USDA Forest Service

Forest Inventory and Analysis National Program


Forest Inventory & Analysis
National Office
U.S. Forest Service
1400 Independence Ave., SW
Washington, D.C. 20250-0003

(703) 605-4177

United States Department of Agriculture Forest Service.

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Spatial Data Services


In 2000, the Department of the Interior and Related Agencies Appropriations Act (H.R. 3423) amended the Food Security Act of 1985 (H.R. 2100) to include the USDA Forest Service’s Forest Inventory and Analysis (FIA) program in a list of activities that may not make data available to the public if the owner of the land on which the data were collected can be identified. Penalties for violating the law can include fines up to $10,000 and/or a year in jail. In recognition of the fact that two-thirds of the forest land in the United States is privately owned and of the importance of private landowner participation in the FIA program, FIA was placed under the same privacy protection provisions as other critical agricultural inventory, monitoring, and census programs operated by the National Agricultural Statistical Service (NASS). A new privacy law was not created for FIA. Rather, Congress gave private forest landowners participating in the FIA program the same legal protections already enjoyed by farmers participating in the other USDA programs.

Since many of the FIA plots are, or soon will be, geo-referenced using a global positioning system (GPS) and ownership maps are freely available to the public in county tax offices, making public the plot data with GPS or digitized location is tantamount to revealing the owner’s name and thus violating the law. A privacy policy was adopted by the Forest Service (Forest Service Handbook Directive 4809.11_10) regarding the FIA program with the goal of protecting the privacy of private forest landowners who allow FIA field crews to collect data on their property. The policy ensures that data for any plot cannot be linked with certainty to the participating private landowner.

In addition to addressing legal concerns, maintaining privacy of the plot locations is essential to FIA’s mission for several reasons. First, access to private property is granted voluntarily. Permission to collect data on private lands is vital to the continued credibility of the FIA program. Owners are concerned about how the information being collected on their land is being used and who has access to it. Owners must also understand that FIA is not concerned with any regulatory or taxation issues. So, we want to preserve landowner privacy and reduce the nuisance factor of having strangers on their property.

Second, if the plot location were freely available, individuals could either intentionally or unintentionally alter the ecological conditions on the plot, impacting the integrity of data that are collected the next time the plot is measured (in 5 to 10 years). Since we have no control over access to sample locations, the best way to protect the locations is to keep them confidential. Furthermore, the value of the data is degraded if it is felt that land managers might intentionally alter land management around FIA plots to affect (or avoid affecting) the survey. In other words, plot confidentiality assures that management of the plot area is typical of surrounding lands.These are the primary considerations for plot confidentiality on public lands.

Nonetheless, FIA wants to assist users in utilizing the spatial nature of the FIA data while preserving privacy. To reach this goal, FIA developed a technique whereby the plot coordinate data are slightly altered (fuzzed) and some of the plot data are exchanged (swapped). The purpose is to maintain the functional value, or “ecological signal” of the data while introducing enough uncertainty to decouple the plot-landowner relationship. The ‘fuzzing’ procedure consists of randomly relocating most plot latitude and longitude coordinates within one-half mile of their actual coordinates, with the remainder relocated up to 1 mile. This means that the actual plot location is generally masked within a 500-acre area.

“Swapping” consists of exchanging the plot coordinates for a small number of similar plots within the same county. Swapping only occurs on private forested plots and depends on the region of the country. Between 0 and 10 percent of the forested plots are randomly selected for swapping with plots from the remaining data for a total swapping of between 0 and 25 percent. The primary criterion for swapping is based on a measure of ecological similarity. Plots with the smallest ecological difference are swapped. This induces enough uncertainty as to the actual property owner to satisfy the legal requirements without introducing an unacceptable amount of error in the population estimates computed for analyses.













USDA Forest Service
Last Modified: May 4, 2020

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