Data Availability and Use
The great thing about standards is that there are so
many to choose from.
-Anonymous.
7.1 How To Obtain Wyoming Gap Analysis Data
The digital spatial databases produced by WY-GAP are available for down-loading from the Internet, via the World Wide Web (WWW). The National Gap Analysis Program (GAP) has a Gap Analysis Encyclopedia home page which can be accessed through this universal resource locator (URL) address:
http://www.gap.uidaho.edu/gap
The Gap Analysis Encyclopedia brings together all aspects of GAP into one package, and facilitates the dissemination of GAP information to the user community. The Encyclopedia offers information on the technical aspects of GAP, including the GAP "how-to" handbook, national standards, metadata standards, recent bulletins, references, and state Gap project contacts. It also directs the Internet user to distributed servers maintained by state organizations that store and maintain Gap data.
The WY-GAP databases and accompanying information (including this report) reside on the computing system of the Spatial Data and Visualization Cluster (SDVC) at the University of Wyoming. Access to the SDVC server will be made available through the National GAP Encyclopedia, or directly through the URL address:
/wbn/gap.html
The three digital databases provided by WY-GAP are state land cover, predicted distribution of terrestrial vertebrate species, and land stewardship/management status. These databases are in Arc/Info export format, for use with workstation Arc/Info 7.0+, PC Arc/Info 3.4D+ or Arcview 2.0+. The export files for each of the three databases are available in either statewide extent or in 1:100,000-scale U.S. Geological Survey quadrangle. Due to their size, the full statewide databases will require the use of workstation Arc/Info or Arcview. PC Arc/Info has polygon limits which will limit the use of these data to the 1:100,000-scale quadrangles.
Both statewide and quadrangle databases have complete FGDC-compliant metadata (see Metadata below), available in word processor and ASCII text file format. This report is also available in postscript format via the internet. In addition to the report, the Wyoming Land Cover Atlas (Merrill et al. 1996a) and the Wyoming Terrestrial Vertebrate Species Atlas (Merrill et al. 1996b) will also be made available. These atlases includes maps of land cover and species distributions along with descriptions of the land cover types, habitat associations, area statistics and references for each species (see Appendices 2.6 and 3.4 for examples).
7.2 Appropriate and Inappropriate Use of Gap Analysis Data
All information is compiled with a specific end use or uses in mind. This is especially true for GIS data, which is expensive to produce and must be directed to meet immediate program needs. For the GAP data, minimum standards were set to meet program needs (Scott and Jennings 1994, Scott et al. 1993). These standards include: scale or resolution (1:100,000 or 100 hectare minimum mapping unit), accuracy (80% accurate at 95% confidence level), and format (ARC/INFO coverage tiled to the 30'x60' USGS quadrangle). For complete project standards, consult the GAP home page (see How to Obtain the Data).
Recognizing, however, that GAP data would be the first, and for many years likely the only, source of statewide biological GIS maps, the data were created with the expectation that they would be used for other applications. Therefore, we list below both appropriate and inappropriate uses. This list is in no way exhaustive but should serve as a guide to assess whether a proposed use can or cannot be supported by GAP data. For most uses, it is unlikely that GAP will provide the only data needed, and for uses with a regulatory outcome, field surveys should verify the result. In the end it will be the responsibility of each data user to determine if GAP data can answer the question being asked, and if they are the best tool to answer that question.
7.2.1 Scale
First, we must address the issue of appropriate scale to which these data may be applied. These data were produced with an intended application at the state or ecoregion level - geographic areas from several hundred thousand to millions of hectares in size. The data provide a coarse-filter approach to analyses, meaning that not every occurrence of every plant community or animal habitat is mapped; only larger, more generalized distributions are mapped. The data are also based on the USGS 1:100,000 mapping scale in both detail and precision. In deciding whether or not GAP data would be useful in a particular application, it would be appropriate to ask "Are the smallest features of interest in this application greater or less than 100 ha in size?" or, "Could I draw the features of interest with a satisfactory level of detail on a 1:100,000 quad sheet?"
7.2.2. Appropriate Uses
GAP data can be used appropriately for coarse-scale (> 1:100,000) applications, or to provide context for finer-level maps/applications. Examples of other appropriate uses:
7.2.3 Inappropriate Uses
It is far easier to identify appropriate uses than inappropriate ones, but there is a fuzzy line that is eventually crossed when the differences in resolution of the data, size of geographic area being analyzed, and precision of the answer required for the question are no longer compatible. Examples include:
7.2.4 Current Uses of WY-GAP Data
In the preliminary stages of WY-GAP database development, we requested that data users fill out a "WY-GAP Data Request Form" which was developed to track the use and applications of these data. To date, the WY-GAP databases have already been used for a variety of applications ranging from grizzly bear research/management, county land use planning, and predictions of vegetation change in response to climate change (Appendix 6.1). Most of the applications to date have involved the land stewardship/management layer. However, with the completion of the land cover and terrestrial vertebrate species layers, we expect the use of the WY-GAP databases to broaden.
7.3 Metadata
Proper documentation of all information sources used to assemble GAP data layers is central to the scientific defensibility of the Gap Analysis Program. The information used to describe gap analysis data is called metadata. Metadata are information about data. Metadata contain information about the source(s), lineage, content, structure, and availability of a data set. Metadata also describe intentions, limitations, and potential uses, allowing for the informed and appropriate application of the data. Descriptions of metadata function have recently been published by the Federal Geographic Data Committee (FGDC 1994) and a postscript file is available from the GAP web page listed above.
The GAP metadata standards have been closely matched to the FGDC standards to ensure current and future compatibility (Cogan and Edwards 1994). As the FGDC standards evolve beyond the current publication, we anticipate corresponding refinements in GAP documentation. The format of the GAP metadata consists of eight major documentation sections (Table 7.1) containing one or more metadata elements. Each element is named (e.g. Map Projection Name), and the "Type" of entry (text, integer, date, time) and "Domain" of the entry (e.g. x > 0) are also defined. Standardized metadata formats can be obtained from the FGDC Internet site (http://geochange.er.usgs.gov/pub/tools/metadata/standard/metadata.html).
Table 7.1. Federal Geographic Data Committee's metadata element categories used by the Gap Analysis Program.
2. Data Quality Information: Accuracy, consistency, and data sources.
3. Spatial Data Organization Information: Data structure - raster, vector, point, etc.
4. Spatial Reference Information: Coordinate units, map projection, spatial resolution.
5. Entity and Attribute Information: Attribute codes and reference citations.
6. Distribution Information: How to order the data, on-line access, transfer size.
7. Metadata Reference Information: Date of the metadata, contact for metadata updates.
8. Contact Information: General data contact, mail, voice, fax, web, e-mail.
Demands for metadata will increase as electronic networks expand across the national and international scene and more requests are made for distribution of information. As the number of users and the diversity of disciplines and programs sharing the data expand, the information carried by metadata will become increasingly important. One of the goals in defining today's metadata standards is to anticipate these future needs.
7.4 Disclaimer
Following is the official NBS disclaimer as of 1 November 1996 followed by additional disclaimers from GAP. Prior to using the data you should consult the GAP home page (see How to Obtain the Data) for the current disclaimer.
"Although these data have been processed successfully on a computer system at the USGS Biological Resources Division, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from a USGS Biological Resource Division server [see above for approved data providers] and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the content of the metadata file associated with these data. The Biological Resource Division shall not be held liable for improper or incorrect use of the data described and/or contained herein.
These data were compiled with regard to the following standards. Please be aware of the limitations of the data. These data are meant to be used at a scale of 1:100,000 or smaller (such as 1:250,000 or 1:500,000) for the purpose of assessing the conservation status of vertebrate species and vegetation cover types over large geographic regions. The data may or may not have been assessed for statistical accuracy. Data evaluation and improvement may be ongoing. The Biological Resource Division makes no claim as to the data's suitability for other purposes. These are writable data which may have been altered from the original product if not obtained from a designated data distributor identified above."