The Wisconsin Natural Heritage Inventory Program
- What makes the Heritage approach unique
- NHI Data Sources
- NHI Data Management
- Determining an Element Occurrence
- The Wisconsin NHI Working List
- General Guidelines
- Data Confidentiality
Introduction
The Wisconsin Natural Heritage Inventory (WNHI) program is part of an international network of Heritage programs. The defining characteristic of this network, and the feature that unites them, is their use of a standard methodology for collecting, processing, and managing data on the occurrences of natural biological diversity. This network of data centers was established by The Nature Conservancy (TNC), an international non-profit organization, and is coordinated today by NatureServe, a new organization that has assumed the Heritage functions from TNC.
Since its inception in 1950, TNC has maintained a strong science-driven approach to biodiversity and natural area conservation. As the organization became more active in the protection of biological diversity through direct land purchase, it was apparent that there was a need for better information on which to base its conservation decisions. TNC wished to ensure that scarce funds were invested in areas that were true priorities from the standpoint of biological diversity, and not simply attractive open spaces. Unfortunately, there was no source for well-organized, easily accessible information on the condition, status, and location of species and ecosystems deemed important for conservation. To meet its needs, TNC pioneered a unique private-public partnership -- the Natural Heritage Network.
After developing a standardized methodology for collecting and organizing data, TNC set about establishing a series of locally-based programs to operate as a unified network of permanent biological resource databases. The first "strand" of the network took hold in 1974 with the establishment of the South Carolina Natural Heritage program. The Wisconsin NHI program was formally established in 1985. There are now 85 "primary" data centers operating in the western hemisphere, covering all 50 states, six provinces of Canada, and 13 countries in Latin America and the Caribbean. In addition, there are more than one hundred secondary or "satellite" data centers housed in cooperating agencies and operating units such as National Parks and National Forests. The Natural Heritage Network continues to evolve, as does the methodology for collecting and managing biodiversity information. Under the leadership of NatureServe, new tools are being developed to use Heritage data in the conservation of biodiversity.
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What makes the Heritage approach unique
Of course, inventories of areas containing exceptional natural resources or features, both in Wisconsin and throughout the country, have been conducted for many years by a variety of organizations, universities and agencies. Many inventories have been, and continue to be, focused on one resource type, such as timber stand composition, game animal population status, and surface water location and description. Inventories of high-quality natural areas in the U.S. have been conducted since the early part of this century. In Wisconsin, in-depth statewide natural area surveys conducted by the Department of Natural Resources from the late-1960s through the early-1980s attempted to identify sites retaining the most natural and native (pre Euro-American settlement) conditions. The Department's goal for these inventories was to incorporate the best of these sites into the State Scientific Areas (now the State Natural Areas) program.
Because past natural resource inventories had different goals and objectives, their analyses of resources were viewed through different "lenses." Although this did not prevent these inventories from reaching their individual desired objectives, as a group they suffered from a compatibility problem. Not only did the scale of these inventories vary from a local to national view, but each inventory had different criteria in characterizing an area's biological and ecological diversity making it very difficult to meld the results.
The approach used by the Heritage Network is different in that it assesses biological diversity using discrete, common, workable data units. That is, rather than attempt to assess the overall composition and structure of an ecosystem, the Heritage method evaluates the biologic components of the system at a simpler scale. The Heritage system refers to these components as "elements," and they are grouped into three categories: species, natural plant communities, and "others" (a conveniently broad category encompassing an eclectic mix of natural resources or features that a particular Heritage program believes are worthy of attention). In Wisconsin, the WNHI program's "other" category includes animal concentration areas (hibernacula, mussel beds, and migratory bird concentration points) and special geologic features (caves).
Although each Heritage program is expected to expend some time and resources documenting and assessing the occurrences of more common elements occurring in their area, each program's primary focus is on the rare or declining species, the high-quality or rare natural communities, and the unique or significant natural features. In Wisconsin, these three types of elements comprise the WNHI Working List.
One of the strongest attributes of the Heritage approach is that by classifying and characterizing these elements, and then collecting specific information about their occurrences on the landscape, each Heritage program amasses comparable data. These data can be used to determine (at different scales) the relative endangerment of the elements and to ascertain which occurrences of each element are the most critical for conservation. The other primary strength of the Heritage approach is that by recording data as discrete facts, not only does each datum remain subject to continual rechecking and updating, but the data can be used for a wide range of analyses and applied to the broadest possible array of users. Furthermore, previously collected information does not lose its usefulness as our perceptions of significance change - the data can always be re-analyzed with changed criteria.
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The Wisconsin NHI Working List
The 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. The listing of species as Endangered or Threatened (E/T) in Wisconsin is a legislative action that is typically updated every three or four years (the last update to the state's E/T list became effective August 1, 1997). Currently, there are 134 species listed as Endangered (73 plants, 61 animals) and 105 species listed as Threatened (65 plants, 40 animals).
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 WNHI 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 WNHI program. In some cases, as more data on a species' status and distribution are gathered, it becomes clear that the species is more common than originally thought and the species is dropped from the Working List. In other cases, additional data indicate a decline in a species' status and/or distribution in the state that warrants proposing it for listing as Endangered or Threatened.
The WNHI natural community list was initially based on the types described by John Curtis in his seminal work, The Vegetation of Wisconsin. The WNHI 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.
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When Heritage programs are initially established, one of the first tasks facing staff is to consolidate existing information on the condition and known locations of potentially rare elements. Beginning with its establishment in 1985, the WNHI program gathered this information from museums, herbaria, and a variety of texts, guides, and dissertations describing the state's flora and fauna. These data were used to determine initial rarity ranks of the different elements and establish priorities for further data collection. After having assimilated much of the existing information on rare elements into the database, the WNHI program now concentrates its efforts on two fronts: (1) conducting a variety of species-specific and area-specific inventories, and (2) incorporating the results of inventories conducted by other Bureaus in the DNR, other agencies, faculty and staff at universities and colleges around the region, and a wide range of organizations and individuals involved in resource inventories as either a hobby or profession. Simply put, were it not for the information, expertise and cooperation of our partners, the quality and utility of the WNHI database would be greatly diminished.
In general, there are two approaches to inventorying biodiversity. The first approach focuses on locating occurrences of particular elements (e.g., where do phlox moths occur in Wisconsin). The second approach focuses on assessing the biological components of a particular area (e.g., what elements occur within the Black River State Forest). The latter approach often employs a "top down" analysis that begins with an assessment of the natural communities present and their relative quality and condition. This information is subsequently used to determine where different species-oriented surveys should be conducted. This second approach, commonly referred to as "coarse filter-fine filter," concentrates inventory efforts on those sites most likely to contain target species. It also allows sites to be placed in a larger, landscape context for broader applications of ecosystem management principles.
Ideally, from WNHI's perspective, these two approaches should be integrated and result in coordinated surveys which inventory different taxonomic groups and geographic areas in a comprehensive and complimentary manner. However, inventory scheduling has been and continues to be dictated primarily by funding sources, development pressures, and individual priorities. The resulting reality is that the WNHI database continues to be populated with a variety of survey results. Examples of inventories that generate data incorporated in the WNHI database include:
- inventories of federally-listed species funded by the U.S. Fish & Wildlife Service
- status surveys of particular species undertaken for management purposes
- site-specific inventories conducted in conjunction with DNR's regulatory review and permit process
- information gleaned from theses, dissertations, and other university studies
- species observations from a variety of naturalists throughout the state who set their own inventory priorities
More and more of the inventories that the WNHI program are involved with utilize the coarse filter-fine filter approach. Two notable examples are the inventories conducted in partnership with the Southeastern Wisconsin Regional Planning Commission (SEWRPC) in seven southeastern counties and with the Bureau of Forestry in the Northern Highland-American Legion State Forest (NHALSF). In each case, these inventories were driven by the realization that successfully resolving important land use issues requires adequate site-specific data that can be evaluated in a landscape-scale context.
The initial analysis for both the SEWRPC and NHALSF inventories began with both an assessment of the entire region where important ecological attributes and the biological processes that supported them were determined as well as an examination of existing data on the distribution and status of rare elements. Criteria to evaluate sites were established and then vegetative communities were identified and characterized. Based upon existing habitat characteristics and the habitat preferences of different rare species, sites were identified where species-specific surveys were most appropriate. No doubt several occurrences of rare species exist that were not located through these inventories. However, by concentrating species-specific inventory efforts on those sites most likely to support the populations with the highest conservation value, the organizations involved were able to gather productive information efficiently. As a result, adequate data are now available to formulate appropriate solutions regarding endangered resource protection that face agencies and organizations in these two locations.
In general, the "randomness" of information sources that contribute to the WNHI database does not necessarily create a problem. However, it does make interpretation of the database more complex. Users need to recognize that much of the state has not been inventoried using a coarse filter-fine filter approach. Thus, not only should an "absence of evidence is not evidence of absence" philosophy be employed when using WNHI data, but also the presence of one element does not imply that other elements were surveyed for but not found.
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The Heritage methodology for organizing and storing data is actually a system of three inter-related data storage techniques: structured manual information files, topographic map files, and a computer database that integrates the various information. The computer component, known as the Biological & Conservation Data (BCD) System, was developed by TNC for use by the Heritage Network. It is a sophisticated relational database management application built upon the Advanced Revelation software environment. Owing to the diversity and complexity of the information managed (from species taxonomy and natural community classification to real estate transactions) the system contains 36 database files and more than 2,000 information fields. Many of the database files and information fields are not critical to the operations of the WNHI program and have not been populated. However, the potential exists to populate these files and fields in the future as different data needs arise. The two databases most extensively used by the WNHI program are the Element Tracking (ET) and the Element Occurrence Record (EOR) databases.
The ET database contains information specific to each element in Wisconsin. Each element has a unique record with information pertaining to its state, national, and global rarity, both state and federal protection status, as well as the standard global and state scientific and common names. In addition, each element is assigned a unique 10-character code which is consistent throughout the Heritage Network (i.e., the Yellow-throated Warbler's element code is "ABPBX03130" in Wisconsin and every other state).
The EOR database contains information pertaining to individual occurrences of elements in Wisconsin and can be considered the heart of the BCD. This database contains numerous fields that describe the location and status of each species, natural community, and natural feature occurrence. The EOR database includes locational (county, legal description, latitude, longitude, and the USGS 7½ -minute topographic quadrangle name), biological (population size, threats to the element occurrence, rank of the element occurrence) and general (first and last observed date, best source of information on the element occurrence, sitename, general description of the site, mapping precision) information fields.
The concept of "element occurrences" is the foundation of the Heritage approach to assessing biodiversity and it is imperative that users of the NHI database understand what an element occurrence is and what it is not. An element occurrence (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. That's a complicated definition worth reading again - the important concepts have been underlined. In somewhat simpler terms, an EO is a population of a species or an example of a natural community or feature naturally occurring at a specific, ecologically appropriate location. Keep in mind that an EO is not each individual example of the element itself. A population of 17 calypso orchids at a site in the Nicolet National Forest constitutes one EO, not 17.
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Determining an Element Occurrence
Because the defining aspect of an EO is that it is a place on the landscape that sustains or contributes to the survival of an element, the criteria that establish what does and does not qualify as an EO are necessarily dependent upon the biological requirements of the element. For example, what constitutes an EO for a plant is quite different from a bird which in turn is different from a natural community. A plant EO may contain thousands of individuals spread over hundreds of acres or it may contain just one individual; bird EOs, however, are mostly limited to one or more breeding pairs. As a general rule for species occurrences, if a species is located in appropriate habitat, at the appropriate time of the year, and is naturally occurring, then it is considered an element occurrence.
Of course, "appropriate" is the operative word here -- it is not meant to imply that some occurrences are not included in the NHI database because the elements are found in habitats where they don't appear to belong. Rather, users should recognize that a fair amount of screening of the data is conducted to ensure that only ecologically valid occurrences are incorporated into the WNHI database. For example, transitory use of an area by an element (e.g., a Yellow-throated Warbler seen flying over a soybean field) is not considered an EO, nor is a population of pale purple coneflowers which has been planted. A report of singing male Yellow-throated Warblers in early summer in a southern mesic forest containing silver maple and elms does constitute an EO. Nearly all naturally occurring plant locations are considered EOs.
Another important aspect in determining what constitutes an EO is the issue of occurrences that are close, but not contiguous, to one another. For example, it is not uncommon for butterflies associated with pine and oak barrens to exist in several "sub-populations" separated by small wooded areas. Although they are not contiguous, these sub-populations interact genetically and thus the entire site is considered one EO (or meta-population).
Analogous to the consolidation of nearby occurrences is the incorporation of new information into existing EOs. Many times, information submitted to the WNHI program does not represent a new occurrence of an element, but rather is updated (or clarifying) information on an EO that is already in the database. Of course, this can be just as valuable as information on a new EO because it allows an occurrence to be evaluated over time.
A final issue to keep in mind is that EO records are deleted from the BCD only under certain circumstances -- the two standard reasons being that either the element was mis-identified or that the element is no longer tracked by the WNHI program. Neither element occurrences with very old "last observed dates" nor those that have been destroyed are deleted from the database because they can be useful information when evaluating population trends and other biological issues. Most printouts and maps generated by the WNHI program do not include extirpated occurrences.
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What follows are general guidelines the WNHI program uses when determining element occurrences within different taxonomic groups.
Mammals: Most small mammals on the Working List are not wide-ranging and collections or observations from any natural habitat can typically be considered an EO because it is assumed that the habitat contributes to their conservation. For bats, sites such as caves and mines where breeding or wintering occurs (hibernacula) are considered EOs. For larger, wider-ranging mammals typically evidence of breeding must be present. In the case of wolves, it is the pack's territory, not the pack, that is considered an EO. Due to the difficulty in representing EOs that cover very large areas in the BCD, wolf territories are tracked in a separate database.
Birds: Typically, there must be evidence of breeding and/or nesting for the observation of a bird to be considered an EO. A fly-over observation is not usually considered an EO. In cases of colonial birds (e.g., terns), or birds with more than one nest site (e.g., eagles), the colony or nesting territory is considered the EO. Information on re-introduced species, such as the Trumpeter Swan, is collected by the Bureau of Endangered Resources but is not processed in the BCD. Similarly, natural Peregrine Falcon aeries are tracked, but not the recently re-introduced populations nesting in hack boxes. Some non-breeding habitats are critical to the survival of some species --for example migration concentration areas and communal winter roosts-- and are tracked.
Herptiles: Any natural habitat where an amphibian or reptile is collected or observed constitutes an EO. Since road kills indicate the presence of suitable habitat nearby, they may also qualify as EOs. As with bats, herptile hibernacula also constitute EOs. If more than one rare species occupies the same hibernaculum, the species are individually recorded.
Fishes: Collection points in a lake or pond are typically considered EOs. Multiple collections (including those over a range of years) within a similar stretch of stream or in a lake are grouped together into one EO. Based upon a species' life history, collections made some distance apart (e.g., 5 or 10 miles) may be considered two distinct populations and thus two EOs. Dams and the associated impoundments often act as barriers to movement and thus observations made up and downstream of a dam are often considered two distinct EOs.
Aquatic Invertebrates (e.g., mussels, dragonflies): One or more collection points of species that tend to be distributed throughout a similar stretch of stream or type of lake are consolidated into one EO that represents the population. Species with other distribution patterns usually have each collection location recorded as a separate EO.
Terrestrial Invertebrates: With most terrestrial insects, the observation of an individual in its immature life stage in its natural habitat is considered an EO. In many cases, an observation of an adult may be considered an EO depending on behavior, presence of suitable habitat and how wide-ranging the species is and its flight capabilities. If two or more individuals are found in an area, one EO is mapped as long as the habitat between them is relatively homogeneous. As was stated previously, often several sub-populations may exist within a matrix of vegetative communities. In cases where individuals disperse from one site to another --even though these sub-populations may occur in habitats that are separated from one another-- the entire site (or meta-population) is considered one EO. Generally, if the distance between sightings is greater than the typical dispersal limit, two EOs are mapped.
Plants: In most cases, the observation of a native species in a natural, semi-natural, or even degraded habitat constitutes an EO. Cases where a verified observation of a native plant does not constitute an EO are: 1) when the observation consists of an isolated portion or fragment of a plant (this is most common with aquatic plant species), or 2) when a population is believed, or is known, to have been planted.
Natural Communities: As mentioned earlier, the WNHI program tracks occurrences of all types of natural communities, not just those that are rare (see the Working List for all types currently identified and recognized). For conservation purposes, communities are treated as important in their own right and also as "coarse filters". Effective protection of a natural community will also maintain populations of many native plants and animals, their interactions, and the ecological processes upon which they are dependent.
Among rare natural communities, such as oak openings, mesic prairies, and algific talus slopes, all but the most hopelessly degraded occurrences are tracked. For common, widespread natural communities, such as northern mesic forest and emergent aquatic marshes, the tracked occurrences represent those stands least disturbed by human actions (such as old-growth successional stages of forests) as well as stands which may support exceptionally high biotic diversity, are large, or are associated with other important natural features. The WNHI community database represents a proportionately smaller subset of the known occurrences of common communities relative to those types that are rare.
The significance of a given natural community occurrence is therefore related to not only its quality and condition, but also to its size and context.
As with re-introduced species, occurrences of natural communities that are re-created or planted are not considered EOs. However, communities that have received active management (e.g., burning) to restore or improve their condition are considered EOs.
Species Concentration Sites (e.g., Mussel Beds, Hibernacula, Migratory Bird Concentration Sites, Bird Rookeries): These are biologically important sites where a catastrophic event at any one location could have a significant impact on an entire taxonomic group. These animal concentration sites are tracked regardless of whether any rare species are known to occur there.
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Processing field data into element occurrence records (EORs) starts with the appropriate WNHI biologist reviewing the data and assessing its validity. Believing that the database is only as good as its weakest datum (and that users must have confidence that the data are as accurate and correct as possible), the entire Heritage Network is quite meticulous about the information that is entered into the database. The verification process includes considering the observation date, the habitat in which the element was observed, documentation of the occurrence and the knowledge and expertise of the observer. If the WNHI botanist, zoologist, or ecologist is unsure about some aspect of the submitted data, they will often try to arrange a visit to the site with the observer to verify the information or have a specimen identified by an expert.
Once the appropriate biologist has reviewed the data and determined that the information represents a new element occurrence or an update to a previously recorded occurrence, the data can be processed. Data processing includes transcribing the data onto standardized forms, representing the EO on a USGS 7½-minute quadrangle (quad) map, and entering the data into the BCD. Transcription of data often requires the summarization of information contained on the raw data forms. WNHI has manual files that contain printed copies of each element occurrence record attached to the raw data forms, along with any additional data provided such as maps, photos, etc. These manual files are utilized when more detailed data are needed than the summarized data provided on the EOR.
As part of data processing, each occurrence is assigned a mapping precision which reflects the locational accuracy to which the occurrence is known. As one can imagine, there is a wide range in the quantity and specificity of information that is submitted regarding where elements were observed. In the best cases, adequate information is included with an observation report that allows the occurrence to be represented on the quad maps very precisely. In other cases, it is only possible to ascribe a very general location to the occurrence. It is important to note that the precision to which the occurrence is known is independent of the amount of area the EO occupies. That is, it is possible to know precisely where a 600-acre southern sedge meadow occurs and its boundary, or to know only generally where a small, historical plant population was located.
The Heritage system groups mapping precisions using common distance and area measurements. These categories are arbitrary and are simply used to standardize the data. The WNHI uses the following seven precision levels:
S: "Seconds" mappable to a precision of a 3-second (about 200 feet) radius.
F: "Forty" mappable to a 40-acre (Quarter-Quarter Section) area, or within 1/8 mile radius.
Q: "Quarter" mappable to a 160-acre (Quarter Section) area, or within ¼-mile radius.
M: "Minute" mappable to a one-Minute radius, or within a 1 to 1½-mile radius.
G: "General" mappable to a 5-mile radius.
NM: "Not Mapped" generally EOs are not mapped for one of two reasons:
U: "Unmappable" the information available does not allow for the location to be identified within a ten-mile area.
Understanding and considering mapping precision is critical when using Heritage data.
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When the WNHI program was established, the legislature specifically exempted the WNHI database from the state's open records law. The Department has the authority to decide how and what information in the WNHI database is distributed outside the agency and has delegated this responsibility to the WNHI program. The WNHI database is considered sensitive for several reasons and thus not appropriate for general public distribution. The most obvious is the potential threat to rare species when their locations are publicly known. Illegal collecting, in addition to actions of well-intended people who simply are interested in viewing rare species, have impacted several populations of showy and highly sought after species. Although first-hand experience is a good way to engage the public in endangered resource protection, there is little question that for some species (such as turtles and orchids) it can have disastrous consequences. Also, the potential exists for outright destruction of rare species and their habitat by those who view them as barriers to resource utilization.
A less obvious threat is the commercialization and subsequent distribution of the database. The Department, and particularly the Bureau of Endangered Resources, has invested considerable resources in the WNHI database and as a result, it is now the most comprehensive collection of information on natural communities and rare species in the state. As the demand for this type of information has grown, the value of the data within the WNHI database, as well as the entire Heritage Network, has dramatically increased. Many programs within the Heritage Network have received requests for their databases from organizations that wish to market and sell their data. Commercial, unrestricted distribution of sensitive data, particularly information in the EOR database, is not compatible with goals of the WNHI program or the Heritage Network. Furthermore, several sources of data outside the Department are unwilling to provide important information on endangered resources to the WNHI program if we are unable to protect the data from public distribution.
A final threat, that public distribution of the WNHI database presents, is the great potential for misinterpretation and, worse, misapplication of the data. Because the Heritage methodology breaks the assessment of areas into simpler, more manageable data units, not understanding how these pieces fit together or what they are actually "telling" the user can easily lead to misinterpretation. Although inadvertent, the consequences of users incorrectly applying Heritage data can lead to inadequate protection and controversy. To avoid this, the WNHI program spends considerable time training users within the Department, as well as outside partners, on proper data interpretation and application.
In spite of the potential problems with distributing information outside the Department on where rare species and high-quality natural communities occur, the WNHI program believes sharing data with responsible users is one of the most powerful means of protecting endangered resources. The WNHI program invests considerable effort into collecting and managing data with the hope that the product of this work, the WNHI database, will be used to protect our state's biodiversity, not sit on a shelf. As a solution to data sharing problems, the NHI program follows specific guidelines when distributing information on endangered resources to individuals and organizations outside the Department. The BER maintains the responsibility for providing endangered resource data sets to external customers.
Top of page19 March 1998
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