Forest Inventory Data Online (FIDO) and EVALIDator

Overview & Applicability

FIDO and EVALIDator applications both draw from US Forest Service FIA (Forest Inventory and Analysis) data to produce estimates with associated sampling errors for user selected forest attributes. These forest attributes include: forest area, number of trees, biomass, volume, carbon, growth, removals and mortality. Carbon estimates can be produced for several carbon pools, including total forest carbon, above and belowground carbon in live trees, standing dead trees, and live seedlings shrubs and bushes; litter; soil; and stumps, roots and woody debris. General users may find FIDO to be most useful because the standard reporting options, whereas advanced users that are familiar with FIA data and/or SQL may prefer some of the more customizable options available in EVALIDator.

Screenshot of FIDO output

A map generated by FIDO shows an estimate of total above- and below-ground carbon in live trees on timberland in three counties in Michigan.


USFS Forest Inventory and Analysis is widely known as the “Nation’s Forest Census”, and many carbon estimation tools are based on FIA data (e.g. COLE). Forest Inventory and Analysis has been providing online tools to access FIA’s database since 1996. FIDO was originally launched in 2008 and has been through multiple updates since. See the FIDO “Previous Release” information for more detail. The EVALIDator program was introduced in 2009 as a replacement for the Forest Inventory Mapmaker (released in 2002). The first version of the EVALIDator program could produce estimates for a single classification variable. The next version could produce 3-way matrix reports (pages, rows, and columns) and introduced shaded county maps based on KML files that could be viewed using the OpenLayers module within EVALIDator or exported for use in GoogleEarth or ArcMap. Ratio reporting was introduced in 2013 and group reports were added in 2015.

Inputs and outputs

For each application, users run through a variety of selections, and have slightly different output options


In FIDO, there is an option to generate an FIA Standard Report, or to do a Custom retrieval. Standard reports is being discontinued in the future and visitors are encourage to use Custom reports. Custom retrievals generate options as you move through the online interface, giving a little more flexibility in the layout of the final report. Users select:

  1. Area of interest (counties, regions or states).
  2. Reports, or which forest attributes to view. Available carbon data include estimates for several carbon pools, including total forest carbon, above and belowground carbon in live trees, standing dead trees, and live seedlings shrubs and bushes; litter; soil; and stumps, roots and woody debris. It is advised to select as few variables as necessary for each report, or results will take a long time to generate.
  3. Years of interest (years will vary depending on the selected location).
  4. Filter results, for example by land ownership, tree species, etc. This step is optional.

FIDO provides a few options for how the final tables will be labelled, and lets users export results as a table (html, CSV, or pdf) or a map (google maps). Sampling errors are given as general color coded values (e.g. 25%-50%), but exact numbers are available by hovering over the general values. FIDO can report on multiple sets of statistics in one query, and FIDO report templates can also be saved and used for later.


To generate a report in EVALIDator, users move through the following selections:

  1. General area of interest (State or circular radius from a latitude/longitude; option to choose the specific state or to add a custom polygon occur later).
  2. Reports, or which forest attributes to view. Users can select a single attribute of interest (e.g. total aboveground carbon in live trees), or generate a ratio estimate by selecting a numerator and a denominator (e.g. aboveground carbon in live trees per acre of forested land).
  3. Geographic area and inventory. Depending on the attribute selected, a list of inventories will be listed by state and sample year(s). There is also the option at this time to add a custom polygon using a SQL filtering clause. Users can select multiple options from this list of inventories, but EVALIDator will only generate separate results for each selection if ‘Trend analysis” is chosen in the next step.
  4. Select classification variables. Choose how your results are displayed by choosing a page break, a row variable, and a column variable. For example, if you’ve chosen to get an estimate of total forest carbon, you can select a row variable of ‘forest type’ and a column variable of ‘all live stocking’ to generate a table that displays carbon totals for each forest type, by stocking condition. As noted above, if multiple inventories are selected, ‘Trend analysis’ must be chosen as the row variable to generate results that make sense.
  5. Filter results, for example by land ownership, tree species, etc. This step is optional.

Results will be produced in a series of tables as specified by the user choice of row and column variables. Separate tables will be produced for the estimate or the ratio estimate and for the sampling error percent. If ‘county code and name’ is selected as the row variable, EVALIDator provides the option to produce a county map. Results are also provided as SQL code.

Restrictions and limitations

  • Since these tools draw from FIA data, the accuracy of generated carbon reports is related to the sample size of the underlying data. The more filters that a user applies, the more important it becomes to choose a larger (multiple counties, states, etc.) area over which to apply these filters. While it is possible to generate a very specific report (e.g. an aboveground carbon stock report for privately owned, white oak/red oak/hickory stands in Elk County, PA), the user should be aware that such a detailed report on a small scale is subject to sample-size inaccuracies.
  • Some caution is also necessary if comparing reports from different years (in either application). Because FIA methods have evolved over time, calculation methods may differ between time periods (particularly those occurring before the advent of annual inventory, in 1999. Some states do not yet have a full annual inventory completed.
  • Variables are not described in the user interface for either tool, so it is helpful to be familiar with FIA data and terminology before attempting a report. See the FIA Database Users Manual for more.
  • EVALIDator provides enough options for customization that it is relatively easy to produce reports that don’t make any sense or that sum variables together in ways that may be unintended. Knowledge of FIA data is very helpful in being able to generate meaningful estimates. Please be very aware of what data you are using and summarizing.
  • In EVALIDator, if you choose more than one inventory, the user guide advises you to select “Trend analysis” as the row classification; otherwise, the report will add the estimates for the same area together (a nonsensical query). At the same time, the EVALIDator is unable to produce estimates of growth, removals and mortality for multiple inventories when "Trend analysis" is chosen as the row classification variable and the inventories chosen have different sampling designs (i.e., a mix of periodic and annual inventories). In the event that a user inadvertently runs such a retrieval the EVALIDator will return zeroes for the periodic inventories and the correct numbers for the annual inventories. It may be least problematic to run reports for one inventory at a time.

Accessing the tool and additional information

Training and tutorial information for FIDO and EVALIDator:

FIA Data Base (FIADB) Documentation:

If interested in carbon, please see the following publications on how carbon is estimated using FIA data:

For questions regarding FIA's online tools, please see the four regional contacts listed under “Technical Assistance”: