1 square foot of basal area per acre = 0.229568 m2/ha

1 cubic foot per acre = 0.0699722 m3/ha

1 pound = 0.454 kg

1 ton = 0.908 metric ton
11

Appendix

Reading Tables

Identify FIA volume variable(s) of interest. Ascertain needed coefficients. Use table A.1 to identify species of interest by 

common name (COMMON_NAME) or FIA species code (SPCD) and associated equation number (SPCD_EQ). Use the 

SPCD_EQ code to identify corresponding coefficients in table A.2 (total gross cubic-foot volume for saplings), table A.3 

(total gross cubic-foot volume for planted saplings), table A.4 (VOLCFGRS for poles and sawtimber), table A.5 (total 

cubic-foot volume from stump to tip for poles and sawtimber), table A.6 (total cubic-foot volume from stump to tip for planted 

poles and planted sawtimber), table A.7 (conversion of CV4 to CUSAW), and/or table A.8 (conversion of CV4 to board-foot 

volume).

Guide to Coefficient Tables

Table A.2

A1, A2 Coefficients to compute sapling total cubic-foot volume stump to tip

Table A.3

B1, B2 Coefficients to compute sapling total cubic-foot volume stump to tip for plantation trees

Table A.4

C1, C2 Coefficients to compute pole cubic-foot volume from stump to 4-inch top

D1, D2 Coefficients to compute sawtimber cubic-foot volume from stump to 4-inch top

Table A.5

E1, E2 Coefficients to convert poles from CV4 (cubic volume to a 4-inch top) to total stem

F1, F2 Coefficients to convert sawtimber from CV4 (cubic volume to a 4-inch top) to total stem

Table A.6

G1, G2 Coefficients to convert plantation trees from CV4 (cubic volume to a 4-inch top) to total stem

Table A.7

H1, H2 Coefficients to convert CV4 (cubic volume to a 4-inch top) to CUSAW (cubic saw-log volume)

Table A.8

I1, I2 Coefficients to convert CV4 (cubic volume to a 4-inch top) to board-foot

13

Table A.1—Species code, common name, and the species code for the equation (or set of coefficients – SPCD_EQ) used for each 

species 

SPCD Common name

Species 

number SPCD_EQa SPCD Common name

Species 

number SPCD_EQa

10 Fir spp. 10 10 320 Norway maple 320 318

12 Balsam fir 12 10 321 Rocky Mountain maple 321 Chojnacky 1988

16 Fraser fir 16 10 323 Chalk maple 323 317

43 Atlantic white-cedar 43 43 330 Buckeye, horsechestnut 330 330

58 Pinchot juniper 58 Chojnacky 1994 331 Ohio buckeye 331 330

59 Redberry juniper 59 Chojnacky 1994 332 Yellow buckeye 332 330

61 Ashe juniper 61 Chojnacky 1994 334 Texas buckeye 334 330

63 Alligator juniper 63 Chojnacky 1994 341 Ailanthus 341 999

66 Rocky Mountain juniper 66 Chojnacky 1994 345 Mimosa, silktree 345 491

67 Southern redcedar 67 67 356 Serviceberry 356 999

68 Eastern redcedar 68 68 367 Pawpaw 367 999

69 Oneseed juniper 69 Chojnacky 1994 370 Birch spp. 370 370

90 Spruce spp. 90 90 371 Yellow birch 371 371

93 Engelmann spruce 93 90 372 Sweet birch 372 371

97 Red spruce 97 90 373 River birch 373 370

106 Common pinyon 106 Chojnacky 1994 379 Gray birch 379 371

107 Sand pine 107 107 381 Chittamwood, gum bumelia 381 999

110 Shortleaf pine 110 110 391 American hornbeam,

111 Slash pine 111 111 musclewood 391 999

115 Spruce pine 115 115 400 Hickory spp. 400 400

121 Longleaf pine 121 121 401 Water hickory 401 400

122 Ponderosa pine 122 Hann and Bare 1978 402 Bitternut hickory 402 400

123 Table Mountain pine 123 123 403 Pignut hickory 403 400

126 Pitch pine 126 126 404 Pecan 404 400

128 Pond pine 128 128 405 Shellbark hickory 405 400

129 Eastern white pine 129 129 406 Nutmeg hickory 406 400

131 Loblolly pine 131 131 407 Shagbark hickory 407 400

132 Virginia pine 132 132 408 Black hickory 408 400

140 Mexican pinyon pine 140 Chojnacky 1994 409 Mockernut hickory 409 400

202 Douglas-fir 202 Hann and Bare 1978 410 Sand hickory 410 400

221 Baldcypress 221 221 421 American chestnut 421 999

222 Pondcypress 222 222 422 Allegheny chinkapin 422 999

241 Northern white-cedar 241 241 423 Ozark chinkapin 423 999

260 Hemlock spp. 260 260 450 Catalpa spp. 450 999

261 Eastern hemlock 261 260 451 Southern catalpa 451 999

262 Carolina hemlock 262 260 452 Northern catalpa 452 999

299 Unknown conifer 299 10 460 Hackberry spp. 460 460

310 Maple spp. 310 318 461 Sugarberry 461 460

311 Florida maple 311 311 462 Hackberry 462 460

313 Boxelder 313 313 463 Netleaf hackberry 463 460

314 Black maple 314 317 471 Eastern redbud 471 999

315 Striped maple 315 999 481 Yellowwood 481 491

316 Red maple 316 316 491 Flowering dogwood 491 491

317 Silver maple 317 317 492 Pacific dogwood 492 491

318 Sugar maple 318 318 500 Hawthorn 500 999

319 Mountain maple 319 999 501 Cockspur hawthorn 501 999

continued
14

Table A.1—Species code, common name, and the species code for the equation (or set of coefficients – SPCD_EQ) used for each 

species (continued)

SPCD Common name

Species 

number SPCD_EQa SPCD Common name

Species 

number SPCD_EQa

502 Downy hawthorn 502 999 742 Eastern cottonwood 742 740

510 Eucalyptus 510 999 743 Bigtooth aspen 743 741

521 Common persimmon 521 521 744 Swamp cottonwood 744 740

531 American beech 531 531 745 Plains cottonwood 745 740

540 Ash spp. 540 540 755 Mesquite 755 Chojnacky 1988

541 White ash 541 540 756 Western honey mesquite 756 Chojnacky 1988

543 Black ash 543 540 758 Screwbean mesquite 758 Chojnacky 1988

544 Green ash 544 540 760 Cherry and plum spp. 760 999

545 Pumpkin ash 545 540 761 Pin cherry 761 999

546 Blue ash 546 540 762 Black cherry 762 762

548 Carolina ash 548 999 763 Chokecherry 763 762

551 Waterlocust 551 999 765 Canada plum 765 999

552 Honeylocust 552 552 766 Wild plum 766 999

555 Loblolly-bay 555 555 800 Oak deciduous 800 812

571 Kentucky coffeetree 571 999 802 White oak 802 802

580 Silverbell 580 580 804 Swamp white oak 804 804

591 American holly 591 591 806 Scarlet oak 806 806

600 Walnut 600 601 808 Durand oak 808 808

601 Butternut 601 601 809 Northern pin oak 809 830

602 Black walnut 602 602 810 Emery oak 810 Chojnacky 1988

605 Texas walnut 605 601 812 Southern red oak 812 812

611 Sweetgum 611 611 813 Cherrybark oak 813 813

621 Yellow-poplar 621 621 816 Bear oak, scrub oak 816 842

641 Osage-orange 641 999 817 Shingle oak 817 817

650 Magnolia spp. 650 652 819 Turkey oak 819 817

651 Cucumbertree 651 651 820 Laurel oak 820 820

652 Southern magnolia 652 652 822 Overcup oak 822 822

653 Sweetbay 653 653 823 Bur oak 823 823

654 Bigleaf magnolia 654 651 824 Blackjack oak 824 824

655 Mountain magnolia 655 651 825 Swamp chestnut oak 825 825

660 Apple spp. 660 999 826 Chinkapin oak 826 826

680 Mulberry spp. 680 680 827 Water oak 827 827

681 White mulberry 681 999 828 Nuttall oak 828 813

682 Red mulberry 682 680 830 Pin oak 830 830

691 Water tupelo 691 691 831 Willow oak 831 831

692 Ogechee tupelo 692 999 832 Chestnut oak 832 832

693 Blackgum 693 693 833 Northern red oak 833 833

694 Swamp tupelo 694 694 834 Shumard oak 834 834

701 Eastern hophornbeam 701 999 835 Post oak 835 835

711 Sourwood 711 999 836 Delta post oak 836 836

712 Paulownia, empress-tree 712 999 837 Black oak 837 837

721 Redbay 721 999 838 Live oak 838 838

722 Water-elm, planertree 722 999 840 Dwarf post oak 840 840

731 Sycamore 731 731 841 Dwarf live oak 841 840

740 Cottonwood and poplar spp. 740 740 842 Bluejack oak 842 842

741 Balsam poplar 741 741 843 Silverleaf oak 843 Chojnacky 1988

continued
15

Table A.1—Species code, common name, and the species code for the equation (or set of coefficients – SPCD_EQ) used for each 

species (continued)

SPCD Common name

Species 

number SPCD_EQa SPCD Common name

Species 

number SPCD_EQa

844 Oglethorpe oak 844 842 970 Elm spp. 970 970

845 Dwarf chinakapin oak 845 842 971 Winged elm 971 970

846 Gray oak 846 Chojnacky 1988 972 American elm 972 970

901 Black locust 901 901 973 Cedar elm 973 970

911 Palmetto spp. 911 999 974 Siberian elm 974 970

919 Western soapberry 919 999 975 Slippery elm 975 970

920 Willow 920 920 976 September elm 976 970

921 Peachleaf willow 921 920 977 Rock elm 977 970

922 Black willow 922 920 989 Mangrove 989 999

927 White willow 927 920 992 Melaleuca 992 999

931 Sassafras 931 999 993 Chinaberry 993 999

935 American mountain-ash 935 999 994 Chinese tallowtree 994 999

950 Basswood spp. 950 950 995 Tung-oil-tree 995 999

951 American basswood 951 950 996 Smoketree 996 999

952 White basswood 952 950 997 Russian-olive 997 999

953 Carolina basswood 953 950 999 Unknown hardwood 999 999

Note: Some species will require the use of equations built by other regions and are denoted by the appropriate citation.

SPCD = Forest Inventory and Analysis species code; SPCD_EQ = species code equation.

a Citation listed when published equations available.
16

Table A.2—Species code equation and associated coefficients for use in SRS FIA gross volume equations 

(total) for saplings (use equation form CU000067)

SPCD_EQ

Coefficients Coefficients Coefficients

A1 A2 SPCD_EQ A1 A2 SPCD_EQ A1 A2

10 0.065755 0.002813 400 0.047620 0.002192 808 0.080702 0.002467

43 0.010169 0.002839 460 0.054564 0.002565 812 0.080702 0.002467

60 0.052928 0.002853 491 0.037005 0.002729 813 0.041238 0.002603

67 0.052928 0.002853 521 0.034641 0.002546 817 0.041238 0.002603

68 0.052928 0.002853 531 0.058647 0.002378 820 0.024511 0.002637

90 0.065755 0.002813 540 0.064004 0.002410 822 0.041238 0.002603

107 0.079225 0.002490 552 0.058647 0.002378 823 0.041238 0.002603

110 0.066654 0.002168 555 0.012745 0.003005 824 0.053215 0.002475

111 0.070229 0.002111 580 0.054564 0.002565 825 0.041238 0.002603

115 0.081287 0.002219 591 0.058647 0.002378 826 0.041238 0.002603

121 0.058586 0.002429 601 0.054564 0.002565 827 0.030987 0.002670

123 0.081287 0.002219 602 0.058647 0.002378 830 0.041238 0.002603

126 0.081287 0.002219 611 0.045146 0.002357 831 0.041238 0.002603

128 0.047587 0.002354 621 0.019361 0.002514 832 0.014284 0.002521

129 0.074791 0.002881 651 0.051279 0.002641 833 0.041238 0.002603

131 0.060342 0.002197 652 0.051279 0.002641 834 0.041238 0.002603

132 0.034943 0.002569 653 0.057904 0.002603 835 0.051922 0.002631

221 0.094132 0.002743 680 0.058647 0.002378 836 0.053210 0.002475

222 0.101432 0.002744 691 0.062785 0.002458 837 0.042519 0.002613

241 0.065755 0.002813 693 0.048582 0.002498 838 0.050820 0.002776

260 0.065755 0.002813 694 0.088427 0.002681 840 0.053210 0.002475

311 0.058647 0.002378 731 0.054564 0.002565 842 0.053210 0.002475

313 0.054564 0.002565 740 0.054564 0.002565 899 0.053215 0.002475

316 0.023326 0.002860 741 0.054564 0.002565 901 0.058647 0.002378

317 0.054564 0.002565 762 0.155471 0.002461 920 0.054564 0.002565

318 0.058647 0.002378 802 0.044339 0.002539 950 0.054564 0.002565

330 0.054564 0.002565 804 0.041238 0.002603 970 0.032199 0.002589

370 0.058647 0.002378 806 0.067831 0.002660 999 0.062125 0.002494

371 0.058647 0.002378

SRS FIA = Southern Research Station, Forest Inventory and Analysis; SPCD_EQ = species code equation; A1 = coefficient to 

compute sapling total cubic-foot volume stump to tip; A2 = coefficient to compute sapling total cubic-foot volume stump to tip.

Table A.3—Species code equation and 

associated coefficients for use in SRS 

FIA gross volume equations (total) for 

planted saplings (use equation form 

CU000067)

SPCD_EQ

Coefficients

B1 B2

111 0.132056 0.002113

131 0.150292 0.001994

SRS FIA = Southern Research Station, Forest 

Inventory and Analysis; SPCD_EQ = species 

code equation; B1 = coefficient to compute 

sapling total cubic-foot volume stump to 

tip for plantation trees; B2 = coefficient to 

compute sapling total cubic-foot volume stump 

to tip for plantation trees.
17

Table A.4—Species code equation and associated coefficients for use in SRS FIA gross volume equations for poles and 

sawtimber (use equation form CU000067)

SPCD_EQ

Coefficients Coefficients

Pole Sawtimber Pole Sawtimber 

C1 C2 D1 D2 SPCD_EQ C1 C2 D1 D2

10 -0.099920 0.002097 0.879371 0.001845 651 -0.198410 0.001901 0.735415 0.001775

43 0.247418 0.002161 1.668389 0.001822 652 -0.198410 0.001901 0.735415 0.001775

60 -0.315878 0.002207 -0.104252 0.002145 653 -0.198410 0.001901 0.735415 0.001775

67 -0.315878 0.002207 -0.104252 0.002145 680 -0.347844 0.001837 -0.202284 0.001818

68 -0.315878 0.002207 -0.104252 0.002145 691 -0.267107 0.001904 1.749738 0.001659

90 -0.099920 0.002097 0.879371 0.001845 693 -0.225146 0.001902 0.690730 0.001767

107 -0.514855 0.002472 0.377006 0.002239 694 -0.466949 0.001972 1.284413 0.001760

110 -0.706167 0.002215 -0.687060 0.002211 731 0.229691 0.001901 2.326908 0.001649

111 -0.797881 0.002128 -0.611225 0.002088 740 -0.451948 0.001921 0.518892 0.001802

115 0.248714 0.002143 0.118241 0.002168 741 -0.451948 0.001921 0.518892 0.001802

121 -0.944222 0.002265 -0.443190 0.002165 762 -0.547200 0.001948 -0.607326 0.001957

123 -0.013552 0.002453 0.870587 0.002205 802 -0.376980 0.001948 0.148434 0.001880

126 -0.470660 0.002194 -0.379670 0.002171 804 -0.279035 0.001894 0.248363 0.001823

128 -0.632942 0.002177 -0.279600 0.002093 806 -0.225632 0.001917 0.003343 0.001887

129 -0.040964 0.002011 0.604023 0.001857 808 -0.316577 0.001817 -0.085426 0.001783

131 -0.819681 0.002140 -0.658316 0.002107 812 -0.316577 0.001817 -0.085426 0.001783

132 -0.284955 0.002264 0.333364 0.002118 813 0.046929 0.001950 1.212451 0.001791

221 0.241431 0.002047 1.757944 0.001752 817 -0.279035 0.001894 0.248363 0.001823

222 -0.296106 0.002037 1.044195 0.001712 820 -0.351135 0.002014 0.846919 0.001840

241 -0.099920 0.002097 0.879371 0.001845 822 -0.279035 0.001894 0.248363 0.001823

260 -0.259181 0.001808 -0.216081 0.001798 823 -0.279035 0.001894 0.248363 0.001823

311 -0.347844 0.001837 -0.202284 0.001818 825 0.343571 0.001822 0.376354 0.001818

313 -0.451948 0.001921 0.518892 0.001802 826 -0.279035 0.001894 0.248363 0.001823

316 -0.104018 0.001850 0.680247 0.001742 827 -0.265687 0.001986 1.195722 0.001795

317 -0.451948 0.001921 0.518892 0.001802 830 -0.279035 0.001894 0.248363 0.001823

318 -0.052827 0.001891 0.352087 0.001838 831 -0.383480 0.001893 -0.460755 0.001904

330 -0.439762 0.001940 0.218924 0.001833 832 -0.377981 0.001859 -0.069945 0.001818

370 0.371605 0.001773 0.543581 0.001751 833 -0.095806 0.001889 0.793996 0.001779

371 0.998628 0.001765 0.169526 0.001893 834 -0.279035 0.001894 0.248363 0.001823

400 -0.665929 0.001868 -0.793179 0.001884 835 -0.361464 0.001892 0.301286 0.001791

460 -0.193680 0.001770 0.500522 0.001670 837 -0.513128 0.001775 -0.515373 0.001775

491 -0.347844 0.001837 -0.202284 0.001818 838 0.459129 0.001560 0.344387 0.001580

521 -0.402944 0.001931 -1.173042 0.002028 899 -0.183950 0.001841 -0.035319 0.001807

531 -0.398996 0.002026 1.468854 0.001765 824 -0.183950 0.001841 -0.035319 0.001807

540 -0.392822 0.001921 0.172701 0.001851 840 -0.183950 0.001841 -0.035319 0.001807

552 -0.347844 0.001837 -0.202284 0.001818 842 -0.183950 0.001841 -0.035319 0.001807

555 -0.198410 0.001901 0.735415 0.001775 836 -0.183950 0.001841 -0.035319 0.001807

580 -0.451948 0.001921 0.518892 0.001802 901 -0.206213 0.001592 0.603856 0.001483

591 -0.172555 0.002151 0.762909 0.001965 920 -0.451948 0.001921 0.518892 0.001802

601 -0.451948 0.001921 0.518892 0.001802 950 0.198966 0.001860 0.034400 0.001882

602 -0.033805 0.001656 0.421890 0.001596 970 -0.155066 0.001828 -0.316500 0.001851

611 -0.936122 0.001991 -0.629168 0.001955 999 -0.378830 0.001855 0.823520 0.001630

621 -0.553182 0.001922 0.485232 0.001807

SRS FIA = Southern Research Station, Forest Inventory and Analysis; SPCD_EQ = species code equation; C1 = coefficient to compute pole cubicfoot volume from stump to 4-inch top; C2 = coefficient to compute pole cubic-foot volume from stump to 4-inch top; D1 = coefficient to compute 

sawtimber cubic-foot volume from stump to 4-inch top; D2 = coefficient to compute sawtimber cubic-foot volume from stump to 4-inch top.
18

Table A.5—Species code equation and associated coefficients for use in SRS FIA total cubic-foot volume equations for 

poles and sawtimber (use equation form CU000068)

SPCD_EQ

Coefficients Coefficients

Pole Sawtimber Pole Sawtimber 

E1 E2 F1 F2 SPCD_EQ E1 E2 F1 F2

10 1.146541 2.146242 1.146541 2.146242 651 1.158363 2.382274 1.158363 2.382274

43 1.152171 1.259555 1.152171 1.259555 652 1.158363 2.382274 1.158363 2.382274

60 1.176439 2.550195 1.176439 2.550195 653 1.166687 2.242538 1.166687 2.242538

67 1.176439 2.550195 1.176439 2.550195 680 1.186636 2.417775 1.186636 2.417775

68 1.176439 2.550195 1.176439 2.550195 691 1.264347 1.821700 1.264347 1.821700

90 1.146541 2.146242 1.146541 2.146242 693 1.156640 2.035818 1.156640 2.035818

107 1.112564 2.775872 1.112564 2.775872 694 1.187896 2.444066 1.187896 2.444066

110 1.113788 2.208955 1.113788 2.208955 731 1.150504 1.590116 1.150504 1.590116

111 1.109247 2.429713 1.109247 2.429713 740 1.145017 2.255001 1.145017 2.255001

115 1.116228 2.142989 1.116228 2.142989 741 1.145017 2.255001 1.145017 2.255001

121 1.107343 2.384360 1.107343 2.384360 762 1.164183 1.513173 1.164183 1.513173

123 1.127272 1.123936 1.127272 1.123936 802 1.223605 2.051445 1.223605 2.051445

126 1.139310 1.300282 1.139310 1.300282 804 1.218003 2.181659 1.218003 2.181659

128 1.125409 1.877110 1.125409 1.877110 806 1.216303 1.553713 1.216303 1.553713

129 1.145631 1.610693 1.145631 1.610693 808 1.206835 3.453587 1.206835 3.453587

131 1.111780 2.473630 1.111780 2.473630 812 1.206835 3.453587 1.206835 3.453587

132 1.134089 1.531460 1.134089 1.531460 813 1.223374 1.367666 1.223374 1.367666

221 1.188594 2.394869 1.188594 2.394869 817 1.218003 2.181659 1.218003 2.181659

222 1.237591 3.561137 1.237591 3.561137 820 1.237288 2.395208 1.237288 2.395208

241 1.146541 2.146242 1.146541 2.146242 822 1.218003 2.181659 1.218003 2.181659

260 1.131783 2.320512 1.131783 2.320512 823 1.218003 2.181659 1.218003 2.181659

311 1.186636 2.417775 1.186636 2.417775 825 1.237249 1.578554 1.237249 1.578554

313 1.145017 2.255001 1.145017 2.255001 826 1.218003 2.181659 1.218003 2.181659

316 1.179791 1.882807 1.179791 1.882807 827 1.224892 2.664642 1.224892 2.664642

317 1.145017 2.255001 1.145017 2.255001 830 1.218003 2.181659 1.218003 2.181659

318 1.190063 1.712613 1.190063 1.712613 831 1.202078 3.487957 1.202078 3.487957

330 1.172535 1.535447 1.172535 1.535447 832 1.205365 1.671724 1.205365 1.671724

370 1.216170 1.355783 1.216170 1.355783 833 1.224449 1.277306 1.224449 1.277306

371 1.212153 1.359713 1.212153 1.359713 834 1.218003 2.181659 1.218003 2.181659

400 1.189261 3.074669 1.189261 3.074669 835 1.237511 2.241176 1.237511 2.241176

460 1.188803 1.641479 1.188803 1.641479 837 1.214240 2.375921 1.214240 2.375921

491 1.186636 2.417775 1.186636 2.417775 838 1.193954 4.298451 1.193954 4.298451

521 1.214404 1.834798 1.214404 1.834798 899 1.218003 2.181659 1.218003 2.181659

531 1.219447 2.401295 1.219447 2.401295 824 1.218003 2.181659 1.218003 2.181659

540 1.128655 2.349280 1.128655 2.349280 840 1.218003 2.181659 1.218003 2.181659

552 1.186636 2.417775 1.186636 2.417775 842 1.218003 2.181659 1.218003 2.181659

555 1.152686 2.649964 1.152686 2.649964 836 1.218003 2.181659 1.218003 2.181659

580 1.145017 2.255001 1.145017 2.255001 901 1.194258 1.609426 1.194258 1.609426

591 1.203433 1.865955 1.203433 1.865955 920 1.145017 2.255001 1.145017 2.255001

601 1.145017 2.255001 1.145017 2.255001 950 1.135107 1.257835 1.135107 1.257835

602 1.173659 1.863595 1.173659 1.863595 970 1.159555 2.270106 1.159555 2.270106

611 1.122118 2.802714 1.122118 2.802714 999 1.218003 2.181659 1.218003 2.181659

621 1.115123 1.788864 1.115123 1.788864

SRS FIA = Southern Research Station, Forest Inventory and Analysis; SPCD_EQ = species code equation; E1 = coefficient to convert poles 

from CV4 (cubic volume to a 4-inch top) to total stem; E2 = coefficient to convert poles from CV4 (cubic volume to a 4-inch top) to total stem; 

F1 = coefficient to convert sawtimber from CV4 (cubic volume to a 4-inch top) to total stem; F2 = coefficient to convert sawtimber from CV4 

(cubic volume to a 4-inch top) to total stem.
19

Table A.6—Species code equation 

and associated coefficients for use 

in SRS FIA total cubic-foot volume 

equations for planted poles and 

planted sawtimber (use equation form 

CU000068)

SPCD_EQ

Coefficients

G1 G2

111 1.081908 2.607333

131 1.081556 3.659920

SRS FIA = Southern Research Station, Forest 

Inventory and Analysis; SPCD_EQ = species 

code equation; G1 = coefficient to convert 

plantation trees from CV4 (cubic volume to 

a 4-inch top) to total stem; G2 = coefficient 

to convert plantation trees from CV4 (cubic 

volume to a 4-inch top) to total stem.

Table A.7—Species code equation and associated coefficients for use in SRS 

FIA equation to convert cubic-foot volume to a 4-inch top to cubic-foot 

volume of the saw-log portion (use equation form CU000069)

SPCD_EQ

Coefficients Coefficients

H1 H2 SPCD_EQ H1 H2

10 0.987226 -4.396825 651 1.016073 -15.025004

43 1.006045 -4.962611 652 1.016073 -15.025004

60 0.987563 -4.027958 653 1.005781 -14.518615

67 0.987563 -4.027958 680 0.970888 -12.114880

68 0.987563 -4.027958 691 0.973498 -12.868316

90 0.987226 -4.396825 693 0.967984 -13.248708

107 1.005598 -4.595382 694 0.975950 -12.390384

110 1.017129 -5.035009 731 0.977294 -16.118257

111 1.018317 -5.202751 740 0.993648 -14.095485

115 1.012739 -5.021693 741 0.993648 -14.095485

121 1.007357 -4.383530 762 0.967082 -11.074226

123 1.019967 -3.831951 802 0.984900 -12.754068

126 0.990799 -4.465552 804 0.970577 -11.942936

128 1.015474 -4.750206 806 0.985882 -12.214161

129 0.985634 -4.484123 808 1.004199 -14.775319

131 1.018534 -5.661877 812 1.004199 -14.775319

132 0.988876 -4.339684 813 1.011594 -16.475117

221 0.976887 -6.372196 817 0.970577 -11.942936

222 0.982780 -4.980440 820 0.962858 -10.854013

241 0.987226 -4.396825 822 0.970577 -11.942936

260 0.979075 -4.860084 823 0.970577 -11.942936

311 0.970888 -12.114880 825 1.022046 -16.551048

313 0.993648 -14.095485 826 0.970577 -11.942936

316 0.957247 -12.838405 827 0.951738 -10.055145

317 0.993648 -14.095485 830 0.970577 -11.942936

318 0.986670 -13.285690 831 0.976525 -12.140112

330 0.993648 -14.095485 832 0.968616 -11.614055

370 0.990427 -14.816790 833 0.925404 -10.109039

371 0.970888 -12.114880 834 0.970577 -11.942936

400 0.975054 -11.967499 835 0.981927 -11.738632

460 0.884844 -10.966955 837 0.973573 -13.391067

491 0.970888 -12.114880 838 0.956531 -10.588513

521 1.017439 -13.174563 899 0.970577 -11.942936

531 0.939240 -10.377629 824 0.970577 -11.942936

540 0.990354 -13.866570 840 0.970577 -11.942936

552 0.970888 -12.114880 842 0.970577 -11.942936

555 1.016073 -15.025004 836 0.970577 -11.942936

580 0.993648 -14.095485 901 0.920003 -9.999206

591 0.970888 -12.114880 920 0.993648 -14.095485

601 0.993648 -14.095485 950 0.977669 -12.161698

602 0.939211 -10.789604 970 0.944758 -11.243663

611 1.013706 -14.690715 999 0.970577 -11.942936

621 1.015683 -15.253771

SRS FIA = Southern Research Station, Forest Inventory and Analysis; SPCD_EQ = species 

code equation; H1 = coefficient to convert CV4 (cubic volume to a 4-inch top) to CUSAW 

(cubic saw-log volume); H2 = coefficient to convert CV4 (cubic volume to a 4-inch top) to 

CUSAW (cubic saw-log volume).
20

Table A.8—Species code equation and associated coefficients for use in SRS FIA 

equation to convert cubic-foot volume to a 4-inch top to board-foot volume (use 

equation form BD000049)

SPCD_EQ

Coefficients

SPCD_EQ

Coefficients

I1 I2 I1 I2

10 -32.968494 40.900754 651 -43.831114 51.473501

43 -36.443637 44.723860 652 -43.831114 51.473501

60 -31.928229 40.082406 653 -32.151472 38.751286

67 -31.928229 40.082406 680 -33.469593 40.320487

68 -31.928229 40.082406 691 -62.218744 70.635109

90 -32.968494 40.900754 693 -42.670508 50.056472

107 -39.657770 48.447531 694 -45.206541 53.020202

110 -40.778119 49.493703 731 -45.419797 53.050199

111 -44.573295 53.682127 740 -46.585716 54.641538

115 -30.697896 38.676749 741 -46.585716 54.641538

121 -37.533739 46.221683 762 -46.585716 54.641538

123 -36.169514 44.588514 802 -40.853917 48.314853

126 -47.178011 56.153368 804 -39.207446 46.599115

128 -39.081750 47.663171 806 -41.609919 49.261334

129 -38.021863 46.299422 808 -39.405006 46.869861

131 -45.233296 54.320184 812 -39.405006 46.869861

132 -30.487486 37.943803 813 -57.253809 66.161822

221 -39.852794 47.638868 817 -39.207446 46.599115

222 -37.780331 45.512476 820 -39.258381 46.972932

241 -32.968494 40.900754 822 -39.207446 46.599115

260 -35.837266 43.682868 823 -39.207446 46.599115

311 -33.469593 40.320487 825 -52.928852 61.522970

313 -46.585716 54.641538 826 -39.207446 46.599115

316 -37.873060 44.918110 827 -33.821051 41.219217

317 -46.585716 54.641538 830 -39.207446 46.599115

318 -23.292189 29.478650 831 -46.836658 55.060205

330 -46.585716 54.641538 832 -37.716845 44.770685

370 -23.210675 29.141604 833 -34.016058 40.773236

371 -33.469593 40.320487 834 -39.207446 46.599115

400 -43.385922 51.122382 835 -41.637640 49.438943

460 -46.585716 54.641538 837 -42.235900 49.659282

491 -33.469593 40.320487 838 -32.557196 39.284646

521 -33.469593 40.320487 899 -39.207446 46.599115

531 -7.036861 11.665187 824 -39.207446 46.599115

540 -44.046785 51.632536 840 -39.207446 46.599115

552 -33.469593 40.320487 842 -39.207446 46.599115

555 -43.831114 51.473501 836 -39.207446 46.599115

580 -46.585716 54.641538 901 -7.456203 11.992934

591 -33.469593 40.320487 920 -46.585716 54.641538

601 -46.585716 54.641538 950 -37.777411 44.944982

602 -16.280751 21.457858 970 -33.168491 39.961348

611 -50.712592 59.264535 999 -39.207446 46.599115

621 -54.639851 63.549737

SRS FIA = Southern Research Station, Forest Inventory and Analysis; SPCD_EQ = species 

code equation; I1 = coefficient to convert CV4 (cubic volume to a 4-inch top) to board foot; I2 = 

coefficient to convert CV4 (cubic volume to a 4-inch top) to board foot.
21

Examples

We present three examples for using the Southern FIA 

Volume Equations User’s Guide: 

Example 1) Volume of interest—VOLCFGRS

Species—white oak

Diameter—18 inches

 Height—78 feet

 Defect—3 percent

Step 1—Use table 1 and figure 1 to identify the volume 

variable of interest. For example 1, we will use VOLCFGRS.

Step 2—From table A.1., locate the species equation code 

(SPCD_EQ) that corresponds to white oak (SPCD_EQ = 

802).

Step 3—Use table 2 to identify the ultimate equation 

necessary for calculating the desired volume—Equation = 

CU000067

Step 4—Use tree size specifications to identify the necessary set of coefficients. The example tree is a hardwood 

species with a d.b.h. >11 inches, and is therefore a sawtimber tree—Coefficients set = D1 and D2. 

Step 5—Use the Guide to Coefficients Tables to identify 

the individual coefficients for plugging into the appropriate 

equation—Coefficients table = table A.4.

Step 6—Pull individual coefficients from table A.4 for 

SPCD_EQ code 802—Coefficients = 0.148434 (D1) and 

0.00188 (D2). 

Step 7—Use equation CU000067 along with d.b.h., HT, and 

coefficients D1 and D2 to calculate cubic-foot volume from 

a 1-foot stump to a 4-inch top. 

Sawtimber Cubic Volume = 0.148434 + 0.00188 * (182 * 78)

Sawtimber Cubic Volume = 47.70

Example tree 1 has a total of 47.70 gross cubic feet.

Example 2) Volume of interest—VOLBFNET 

Species—loblolly pine

Diameter—10 inches

 Height—48 feet

 Defect—2 percent

Step 1—Use table 1 and figure 1 to identify the volume 

variable of interest. For example 2, we will use VOLBFNET.

Step 2—From table A.1, locate the species equation code 

(SPCD_EQ) that corresponds to loblolly pine (SPCD_EQ = 

131).

Step 3—Use table 2 to identify the ultimate equation 

necessary for calculating the desired volume—Equation = 

BD000049*

*Note—Equation BD000049 calculates a 

conversion ratio that is applied to cubic-foot 

volume calculated with equation CU000067 

to calculate board-foot volume.

Step 4—Use tree size specifications to identify the necessary set of coefficients. The example tree is a softwood 

species with a d.b.h. >9 inches, and is therefore a sawtimber 

tree—Coefficients set = D1, D2, I1, and I2. 

Step 5—Use the Guide to Coefficients Tables to identify 

the individual coefficients for plugging into the appropriate 

equation—Coefficients table = tables A.4 and A.8.

Step 6—Pull individual coefficients from table A.4 for 

SPCD_EQ code 131 for equation CU000067—Coefficients 

= –0.658316 (D1) and 0.002107 (D2) and table A.8 for 

SPCD_EQ code 131 for equation BD000049—Coefficients 

= –45.233296 (I1) and 54.320184 (I2). 

Step 7—Use equation CU000067 along with d.b.h., HT, and 

coefficients D1 and D2 to calculate cubic-foot volume from 

a 1-foot stump to a 4-inch top. 

Sawtimber Cubic Volume = –0.658316 + 0.002107 

 * (102 * 48)

So,

Sawtimber Cubic Volume = 9.46
22

Step 8—Use equation BD000049 along with d.b.h. and 

coefficients I1 and I2 to calculate board-foot volume from a 

1-foot stump to a 4-inch top.

So,

R = 3.65

Step 9—Multiply the sawtimber cubic volume from step 7 

by the conversion factor in step 8. 

Board-foot volume = 9.46 * 3.65

Board-foot volume = 34.58

VOLBFGRS = 34.58

Step 10—The example tree was recorded as having a total 

defect of 2 percent. Therefore, use the cubic-foot cull defect 

equation to deduct for missing and/or rotten material. 

VOLBFNET = 34.58 – (34.58 * ) 2.0

100

VOLBFNET = 33.89

Example tree 2 has a total of 33.89 board feet.

R = –45.233296 + 54.320184 * (1 – ) 1

10

Example 3) Volume of interest—VOLCFGRS

Species—Emory oak

Diameter—20 inches (d.r.c.)

 Height—35 feet

 Defect—not applicable 

Step 1—Use table 1 and figure 1 to identify the volume 

variable of interest. For example 1, we will use VOLCFGRS.

Step 2—From table A.1, locate the species equation code 

(SPCD_EQ) that corresponds to Emory oak (SPCD_EQ = 

810).

*Note—Table A.1 provides a citation (Chojnacky 

1988) instead of a species equation code. In some 

cases, particularly tree species collected in western 

Texas, SRS FIA utilizes volume equations developed 

outside of the southern region. When applicable, table 

A.1 provides the citation for the publication where the 

appropriate volume equation(s) can be found. 

Step 3—Use the citation provided to locate the appropriate 

equation. In this case Chojnacky (1988) provides the 

following equation for single-stem oaks:

where

Example tree 3 has a total of 38.97 gross cubic feet.

*Note—Chojnacky (1988) states that gross cubic 

volume includes all wood and bark of all stems and 

branches >1.5 inches.

X = ( ) DRC2

1000

Gross Cubic – foot Volume = 6.571 + (2.4048 * X) 

– ( ) 17.704

X


Oswalt, Christopher M.; Conner, Roger C. 2011. Southern forest inventory and 

analysis volume equation user’s guide. Gen. Tech. Rep. SRS–138. Asheville, NC: 

U.S. Department of Agriculture Forest Service, Southern Research Station. 22 p.

Reliable volume estimation procedures are fundamental to the mission of the Forest 

Inventory and Analysis (FIA) program. Moreover, public access to FIA program 

procedures is imperative. Here we present the volume estimation procedures used 

by the southern FIA program of the U.S. Department of Agriculture Forest Service 

Southern Research Station. The guide presented includes a description of the relevant 

variables populated in the public FIA database, a description of the set of equations 

used to estimate tree volume in the south, the volume equations, definition of terms, 

species-specific (or species group) coefficients for each equation, and examples of 

estimating individual tree volume.

Keywords: Biomass, FIA, volume, volume equation, volume estimation. 
The Forest Service, U.S. Department of Agriculture (USDA), is 

dedicated to the principle of multiple use management of the 

Nation’s forest resources for sustained yields of wood, water, 

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provide increasingly greater service to a growing Nation.

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