What are Natural Heritage Inventory (NHI) Data?

NHI data are information collected on three types of elements in the state which include:

• rare or declining species of plants and animals, for example the pale-purple coneflower or the peregrin falcon.
• high-quality or rare natural communities, like hemlock relicts or pine barrens, and
• unique and significant natural features which include animal concentration areas like hibernacula, mussel beds, and migratory bird concentration points, and special geologic features like caves.

In Wisconsin, these three types of elements comprise the NHI Working List and locational information on where these elements occur on the landscape is recorded in the NHI database as an element occurrence record.

• What is an Element Occurrence?
• What is the NHI Working List?
• What are Special Concern Species?
• What are Natural Communities?
• Where do the NHI data come from?
• What are the Limitations of the NHI Data?
• Why is NHI Methodology helpful?
• What is the Sensitive Species List?

What is an Element Occurrence?
An element occurrence (EO) is a population of a species or an example of a natural community or feature naturally occurring at a specific ecologically appropriate location. More specifically, an EO is a locational record representing a single, extant habitat which sustains or otherwise contributes to the survival of a population or self-sustaining example of a particular element. It is not each individual example of the element itself. For example, a population of seventeen calypso orchids at a site constitutes one EO, not seventeen. In the same way, each taxa group has general guidelines as to what constitutes an element occurrence. So, for a siting of a bird to be considered an EO, there must be evidence of breeding and/or nesting. A fly-over observation would not by itself be considered an EO.

What is the NHI Working List?
The NHI Working List contains native species known or suspected to be rare and/or declining in the state, natural communities, and natural features occurring in Wisconsin. The Working List includes species legally designated as "Endangered" or "Threatened" by either the State of Wisconsin or the federal government, as well as species in the Department's advisory "Special Concern" category and the U.S. Fish & Wildlife's "Candidate" and "Species of Concern" lists.

What are Special Concern Species?
Special Concern species are those about which some problem of abundance or distribution is suspected but not yet proven. The main purpose of this category is to focus attention on certain species before they become Endangered or Threatened. The NHI program -- in consultation with staff from a variety of state and national agencies, organizations, and universities, as well as naturalists throughout Wisconsin -- determines which species to include in the Special Concern category. The Special Concern list is quite dynamic with species added or removed from the list as additional information is collected and consolidated by the NHI program.

What are Natural Communities?
The natural communities included in the working list were initially based on the types described by John Curtis in his seminal work, The Vegetation of Wisconsin. The NHI program has subsequently expanded its natural community list to include several less common, or more distinct, community types and geologic features not covered by Curtis (e.g., algific talus slope, forested seep, cobble beach, and sedge fen) as well as many aquatic communities.

Where do the NHI data come from?
Data collected by the Wisconsin NHI Program come from a variety of sources, including museum and herbarium records, reports from individuals, as well as from field surveys and biotic inventories, to name a few. The NHI program maintains high standards of data quality control and the NHI database is the most up-to-date and comprehensive database on the occurrences of rare species and natural communities available for the state.

What are the Limitations of the NHI Data?
Certain limitations exist with the data that need to be considered. First, significant portions of the state have not undergone thorough and systematic inventories. As a result, the absence of occurrences for a particular area does not conclusively signify that there are no known rare resources. Rather, suitable habitat for likely species known to occur in the surrounding landscape should be considered at the site to determine likelihood of presence. Second, the presence of one element does not imply that other elements were surveyed for. Finally, some NHI records are considered historic (pre-1970) and have not been confirmed since the Last Observation Date. Land use history should be considered and surveys may be appropriate in these circumstances.

Why is NHI Methodology helpful?
One of the strongest attributes of the NHI data is that by classifying and characterizing these elements, and then collecting specific information about their occurrences on the landscape with a consistent methodology, we amass comparable data. These data can be relied upon to make decisions, they can be used at different scales, and they can be compared within the state and beyond. This methodology is consistent across all heritage programs [exit DNR].

What is the Sensitive Species List?
Sensitive species list [PDF 133KB] is a set of species that are particularly vulnerable to collection or disturbance. The locations of these species are generalized when working with the public in order to minimize impacts to these species. The list describes the species and the level of generalization that DNR staff should use when describing the location of occurrences to the public.