Illinois Natural Areas Inventory

The Illinois Natural Areas Inventory is a collection of ecological information on natural areas evaluated to have statewide conservation significance. These areas allow for the preservation biodiversity. Diverse native species life allows for ecosystem to function efficiently and effectively, producing services such as the ability to pollinate food and convert Carbon Dioxide to Oxygen. Additionally, biodiversity improves the health and resiliency ecosystems, and their abilities to adapt to land use and resource changes.

Beginning in 1978, the INAI was established to identify and document natural areas with conditions that reflect the areas' historical composition. Sites are categorized based on their qualifying features and those features are periodically assessed for changes. The natural communities of each INAI site are broken up into classes, subclasses, and types that best describe their attributes, and are graded based on their quality. Distinct Natural Divisions and Sections occur within Illinois, and natural communities vary in composition depending on where in the state they are located.

In addition, the Illinois Nature Preserves Commission works closely with the Natural Areas Program to register eligible sites to their directory as well, providing legal protection for these particularly valuable natural areas. With help from the INAI, a balance between human activities and the identification and preservation of sensitive natural resources can worked towards, allowing for future generations to experience remnants of the state's natural heritage.

I. High-quality natural communities

II. Specific suitable habitat occupied by endangered and/or threatened species

III. Illinois Nature Preserves, Land & Water Reserves, and Natural Heritage Landmarks

IV. Outstanding geologic features

V. (currently unused)

VI. Unusual concentration of flora and/or fauna

The Standards and Guidelines for the Illinois Natural Areas Inventory (INAI) provide practitioners with a framework for evaluating landscape features and species habitats, the standards by which these features and habitats can be compared to others, and guidelines for evaluating and seeking recognition of these sites as significant to the preservation of Illinois' natural history. The Standards and Guidelines provide a summary of the historical origin and necessity for identifying Illinois' remnant natural community types and rare species habitats before it is too late. But more, this guidance summarizes the natural community classification system used by the State to characterize some common attributes, such as geology, hydrology, position on the landscape, and floral and/or faunal species assemblages. The Standards and Guidelines is a manual based on decades of natural area evaluation, coordinative meetings, targeted comparative research, and continual adaptive progress. The integrity of the process and this document depends on recurrent improvements based on site assessments and updates to our methods coupled with the recognition of a changing environment.

• INAI Checklist for Site Nomination
• INAI Nomination and Approval Form
• INAI Site Evaluation Form
• INAI Grading Form and Guidance
• INAI Grading Form (Fillable)
• INAI Qualitative Vegetation Sampling
• INAI Vegetation Sampling (Understory)
• INAI Vegetation Sampling (Overstory)
• INAI Vegetation Sampling (Ground layer)
• INAI Specific Suitable Habitat Form
• INAI Category II Feature Deletion Form
• INAI Steam Grading Form
• EOR Form
• Site Surveillance Form

*Forms might need to be downloaded to computer to work properly
Contact DNR.NaturalAreas@illinois.gov with any questions.