| This PNW Habitat Classification Systems database (PHaCS from this point forward) is a result of work done to fulfill task 4.4 of the Northwest Environmental Data-Network’s Scope of Work. The compilation of
Habitat Classification Systems (Systems from this point forward) was accomplished by contacting 95 individuals from various governmental and non-governmental agencies and organizations, in addition to extensive searches via the internet. A total of 64 Systems were reviewed for this project with citations for each included in
PHaCS (please see
System Details below). Of those, categories were listed (with definitions when available) for 41 Systems; cross-walks to Habitat Type were completed for 27 of those Systems; cross-walks to Structural Conditions were completed for 10 of those Systems; and cross-walks to Key Environmental Correlates were completed for 30 of those Systems.
Semantic differences existed from the beginning, and at the very least, provided challenge for this project. Questions and different interpretations surround the term habitat; this has been previously recognized by Hall et al. (1997), and became evident when acquiring Systems for this project. Various interpretations of exactly what is a Habitat Classification System also exist, probably rooted in the fuzzy understanding of the term habitat.
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Semantic differences existed from the beginning, and at the very least, provided
challenge for this project. Questions and different interpretations surround the
term habitat; this has been previously recognized by Hall et al. (1997), and
became evident when acquiring Systems for this project. Various interpretations
of exactly what is a Habitat Classification System
also exist, probably rooted in the fuzzy understanding of the term habitat.
Subsequently, the Systems compiled in PHaCS vary in detail, organization, and
content. Individual classification groups, habitat elements, biological
indicators, geomorphic classes, etc. are described as System categories
in PHaCS.
Terrestrial and Aquatic Systems became the primary focus for acquisition for two
reasons:
- A previous effort provided cross-walks between several Wetland Systems.
- Marine Systems were difficult to track down aside from NOAA’s efforts. However,
Wetland and Marine systems were included when found.
Further,
PNW states took precedence for cross-walking; California Systems were
included in PHaCS, but were not cross-walked due to time
constraints.
Cross-walks were established between System categories and the Interactive
habitat and Biodiversity Information System (IBIS), developed
by the Northwest Habitat Institute. The IBIS System was used because it provides
detailed descriptions of three category levels (Habitat Types, Structural
Conditions, and Key Environmental Correlates), and applies to terrestrial,
aquatic, wetland, and marine environments. To accomplish the cross-walking
effort, System categories were matched as closely as possible to the appropriate
IBIS category by reading each category definition and matching parameters when
possible.
A confidence level was also associated with each cross-walk. If category
definitions existed, the cross-walk was usually straight-forward and therefore
received a confidence level of high. A confidence level of medium was tagged to
those cross-walks where the category did not have a definition, yet the category
name made it possible to interpret a likely cross-walk. Some categories were
more obscure, either in name or definition, and therefore cross-walks were
merely suggestions; these cases were given a confidence level of low. If
confidence levels do not exactly follow this process, comments were included.
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For example, Terrestrial Systems may use a physiognomic or a
floristic approach to characterize habitats—and they may or may not include
structural characteristics. Because IBIS uses a physiognomic approach,
cross-walking to floristic Systems required the compilation of a spreadsheet
listing all dominant and sub-dominant plant species found in each IBIS Habitat
(as described in Johnson & O’Neil, 2001). Each floristic-based (e.g.
plant-association-based) Terrestrial System category was then matched to an IBIS
Habitat by searching the compiled dominant and sub-dominant plant species lists.
This was incredibly time-consuming and resulted in the cross-walking of only a
portion of the USDA Forest-Service Ecoclasses (over 2,000
total). Furthermore, some Systems were associated with maps
using a GIS (mostly the EPA Ecoregion Systems). For these systems, if a map of
IBIS Habitats also existed for a given geographic area, the cross-walking was
accomplished by importing both maps into ArcMap and tabulating
areas occupied by pixels of a particular IBIS Habitat. If the IBIS Habitat was
occupied by >10% of a habitat from the other System, a cross-walk was recorded.
Few Systems allowed this technique.
Future work might include gathering and cross-walking additional Systems which
could be added to PHaCS. Because Systems vary in organization
and detail, it may be useful to include any GIS mapping efforts using each
system so that cross-walking could be done not only with definitions but also
spatially, by map units. With refinement, a tool such as this could improve
communication between agencies/organizations using different Systems, as
implementing a “One System Fits All†approach may not prove practical.
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Literature Cited
Hall, L. S., P. R. Krausman, and M. L. Morrison. 1997. The habitat concept and a
plea for standard terminology. Wildlife Society Bulletin, 25(1): 173-182.
Johnson, D.H., and T.A. O’Neil. 2001. Wildlife-habitat relationships in Oregon
and Washington. Oregon State University Press, Corvallis, Oregon.
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