Changes to the standard EWDB structure required for the Maine Inventory are italicized

Foreword

Forest Inventory and Analysis (FIA) is a continuing endeavor mandated by Congress in the Forest and Rangeland Renewable Resources Planning Act of 1974 and the McSweeney-McNary Forest Research Act of 1928. Its objective is to periodically determine the extent, condition, and volume of timber, growth, and depletions of the Nation's forest land. This kind of up-to-date information is essential to frame realistic forest policies and programs. USDA Forest Service regional experiment stations are responsible for conducting these inventories and publishing summary reports for individual states.

Forest inventories for the eastern United States are conducted by four experiment stations. The locations of the headquarters of each of these stations and the states for which they conduct inventories are shown in figure 1.

In addition to published reports, the Forest Service can also provide portions of the data collected in each inventory to those interested in further analysis. This report describes a standard format in which data can be obtained at a reasonable cost by anyone. This standard format, referred to as the Eastwide Data Base (EWDB) structure, was developed to provide users with as much data as possible in a manner consistent between states. EWDB files can be obtained for any State inventory conducted after 1988, shortly after the inventory is finalized. Files for many State inventories conducted before 1988 are also available; however, some data fields may be empty or the items may not have been collected or computed as described in this report. These inconsistencies will be described in an addendum to this document for the particular state.

Table of Contents

Chapter 1 -- The Eastwide Data Base

Chapter 2 -- FIA Sampling and Estimation Procedures

Chapter 3 -- Data Base Structure

Record type 10

Record type 20

Record type 30

Chapter 4 -- Using the Eastwide Data Base

Chapter 5 -- Ordering data

Appendix 1 -- Eastwide Core Tables

Appendix 2 -- FIA Survey Unit Names and Codes

Appendix 3 -- Species Groups Used by eastern FIA projects

References

Chapter 1 -- The Eastwide Data Base

Periodic forest inventories are conducted for every State in the United States. In the east, these inventories are usually conducted every five to 15 years. Inventory findings are published in a series of statistical and analytical reports published by the regional USDA Forest Service Experiment stations. Many forest inventory data users require unpublished information that can be produced from the data collected in the State inventories. Special information needs include:

1) Standard tables for geographic areas other than those published

2) Resource data which is consistent between States and Regions

3) Projections of timber resources based on various assumption and models

4) Information about specific conditions and/or species needed for detailed analyses

In the past, individual special data requests have been handled differently by each of the four eastern FIA projects, depending on the type of request and the projects' data processing capabilities. It has been particularly difficult to analyze data from more than one FIA project because of inconsistencies in data collection and processing methods between FIA projects.

One effort to make FIA data more compatible between States was the development of core tables which are being published in every eastern FIA report. A sample set of these tables is provided in Appendix 1. The core tables present basic timber resource information in a consistent format from one State to another. The introduction of the core tables in 1985 made it easier to compare the forest resources of areas in different States and to assess the total resource of an area that crosses State and/or Region boundaries.

A more recent effort to provide FIA data consistent throughout the east, has been the creation of the Eastwide Data Base (EWDB) for FIA plot data. The idea of the EWDB was for each project to produce a set of data files for the most recent inventory of each State in its area of responsibility. All the files are written in the same format and contain all the data items needed to produce the core tables, plus other data items that all four projects collect. The EWDB contains all the data needed to run the Timber Resource Inventory Model (TRIM). Items which are not available from all four projects are not part of the EWDB. The EWDB data files could be produced for a State as soon as the state statistical report is completed. An outside user can then easily obtain a copy of this file at a reasonable cost (presently $500 per State) and use it to do analysis suited to their individual needs.

Chapter 3 of this publication gives a detailed description of the EWDB structure. Chapter 4 explains how to use the files to compute basic estimates of area, volume, biomass, number of trees, growth, mortality, and removals. The last chapter tells how to obtain copies of the EWDB for a State.

Chapter 2. FIA Sampling and Estimation Procedures

Users of the EWDB need a basic understanding of FIA sampling and estimation procedures in order to understand the type of data available. Here, we present a general discussion of these sampling procedures. Specific sampling methods vary between Regions, and even between States within a Region. Publications cited in this manual give more detailed information concerning methods used by each Region. Users who require additional information about sampling procedures for a specific State should contact the FIA project responsible for the State's inventory.

Each State inventory begins with the interpretation of an aerial-photo sample that classifies the land by various photo classes. The total area of a sample comes from outside sources (usually Bureau of Census reports). The photo classes used are based on land-use (pasture, cropland, urban, etc.). For forested land, more detailed classes are sometimes defined based on criteria such as forest type, volume per acre, stand size, stand density, ownership and/or stand age. Then, ground plots are taken to adjust the aerial photo sample for changes since the date of photography and misclassification and to obtain estimates that can not be made from the aerial photography. The photo classification of these ground plots, together with the area estimates from the photo sample, is used to assign area expansion factors to all ground plots. These area expansion factors are used to expand values observed on the plot from a per acre basis to a population basis. An area expansion factor is basically the area (in acres) that the plot represents for estimation purposes. The sampling area, or level at which expansion factors are assigned, is different from State to State, as is the scheme used to assign photo-interpretation classes. Persons interested in the details of how these expansion factors were assigned to the ground plots for a particular State should contact the appropriate FIA project.

FIA plots are designed to cover a one-acre sample area; however, not all trees on the acre are measured. Various arrangements of fixed radius and variable radius (prism) sample points are used to select sample trees to be measured. Ground plots may be new plots that have never been measured before, or remeasurement plots that have had measurements taken for the previous inventory. For all plots, several observations are recorded for each sample tree, including its DBH, species, and other measurements that enable us to predict the tree's volume, growth rate and quality. These tree measurements form the basis of the data on the tree records in the EWDB.

Some of the data items in the EWDB come directly from field measurements; others are computed from tree measurements. Net cubic foot volume is a computed item. Each FIA project uses some type of volume equation to compute this volume based on diameter breast height (DBH) and other tree and/or stand attributes. Although equations vary from State to State, they were all designed to compute the same volume.

One important computed item is the tree expansion factor VOLFAC. This item expresses the number of trees per acre that each sampled tree represents in the current inventory. It is the inverse of the size of the plot the tree was sampled on. For example, if the plot design samples trees under 5 inches DBH on a single 1/100th acre fixed radius plot, this item would have the value 100 trees per acre for a tree less than 5 inches DBH. If trees 5 inches DBH and larger are sampled with ten 37.5 BAF (English) prism points, as is common with FIA plots, the expansion factor would depend on the DBH of the tree. Under such a sample, a 14.0 inch tree would have an expansion factor of 3.51 trees per acre, again the inverse of the plot size1.

There are three other computed expansion factors in the data base, GROFAC, MORTFAC and REMVFAC. They are used to compute growth, mortality and removals. The growth factor (GROFAC) expresses an estimate of how many trees per acre of annual growth are represented by a given sample tree. In sample designs that have remeasurement plots this factor is applied to trees that were live and measured at both occasions. (survivors) and to live trees that are measured for the first time (ingrowth). The mortality factor (MORTFAC) expresses an estimate of how many trees per acre of annual mortality are represented by a given sample tree In sample designs that have remeasurement plots, this value is zero for a tree that did not die over the remeasurement period. For trees that did die, MORTFAC is a function of the tree expansion factor and the remeasurement period. Some State inventories also estimate mortality from new ground plots. In these cases, mortality is estimated from either a mortality prediction equation that predicts the probability that a tree will die over some time period, or from a field estimate of mortality based on the measurement of dead trees and an estimate of when they died.

The removals factor (REMVFAC) is computed and used like MORTFAC. REMVFAC is the number of trees per acre of annual removals that the sample tree represents. It is computed based on observations of trees cut on either new or remeasured plots, depending on the inventory design. None of the eastern FIA projects use removals prediction equations to estimate removals.

The items in the plot record are either observations of a specific condition at the plot center, or estimates of average conditions on the acre sampled by the plot. Ownership is an example of a specific condition recorded at plot center, rather than averaged over the plot. It is possible that a plot area may overlap more than one owner. When this occurs, the ownership at plot center determines the recorded ownership class. Basal area is an example of an item averaged over the entire plot. If the plot fell in two stands with different basal areas, the value recorded in BA will represent their average basal area. In some State inventories, plots falling on more than one stand were shifted so that they fell in one stand. EWDB users concerned about field procedures should check with the FIA project for more information.

____________________________________________________

The plot size of a 14.0 inch tree on a single 37.5 BAF (English) prism plot would be:

(14.02 x pi)/(37.5 x 22 x 122) = .0285 acres.

The plot size of this tree on a ten point cluster would be ten times this or .285 acres, producing an expansion factor of 3.51

We have made every effort to make the data in the EWDB as consistent as possible from one State to another. Therefore, although differences in field and estimation procedures do exist between States, the data in the EWDB for different States is compatible. Differences that do exist are minor, and should have little or no impact on most uses of this data.

Accuracy Standards

Forest inventory plans are designed to meet sampling error standards for area, volume, growth and removals provided in the Forest Service Handbook. These standards, along with other guidelines, are aimed at obtaining comprehensive and comparable information on timber resources for all parts of the country. In the east, FIA inventories are commonly designed to meet the specified sampling errors at the State level at the 67 percent confidence limit (one standard error). A three percent error per one million acres of timberland is the maximum allowable sampling error for area. Five percent per one billion cubic feet of growing stock on timberland is applied to volume, removals, and net annual growth. While the sampling error for area is the maximum allowable, the sampling errors for volume, removals, and growth are to be achieved as closely as possible.

How does this impact the user of the EWDB? It should sound a cautionary note. FIA inventories are extensive inventories which provide reliable estimates for large sampling areas. As data are subdivided to smaller and smaller areas, such as a geographic unit or a county, the sampling errors increase and the reliability of the estimates goes down. For example, a State with 5 million acres of timberland would have a maximum allowable sampling error for area of 1.3%, a geographic unit within that State with 1 million acres of timberland would have a 3.0% maximum allowable sampling error, and a county within that State with 1 hundred thousand acres would have a 9.5% maximum allowable sampling error at the 67 percent level.

Chapter 3. Data Base Structure

The EWDB has a simple hierarchical structure. This structure corresponds to FIA plot collection and data processing methods and contains data at three levels. The highest level is the county, followed by the plot level, and then, finally, the tree level.

Data is stored as one of three record types (10-county, 20-plot, 30-tree), each with its own format. A record contains information for one level of the hierarchy.

The EWDB consists of separate sequential files for each State. Each flat file is made up of all three record types. Files for a particular State are maintained by the FIA project responsible for the State's inventory (fig. 1). Copies can be obtained directly from the FIA projects (see Chapter 4).

The following is a detailed description of the format of the 3 record types in the EWDB. The description of each record type begins with a table (Tables 1, 2 and 3) that gives the name of each element or data item in the record, the FORTRAN format that should be used to read the item, the columns it occupies, and finally the unit of measure of the item. The final column in each of these tables indicates the key items that uniquely identify an occurrence of a data record. For record type 20, the plot record, this table also contains a section that explains what kinds of plots each data item comes from. For example, data items related to forest cover were not recorded for plots on nonforest land.

For each data item in a record, there is a section that includes all the information in Tables 1, 2 and 3, plus a longer name for the data item, a detailed description including explanations of it, how the item was measured or estimated and how the item can be used. For coded items, a listing of the possible codes and their meanings is also given.

Record Type 10

Table 1. Record type 10, County Record

Columns 9-12 contain 0000 on all county records.

1. RECTYPE Record type -- Record type 10 contains information that

(coded) identifies and describes the county. There is one record type

10 for every county in the state covered by an EWDB file.

Col. 1-2

2. STATE State code -- The two-digit Bureau of the Census, Federal

(coded) Information Processing Standards (FIPS) code number of the

state. For states in the EWDB these code are:

Col. 3-4

3. UNIT Survey unit number -- Forest inventory and analysis survey

(coded) unit identification number. Survey units are groups of

counties within each state. See appendix 2 for codes.

Col. 5

4. COUNTY County code -- The three-digit FIPS code number for each

(coded) county, parish or other similar governmental unit in a state.

1980 Bureau of the Census FIPS codes are used.

Col. 6-8

5. CTYNAM County name -- County name as recorded by the Bureau of the

(name) Census, 1980. County names are left justified. If a county

name is longer than 28 characters it is truncated to the first 28

Col. 13-40 characters.

6. STNAME State name -- The 2 character state abbreviation.

(name)

Col. 41-42

7. CYCLE Inventory cycle number -- Identifies the current cycle number

(number) for the data in a data base. For example, a 4 would indicate the

data came from the fourth inventory of that state.

Col. 43-44

8. DATE Date of inventory -- The calendar year that the current

(year) inventory data represents, for example 1984. FIA data is often

collected over more than one year however, a specific year is

Col. 45-48 selected that indicates when the majority of the data was collected. FIA publications based on an inventory are said to be an analysis of the forest resource as of this date.

Record Type 20

Table 2. Record type 20, plot record

A = Recorded on all plots; F = Recorded on all forested plots (GLUCUR or GLUOLD = 20, 25, 40 or 45); T = Recorded on all timberland plots (GLUCUR or GLUOLD = 20). An item will be zero for plots that the element is not recorded on.

1. RECTYPE Record type -- Record type 20 contains information that

(coded) identifies and describes the plot.

There is one record type 20 for every plot in an EWDB file.

Col. 1-2

2. STATE State code -- The two-digit Bureau of the Census, Federal

(coded) Information Processing Standards (FIPS) code number of the

state. For states in the EWDB these code are:

Col. 3-4

3. UNIT Survey unit number -- Forest inventory and analysis survey

(coded) unit identification number. Survey units are groups of

counties within each state. See appendix 2 for codes.

Col. 5

4. COUNTY County code -- The three-digit FIPS code number for each

(coded) county, parish or other similar governmental unit in a state.

1980 Bureau of the Census FIPS codes are used.

Col. 6-8

5. PLTNUM Plot number -- A four digit plot number.

(coded) Plot numbers are unique within counties, but may be repeated

within a state or survey unit.

Col. 9-12

6. CNDTN Condition/ecotype code – A code used to distinguish between

(coded) two or more distinct conditions on the plot, where condition

is defined as a distinct change in land use, forest type

Col. 13-14 stand origin or stand size.

7. OWNER Ownership code -- Legal owner of the land the plot was taken

(coded) on at the time of the current inventory. In addition, this code

indicates if private lands have been leased to forest industry.

Col. 15-16

If lease status was unknown, the owner codes for unleased (40, 60, 70) were recorded. If corporate status was unknown, the owner codes for individual were recorded (70, 90).

8. TYPCUR Current forest type -- The predominant forest type of the area

(coded) the plot was taken in. Forest type is determined for each forested condition. This type is based on the tree species

forming a plurality of all live stocking within the stand.

Col. 17-18 This is a two digit coded element, where the first digit represents a general type group and the next digit specifies an eastwide standard type, as shown below. These types come from the standard set of local forest types in the Forest Service handbook, with several types added. Not every type is recognized in every state and type names used in published reports may differ from state to state. For example, the 1986 Indiana report shows area in a type called lowland oak. In the data base, the plots that represent this area are coded 61--swamp chestnut oak-cherrybark oak. The assignment of a forest type to a stand is dependent on the determination of stocking. Each FIA project has somewhat different methods of assigning stocking. Information on how data was assigned to these types for a particular state can be obtained directly from the FIA project responsible for the inventory and/or in the following publications:

North central:

Hansen & Hahn, 1992

Northeastern:

Contact Thomas Frieswyk, Northeastern Forest Experment Station.

Southeastern:

Contact Joseph F. Glover, Southeastern Forest Experment Station.

Southern:

May, 1990

9. TYPOLD Old forest type -- Forest type at the previous survey. Criteria

(coded) for assigning types and codes are the same as for TYPCUR.

TYPEOLD is zero for new or temporary plots.

Col. 19-20

10. STDAGE Stand age -- The age (in years) of the stand the plot is in. Stand age is determined for each forested condition. If

(years) actual age is unavailable, or the stand is a mixed age stand,

999 was entered. For some older inventories this was recorded

Col. 21-23 in ten or twenty year age classes and the value recorded is the center of the age class. Any inventory dated 1983 or later will contain stand ages recorded to the nearest year. Some inventories dated 1982 or earlier may have used age classes.

11. STDSIZE Stand size class -- A classification of forest land based on the

(coded) predominant stocking by the size of all live trees present on

each forested condition.

Col. 24 Sawtimber trees are 9" DBH or larger for softwoods, and 11" DBH or larger for hardwoods. The dbh range for poletimber trees is from 5.0" to 8.9" for softwoods and from 5.0" to 10.9" for hardwoods. Seedling and sapling trees are smaller than 5" dbh. Stand size class is determined by the percent stocking represented by various size trees. More detailed information on how stand size class was determined from plot data in a particular state can be obtained directly from the FIA project responsible for the inventory and/or in the following publications:

North central:

Hansen & Hahn, 1992

Northeastern:

Contact Thomas Frieswyk, Northeastern Forest Experment Station.

Southeastern:

Contact Joseph F. Glover, Southeastern Forest Experment Station.

Southern:

May, 1990

12. STORCUR Current stand origin -- Identifies whether the condition is

(coded) planted or of natural origin. To be a planted

stand the majority of the trees that define the stand size

Col. 25 class and forest type must have been originated by planting or direct artificial seeding.

13. STOROLD Old stand origin -- Same as STORCUR at the time of the last

(coded) inventory. STOROLD is zero for new or temporary plots.

Col. 26

14. SITECL Site productivity class -- A classification of timber lands in

(coded) terms of inherent capacity to grow crops of industrial wood.

The class identifies the average potential growth in cubic

Col.27 feet/acre/year (trees 5 inches dbh or greater to a 4 inch top) and is based on the culmination of mean annual increment of fully stocked natural stands. Site productivity class is determined for each forested condition level.

15. SI Site index -- Site index in feet of the forested condition

(feet) A site index of 100 or more is recorded as 99.

Col. 28-29

16. SIAGE Site index base age -- The base age of the site index curves used

(years) to get Site index.

Col. 30-31

17. ADFOR Administrative forest -- A three digit code that indicates the

(coded) National Forest that the plot is located on. Present for

National Forest plots only (owner=11), zero for all other

Col. 32-34 owners.

18. GLUCUR Current land use class -- A classification that indicates the

(coded) basic biological potential of the land and its current use and

legal status. Initially, land is broken into two broad

Col. 35-36 classes (forest and non-forest). These broad classes are separated into more specific classes. It is these specific classes that are actually coded. Current land use class is determined for each condition on the plot.

19. GLUOLD Old land use class -- Same as GLUCUR at the time of the last

(coded) inventory. GLUOLD is zero for new or temporary plots.

Col. 37-38

20. BA Basal area -- The summed-cross sectional area at breast height

(sq. ft.) of all live trees 1.0 inches dbh or larger on the plot.

BA is determined for each forested condition.

Col. 39-41

21. SLOPE Slope -- The average percentage of the deviation from the

(percent) horizontal over the sample acre. Valid values are 0 through

99. Slope is determined for each forested condition.

Col.42-43

22. ASPECT Aspect -- The direction of drainage for the majority of the plot,

(degrees) recorded as the azimuth of this direction. Valid values are 0

through 360. 0 is only valid when slope is also 0.

Col. 44-46 Aspect is determined for each forested condition.

23. PHYSIO Physiographic class -- A measure of soil and water conditions

(coded) that affect tree growth on the plot.

Physiographic class is determined for each forested condition.

Col. 47

24. TREATOP Treatment opportunity class -- Identifies the physical

(coded) opportunity to improve stand conditions through application

of management practices. The 11 classes are defined as follows:

Col. 48-49 Treatment opportunity is determined for each forested condition.

25. INHIBPC Percent inhibiting vegetation -- Percent of the area coverd by

(percent) inhibiting vegetation. A value of 99 is recorded for areas that

are entirely (100%) covered with inhibiting vegetation. This

Col. 50-51 item is not collected in the Northeastern region.

26. NONSTPC Percent nonstocked -- Percent of the area the plot was taken in

(percent) that is nonstocked with all live trees (0-100 percent basis). A

value of 99 is recorded for plots that have no live stocking

Col. 52-53 (100% nonstocked.) This item is not available for states inventoried by the Northeastern Forest Experiment Station

27. GRSTKPC Growing stock stocking -- Stocking of the forested condition by

(value) growing-stock trees. Data is in the form of an absolute

stocking value (0-167). The Northeastern project is using the

Col. 54-56 national standard stocking algorithm for all states dated 1995 and later. Data is in the form of an absolute stocking value (0-100) More detailed information on how stocking values were determined from plot data in a particular state can be obtained directly from the FIA project responsible for the inventory and/or in the following publications:

North central:

Hansen & Hahn, 1992

Northeastern:

Contact Stan Arner, Northeastern Forest Experment Station.

Southeastern:

Contact Joseph F. Glover, Southeastern Forest Experment Station.

Southern:

May, 1991

28. ALSTKPC All live stocking -- Stocking of the forested condition by live

(value) trees of any species. Data is in the form of absolute stocking

value. See item 27,

Col. 57-59 The following classification of plots based on the stocking value (all live and/or growing stock) is common in FIA reports.

Stocking values for states other than NEFIA and for NEFIA states dated 1994 and earlier

Stocking values for NEFIA states dated 1995 and later

29. REMPER Remeasurement period -- The number of years between

(years) measurements of remeasured plots. This item is zero for new

F3.1 or temporary plots. Remeasurement period is based on the

Col. 60-62 number of growing seasons between measurements. Allocation of portions of the growing season by month is different for each station. Contact the individual station for information on how this was done for a particular state.

30. EXPACR Area expansion factor -- The number of acres this condition

(acres) represents for estimates of area variables such as forest type

and land use class. The sum of EXPACR over all record 20's

Col. 63-67 in a file is the total land area of the state.

31. EXPVOL Volume expansion factor -- This is the number of acres that the

(acres) plot represents for estimating current volume and number of

trees. Volume will be 'expanded' over the appropriate acreage

Col. 68-72 by multiplying EXPVOL x each volume/acre element on the tree record (record type 30). Total volume in a state is calculated by summing the expanded volume estimates from all trees on all plots in an EWDB file. Number of trees are expanded in a similar fashion.

32. EXPGRO Growth expansion factor -- This is the number of acres that the

(acres) plot represents for growth estimation. Growth will be

'expanded' over the appropriate acreage by multiplying

Col. 73-77 EXPGRO x each growth/acre element on the tree record (record type 30). Total growth in a state is calculated by summing these expanded estimates from all trees on all plots in an EWDB file. Some plots will not have a value in this field. In some state inventories, growth is only estimated on remeasured plots. In such cases, this item would be zero for new or temporary plots.

33. EXPMOR Mortality expansion factor -- This is the number of acres that

(acres) the plot represents for mortality estimation. Mortality will be

'expanded' over the appropriate acreage by multiplying

Col. 78-82 EXPMOR x each mortality/acre element on the tree record (record type 30). Total mortality in a state is calculated by summing these expanded estimates from all trees on all plots in an EWDB file. Some plots will not have a value in this field. In some state inventories, mortality is only estimated on remeasured plots. In such cases, this item would be zero for new or temporary plots.

34. EXPREM Removals expansion factor -- This is the number of acres that

(acres) the plot represents for removals estimation. Removals will be

'expanded' over the appropriate acreage by multiplying

Col. 83-87 EXPREM x each removals /acre element on the tree record (record type 30). Total removals in a state is calculated by summing these expanded estimates from all trees on all plots in an EWDB file. Some plots will not have a non-zero value in this field. In some state inventories, removals are only estimated on remeasured plots. In such cases, this item would be zero for new or temporary plots.

36. LONG Longitude -- The longitude of the plot recorded to the nearest

(seconds) 100 seconds.

F7.1

Col. 88-94

37. LAT Latitude -- The latitude of the plot recorded to the nearest 100

(seconds) seconds.

F7.1

Col. 95-101

38. MDATE Measurement date -- The date the plot was actually measured.

(date) This date is coded YYMM where YY is the last 2 digits of the

YYMM year (88 for 1988) and MM is the month (02 for February). This

Col. 102-105 date may be different from DATE on the county record.

Record type 30

Table 3. Record type 30, tree record

1. RECTYPE Record type -- Record type 30 contains information that

(coded) identifies and describes each tree on a plot.

Col. 1-2

2. STATE State code -- The two-digit Bureau of the Census, Federal

(coded) Information Processing Standards (FIPS) code number of the

state. For states in the EWDB these code are:

Col. 3-4

3. UNIT Survey unit number -- Forest inventory and analysis survey

(coded) unit identification number. Survey units are groups of

counties within each state. See appendix 2 for codes.

Col. 5

4. COUNTY County code -- The three-digit FIPS code number for each

(coded) county, parish or other similar governmental unit in a state.

1980 Bureau of the Census FIPS codes are used.

Col. 6-8

5. PLTNUM Plot number -- A four digit plot number.

(coded) Plot numbers are unique within counties, but may be repeated

within a state or survey unit.

Col. 9-12

6. CNDTN Condition/ecotype code – A code used to distinguish between

(coded) two or more distinct conditions on the plot, where condition

is defined as a distinct change in land use, forest type

Col. 13-14 stand origin or stand size.

7. POINT Point number -- A two-digit point number used to identify the

(number) point (of the sample cluster) the tree was measured on.

Col. 15-16

8. TREE Tree number -- A number used in combination with

(number) status to uniquely identify a tree on a point.

Col. 17-21

9. STATUS Tree status -- A one-digit code that identifies whether the

(coded) sample tree is live, cut, or dead.

Col. 22

10. SPP Species code -- A three-digit standard tree species code. Codes

(coded) for trees in the EWDB are listed in appendix 3.

Col. 23-25

11. SPPGRP Species group -- A two-digit eastwide species group number.

(coded) This number is used to produce many of the core tables.

The assignment of individual species (SPP) to these groups is

Col. 26-27 shown in appendix 3. Individual stations may further break these species groups down for published tables, however this is a common list that all published core tables must match. For example the North Central Station routinely separates the eastern white and red pine group into two groups for publication in Minnesota, Wisconsin and Michigan. What is not allowed is for a station to combine groups in these groups in the core tables. For example SPPGRP 26 and 27 will not be combined in tables and reported as "other hardwoods".

12. DBHCUR Current diameter -- The current diameter of the sample tree at

(inches) breast height (in inches, to last one-tenth inch). For dead,

F3.1 salvageable dead, or snag trees (STATUS = 2, 4 or 5) this is the

Col. 28-30 measured diameter of the tree. If the bark has fallen off the tree, an estimated bark thickness was used to obtain this diameter so that it is an estimator of the diameter at the time the tree died. For cut trees (STATUS=3) the value in this item is somewhat different depending on the FIA Unit that produced the file. The Southern and Southeastern units estimate the dbh of a cut tree at the time it was cut, and the Northeastern and North Central units record this diameter as the diameter at the last measurement. The Southern unit records this diameter as the diameter at the last measurement for trees on plots that change land use from timberland to other land uses.

13. DBHOLD Old diameter -- The diameter of the sample tree at breast height

(inches) recorded at the previous measurement (in inches, to the last

F3.1 one-tenth inch).

Col. 31-33

14. TGRADE Tree grade -- This item is measured somewhat differently by

(coded) each eastern FIA unit. The following is a short discussion of

each unit's grading procedures. For more information, check

Col. 34 with the individual FIA project.

North central:

For hardwoods the tree grade is based on Hanks, 1976. For softwoods tree grade is the log grade of the first sawlog in the tree. If a sawtimber size tree does not have one 12-foot or two 8-foot sawlogs that meet minimum log grade requirements, it is a cull tree (tree grade 5) and is also given a TCLASS other than 2. A growing stock hardwood tree may also have a tree grade 5 if there is not a gradeable 12-foot log in the first 16, but there are at least one 12-foot or two 8-foot sawlogs in the tree. Tree grade is only recorded on a subset of the sample plots in many states in the north central region. On plots where tree grade was not taken, all sawtimber size trees will have a tree grade 9.

Northeastern:

For hardwoods and cypress, the tree grade is based on Hanks, 1976. For yellow pines, the tree grade is based on Schroeder et al., 1968. For other softwoods, tree grade is based on Brisbin and Souderman, 1971.

Southeastern:

For hardwoods and cypress, the tree grade is based on Hanks, 1976. For yellow pines, the tree grade is based on Schroeder et al., 1968. For other softwoods, tree grade is based on Brisbin and Souderman, 1971.

Southern:

Tree grades 1-3 for hardwoods and cypress are based on standards defined in Hanks, 1976; grade 4 is used for trees that do not qualify for grade 3, but which contain a butt log that qualifies them for a tie and timber grade. Softwoods are assigned grades as described in USDA, Forest Service Handbook, 1972, Forest Survey Handbook (4809.11), Sections 46.8 and 75.1

This item is nonzero for all sawtimber size trees regardless of status. Tree grade is not measured on all sawtimber size trees on every plot. Sawtimber size trees that were graded but do not contain a gradable log are given a tree grade 5. Procedures differ from one state to the next. Sawtimber size trees that were not graded because of the sampling design have a tree grade of 9. Trees smaller than sawtimber receive a tree grade of zero.

15. TCLASS Tree class -- A one-digit code that indicates the general quality

(coded) of the tree. For cut, dead and salvageable dead trees, TCLASS

reflects conditions at the time the tree died or was cut. The

Col. 35 following classes are represented:

16. CRATIO Crown ratio -- A one-digit code that indicates the percentage of

(coded) the total tree height that supports a full, live, green, healthy

foliage that is effectively contributing to tree growth.

Col. 36 (Expressed as a percent of total tree height to the nearest 10% and recorded as a one digit code for all trees 1-inch dbh and larger).

17. CRCLS Crown class -- A one-digit code that primarily reflects the

(coded) amount of sunlight received rather than the conventional

"crown position" found in forestry textbooks. Recorded as a

Col. 37 one-digit code for the following classes:

18. DAMAGE Damage -- Damage is recorded for live trees if the presence of

(coded) damage or pathogen activity is serious enough to reduce the

quality or vigor of the tree. When a tree is damaged by more

Col. 38-39 than one agent, the most severe damage is coded. When no damage is observed on a live tree, 00 is recorded. Damage recorded for dead trees is the cause of death. When the cause of death cannot be determined for a tree, 00 is recorded. Each inventory unit records specific codes that may vary from one state to the next. These codes fall within the following ranges. For the specific codes used in a particular state, please contact the FIA unit responsible for that state directly.

19. VOLFAC Volume expansion factor -- This is the number of trees per acre

(trees/acre) (current) that the tree record represents for calculating

volume, biomass, number of trees and growth.

Col. 40-47 Per acre tree values are calculated by multiplying VOLFAC x (NETCFVL, NETCFSL, NETBFVL, TOTBIO, MERBIO) for each tree (record type 30). Totals are calculated by summing the product of per acre values and the appropriate area expander from record 20.

20. GROFAC Growth expansion factor -- This is the number of trees per

(trees/acre) acre that the tree record represents for calculating

growth. Growth per acre is calculated by multiplying

Col. 48-55 GROFAC x (NETCFGR, or NETBFGR) for each tree (record type 30). Total growth is calculated by summing the product of per acre growth and the appropriate area expander from record 20. This item is zero if the tree does not contribute to growth.

21. MORTFAC Mortality expansion factor -- This is the number of trees per

(trees/acre) acre that the tree record represents for calculating

mortality. Mortality per acre is calculated by multiplying

Col. 56-63 MORTFAC x (NETCFRM, or NETBFRM) for each tree (record type 30). Total mortality is calculated by summing the product of per acre mortality and the appropriate area expander from record 20. This item is zero if the tree does not contribute to mortality.

22. REMVFAC Removals expansion factor -- This is the number of trees per

(trees/acre) acre that the tree record represents for calculating

removals. Removals per acre are calculated by multiplying

Col. 64-71 REMVFAC x (NETCFRM, or NETBFRM) for each tree (record type 30). Total removals are calculated by summing the product of expanded per acre removals and the appropriate area expander from record 20. This field should be zero if the tree does not contribute to removals.

23. NETCFVL Net cubic foot volume -- The net volume of wood in the

(cubic feet) central stem of a sample tree 5-inches dbh or larger from a 1-

F8.4 1-foot tall stump to a minimum 4-inch top dob or to where the

Col. 72-79 central stem breaks into limbs all of which are less than 4 inches dob. This is a per tree value and must be multiplied by one of the above tree factors to obtain per acre information. Trees with DBHCUR less than 5.0 have zero in this field. All trees with DBHCUR 5.0 or larger (including dead, salvageable dead and cut trees) have entries in this field.

24. NETCFSL Net cubic foot volume in the sawlog -- The net volume of

(cubic feet) wood in the central stem of a sample tree of sawtimber size

F8.4 (9 inches dbh minimum for softwoods, 11 inches dbh

Col. 80-87 minimum for hardwoods) from a 1-foot stump to a minimum top dob (7 inches for softwoods, 9 inches for hardwoods) or to where the central stem breaks into limbs all of which are less than the minimum top dob. This is a per tree value and must be multiplied by one of the above tree factors to obtain per acre information. Trees with DBHCUR less than 9.0 (11.0 for hardwoods) should have zero in this field. All larger trees (including dead, salvageable dead and cut trees) have entries in this field if they are growing stock trees (TCLASS = 2). All rough and rotten trees (TCLASS = 3 or 4) have zero in this field).

25. NETBFVL Net cubic foot volume in the sawlog -- The net volume of

(Board feet) wood in the central stem of a sample tree of sawtimber size

(9 inches dbh minimum for softwoods, 11 inches dbh for hardwoods)

Col. 88-95 minimum for hardwoods) from a 1-foot stump to a minimum top dob (7 inches for softwoods, 9 inches for hardwoods) or to where the central stem breaks into limbs all of which are less than the minimum top dob. Volume is based on International 1/4 inch scale. This is a per tree value and must be multiplied by one of the above tree factors to obtain per acre information. Trees with DBHCUR less than 9.0 (11.0 for hardwoods) have zero in this field. All larger trees, including dead, salvageable dead and cut trees, should have entries in this field if they are growing stock (TCLASS = 2). All rough and rotten trees (TCLASS = 3 or 4) have zero in this field.

Note:

NETCFVL, NETCFSL and NETBFVL are computed values. These volumes are all based on DBHCUR and therefore represent the volume at current inventory for live trees (STATUS = 1) and volume at the time the tree died for dead, salvageable dead and snags (STATUS = 2, 4, or 5). For cut trees (STATUS = 3) the differences between FIA units presented in DBHCUR are applicable here. Methods used to compute these volumes are given in the following publications:

North central:

MN, WI, MI, ND, SD: Hahn, 1984

IA, MO, NE, KS: Hahn & Hansen, 1991

IL, IN: Smith and Weist, 1982

Northeastern:

All states: Scott, 1979 and Scott, 1981

Southeastern:

All states: Cost, 1978

Southern:

Current volumes are computed using Simalian's formula with measured merchantable heights and upper stem diameters following procedures described in Grosenbaugh, 1964. Volumes for dead and cut trees are computed using regression equations developed by species groups in each survey (see Kelly and Beltz, 1987). General information is also contained in selected state survey reports (Rossen et al., 1988; McWilliams and Lord, 1988 and Birdsey and May, 1988 and Kelly and Sims, 1988)

26. NETCFGR Net cubic foot growth -- The net change in cubic foot volume

(Cu.ft./year) per year as a result of natural occurrences that this tree

represents. Removals are not considered to be a part of net

Col. 96-103 growth. Negative numbers in this field are usually due to mortality but can also occur on live trees that have a net loss in volume due to damage, rot or other causes. Net cubic foot growth per acre basis is computed by taking the product of this number and VOLFAC.

27. NETBFGR Net board foot growth -- The net change in board foot volume

(Bd.ft./year) per year as a result of natural occurrences that this tree

represents. Removals are not considered to be a part of net

Col. 104-111 growth. Negative numbers in this field are usually due to mortality but can also occur on live trees that have a net loss in volume due to damage,rot or other causes. Net board foot growth per acre is computed by taking the product of this number and VOLFAC.

28. NETCFRM Net cubic foot removals/mortality -- The net cubic foot volume

(Cu.ft./year) per year that this tree represents for removals or mortality.

Removals/mortality per acre per year is calculated by

Col. 112-119 multiplying this volume by the appropriate trees per acre value (REMVFAC or MORTFAC).

29. NETBFRM Net board foot removals/mortality -- The net board foot volume

(Bd.ft./year) per year that this tree represents for removals or mortality.

Removals/mortality per acre per year is calculated by

Col. 120-127 multiplying this volume by the appropriate trees per acre value (REMVFAC or MORTFAC).

30. TOTBIO Total gross biomass -- The total above-ground biomass of a

(Green lbs.) sample tree 1-inches dbh or larger, including all tops and

limbs. This is a per tree value and must be multiplied by one

Col. 128-133 of the above tree factors to obtain per acre information. Recorded in green pounds per tree. This field should have an entry if DBHCUR is 1.0 or larger, regardless of status or TCLASS, zero otherwise.

29. MERBIO Merchantable biomass -- The total gross biomass of a tree

(Green lbs.) 5-Inches dbh or larger from a 1-foot stump to a minimum

4-inch top diameter outside bark of the central stem. This is

Col. 134-139 a per tree value and must be multiplied by one of the above tree factors to obtain per acre information. Recorded in green pounds per tree. This field should have an entry if DBHCUR is 5.0 or larger, regardless of status or TCLASS, zero otherwise.For dead or cut trees this number represents their biomass at the time of death or last measurement.

Note:

TOTBIO and MERBIO are computed values. These weights are all based on DBHCUR and therefore represent the weight at current inventory for live trees (STATUS = 1) and weight at the time the tree died for dead, salvageable dead and snags (STATUS = 2, 4, or 5). For cut trees (STATUS = 3) the differences between FIA units presented in DBHCUR are applicable here. Methods used to compute these biomasses are given in the following publications:

North central:

MN, WI, MI, ND, SD: Hahn, 1984

IA, MO, NE, KS: Hahn & Hansen, 1991

IL, IN: Smith and Weist, 1982

Northeastern:

All states: Monteith, 1979; Wiant et. al; 1977

Southeastern:

All states: Cost and McClure, 1982

Southern:

All states: Rosson, 1989

Chapter 4. Using the Eastwide Data Base

The flat file structure of the EWDB was designed to be used easily with most any data base management systems, statistical packages, or other data summary software. It is not dependent on a particular hardware or software system, but the system must accept input in the form of a flat ASCII or EBCDIC file up to 110 characters wide. EWDB files have been loaded and analyzed by a number of commercial software packages, including SAS, ORACLE, dBASE III, RBASE, INGRES, SIR, SPSS, Hypercard and Foxbase, on hardware ranging from portable microcomputers to large mainframes. Database management systems that support hierarchical data structures, as well as those based on the relational model, can easily process EWDB files. The information provided in Chapter 3 should provide the user of almost any software package with the information needed to input an EWDB file into their processing system.

To assist users of EWDB files and to provide them with a benchmark or checkpoint for comparison to their own data processing systems, the FIA projects provide a set of tables with any EWDB State file. The tables are a set of the core tables produced directly from the EWDB file. These core tables may not match published core tables exactly. Differences will vary by FIA project and relate to rounding error and the allocation of State level estimates down to the county level. Any differences that users are concerned about can be explained on request. Appendix 1 contains an example set of the core tables produced from an EWDB file.

The user may wish to duplicate the core tables on their hardware. In doing so, users may find minor differences due to rounding and word length differences between their machine and the machine used to produce the original tables. Users may also want to screen the input data file so that it only includes plot and tree records for a limited geographic area, such as a group of counties. Then they could produce core tables for only that area.

EWDB users must be aware that mapping conditions on ground plots causes some differences in the way data is summarized. In order to obtain estimates of volume or numbers of trees by forest type, you must include the following join as part of your where clause - plot.condition=tree.condition. In fact, whenever you want to summarize tree level data by some condition level variable you must include a condition join to obtain the proper results.

EWDB file users will require the procedure or algorithm used to compute various tree level data and expand it to population level estimates. Table 4 summarizes how this is done for many commonly requested data elements. Using Table 4, the proper way to compute the total number of all live trees on timberland in a state from the EWDB file from that state would be to multiply the value in VOLFAC on the tree record by the value in EXPVOL on the matching plot record, and sum this product (VOLFAC*EXPVOL) over every tree record where STATUS is equal to one and GLUCUR on the plot record is equal to 20. If you were interested in knowing the current number of live trees over 5.0 inches DBH, the process would be the same, with the added restriction that only tree records with DBHCUR over 5.0 are included in the summation.

Those familiar with the relational data model and the standard Structured Query Language (SQL) database language available in many database management systems will find it easy to load EWDB files into one of these systems and to retrieve information from a loaded database. EWDB files are written in normal form as defined by the relational model. The two retrievals described in the last paragraph are relatively easy to perform using SQL. The SQL command to obtain the total number of all live trees on timberland in a state from a database containing data from just that state would be:

select sum(VOLFAC*EXPVOL)

from PLOT, TREE

where PLOT.COUNTY = TREE.COUNTY

and PLOT.PLTNUM = TREE.PLTNU

and PLOT.CONDITION = TREE.CONDITION

and TREE.STATUS = 1

and PLOT.GLUCUR = 20

and the SQL command to retrieve the same information for trees over 5.0 inches dbh would be:

select sum(VOLFAC*EXPVOL)

from PLOT, TREE

where PLOT.COUNTY = TREE.COUNTY

and PLOT.PLTNUM = TREE.PLTNUM

and PLOT.CONDITION = TREE.CONDITION

and TREE.STATUS = 1

and PLOT.GLUCUR = 20

and DBHCUR > 5.0.

It is suggested that EWDB users accessing with SQL begin with an SQL query designed to retrieve a known quantity in one of the core tables, such as the first example in the last paragraph. Once you verify that your basic retrieval is working correctly, you can modify it to retrieve only the data of interest to you. For example, you may be interested in the volume of select white oak sawtimber in trees at least 20 inches dbh in a four county area. Begin by testing a retrieval to get the total sawtimber volume in the four county area using the following SQL query:

select sum(NETBFVL*VOLFAC*EXPVOL)

from PLOT, TREE

where PLOT.COUNTY = TREE.COUNTY

and PLOT.PLTNUM = TREE.PLTNUM

and PLOT.CONDITION = TREE.CONDITION

and TREE.STATUS = 1

and PLOT.GLUCUR = 20

and TCLASS=2

and (PLOT.COUNTY = C1 or PLOT.COUNTY = C2 or

PLOT.COUNTY = C3 or PLOT.COUNTY = C4)

where C1, C2, C3 and C4 are the county codes of the four counties of interest. Once you verify that this query is working by comparing the total volume retrieved to core table 15, you can modify the query to get only select white oak trees (SPPGRP = 10) at least 20 inches in dbh. This SQL query would look like this:

select sum(NETBFVL*VOLFAC*EXPVOL)

from PLOT, TREE

where PLOT.COUNTY = TREE.COUNTY

and PLOT.PLTNUM = TREE.PLTNUM

and PLOT.CONDITION = TREE.CONDITION

and TREE.STATUS = 1

and PLOT.GLUCUR = 20

and TCLASS=2

and (PLOT.COUNTY = C1 or PLOT.COUNTY = C2 or

PLOT.COUNTY = C3 or PLOT.COUNTY = C4)

and TREE.SPPGRP = 10

and DBHCUR >= 20.0

Those using EWDB files to estimate any population level quantity should always be aware of the number of plot and tree measurements that the estimate is based on. For small geographic areas or very specific criteria the number of plots will be small. In the last example, the user could easily find out how many sample plots the retrieval was based on. The following retrieval would count the number of timberland conditions within the four county area used in the last example:

select count(*)

from PLOT

where GLUCUR = 20

and (COUNTY = C1 or COUNTY = C2 or COUNTY = C3 or

COUNTY = C4)

To obtain the number of trees measured that met the criteria (live select white oak, at least 20 inches dbh within the four county area the following retrieval would be run:

select count(*)

from PLOT, TREE

where PLOT.COUNTY = TREE.COUNTY

and PLOT.PLTNUM = TREE.PLTNUM

and PLOT.CONDITION = TREE.CONDITION

and TREE.STATUS = 1

and PLOT.GLUCUR = 20

and TCLASS=2

and (PLOT.COUNTY = C1 or PLOT.COUNTY = C2 or

PLOT.COUNTY = C3 or PLOT.COUNTY = C4)

and TREE.SPPGRP = 10

and DBHCUR >= 20.0

This type of information should give the EWDB user an idea of the reliability of the data retrieved from EWDB files. Retrievals based on just a few plots or trees have high sampling errors.

For those interested in obtaining additional information on SQL there are many references available, including Date (1986 and 1987), Cronin (1989), Cardenas (1979) and Everest (1986). Many of the database management systems that support SQL have excellent user manuals and tutorial guides for their implementations of SQL. Many of these systems also support enhancements that go beyond standard SQL, allowing additional flexibility and formatting of output, or that take advantage of other features of the database management system.

Table 4. Algorithms to expand tree level items to population estimates from EWDB files. Each item is computed by summing the corresponding quantity over all trees that meet test requirements.

Chapter 5. Ordering Data

EWDB files for a State must be obtained from the FIA project responsible for the State's inventory (fig. 1, table 5). Currently, files can be obtained from all projects on standard 9 track tapes (1600 or 6250 BPI, ASCII or EBCDIC). There is a charge of $500 per State to cover the cost of producing files and maintaining the EWDB system. Please use the form on the next page to order a particular EWDB file. Table 5 shows the status of each State in the EWDB system, the date of the last inventory, the date when the next inventory is scheduled to be completed, and the approximate size of the EWDB files. These figures are only estimates based on projected budgets at the time this report was written. For current information on a particular State, contact the individual FIA project.

Some projects may be able to provide EWDB files as MS-DOS ASCII files on a medium more easily read by microcomputers that use the MS-DOS operating system. Because technology and equipment for data storage and transportation is rapidly changing, some projects may be able to provide EWDB files on diskettes, Bernoulli cartridges or laser disks for an additional charge. This information is available from the individual projects.

Table 5.--Status and size of each EWDB State file.

1 Current inventory

_____________________

(Place)

_____________________

(Date)

Director (Circle appropriate station)

North Central Forest Experiment Station Southeastern Forest Experiment Station

1992 Folwell Avenue PO Box 2680

St. Paul, MN 55108 Asheville, NC 28802

Northeastern Forest Experiment Station Southern Forest Experiment Station

5 Radnor Corp. Center 701 Loyola Avenue

100 Matsonford Rd. New Orleans, LA 70112

Suite 200

Radnor, PA 19087

Dear Sir:

Under the authority of the Forest and Rangeland Renewable Resources Research Act of 1978 (92 Stat. 353, PL 95-307), we desire to cooperate with this forest experiment station in distributing the results of Forest Survey findings.

This forest experiment station is requested to furnish data files in the EWDB format for States as described on the attachment. We agree to contribute to the Station the sum of $500 per State to help defray the computer cost of compiling these data.

This contribution will be mutually beneficial because it will facilitate the dissemination of research information to interested parties, which is the aim of our organization and of this forest experiment station.

No member of, or Delegate to, Congress, or Residence Commissioner, shall be admitted to any share or part of this agreement or to any benefit that may arise therefrom, unless it is made with a corporation for its general benefit.

Sincerely,

___________________________

(Name of Cooperator)

___________________________

(Signature)

___________________________

(Title)

Accepted for the ________________ Forest

Experiment Station______________

(Date)

_________________________________

(Signature)

__________________________________

(Title)

Eastwide Data Base File Request Form

State inventory files being requested: (list each State and the date of the inventory)

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

Format:

______ 9 track tape.

____1600BPI _____6250BPI (check one)

_____ASCII _____EBCDIC (check one)

_____Records per block. All files are fixed length (110 characters/record). Indicate a number of records per block that your system can read.

______ Other format. Other formats available vary by FIA project. Check with them before ordering other than 9 track tapes. Describe alternative format below:

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

Appendix 2

Survey Units for eastern FIA projects

Appendix 3.

Species groups used by eastern FIA projects

The following table (A3-1) shows how FIA groups trees of various species (SPP) into the 28 groups (SPPGRP) in the EWDB and into the 4 groups (Pine, other softwoods, soft hardwoods and hard hardwoods) used in many of the core tables. Not every station recognizes every species code. Some differences exist for minor species, or at the edge of a species range. The last four columns of this table show which species each station recognizes. An X in the column under a station indicates that species is used at that station. The absence of an X indicates either the species has never been found in the region inventoried by the station, or that the station codes that species some other way. For example, the North Central Station does not recognize Fraser fir as a species because none has never been found on an FIA plot in the region and therefore there is no X under NC for Fraser fir. Also the North Central Station does not use SPP 10 (fir sp.) ever. This is a code used by the Southeastern and Northeastern stations for miscellaneous firs that are only identified to the genus level. The list is ordered by SPP code number. Codes 1-299 are softwood species. Codes 300-999 are hardwood species. Within these two groups species are ordered alphabetically by genus and species with the exception of codes 980-999 which are all uncommon or exotic species which have been added to the list after it was first accepted for use.

Table A3-1. Species and species groups included in Eastwide Data Base.

980 tung-oil tree -- -- 28 -- -- -- 4 --

981 sparkleberry -- -- 28 -- -- -- 4 --

983 chinaberry -- -- 28 28 -- -- 4 4

984 water-elm -- -- 28 28 -- -- 4 4

985 smoketree -- -- 28 -- -- -- 4 --

986 mesquite -- -- 28 -- -- -- 4 --

999 unknown or not listed 28 -- -- 28 4 -- -- 4

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Cardenas, A. F. 1979. Data Base Management Systems. Allyn and Bacon, Boston. 519 p.

Birdsey, R.A.; May, D.M. 1988. Timber resources of east Oklahoma. USDA, Forest Service Resource Bulletin S0-135. 29 p.

Brisbin, R. L. and Soderman D. L. 1971. Tree Grades for Eastern White Pine, USDA, Forest Service Research Paper NE-214, 30 p.

Cost, N. D. 1978. Multiresource inventories: a technique for measuring volumes in standing trees, USDA, Forest Service Research Paper SE-196, 18 p.

Cost, N. D. and McClure, J. D. 1982. Multiresource inventories: techniques for estimating biomass on a statewide basis, USDA, Forest Service Research Paper SE-196, 18 p.

Cronin, D. J. 1989. Mastering ORACLE, Featuring ORACLE's SQL Standard. Hayden, Indianapolis. 543 p.

Date, C. J. 1986. An Introduction to Database Systems. Addison-Wesley, Reading, Mass. 639 p.

Date, C. J. 1987. A Guide to the SQL Standard. Addision-Wesley, Reading, Mass. 639 p.

Everest, G. C. 1986. Database Management, Objectives, System Functions, and Administration. McGraw-Hill, New York. 816 p.

Grosenbaugh, L.R. 1964. STX-FORTRAN 4 program - for estimates of tree populations from 3P sample-tree-measurements. Res. Pap. PSW-13. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 49 p.

Hahn, J. T. 1984. Tree Volume and Biomass Equations for the Lake States, USDA, Forest Service Research Paper NC-250, 10 p.

Hahn, J. T. and Hansen, M. H. 1991. Cubic and Board foot Volume Equations for the Central States. Northern Journal of Applied Forestry, 8:2, p. 47-57.

Hanks, L. F. 1976. Hardwood Tree Grades for Factor Lumber. USDA, Forest Service Research Paper NE-333, 81 p.

Hansen, M. H. and Hahn, J. T 1992. Determining Stocking, Forest Type and Stand-size Class From Forest Inventory Data. Northern Journal of Applied Forestry, accepted for publication.

Kelly, J.F.; Beltz, R.C. 1987. A comparison of tree volume estimation models for forest inventory. Res. Pap. S0—233. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 9 p.

Kelly, J.F.; Sims, M. 1989. Forest resources of Mississippi. Resour. Bull. 50-147. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experim~t Station. 63 p.

May, D.M. 1991. Stocking, forest type, and stand size class — the Southern Forest Inventory and Analysis unit's calculation of 3 important stand descriptors. Gen. Tech. Report SO-77. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 7p.

McWilliams, W.H.; Lord, R.G. 1988. Forest resources of East Texas. Resour. Bull. 50-136. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 61 p.

Rosson, J.F., Jr. 1989. Potential residual biomass in mature pine stands of the Midsouth, USA. Biomass 20: 145-153.

Rosson, J.F., Jr.; McWilliams, W.H.; Frey, P.D. 1988. Forest resources of Louisiana. Resour. Bull. 50—130. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 81 p.

Smith, W. B. and Weist, C. A. 1982. A Net Volume Equation for Indiana, USDA, Forest Service Resource Bulletin NC-63, 7 p.

Schroeder, J. G., Campbell, R. A. and Rodenbach, R. C. 1968. Southern Pine Tree Grades for Yard and Structural Lumber, USDA, Forest Service Research Paper SE-40, 15 p.

Scott, C. T. 1981. Northeastern forest survey revised cubic-foot volume equations, USDA Forest Service Research Note NE-304, 3p.

Scott, C. T. 1979. Northeastern forest survey board-foot volume equations, USDA Forest Service Research Note NE-271, 3p.

USDA, Forest Service 1972. Forest Service Handbook, Forest Survey Handbook, USDA Forest Service, GPO 930-002

USDA, Forest Service. 1958. Timber resources for America's Future. Forest Resource Report No. 14. Washington, D.C. 713 p.