Pacific Northwest Forest Inventory and Analysis
P. O. Box 3890
620 SW Main, Suite 400
Portland, OR 97205
Portland, OR 97208-3890
The FIA program has a variety of databases and summary information available for download or request. PNW-FIA maintains databases that contain either periodic or annual inventory data for Alaska. California. Oregon. Washington and the Pacific Islands.
In the west, periodic inventories were conducted by four individual forest inventory programs from two agencies, including the Forest Inventory and Analysis program of the Pacific Northwest Research Station (PNW-FIA), the Continuous Vegetation Survey (CVS) program of the Pacific Northwest Region (Region 6 in Oregon and Washington), the Forest Inventory program of the Pacific Southwest Region (Region 5 in California), and the Natural Resource Inventory program of the Bureau of Land Management (BLM, western Oregon districts only). Although inventories were similar, data and supporting documentation were managed separately by each Program. Each periodic inventory focused on a certain geographic area such as an entire state, half-state (e.g. eastern Oregon ), or National Forest where 100% of the plots were sampled within a period of 1- 4 years. PNW-FIA's periodic inventories include California. eastern Oregon. western Oregon. eastern Washington. western Washington and broad sections of Alaska. For more information on periodic inventories please read: Periodic and annual inventories.
California, Oregon, Washington Data: The PNW-FIA Integrated Database (IDB) contains the most recent periodic inventory data collected by PNW-FIA, the National Forest System (NFS: Regions 5 and 6), and the BLM in California. Oregon. and Washington. Data acquired from each inventory program were compiled into one database with a common set of formats, definitions, codes, measurement units, column names, and table structures. When possible, the same procedures, algorithms, equations, and calculation methods were used to compile all inventory data in the IDB. The IDB is the primary database used for summary and analysis of resource data in the PNW; it contains an extensive amount of measured and calculated information for each inventory plot, including information on plots, conditions, live trees, mortality trees, and site trees. Data on down wood and snags will be added to the IDB by 2005. For more information on the IDB, go to the IDB page.
Alaska Data: Data for the last two periodic inventories in Alaska. southeast Alaska (1999) and southcentral Alaska (2002), can be obtained from George Breazeale at (503) 808-2012 or e-mail him
Pacific Islands Data: Data for those Pacific Islands that have been inventoried by PNW FIA since 2001 can be obtained from Joe Donnegan at (503) 808-2012 or e-mail him Currently databases for American Samoa (2001) and Guam (2002) periodic inventories are available.
National FIA Database (FIADB): The
FIADB contains both periodic and annual inventory data. Periodic inventory
data are available for all states in the country. However, the FIADB
does not contain periodic data for the NFS Regions 5 and 6 or the western
Oregon BLM districts. The FIADB contains a subset of the information
available in the PNW-FIA IDB. The national FIA DB can be accessed on
the FIA Tools and Data Web site: http://fia.fs.fed.us/tools-data/default.asp
Annual inventories are now conducted by FIA for all ownerships in each state across the country. A new sampling design was initiated for these inventories, which is identical in each state. The PNW-FIA program continues to collect data for western states (AK, CA, OR, WA) and the Pacific Islands . The goal is to measure about 10% of the plots in each state each year, and make the data available annually. The annual inventory system was initiated gradually over the last several years and therefore the dates of data collection are staggered over a period of time. In the West, annual inventories began in 2000 for Oregon , 2001 for California , 2002 for Washington , and 2004 for coastal Alaska. Entire states are expected to be completed in 10 years from their starting year. For more information on annual inventories please read: Periodic and annual inventories.
National FIA Database: The FIADB contains both periodic and annual inventory data.
Annual inventory data are available for many states. The FIADB is updated regularly as the process of editing and compiling annual data is completed. To access annual inventory data, use the national program called FIA Mapmaker to download data files, produce summary tables, or create maps from FIA data. The annual tables on display on the Mapmaker web site summarize values obtained from all years of annual data currently available in the FIADB for each state. These years are also shown in the pull-down menu for each state. Note that when a new year is added to the database, the expansion factor per plot (i.e. acres) is recalculated and replaced in the database. As you increase the number of plots in the database, you decrease the acres represented by each plot.
Please note that there is a lag time between data collection, processing, and posting of annual data on the national web site. If you do not find the annual data you need, contact George Breazeale at 503-808-2012 or email him for an estimated timeline.
A NOTE OF CAUTION
ABOUT ANNUAL DATA AVAILABLE ON MAPMAKER WEBSITE: The
data displayed in the Mapmaker annual tables may be from as little
as two-tenths of the inventory plots in a state if the annual inventory
is early in the 10-year cycle for that state. FIA data should be
used with caution until most of the plots in the inventory have
been sampled and compiled. The sample design for the FIA inventory
provides the highest precision when estimates are aggregated at
the state or half-state (for larger states) level. The precision
decreases as the sample is divided into smaller units, such as
Currently, error estimates are not displayed for each Mapmaker table. In the future, standard error, which is a measure of sampling and estimation error, will be displayed for each Mapmaker table. Error estimates are displayed in the Interim Tables for each state produced by PNW FIA (see Interim Tables below).
The national FIA DB can be accessed on the FIA Tools and Data Website:
Interim Tables: A set of national core tables for FIA annual data has been developed to use in FIA 5-year reports. However, until remeasurement data has been collected in the second cycle (years 11-20 for west coast states), an interim set of tables will be produced. PDF files of nine interim tables for each state are available here; these interim tables summarize values obtained from all years of annual data currently available for each state. Standard errors are also displayed in each table.
Alaska: 2004-2006 (combined tables)
Interior Alaska : no tables available because the annual inventory has not been started.
2001-2006 (combined) tables
2001-2006 (combined) tables
2002-2006 (combined) tables
A NOTE OF CAUTION ABOUT ANNUAL
DATA DISPLAYED IN INTERIM TABLES: The data displayed in
the Interim Tables may be from as little as three-tenths of the
inventory plots if the annual inventory is early in the 10-year
values in these tables should be used with caution until most of
the plots in the inventory have been sampled and compiled. Again,
the sample design for the FIA inventory provides the highest precision
when estimates are aggregated at the state or half-state (for larger
states) level. The precision decreases as the sample is divided
into smaller units, such as individual counties.
If you wish to be informed of annual data changes for west coast states such as availability of new data or updated tables, please send in the following form and we will put you on our mailing list for annual data updates.
[Data mailing list form]
Differences Between Periodic and Annual Data
You will notice differences in area and volume estimates between periodic data and annual data for each state. There are several reasons for this, including:
- The annual inventory is several to many years later than the last periodic inventory (depending on the state) so that changes may have occurred to the forest resources during that time. These changes include growth, mortality, harvesting, conversion from forest to non-forest or vice-versa, and changes in reserved designation.
- The annual inventory uses a different plot design (fixed plot with 4 subplots) than that used by the periodic inventories (variable radius plot with 5 subplots). The annual inventory subplots are located closer together and sample a smaller amount of land area than the periodic subplots. This will have some impact on classified attributes such as forest type.
- The annual inventory samples all lands whereas some of the periodic inventories did not sample certain lands such as state and national parks or unproductive forest land (= non-timberland forest). While this land area (acres) was accounted for in the periodic inventory, the volume on these unsampled lands was always zero (i.e., the IDB has proxy acres but not proxy volume for reserved and unsampled areas for some of the periodic inventories).
- Plot stockability factors and stockable proportions were applied to different sets of plots in the periodic and annual inventories. Since stockability influences the level of productivity of a plot and whether or not it is classified as timberland, this could account for some differences in timberland area and volume between the two inventories.
- Slightly different methods were used for calculating forest type for periodic and annual inventories, contributing to different area and volumes for some forest types.
- In order to standardize the annual inventory across all lands nationally, there were changes in definitions and protocols for what was considered a tree, forest land, reserved land, and timberland.
- Some volume discounts, for missing tree tops and hardwood cull, have not yet been applied to the annual data.
These factors, along with the initial higher sampling error in the annual inventory associated with partial samples (fewer plots each year), will result in different estimates especially at finer scales such as county or forest type and especially before the full annual cycle (10 years) is completed for each state.