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Northern Research Station

Forest Inventory and Analysis

Northern Research Station's Forest Inventory and Analysis Program collects, analyzes, and reports information on the status and trends of forests in the Northeast and Midwest.  

Forest Inventory and Analysis

As part of the National Forest Inventory and Analysis (FIA) Program, the Northern Research Station’s FIA team collects, analyzes, reports, and distributes data and information about the nation’s forests through three activities: 

  • an extensive field plot network sampling the forest resource, 
  • a survey of forest landowner preferences and intentions, and
  • a survey of the Nation’s mills.

We use the resulting data as the foundation of our science to understand status and trends of the forest resource across all ownerships. 

The Northern Research Station FIA unit is responsible for creating and maintaining a comprehensive forest inventory for 24 States: Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Vermont, West Virginia, and Wisconsin. The forests in these States cover nearly 176 million acres or about 42 percent of the land they cover.

Visit the National Forest Inventory and Analysis website for more information and tools.

Data Collection

In most of our states fieldwork is completed by USDA Forest Service personnel alone or in some cases in conjunction and cooperation with State personnel. Forest Health data collection is also completed by Forest Service personnel, although State organizations generally have a more active role in the fieldwork.


The field Inventory crew individuals collect basic forest resource data; locate selected points on the ground from aerial photographs or other imagery; run compass lines and measures distances; make plot and tree measurements; identify all woody vegetation on selected plots; classify stands according to forest type, age, site index and various land use classes.


Field Inventory crew individuals count stumps on Inventory plots and contact landowners, county and state officials, and others to collect information on timber removals and to determine land ownership, ownership size, and ownership tenure. 

Data Collection Resources

Landowner Information

The Northern Research Station, Forest Inventory and Analysis (FIA) unit is responsible for creating and maintaining a comprehensive forest inventory for 24 States. FIA field crews collect data from approximately 7500 randomly selected research sites across the Northern Region every year. This inventory allows FIA to monitor the productivity and health of forests, detect changes in many attributes of the forest resource, and recognize trends in forest conditions.

While this inventory includes lands administered by federal, state and local governments, the vast majority of the land is privately owned. FIA relies heavily on the cooperation of private landowners who allow us to access their property to carry out this inventory. Our ability to gain access to these lands is critical to providing high-quality data on the forest resources.


The area we wish to access was selected randomly without regard to ownership. This process helps to ensure that the inventory is free from bias and that it reflects the true condition of all the forest resources. We strive to access every selected site, and in so doing, we are able to provide data that are as reliable as possible. While visiting this site, we will take numerous measurements and assess the condition of the forest within that area.

Although the data from individual sites and landowners is confidential, our data summaries are available to the public. Our research publications are also available on-line. Our data are used by federal and state agencies, research universities and industry for a variety of purposes including forest health risk assessment, forest planning, wildlife habitat evaluation, fire risk assessments, estimating severity of natural disasters to the forest resource, estimating biomass supplies for fuel, estimating and monitoring carbon stocks, species distribution monitoring, forest growth and yield monitoring, and many other uses.

Our research sites are selected randomly from a hexagonal grid system that covers the entire country. The process is designed to preserve the statistical integrity of the sample and ensures that our data represent the full spectrum of forest conditions across our region, even if the site does not appear to represent your property. Many of our research sites are not considered forestland at all. Sampling nonforest areas helps us monitor changes in land use.

Many of our data collectors are US Forest Service personnel. However, depending on where you live you may be visited by state employees or contracted data collectors. One or two individuals will access the site and will typically spend only a few hours at that location.

The specific information collected from the research site on your property is not made public. Only once the information is aggregated with data from other research sites do we provide data summaries. Those summaries cannot be linked to your property. Only specifically designated individuals have access to the data from your property, and those individuals must sign confidentiality agreements and are legally liable for maintaining confidentiality.

The 1998 Farm Bill which authorizes the annualized collection of forest resource data prevents us from disseminating information that can be associated with a specific landowner. It is a criminal offense to release data that can be linked to a specific landowner, punishable by fines or imprisonment.

No. The information we collect is kept strictly confidential. We do not provide any information about your property to any tax authority.

Does this prevent me from managing my property? You should continue to manage your property as you see fit. It is important to us that we do not influence the way you use your property.

The scheduling of our visit can be coordinated with our data collectors at a time that is convenient for you. Nothing is required of you, but if you would like us to work around planned activities, we are happy to do that.

All we need is permission to access your property. Nothing else is required of you.

The information we collect is kept confidential. We do not report locations of endangered species, noxious weeds, pests or diseases on your property.

Yes. We can show you the area where the research site is. However, in order to preserve the integrity of the inventory, we ask that you not let the presence of the site influence the way you manage your property.

Yes. We typically revisit these sites on a 5 or 7-year cycle depending upon the state. We may contact you in approximately 5 to 7 years to again ask permission to access your property. Also, a small percentage of the sites will be revisited, usually within 30 days, to perform a quality assurance inspection. These inspections help us maintain high standards of data quality.

More information is available on the Northern Research Station web page and the National FIA web page.

If a government employee is injured while conducting an inventory on private property, payment of the employee’s medical expenses and lost wages are the responsibility of the federal government through its Office of Worker’s Compensation Program. Federal contractors are required to have Workers’ Compensation and Liability Insurance.

Yes. You can speak directly with our data collectors about the information they are gathering. Our field guides are available to download in the Data Collection section above.

Yes. Although some states permit citizens to access private property so long as it is not posted, we are required under the 1998 Farm Bill to obtain permission before we access private property.

The vast majority of the forest land in the Northern Region is privately owned and can differ significantly from public land. In order to adequately characterize all forests, we must visit sites without regard to ownership.

No. We avoid destructive sampling. Because we wish to see how the resource changes over time, we try not to let our presence influence the growth of the vegetation on the site.

Although we can provide you with that information, it is important to understand that this inventory is intended to provide meaningful data only at a very large scale and is not intended for use on individual properties. It is highly probable that the information collected at this single location would not adequately represent your property in its entirety and could be very misleading if it were to be used as a basis for formulating management plans. If you are interested in an inventory of your property, we recommend contacting your local cooperative forestry extension service or a licensed consulting forester.

See brochures for landowners  >>

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