USA Ecological Definition and Model:

Definitions

Critically Imperiled and Imperiled Species and Subtaxa:  Plant and animal species that are at risk of extinction due to their extremely restricted distribution or limited numbers.  These resources are identified, ranked, and inventoried by Natural Heritage Programs and Conservation Data Centers in conjunction with The Nature Conservancy (TNC). Under the TNC approach, each species is assigned a Global (or range-wide) Conservation Status Rank.  This rank is based on several specific factors, including the number of known occurrences or populations, number of individuals, health of the population, its extinction potential, whether it is experiencing an increasing or decreasing trend, and if there are known threats to the species (Master 1991).  Critically imperiled taxa demonstrate extreme rarity (5 or fewer occurrences or fewer than 1,000 individuals) or extreme vulnerability to extinction due to some natural or man-made factor. There are approximately 1,300 species in the United States that are ranked as critically imperiled globally. Rare or extremely vulnerable subtaxa that are critically imperiled are included in this category, despite the conservation status of the species as a whole.  Imperiled taxa demonstrate rarity (6 to 20 occurrences or 1,000 to 3,000 individuals) or vulnerability to extinction due to some natural or man-made factor. There are approximately 1,800 species in the United States that are ranked as imperiled. Rare or vulnerable subtaxa that are imperiled are included in this category, despite the conservation status of the species as a whole.

Depleted Marine Mammal Species:  Species identified and protected under the Marine Mammal Protection Act of 1972, as amended (MMPA) (16 U.S.C. 1361 et seq.).  The term "depleted" refers to marine mammal species that are listed as Threatened and Endangered, or are below their optimum sustainable populations (16 U.S.C. 1362).  The term "species" includes species, subspecies, or population stocks. There are currently 18 species listed as "depleted" under the MMPA.  Eleven of these species are also listed as endangered and three of these species are listed as threatened under the Endangered Species Act.

Ecological resources:  Fish, wildlife, plants, biota and their habitats which may include land, air, and/or water."

Environmentally sensitive area (ESA) - Drinking water and ecological resources as generally described by the National Oceanic and Atmospheric Administration (NOAA) (59 CFR 14714).

Filter Criteria: Assessment factors that provide parameters by which the USA candidates can be uniformly assessed for inclusion in the final set of unusually sensitive resource areas.

Hazardous liquid - petroleum, petroleum products or anhydrous ammonia (et. seq. 49 CFR 195.2).

Marine mammal: "any mammal which is morphologically adapted to the marine environment (including sea otters and members of the orders Sirenia, Pinnipedia, and Cetacea), or primarily inhabits the marine environment (such as the polar bear)" (16 U.S.C. 1362). The order Sirenia includes manatees, the order Pinnipedia includes seals, sea lions, and walruses, and the order Cetacea includes dolphins, porpoises, and whales.

Pipeline operator - The company, or other entity, which has responsibility for operating and maintaining the pipeline system.

Pipeline system - All parts of a pipeline facility through which a hazardous liquid moves in transportation, including but not limited to, line pipe, valves, and other appurtenances connected to line pipe, pumping units, fabricated assemblies associated with pumping units, metering and delivery stations and fabricated assemblies therein, and breakout tanks.

Threatened and Endangered (T&E) Species:  Animal and plant species that have been listed and are protected under the Endangered Species Act of 1973, as amended  (16 U.S.C. 1531 et seq.). A summary of these listed species is published annually as the "List of Endangered and Threatened Wildlife and Plants" (50 CFR 17.11 and 17.12). In the United States (including Alaska, Hawaii, Puerto Rico, U.S. Virgin Islands, and Pacific Trust Territories), there are currently more than 1,000 listed T&E species..

USA candidates: A subset of drinking water and ecological ESAs. These candidates are areas that contain ecological resources that are potentially more susceptible to permanent or long-term environmental damage, regardless of land ownership, management, or proprietorship.

Western Hemisphere Shorebird Reserve Network (WHSRN) - The Manomet Center for Conservation Services coordinates the effort to conserve areas of critical shorebird habitats throughout the Americas.  WHSRN is a program of Manomet in collaboration with other public and private organizations worldwide.

The program identifies and delimits areas where significant populations of migratory waterbirds congregate during critical periods.  A second program, the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (Ramsar), is also dedicated to the identification of globally critical wetland areas supporting migratory waterfowl.

1.1             The USA Concept

Tasked with the responsibility for describing USAs, DOT initiated a consultative process with federal and state regulatory agencies, environmental organizations, the regulated community, and the public. These provided the framework for the proposed USA definition (64 Federal Register 250, pg. 73464).   

In general USAs are defined as:

Those definable geographic areas that contain drinking water or ecological resources that by their character are irreplaceable and may be subject to irreparable and irreversible injury or irretrievable loss, if they are exposed to the effects of an accidental hazardous liquids release.

There is an abundance of natural resources that are afforded varying levels of protection under a variety of state and Federal laws.  These include such diverse geographies as federally owned lands (e.g. park, forest, and reserve boundaries), ecological regions (e.g. wetlands, estuaries and river systems), water bodies (e.g. lakes, rivers, drainage basins and groundwater aquifers), cultural resources, and locations of individual species occurrence (e.g. threatened and endangered species). Unusually sensitive areas should not incorporate the entirety of all federally protected natural resource areas.  Rather, the term "unusually sensitive areas" represents a subset of these resources that may be subject to "permanent and long-term environmental damage."  

The USA definition focuses upon those environmental resources that are potentially at risk of such damage and are essential to the protection of human health and the continued viability of ecological resources.  Thus, application of the USA definition, as it is established in this document, specifically identifies drinking water resources that are critical to the uninterrupted delivery of consumable water to public water systems (PWS) and areas critical to the survival and viability of threatened, endangered, and imperiled biological species.

2.0           Ecological Data Sources and Data Management

A number of data sources can be used to help identify ecological USAs.  These data sources reflect both the nature of the landscape (i.e. surface of the earth) and the distribution of ecological resources upon the landscape.  The identification of USAs requires spatially explicit candidate resource occurrence data.  Candidate resource occurrence data describe the actual locations where individuals or populations of candidate species or subtaxa occur, or where Ramsar and Western Hemisphere Shorebird Reserve Network (WHSRN) sites have been established.  Spatially explicit means that the actual location of these occurrences is represented in map based [SOC1] terms, as in latitude/longitude coordinates or other geographic units.

Ecological USA candidates must be mappable to sufficient precision such that there is a high likelihood that the species or subtaxa occurs within the identified habitat area. To meet the data specificity needs of the USA process, species or subtaxa distribution data must be based upon known occurrences that are mappable to one minute, or greater, precision.  One minute of a degree roughly translates to 1 mile in most parts of the globe.  Data that meet these requirements allow for the development of effective site-specific risk assessment and protective measures. 

Of the species and subtaxa distribution data sets available, the Natural Heritage Program element occurrence database most effectively meets these data location quality requirements for terrestrial and freshwater ecological resources.  Natural Heritage data are maintained on a state and regional basis under an initiative conceived of and fostered by TNC.  Attributes vary from state to state.  In many states, extensive work has been done to populate the standard Nature Conservancy data model, including attributes on data accuracy, precision and species characteristics.  In other states, only a base level of data is available.  Information on the TNC data model is available on the internet. 

For coastal, marine, and some inland resources, the Environmental Sensitivity Index (ESI) data sets most closely meet the data location quality requirements. The ESI data sets are composed of three primary elements, 1) Shoreline Classification, 2) Human-Use Resources, and 3) Biological Resources (Halls et.al., 1997). Of these three elements, the biological resources element provides ecological USA candidate occurrence data and compliments the Natural Heritage Program element occurrence database. 

The boundaries of migratory waterbird concentration areas identified by the Ramsar and WHSRN programs have not been fully mapped in all cases, but available site descriptions do provide sufficient detail to allow them to be mapped consistent with the above data location quality requirements.  Information on the Ramsar and WHSRN sites is available on the internet or from the U.S. Fish and Wildlife Service, Office of International Affairs.

Other data sources were evaluated for utilization as USA ecological candidate resource occurrence data, but did not meet requirements for data access and standardization, site specificity, or exceed the quality of data more readily available from other sources.  Several of these ecological resource mapping programs may achieve the necessary data location quality requirements in the future.

Data sets and individual data records that do not currently meet these criteria will be periodically re-evaluated for changes in data quality. This re-evaluation is necessary because these data sets and individual records are periodically revised and upgraded by the various responsible entities as new information becomes available.

Ecological USA candidate resource occurrence data can generally be characterized as either points or polygons.   Point data normally represent the location of the center (centroid) of a candidate occurrence, but do not reflect its specific boundaries or total area.  The majority of candidate resource occurrence data are available in this format.  Polygon data can be used to represent two different types of boundaries.  Polygons can represent approximated areas, such as a buffer circle or polygons can provide the specific boundaries of a candidate resource occurrence.  The later type of polygon data, referred to as a resource-based polygon, typically has been established through field investigations. Resource-based polygon data are mapped as complex shapes associated with the landscape or other features.  There are efforts by a number of programs to use resource-based polygonal data for prioritized resource occurrences that are currently available as point data only.

3.0           The USA Definition Process

3.1             DERIVING USAs FROM ESAs

The process that should be used for the definition of USAs has been developed through extensive consultation with drinking water and ecological resource experts, government agencies, and other stakeholders. This multi-step process involves the designation and assessment of environmentally sensitive areas (ESAs), USA candidates, filtering criteria and data requirements (Figure 1).  This guidance document identifies ESAs, USA candidates, filter criteria, and data sources that should be used.

Under this process, ESAs include all potential ecological resources that can be generically considered to be sensitive and would be afforded protection under any number of federal resource protection programs.  In addition to being afforded protection under their individual protective mandates, these resources are also afforded protection under the Oil Pollution Act of 1990 (OPA 90).  As such, these resources are already identified and provided with appropriate response measures through the OPA contingency planning process and may not necessarily need an additional layer of protection as USAs.

From among the ESAs, a subset of USA candidate resources have been identified that are considered to be of greatest significance and potential susceptibility to permanent or long term environmental damage as the result of a hazardous liquid pipeline release. For ecological resources, USA candidates include areas containing species clearly in jeopardy of extinction and areas where large concentrations of a species' world population congregate for a period of time.

Filter criteria are applied to the list of USA candidates to identify those areas that are most critical to the continued existence of biological species.  The application of filter criteria produces the final set of USAs.

Figure 1: Schematic of the USA identification process depicting the relationship between ESAs, USA Candidates, Filter Criteria, and USAs.

It is anticipated that pipeline operators will utilize a risk assessment process to consider the potential impacts to USAs that result from a specific pipeline release.  The results of the risk assessment will either lead to implementation of additional protective measures, or reclassification as an ESA (Figure 1).

3.2             THE PROCESS OF IDENTIFYING ECOLOGICAL USAs

Ecological USAs are defined through the stepwise process of defining ecological ESAs, the selection of USA candidates, and the application of filter criteria to produce the final set of USAs (Section 2.1).  This guidance document utilizes a rationale that ecological USAs should focus upon those geographic areas that support biological resources that are susceptible to permanent loss (i.e. extirpation) and/or irretrievable or long-term impairment on a global basis.  From the broad spectrum of federally protected ecological resources, ESAs [SOC2] are selected based upon the distribution and occurrence of biological resources, rather than upon designated lands (i.e. parks, refuges, estuaries, etc).  Ecological USA candidates select those species that are at risk of extinction or significant and long-term reduction.  Filter criteria identify the priority areas for protecting and maintaining biological species.

This rationale reflects an approach that is based upon an understanding of the geography of species at risk.   Stein et al. (2000) provide an excellent synthesis of an approach to the identification of essential biodiversity refuges that is derived from previous studies including Scott et al. (1987), Kiester et al. (1996), Dobson et al. (1997), Flather et al. (1994 & 1998), Ehrenfeld (1997) and TNC (1996 & 1997). 

3.2.1       Ecological ESAs

Ecological ESAs are based upon areas defined as sensitive to the effects of oil spills (National Oceanic and Atmospheric Administration, 1994 59 FR 14714).  ESAs include sensitive fish, wildlife, plant, and habitat resources that are at risk from hazardous liquid spills.  These include such resources as breeding, spawning, and nesting areas; early life stage concentration and nursery areas; wintering or migratory areas; rare, threatened, and endangered species locations; and other types of high concentration or sensitive areas.

3.2.2       Ecological USA Candidates

Ecological USA candidates are a subset of ecological ESAs. These candidates are areas that contain ecological resources that are potentially more susceptible to permanent or long-term environmental damage, regardless of land ownership, management, or proprietorship.

Four resource categories have been identified as ecological USA candidates (Figure 2).   These categories are susceptible to permanent or long term ecological damage due to inherent characteristics of rarity, imperilment, or the potential for loss of large segments of an abundant population during periods of migratory concentration.

Figure 2: Ecological USA Candidates

A.   Areas Containing Critically Imperiled and Imperiled Species and Subtaxa.  These areas contain known occurrences of animal and plant species that have been designated by The Nature Conservancy (TNC) as Critically Imperiled or Imperiled.

B.   Areas Containing Federally Listed Threatened and Endangered (T&E) Species.  These areas contain known occurrences of animal and plant species that have been listed and are protected under the Endangered Species Act of 1973, as amended  (16 U.S.C. 1531 et seq.).

C.   Areas containing Depleted Marine Mammal Species.  These areas contain known occurrences of depleted species identified and protected under the Marine Mammal Protection Act of 1972, as amended (MMPA) (16 U.S.C. 1361 et seq.).

D.   Areas Containing a Large Percentage of the World's Population of a Migratory Waterbird Species.  These areas contain very high concentrations of the world's population of a species for a short period of time. An example would be the parts of Delaware Bay where a major portion of the world population of red knot (a shorebird species) stop-over to feed during migration.

Two programs of international significance are responsible for identifying and delimiting areas where significant populations of migratory waterbirds congregate during critical periods.  The first program, the Western Hemisphere Shorebird Reserve Network (WHSRN), ranks migratory shorebird concentration areas into four different categories on the basis of biological criteria.  These four categories are:

1)     Hemispheric reserves - these areas host at least 500,000 shorebirds annually or 30% of a species' flyway population;

2)     International reserves - these areas host 100,000 shorebirds annually or 15% of a species' flyway population;

3)     Regional reserves - these areas host 20,000 shorebirds annually or 5% of a species' flyway population; and

4)     Endangered species reserves - these areas are critical to the survival of endangered species and no minimum number of birds is required.

24 WHSRN sites have been established in the United States (Table 1b).

A second program, The Convention on Wetlands of International Importance Especially as Waterfowl Habitat (Ramsar), is dedicated to the identification of globally critical wetland areas supporting migratory waterfowl.  The establishment of a Ramsar site (Ramsar Articles, 1996) includes the following specific criteria for waterfowl:

1)     A wetland area that regularly supports 20,000 waterfowl, or

2)     A wetland area that regularly supports substantial numbers of individuals from particular groups of waterfowl, indicative of wetland values, productivity, or diversity, or

3)     Where data on populations are available, a wetland area that regularly supports 1% of the individuals in a population of one species or subspecies of waterfowl.

There are a total of 17 Ramsar sites in the United States (Table 1a).

3.2.3       Ecological Filter Criteria

Three ecological filter criteria have been developed that are consistent with current trends in conservation ecology. These filter criteria identify areas with critically imperiled species, multi-species protection sites, and migratory waterbird concentrations.  Figure 3 illustrates how these three criteria are applied in a multi-tiered process where all ecological USA candidates receive repetitive consideration for USA status.  For example, an ecological USA candidate resource area is first subjected to filter criterion 1, areas with critically imperiled species, and may be designated as a USA at this point.  If the candidate does not meet filter criterion 1, it then receives consideration under filter criterion 2, multi-species protection areas, and may be designated as a USA at this point.  If the candidate does not meet filter criterion 2, it receives consideration under filter criterion 3, migratory waterbird concentration areas, and may be designated as a USA at this point.  If the candidate does not meet filter criterion 3, it remains a USA candidate.  All candidates would be periodically reviewed to consider changes in resource information or status.  A candidate would become a USA once it meets one of the filtering criteria.

Figure 3:  Flow chart depicting the recommended process for identification of USAs from occurrence records

 Filter Criterion 1 - Areas with Critically Imperiled Species

Filter criterion 1 selects those ecological USA candidates that are viable occurrences of species or subtaxa designated as critically imperiled globally to be USAs. These species or subtaxa demonstrate extreme rarity or extreme vulnerability to extinction due to some natural or man-made factor.  They typically have five or fewer occurrences or fewer than 1,000 individuals globally.  In some cases, species or subtaxa may be identified as critically imperiled because they are subject to an extreme threat of extinction due to factors other than low number of occurrences or individuals.

The critically imperiled designation includes a wide variety of plant and animal species and subtaxa.  It includes approximately 64 percent of the listed threatened and endangered species and 53 percent of those species currently designated as proposed or candidates for listing under The Endangered Species Act. This filter criterion also selects an additional number of plant and animal species and subtaxa that are not designated under The Endangered Species Act.  All ecological USA candidates meeting this criterion are considered USAs.  Ecological USA candidates that do not meet filter criterion 1 are retained for consideration under filter criteria 2 and 3.

Filter Criterion 2 - Multi-species Protection Areas

Filter criterion 2 selects those ecological USA candidates that form multi-species assemblages.  Multi-species assemblages are defined as areas where three or more different critically imperiled or imperiled species, federally threatened or endangered species, species federally-listed as essential experimental populations, depleted marine mammals, or migratory waterbird concentrations co-occur.

Whereas filter criterion 1 selects the critically imperiled occurrences of individual species or subtaxa, filter criterion 2 selects ecological USA candidate areas where multiple species, subtaxa, or migratory waterbird concentrations co-occur. These areas are valuable as they often represent unique ecosystems and they also protect a greater number of sensitive resources per site location.

Filter Criterion 3 - Migratory Waterbird Concentration Areas

Filter criterion 3 selects those ecological USA candidates that are designated as Ramsar sites that meet the specific waterfowl criteria, or WHSRN sites ranked as hemispheric, international, or endangered species reserves. 

Filter criterion 3 focuses on areas where significant populations of migratory waterbirds congregate during critical periods.  Relatively common species may be at risk at such sites. In some cases, as much as 80 percent of the entire North American population of a particular species may occur at one of these sites during critical concentration periods (Harrington and Perry, 1995).

3.2.4       Implementing the USA Identification Process for Ecological USA Candidates

A process has been developed for identifying ecological USAs from base map data and candidate occurrence data that meet the data location quality requirements.  The process is implemented by first creating generic polygons for all candidate occurrences existing only as point locations.  These generic polygons are then combined with existing candidate occurrence polygon data.  This combination creates a complete candidate occurrence data set.  The polygons from this data set are associated with base map data to establish the relationships of individual occurrences with landscape features, and to determine proximity to other occurrences.

3.2.5       Creating Polygons from Candidate Occurrence Data

In the development of an approach to the designation and mapping of USAs, the primary goal of providing adequate protection to areas of unusual ecological sensitivity necessitates the adoption of a rule set that enables resources of innately different ecological character to be dealt with differently within the model.  Further, the inherent limitations of currently available data sets supporting the model tend to favor generalization of mapping procedures, in cases where greater specificity may be justifiable on an ecological basis.  The remainder of this section provides recommendations for procedures to be utilized to resolve a number of specific mapping problems and is based upon current data availability and limitation.

Within the ecological USA methodology, there are three possible types of USA polygons.  The first type of polygon is a resource based mapped polygon.  This type of polygon is derived directly from mapped resource occurrence areas contained within the Natural Heritage and Environmental Sensitivity Index data sets, when available.  As these polygons are mapped on the basis of recent field observations, they are to be accepted as best available characterization of resource areas and are utilized preferentially over other derived areas.  Aside from these relatively rare polygons, the majority of resource occurrence areas are derived as either terrestrial or aquatic areas.  Derived terrestrial areas and isolated aquatic areas will incorporate circular areas of the landscape within one mile of the coordinate location designated in the Natural Heritage data set.  Aquatic, or open non-isolated water, areas will incorporate all connected open waters within a five-mile radius from the occurrence location.  Aquatic occurrences will also extend one-fourth mile on either side of mapped open waters so as to incorporate associated important riparian areas.

3.2.5.1            Differential Treatment of Aquatic and Terrestrial Species

Due to perceived differences in the way that aquatic resources are distributed on the landscape and in the way that spilled hazardous liquids move in aquatic habitats, versus terrestrial habitats, a number of habitat types have been developed with corresponding differences in the size and shape of the candidate USA.  Generally, the occurrence locations of all terrestrial species should be represented as a one-mile radius circle around the coordinates of the occurrence.  Such an area is designated so as to accommodate for uncertainties and inaccuracies about the actual location and area included in the occurrence and to afford an ample geographic buffer of protection around unusually sensitive ecological resources.  Aquatic species should be subdivided according to their dependence upon, or occurrence within, the various aquatic environments listed below based upon Correll and Correll (1975). 

Those species that occur predominately in larger bodies of water and non-isolated water should be treated as open water species.  That is, their occurrences should be represented as all connected waters within a five-mile radius of the coordinates of the occurrence location. 

The occurrences of those species that occur predominately in, or associated with, isolated or ephemeral water bodies should be treated as terrestrial occurrences with a one mile radius circle around the coordinates of the reported occurrence.

Aquatic species: species that spend a significant portion of their lives, a life stage, or important life-history activity within, upon, or regularly in contact with aquatic habitats.  Such species are unable to utilize terrestrial environments or to move significantly away from aquatic environments during an aquatic habitat dependent portion of their life cycle.  Includes species that may live in terrestrial environments but which derive an obligatory portion of their resource needs from aquatic environments.

Terrestrial species: species that are able to utilize habitats that are not dominated by or dependent upon the presence of free water at the surface.  Such species may visit aquatic habitats on a regular basis but do not require constant or regular contact with or derivation of food from aquatic habitats.

Aquatic/Terrestrial species:  Species that utilize both aquatic and terrestrial habitats for discreetly different resource requirements for some portion of their life cycle.  Examples of such species include species that have nests in areas that are distinctly terrestrial but which feed in aquatic or marine environments (e.g. marbled murrelet and peregrine falcon).  As the activities performed in these different habitats are distinct from one another and as the areas may be geographically distinct from one another and different in size and configurations, the areas should be treated as separate areas and should be treated as either terrestrial or aquatic.  For example, old growth forest areas that support nesting of marbled murrelets should be designated by USA candidate areas with a one-mile radius.  The marine feeding areas of marbled murrelets should be designated by five-mile radius circles that include all connected waters plus a � mile overlap onto land. 

3.2.5.2            Classification of Aquatic Species

1. Water standing or essentially so.
   1. Presence of water permanent and level fairly persistent.
      1. Open water surface the most conspicuous feature.
         1. Fresh water: lakes, ponds, reservoirs - O *
         2. Salt water: salt lakes, bays and oceans, estuaries, lagoons - O
      2. Vegetation more conspicuous than water surface.
         1. Vegetation dominantly herbaceous - O
            1. Marshes: alkaline marshes, salt marshes, brackish marshes, freshwater marshes - O
            2. Bogs: quaking bogs, floating bogs, evergreen shrub bogs - O
         2. Vegetation dominated by trees and/or shrubs.
            1. Swamps, bay-galls - O
   2. Presence of water intermittent or at least the level widely fluctuating.
      1. Intermittence seasonal: vernal pools, playa lakes, vernal marshes, savannahs - I **
      2. Intermittence tidal: Salt-water marshes, seasonally salt and fresh-water marshes, fresh-water marshes subject to tidal influence - I
2. Water flowing: live streams, intermittent streams, irrigation ditches, drainage canals, hillside bogs, streamside marshes - O
3. Wet soil adjacent to habitats with standing or flowing water; beaches, strand areas, riparian lands, lacustrine lands, wet meadows, seasonally wet floodlands - I
4. Water subterranean: caves, porous aquifers, wells, sumps - I

* O - Species characteristically dependent upon this type of habitat would be considered to be open water species (5-mile radius USA)

**I - Species characteristically dependent upon this type of habitat would be considered to be isolated water species (5-mile radius USA)

3.2.5.3            GIS derivation of aquatic USAs  

The original intent was for aquatic USAs to include all connected (e.g. source) upstream waters for a distance of five river miles above the point location of a species' occurrence.  The downstream portion of the USA would include only receiving waters below the point location.  That is, tributaries entering a receiving water below the point location would not be included in the designated USA.  All waters not connected to the waterway intersected by the EO location would not be included in the USA. 

This methodology requires the use of data sets that are not currently available (i.e. the USGS/EPA National Hydrography Dataset (NHD) which integrates the USGS 1:100,000-scale DLGs with EPA river reach data (RF3)).  Without this data, it is difficult to assign flow directionality to river segments.  Flow data are available in the EPA Reach File Version 1 (RF1), however this data set is mapped at a scale of 1:250,000 and the coarser resolution precludes the inclusion of a number of significant water courses. Until the NHD data set is available for use, a methodology will be adopted that places a five-mile radius buffer around a point location and incorporates all connected open waters within that buffer zone. The approach likely increases the number of water courses and the mileage of water courses that are included in the USA; however, it conservatively increases the likelihood that the appropriate water body will be included in the USA.  Pipeline operators would retain the capability, however, of examining the USA during the risk assessment phase and discounting any unconnected and non-receiving waters from the USA. 

3.2.6       Applying Filter Criteria to Candidate Occurrence Data to Identify USAs

The USA identification process is depicted in figures 4-8.

Figure 4 represents a spatial distribution of candidate element occurrences  (EOs) as they would be acquired from Natural Heritage Programs and other data sources.  Note that these data are acquired as both point and polygon data as described in section 2.3.5 above. 

Figure 5 depicts the application of filter criterion 1.  Areas with critically imperiled species and subtaxa have been identified as USAs and are represented by the shaded areas.  As discussed in section 2.3.5.1, apparent differences in the size and shape of the generated USAs correspond to the habitat type of their candidate EO.

Figure 6 depicts the application of filter criterion 2.  Multi-species protection areas (MSPAs) are delineated by the area included within the union of habitat areas, where these areas of three or more different candidate EOs overlap.  Note that the size and shape of the generated polygons for candidate EOs have been standardized (i.e. 1 mile radius for terrestrial and isolated aquatic species and 5 mile radius for open water species) to allow all candidates equal opportunity to contribute to a MSPA. 

Figure 7 depicts the application of filter criterion 3.  Occurrences that have been designated as Ramsar sites that meet the specific waterfowl criteria or WHSRN sites ranked as hemispheric, international, or endangered species reserves have been identified as USAs and are represented by the shaded area.

Figure 8 shows the final USAs that have been identified by the application of all three ecological filtering criteria.

Figure 4: Spatial distribution of candidate element occurrences.  Point data indicated by an "x".  The hatched polygon is a WHSRN site.  The outlined areas are resource-based polygons.  Note that the WHSRN site overlies a resource-based polygon.

Figure 5: Application of filter criterion 1, the identification of occurrences of critically imperiled species and subtaxa.  Note that the WHSRN site does not become a USA under this criterion, but the resource-based polygon that underlies it does.

 Figure 6: Application of filter criterion 2, identification of multi-species protection areas (MSPAs).  Note that the WHSRN site does becomes a USA under this criterion, due to its contribution to a MSPA.

Figure 7: Application of filter criterion 3, identification of migratory waterbird protection areas.  Only the WHSRN site becomes a USA under this criterion.

Figure 8: USAs identified by all 3 ecological filtering criteria.

4       USING A GEOGRAPHIC INFORMATION SYSTEM (GIS) TO IDENTIFY ECOLOGICAL USAs

4.1 BENEFITS OF A GIS

A Geographic Information System (GIS) is software that combines the query and statistical analysis tools of a relational database with the spatial analysis capabilities and visual advantages offered by digital maps.  A GIS enables simultaneous manipulation of all types of information that have a common link through geography.  The information is stored in thematic layers that can be easily overlaid and analyzed through their relative location on the earth's surface.  The GIS software package that is utilized in the pilot test is ArcInfo, developed by Environmental Systems Research Institute, Inc. (ESRI), Redlands, CA.

4.2  INPUT DATA USED IN THE PILOT TEST OF THE ECOLOGICAL USA MODEL

4.2.1       BIOLOGICAL RESOURCES DATA

For species and subtaxa distributions on land, (and sporadically in marine environments, also), the model accepts the Natural Heritage Program (NHP) element occurrence (EO) databases from each pilot test state, (i.e., California, Louisiana, and Texas).

For species and subtaxa distributions along the coast and in marine environments the model accepts the sensitive biological resources information from the Environmental Sensitivity Index (ESI) data sets.  In general, these data sets are published by the National Oceanic and Atmospheric Administration (NOAA).  Some states, however, have a proprietary biological resources database that is considered the state accepted ESI data set.  For the pilot test, NOAA ESI data sets are used for San Francisco Bay, the coast and offshore islands of California, and the upper Gulf Coast of Texas.  For the central and lower Gulf Coast of Texas, biological resources information from the Texas General Land Office (TGLO) is used by the model, because it is considered to be the state accepted ESI data set.  A digital ESI data set for the coast of Louisiana was not available at the time of the pilot test and was not included in the ecological USA model run for Louisiana.

4.2.2       HYDROGRAPHY

The model uses USGS 1:100,000-scale Digital Line Graph (DLG) information to represent the hydrography (or surface water features) in each pilot test state.  The DLG data are digital representations of points, lines, and areas of planimetric information derived from 30- by 60-minute intermediate scale quadrangle maps.  The data are considered DLG - Level 3 (DLG-3), which means the data contain a full range of attribute codes, have full topological structuring, and have passed certain quality-control checks described in the Federal Geographic Data Committee's (FGDC) Content Standards for Digital Geospatial Metadata.  DLG information is available on the internet at http://edc.usgs.gov/doc/edchome/ndcdb/ndcdb.html.

For the pilot test, the data files were downloaded by file transfer protocol (ftp) in the spatial data transfer standard (SDTS) format.

Another nationwide digital database is currently being developed by USGS and EPA that will soon provide a better representation of statewide hydrography for use in the model.  It is called the National Hydrography Dataset (NHD) and is comprised of the USGS 1:100,000-scale DLGs integrated with reach-related information from the EPA Reach File Version 3 (RF3).  The integration of these two data sets enables the analysis and display of water-related data in upstream and downstream order at an intermediate data resolution scale.  The information is being compiled in hydrologic cataloging units across the United States.  At this time, quality control checks meeting FGDC standards have not been completed for all HUC areas to make statewide applications practical yet.  More information can be obtained from the web site, http://nhd.usgs.gov/.

4.2.3       WHSRN AND RAMSAR SITES

A summary list of Ramsar sites can be downloaded from http://ramsar.org/.  A list of WHSRN reserve sites can be downloaded from http://www.manomet.org/.

In order to represent the site boundaries as best as possible in the model, each agency that is responsible for a migratory waterbird protection area in a pilot test state was contacted to determine if any digital geographic information was available for the site.  Most agencies had some type of geographic information about the site boundaries.  However, the information is maintained in a multitude of formats, (both digital and hard copy), with varying levels of locational accuracy and data quality.  The model accepted the data as they were received from the agencies.  Interactive data pre-processing was required to convert the information into the format required by ArcInfo prior to the model runs.

4.2.4       BIOLOGICAL RESOURCES DATA FROM ADJACENT STATES

The ecological USA model is built to run on a state-by-state basis.  Because biological resources are not inclined to follow boundaries of political jurisdiction, it is recommended that model input data within 5 miles of a state be included in the model for a state, when the data are available and the model state borders areas within the jurisdiction of the U.S.  This allows the model to fully develop multi-species protection areas (MSPAs) along the state line and avoids discontinuity of ecological USAs across state borders.

Essentially this recommendation calls for all NHP and ESI element occurrences (EOs), hydrography data, and WHSRN and Ramsar sites that are within 5 miles of the border of neighboring states to be pre-processed and included in each model run.  Special consideration should be afforded to EOs from adjacent state databases when evaluating and updating attribute information during the model data pre-processing effort.

For the pilot test, this concept could only be applied for the Louisiana and Texas model runs.  Because all three pilot test states were run during the same time frame, post-processed data from neighboring state model runs was used during the analysis.  When full implementation of the ecological USA model is undertaken, it is feasible that adjacent states may not always be run concurrently.  With the dynamic nature of biological resource information, it is advisable to perform data pre-processing work for adjacent state EOs prior to each model run, when a sufficient time lag exists.

4.3  BIOLOGICAL RESOURCE DATA REPRESENTATIONS

The biological resource data used by the model can be grouped into three different representations: resource-based polygons, approximated areas, and point locations.

4.3.1       RESOURCE-BASED POLYGONS

Resource-based polygons are areas that have been mapped from field observations.  These delineations are typically mapped at a large scale with a fine resolution.  Resource-based polygons are considered by the model to be the best representation of the EO habitat.

4.3.2       GIS DERIVATION OF AREAS FROM POINTS

The purpose of the GIS ecological model is to identify areas that contain biological resources that are described as being unusually sensitive to the effects of an accidental hazardous liquids release.  Some of the USA candidate data sources do not provide the model with polygonal data that accurately represents the habitat boundaries of the EO.  Instead, the data sets represent the EO by a point location or an area where the EO is approximately located.  In these cases, a polygonal representation of the EO's habitat must be created in order to meet the essential aim of the model.

Approximated areas are generalized buffer areas that describe the spatial uncertainty of a point source feature.  For example, the EO is marked as a point on a map, but because of various factors there is uncertainty that the mark is actually the exact location of the EO.  To account for the uncertainty, a buffer is generated around the EO point.  The EO is considered to be located anywhere inside the buffer circle.  For biological resource data mapped as approximated areas, the model uses only the original EO point location.  The type of habitat that the EO is associated with or the habitat that the element (or species) depends on during part or all of its life cycle is evaluated to determine the size and shape of the representative habitat polygon.

Some USA candidate data sources represent some or all EOs as point locations.  Such is the case for many state NHP EO databases that contain no polygonal data.  The model generates representative habitat polygons for these EOs following the protocol used for approximated areas.

4.4  CLASSIFYING ELEMENT OCCURRENCES BY HABITAT TYPE

The derivation of polygonal areas from EO point data relies heavily on the type of habitat the EO is associated with.  There are three habitat types that an EO may be classified as: open water, isolated water, or terrestrial.  In the event that the habitat type of the EO is unknown, the habitat that the species depends on during part of all of its life cycle is evaluated and classified accordingly.  Ideally, the classification is performed by the state NHPs.  Since the majority of EO point data comes from state NHP databases, the state NHP has the unique position of being the most familiar with the data and its possible idiosyncrasies.

Unique species listings of all EOs in the state NHP database represented by approximated areas or point data are compiled during the pre-processing stage of the model.  The listings are refined so that only EOs meeting the ecological filter criteria are sent to the state NHPs for habitat designations.  For the pilot test, botanists and zoologists from Texas and Louisiana NHP performed the habitat classifications for the species in their state databases.  Unfortunately, the California NHP was unable to assist with the classification during the time frame of the pilot test.  Habitat designations for California NHP EO approximated areas and point data were assigned from research performed by the technical contractors.

4.4.1       STATEWIDE DIGITAL HYDROGRAPHY MAPS

To create a polygonal representation of open water habitat that offers the EO an effective protective buffer from accidental pipeline releases in aquatic environments, the methodology calls for the derivation of an area that incorporates all connected waters within a 5-mile radius around the EO point location.  In order to identify the location of surface water features within a state, the GIS requires a digital representation of the hydrography in the state.

Preferably, once it is complete, the National Hydrography Dataset (NHD) would be used as the standard digital representation of hydrography in a state.  The data set contains the information necessary to closely approximate the location of surface water features and determine the flow of water both upstream and downstream.  These data are invaluable when trying to identify connecting waters in a drainage network.

Until the NHD is ready for statewide applications, it was decided that the USGS 1:100,000-scale DLG data set will be used as the standard for representing hydrography in the pilot test states.  For each pilot test state, searches were conducted to locate statewide compilations of the USGS intermediate-scale quadrangles that had already been combined into one seamless hydrography map layer.  The searches were not successful, however.  As a consequence the technical contractors were required to build the seamless hydrography map layers as a pre-processing effort prior to any model runs.

4.4.1.1COMPILATION OF THE HYDROGRAPHY MAP LAYER

The pre-processing effort begins by using file transfer protocol (ftp) to download from the internet every zipped SDTS TAR (tape archived) file in the hydrography directory of all 1:100,000-scale half quadrangles for a state.  Using the capabilities of WinZip, the downloaded files are unzipped and extracted from TAR format.  The resulting files are used in the conversion from SDTS format to ArcInfo coverages.  The arc macro language (AML) program used for the conversion is called sdts2cov.aml.  This program and other helpful tools for working with the SDTS format can be downloaded from the USGS SDTS Information Site, http://mcmcweb.er.usgs.gov/sdts/. 

The conversion program, sdts2cov.aml, was run with the "-combine" option in order to create one ArcInfo coverage from each downloaded file.   AMLs, written by project staff, select out polygon and line features from the coverages that have non-blank USGS entity label information.  The selected features are separated by feature type and placed into new coverages.  As a result, two coverages are created for every file that was downloaded, one coverage contains only line features with definitive attributes; the other coverage contains only polygon features with definitive attributes.  Using ArcInfo's APPEND command, all line coverages are combined to create one coverage that is the seamless map layer of hydrographic line features, (e.g., streams, canals, shorelines, etc.).  Likewise, all polygon coverages are combined together to create a seamless map layer of hydrographic polygon features, (e.g., lakes, inundation areas, tidal flats, etc.).  Quality control checks are performed at every stage of the procedure.  The checks include both visual verification and database confirmation that consistency and continuity among feature attributes is being maintained throughout the process.  The model uses the final two coverages as the digital representation of hydrography for the state.

The entire data conversion and compilation procedure described above involved the download and processing of 264 files for California, 88 files for Louisiana, and 344 files for Texas.  The significant effort required nearly 3 months of labor and computer processing time to complete.

4.4.2       GIS DERIVATION OF POLYGONS THAT REPRESENT OPEN WATER HABITAT

The process of generating open water habitat polygons is only employed for EOs represented by approximated areas or point locations that have been assigned USA status through the ecological filter criteria.  The open water habitat polygon represents the area that is unusually sensitive due to the presence of a critically imperiled species or a species that contributes to a multi-species protection area (MSPA).

Additional pre-processing steps required for the GIS derivation of open water habitat polygons involve classifying the digital hydrographic features of the state by the entity that is mapped.  Entity label attributes describe the types of features mapped by USGS DLGs.  The entity label definitions of the hydrographic line and polygon features are reviewed to identify those features that are associated with an open water environment.  Table 2 lists the unique entity label definitions that appear in the hydrography map layers for the three pilot test states.  Table 2 also indicates which entity labels were identified as "open water" features by the model.

The model utilizes the ArcInfo region feature class in deriving open water habitat polygons.  Regions can be used like polygons, but in contrast to polygons, regions can represent areas that overlap, such as species habitat ranges or land use types.  Regions are represented as a set of polygons.  See Figure 9 for an example of the way regions work.

Figure 9: An example of the way regions work.  Region 1 contains 2 polygons.  Region 2 contains three polygons, one that it shares with Region 1 and two others that it does not.

With the ArcInfo REGIONBUFFER command, a circle is generated around each of the USA-certified open water EO point locations using a radius of 5 miles.  The 5-mile radius buffer circles are allowed to take on the attributes of the input EO points, so that the buffer circles retain the species and ranking information of their input EO.  The buffer circles are then used as cookie-cutters to clip the state hydrography line and polygon coverages.  The two resulting coverages contain only the hydrographic lines and polygons, respectively, that fall within a 5-mile radius of an input EO point location.  Only lines and polygons identified as "open water" features are selected out and placed into new coverages.  In order to ensure that important riparian areas are included in the final habitat polygons, the "open water" features are buffered using a � mile radius.  Two polygon coverages are created from this buffering process.  An attribute within the polygon coverages indicates which polygons represent a buffer zone and which are outside of the buffer zone.  The polygon coverages are then unioned together.  The coverage with the 5-mile radius buffer circles is used again as a cookie-cutter to limit the extent of the unioned open water buffers, so that no open water buffer polygon extends beyond a 5-mile radius of its input EO point location.  Finally, ArcInfo computes a geographic intersection between the open water buffers and the 5-mile radius buffer circles.  The single resulting region coverage contains the open water habitat representations with attributes referencing the species and ranking information of their individual input EO point locations.  Figure 10 gives a pictorial representation of GIS-derived open water habitat polygons.

Figure 10: GIS-derived open water habitat polygons.  The small solid black circles are the original EO point locations.  The black lines are the "open water" features, (i.e., streams and ponds), in the locality of the EO points.  The shaded areas reflect the �-mile buffer zones around the "open water" features.  The "open water" buffers have been limited to the extent of the 5-mile radius buffer circles.  There are two overlapping regions depicted below.  The shaded areas within each faint buffer circle outline take on the attributes of their original EO point and are used as the open water habitat polygon for each EO.

4.4.3       GIS DERIVATION OF POLYGONS THAT REPRESENT ISOLATED WATER OR TERRESTRIAL HABITAT

To create a polygonal representation of isolated water or terrestrial habitat that offers the EO an effective protective buffer from accidental pipeline releases, the methodology calls for the derivation of a polygon that incorporates all area within a 1-mile radius around the EO point location.  Essentially, isolated water and terrestrial habitat polygons are 1-mile radius (or 1 mile radius) buffer circles.

4.5  ECOLOGICAL FILTER CRITERIA

There are three prequalification criteria and three USA filtering criteria defined by the methodology.  If an EO is excluded because it does not meet one or any of the criteria described in this section, it is still considered an environmentally sensitive area (ESA) and will be reevaluated in subsequent reruns of the model.  EOs that are accepted by the model as ecological USA candidates, but become disqualified somewhere in the filtering process are still considered USA candidates after the model run.  These EOs will also have an opportunity to gain USA status in subsequent model reruns.

4.5.1       PREQUALIFICATION CRITERIA

There are three data quality standards that the EOs must meet in order to be considered within the USA  model.

• EOs must be mappable to one minute, or greater, precision.  One minute of a degree roughly translates into 1 mile in most areas of the globe.  Some NHP databases define spatial accuracy in terms of the imperial or metric system, instead of geographic (angular) units.  In these cases, an EO must be mappable to within 1 mile or 1609 meters.
  
• EOs must not be designated as historical, extirpated, or proposed for listing occurrences.
  
• EOs must not be designated as communities, (i.e., marshes, seeps, grassland, etc.), or other features, (i.e., state trees, etc.)

4.5.2       USA FILTER CRITERION 1

Filter criterion 1 seeks to protect those species and subtaxa that have a restricted distribution due to their extreme rarity or because other factors make them especially vulnerable to extinction.  The Association for Biodiversity Information (ABI) / TNC scientists, a designated lead office in the Natural Heritage Network, assign a global (range-wide) conservation status rank to EOs to describe how rare or imperiled they are on a global scale.

EOs that have been assigned a single rank of "G1" or "T1" are considered critically imperiled species by the model and hence are assigned USA status by filter criterion 1.  If the EO is represented by a resource-based polygon, the resource-based polygon becomes the USA.  If the EO is represented by an approximated area or a point location, the GIS model generates a representative polygon based on the habitat type of the EO as described in previous sections.  The representative habitat polygon becomes the USA.

4.5.2.1DETERMINING GLOBAL RANKS FOR ESI DATA

Earlier versions of ESI data sets do not include global ranks in their database structures.  In order to assign global ranks to ESI species, the pilot test endeavored to match ESI species names to NHP species names in the databases of the three pilot test states.  Both the species scientific name and common name were used to correlate between the two data sets.  AMLs written by project staff were used to facilitate the alphabetizing of species names across the biological resource databases, namely ESI and NHP.  The output of the AMLs was opened in Microsoft Excel and the correlation was performed interactively.  See Table 3 for an illustration.  The results of the correlation were read into ArcInfo and queries were performed to select records where an NHP match was found for an ESI species name.  When an accord was found the ESI EO was assigned the global rank from its NHP match.  The list of ESI species names that could not be matched were sent to ABI / TNC for global rank assignments.  Some of the species names could not be ranked because they are too generalized and refer to elements at the genus level.  Conservation rankings are only maintained at the species level.  In other cases, the ESI EO was unable to be ranked because of the difficulties inherent in tracking oceanic species.  ESI species with no global ranking information were evaluated on their federal status alone.

Due to the many variations of species naming conventions and the nuances of species naming conventions used by the NHP, the correlation method used for the pilot test proved unwieldy and susceptible to global ranking assignment errors.  For future model runs, the technical contractors recommend that lists of all unique ESI species in a state be sent to ABI / TNC for global ranking assignments.  Although, this recommendation will still introduce unranked EOs into the model, it provides desirable quality control enhancements to the input data.

4.5.2.2VERIFYING GLOBAL RANKS FOR NHP DATA

Discrepancies were encountered between NHP and TNC global ranks during the validation of the state models.  This could be attributed to outdated NHP attribute data or, in cases where the species in question is endemic to a state, the state NHP may actually be the global rank authority.  It is recommended that global ranks of all unique species in the biological resource data sets be compared with current TNC ranks to determine if there is any disparity.  If incongruity exists, these species should be passed to ABI / TNC and the state NHP to determine which rank is the correct one to use for the species in the state model.

4.5.2.3VARIANT GLOBAL RANKS AND RANK QUALIFIERS

In many instances, ABI / TNC has determined that there is enough uncertainty about the exact status of a taxon to preclude the assignment of a definitive global rank.  Instead a variant rank may be assigned as the global rank for an EO or a rank qualifier may be appended to the surmised global rank to indicate ambiguity.

The GIS model examines the global ranks of all EOs that meet the data quality standards of the model.  Unique listings of global ranks associated with the prequalified EOs are sent to ABI / TNC.  The organization has developed an algorithm that performs a rounding on all ranks to reduce rank ranges and qualified ranks to a single rank.  ABI / TNC ran the algorithm for the unique global ranks found in the EO databases of the three pilot test states and returned the output, so that the model could query on the rounded single rank during its USA filtering process.  Table 4 lists the unique global ranks assigned to prequalified EOs in the three pilot test states.  Table 4 also contains the rounded single rank returned by ABI / TNC that was queried for during the filtering process.

4.5.3       USA FILTER CRITERION 2

Filter criterion 2 strives to identify those areas where multi-species assemblages occur.  The methodology describes multi-species assemblages as areas where three or more unique EOs or sites of high waterbird concentrations co-occur.  The areas of co-occurrence are referred to as multi-species protection areas (MSPAs).  The model determines which EOs will be considered under filter criterion 2 by examining the global rank and federal endangered species or marine mammal listing status.

EOs with a rounded single global rank of "G1", "T1", "G2", or "T2" are considered critically-imperiled or imperiled by the model and are included as candidates in the MSPA analysis.  (For an explanation of how global ranks are rounded, see section 4.5.2.3.)  EOs with a federal status of threatened, endangered, or essential experimental populations, as well as EOs that are depleted marine mammals, are also included as candidates.  In addition, all filter criterion 3 candidates, (i.e., the migratory waterbird concentration areas: WHSRN and Ramsar sites), are included in the process to identify MSPAs.

4.5.3.1VERIFYING THE FEDERAL STATUS FOR ELEMENT OCCURRENCES

Using the species name correlation procedure described in section 4.5.2.1, the species names of prequalified EOs were compared to current U.S. Fish and Wildlife Service (USFWS) species lists of threatened and endangered (T&E) plants and animals.  The USFWS T&E lists can be downloaded from the internet at http://endangered.fws.gov/listdata.html.  All prequalifed EOs were compared from both the ESI and NHP data sets in order to locate possible errors of omission and commission within the native databases, as well as update the static attribute information inherent to ESI data sets.  Species whose federal status differs depending on the geographic location of the population were flagged and examined interactively to ascertain the appropriate federal status that should be assigned to each individual EO.  The results of this correlation effort were far more successful than the similar effort undertaken for ESI global ranking assignments.  This can be accredited to the detailed lists provided by USFWS and the overall accuracy of the federal status information in the ESI and NHP data sets.

In the pilot test, federal status information was updated from the USFWS T&E lists in the American Standard Code for Information Interchange (ASCII text) format.  It was discovered that the ASCII text version of the T&E lists was not as current as the Adobe portable document format (PDF), available for download from the same web site.  For future model runs, the ASCII text format should initially be utilized for the species comparison process, because it is easier to work with.  Prior to assigning or updating federal status information, however, the PDF version should be consulted to correct any outdated statuses.  This interactive process can be facilitated by using the "When listed" column of the USFWS T&E listing.  The column can be searched for dates after the publication date of the ASCII text version.

4.5.3.2DATA INPUT REQUIREMENTS FOR FILTER CRITERION 2

The MSPA analysis requires region data as input.  EOs mapped with resource-based polygons are represented by their mapped habitat boundaries throughout the MSPA process.  A 1-mile radius (or 1-mile radius) buffer circle is generated from the EO point for EOs originally mapped with approximated areas or a single coordinate location.  The 1-mile radius buffer circles represent these EO habitats during the MSPA analysis.

The model utilizes the element occurrence code as the "species name" for an EO in the MSPA analysis.  TNC assigns the ten-character code to each element for data management purposes.  Element occurrence codes are common to all Natural Heritage Programs within the United States and allow efficient inter-jurisdictional communication.  For migratory waterbird concentration areas, the name of the WHSRN or Ramsar site is used as the "species name".

4.5.3.3DETERMINING ELEMENT OCCURRENCE CODES FOR ESI DATA

As encountered with global ranking information, earlier versions of ESI data sets do not include TNC element occurrence codes in their database structures.  The effort conducted to assign NHP global ranks to ESI species was utilized to assign TNC element occurrence codes as well.  As an addendum to the request that ABI / TNC assign global ranks to ESI species unmatched by the comparison procedure, element occurrence codes were also solicited.  Because some of the ESI species are too generalized (referring to elements at the genus level) and due to the difficulties inherent in tracking oceanic species, some ESI EOs were not assigned element occurrence codes.  The model generated a unique identifier for these EOs, based on a concatenation of the source data set and the unique species name, (e.g., NOAA6113 refers to the species, "Anchoa mitchilli - Bay Anchovy"). The unique identifier is used as the "species name" for the EO in the MSPA analysis.  As recommended in section 4.5.2.1, a better solution for future model runs is to compile lists of all unique ESI species in a state and request that ABI / TNC assign both global ranking information and element occurrence codes to them.

4.5.3.4THE MULTI-SPECIES PROTECTION AREA (MSPA) ANALYSIS

The MSPA analysis is actually performed outside of the GIS environment.  Due to the repetitious query cycles and data file size constraints, it was more expeditious to run the analysis in an object-oriented programming environment.   A C++ program was devised to take the output from an ArcInfo REGIONPOLYLIST command, run the analysis, and return an ASCII text file of the region number and answer, ("0" for non-MSPA contributor, "1" for MSPA contributor), for each input candidate.

During the analysis each of the candidate habitat regions is examined individually to determine if its habitat overlaps any others.  If overlap is discovered, a list of "species names" associated with the overlapping habitats is compiled.  The "species name" of the habitat being examined is also added to the list.  If three or more unique names are found in the list, the habitat region being examined is flagged as contributing to a MSPA and all overlapping habitats are flagged as MSPA contributors.  Once a habitat region has been flagged as a contributor, it maintains this status throughout the cyclical process, regardless of the outcome of any subsequent examinations.  The process is repeated until all candidate habitat regions have been examined.  See figure 11 for an example of the process.

Figure 11: An example of the examination and query process used by the MSPA analysis.  Habitat region A (dark hatch) is being examined.  The "species name" list compiled from overlapping regions and the examined region is "B, B, C, A".  Since there are 3 unique "species names" in the list, all hatched regions are flagged as contributing to a MSPA, hence, all the regions overlapping Habitat A and Habitat A, itself, become USAs.

The results of the MSPA analysis are fed back into ArcInfo.  EOs that have been designated as a MSPA contributor are assigned USA status by filter criterion 2.

If the EO is represented by a resource-based polygon, the resource-based polygon becomes the USA.  If the EO is represented by an approximated area or a point location, the GIS model generates a representative polygon based on the habitat type of the EO as described in previous sections.  The representative habitat polygon becomes the USA.  EOs that are not designated as a MSPA contributor are still considered USA candidates and will again have an opportunity to gain USA status in subsequent model reruns.

4.5.4       USA FILTER CRITERION 3

Filter criterion 3 endeavors to protect those areas that harbor large populations of migratory waterbirds during critical concentration periods.  All Ramsar sites and WHSRN sites that have been designated as hemispheric, international, or endangered species reserves are assigned USA status by filter criterion 3.  WHSRN sites that are designated as regional reserves receive consideration under filter criterion 2 by being included in the MSPA analysis.  Due to their regional nature, however, these reserves do not automatically become USAs.

5.0 LITERATURE CITATIONS

Correll, D.S.  and H.B. Correll.  1975.  Aquatic and Wetland Plants of Southwestern United States.  Environmental Protection Agency Research and Monitoring.

Dobson, A.P., J.P. Rodrieguez, W.M. Roberts, and D.S. Wilcove.  1997.  Geographic distribution of endangered species in the United States.  Science 275:550-553.

Ehrenfeld, D.R., R.F. Noss, and G.K. Meffee.  1997.  Letter to the editor.  Science 276:515-516

Federal Register 1999.  64 FR 250: 73464.

Flather, C.H., L.A. Joyce, and C.A. Bloomgarden. 1994. Species Endangerment Patterns in the United States.   USDA Forest Service General Technical Report RM-241.  Fort Collins, CO.:  U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 

Flather, C.H., M.S. Knowles, and I.A. kendall. 1998.  Threatened and endangered species geography: Characteristics of hot spots in the conterminous United States.   BioScience 48:365-376.

Halls, J., J. Michel, S. Zengel, J.A. Dahlin, and J. Petersen. 1997. Environmental Sensitivity Index Guidelines, Version 2.0. NOAA Technical Memorandum NOS ORCA 115.  Hazardous Materials Response and Assessment Division, National Oceanographic and Atmospheric Administration, Seattle, Wa.  79 pp. + appendices.

Kiester, A.R., J.M. Scott, . Csuti, R.F. Noss, B. Butterfield, K. Sahr, and D. White. 1996.  Conservation prioritization using GAP data.  Conservation Biology 10: 1332-1342.

Scott, J.M., B. Csuti, J.D. Jacobi, and J.E. Estes. 1987. Species richness: A geographic approach to protecting future biological diversity.  BioScience 37: 782-788.

Stein, B.A., L.S. Kutner, and J.S. Adams (eds). 2000.  Precious Heritage: The Status of Biodiversity in the United States. . The Nature Conservancy. Arlington, VA.

The Nature Conservancy (TNC). 1996.  Conservation by Design. The Nature Conservancy. Arlington, VA.

_______.  1997. Designing a Geography of Hope: Guidelines for Ecoregion-Based Conservation in the Nature Conservancy. The Nature Conservancy. Arlington, VA.

 [SOC1] Is a mappable a word?