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POTENTIAL USE OF GEOGRAPHIC
INFORMATION SYSTEMS TO ENHANCE
FOREST SOIL MANAGEMENT
Glen O. Klock
overlay with a USGS quad sheet of the same scale, and
find that the boundaries and stream features do not match.
GIS provides the opportunity to correct this error and
increases the credibility of the maps.
GIS is an effective tool to combine soil map data with
other resource data to develop an area resource management plan or assessment. Three projects illustrate the
cost effectiveness of the GIS system.
ABSTRACT
Computerized Geographic Information Systems (GIS)
used as a resource management tool can provide opportunities for more effective input by soil scientists into the
forest management decision process. Examples are given
to show how GIS is now being used in forest soil management strategies. Future opportunities to use GIS models
to predict the landscape position of current and potential
forest productivity are discussed.
WALLOWA VALLEY PROJECT
In July 1989, 25,000 acres of the Wallowa-Whitman
National Forest within the Wallowa Valley Ranger District
were affected by wildfire. This fire, in the Sheep Creek
drainage of the Upper Imnaha River, which drains into
the Snake River, was either in an active timber sale or
in a new sale area. To facilitate salvage logging, an environmental assessment was prepared. I was asked to provide soils information for that assessment.
I have had soils research projects near the affected area,
but it appeared that an extensive field investigation would
be required to evaluate the potential soil and water hazards that might be attributed to salvage logging. Because
of the short timeline to accomplish the project, I chose GIS
as a tool to support my eval uations.
A Soil Resource Inventory (SRI) was available for the
area. As suggested earlier, the SRI map sheets were inadequate for use by themselves. Therefore, the SRI soil
map sheets of the Canal Fire area were digitized and rectified to a UTM coordinate map base. In tum, the fire intensity and the hydrology maps of the area were digitized.
Under the time frame, digital elevation maps (DEM) could
not be secured, so the "slope breaks" by SRI unit were used
to develop a slope map of the project area. In the same
manner, surface erosion potential and mass soil stability
potential maps were generated.
Once the GIS layers were established, a priority rating
system was developed in which GIS modeling was used
to project areas of soil management concern. For example,
one objective was to map all areas with the common feature of high burn intensity, severe mass failure probability,
and slopes over 35 percent. Likewise, common areas in
which the erosion or mass failure potential were low were
also identified. This computerized GIS method for the
Canal project required less than 40 hours.
GIS maps showing areas of soil management concern
were used as field guides to verify predicted hazards.
Combining their use with aerial photos gave me an
effective and efficient system to complete the project
requirements.
INTRODUCTION
The use of computerized Geographic Information Systems (GIS) has expanded into most natural resource management organizations in the past few years. Although
GIS does not provide a new method, it does give faster
and more visually effective opportunities for managers
to display and analyze resource data. The use of GIS as
a resource management tool can provide opportunities for
more effective input into the forest management decision
process by soil scientists.
Some opportunities where GIS outputs can be used to
manage forest soils effectively include:
1. Create more spatially accurate and readable soil
maps.
2. Provide a common medium to interact with other
resource needs.
3. Analyze potential productivity of forest landscapes.
4. Analyze dynamics offorest productivity as affected
by local management alternatives as well as other anthropogenic inputs.
Soils maps are a valuable tool for the analysis of the
forest environment. However, too often the necessary
soil map's scale is so large or the detail shown is so inadequate that the soil map is almost impossible to use. The
storage requirements and cost to maintain needed field
information on map sheets are often difficult to support.
Once the proper soils data base has been installed in the
computerized GIS system, maps and other ancillary data
can quickly be displayed and plotted at the scale and level
of detail needed. This capability gives the GIS an advantage over traditional methods.
Distortion of soil map data is another concern. It is disconcerting to assemble several soil map sheets together,
Paper presented at the Symposium on Management and Productivity
of Western-Montane Forest Soils, Boise, ID, April 10-12, 1990.
Glen O. Klock is President of Western Resources Analysis, Wenatchee,
WA 98801.
180
factors, such as climate, topography, and geology, provide
the framework ecosystems develop on and are most influential in determining long-term regional productivity levels. Although all extrinsic factors can change or fluctuate
over time, these factors are not influenced by the presence
or absence of vegetation.
Intrinsic factors represent site characteristics that can
affect productivity, influence ecosystem processes, and
are at least semicontrollable by management. The most
important intrinsic factors deal with soil properties because they can affect potential productivity. Soil-moistureholding capacity, soil-nutrient status, and soil porosity or
aeration are the factors that correlate best with site productivity (Carmean 1975; Ralston 1964).
It is generally not difficult to assemble in a GIS data
that show the distribution of extrinsic factors across the
landscape. Climate can be shown by precipitation distribution, degree days, etc. Topography can be easily defined
by slope, aspect, elevation, and slope position. Geologic
data can be defined to show soil parent material as well
as the effects of soil-forming processes. Data of this type
can be molded into a GIS spatial model to predict potential
productivity, particularly of regional scale. This approach
really does not address many of the specific intrinsic factors that affect site productivity nor those factors that may
be controllable by management.
Because of the downstream fisheries, concern was expressed about the effects of the fire and potential salvage
logging on water quality. Buffers of various widths based
on stream class were suggested to protect the streams.
The GIS h~lped the District staff determine how harvest
volumes might be affected by various stream buffer widths.
In addition, information on soil types sensitive to disturbance and potential erosion could be identified in the various proposed stream channel buffer zones.
GIS was also used to check if the salvage logging plans
were consistent with the soil and water protection requirements in the environmental assessment. This "office evaluation" was quite effective, but difficult to complete as the
logging engineers were not accustomed to using stable map
bases to develop their logging plans.
DINKELMANN PROJECT
The second example of using GIS with soils data is the
Seattle Water Department Dinkelmann Fire Salvage Project near Wenatchee, WA. Nearly 5,000 acres of Department forest land was affected by a 1988 fire. To assist
in the salvage effort, low-cost information was needed on
environmental concerns as well as appraisal information
for both the timber sale offering and securing necessary
Washington Forest Practices harvest permits. To meet
this need, GIS soils maps were used to generate spatial
statistics and maps for determining logging and transportation system design, defining environmentally sensitive
areas, outlining erosion hazard areas, and developing regeneration plans. The use of GIS was again helpful in
developing accurate and cost-effective land management
data, mainly on soils information.
OPTIONS AVAILABLE
At this point there appear to be two options for the use
of GIS to evaluate productivity at a site-specific level. The
first method is to use the current vegetation community or
plant association as an indicator of potential productivity.
It is extremely difficult to map plant associations because
of a host of factors such as fire and logging that may affect
the current plant community condition. Spatially variable
site characteristics collectively representing a set of environmental site conditions can, however, be determined for
most plant associations. Modeling can be used, in turn, to
project across the landscape an estimate of potential productivity. It is unlikely that enough soil intrinsic factor
information will be available to project effectively how
management activities will affect any given site's productivity by this method over a wide range of environmental
conditions.
The second approach is through the use of research data
to develop a scoring method of key spatial variable intrinsic soil properties-moisture-holding capacity, fertility,
and aeration/drainage. From this information, using GIS,
a productivity index projection can be made across the
landscape. This approach, possibly supplemented with
extrinsic site factor data, would be more effective in predicting the long-term effects of management activities than
use of the first method using plant association indicators.
This approach using GIS, however, is rather hypothetical
at this time and further development work is needed.
Changes in climate and input of anthropogenic-produced
pollutants have been suggested to affect forest productivity. The research community is currently attempting
to link dynamic simulations of forest communities and
Geographic Information Systems in an interactive environment to study these changes in our environ~ent.
LAKEVIEW PROJECT
The third example focused on defining the affected environment in potential timber sales in the Lakeview District,
Fremont National Forest, in Oregon. GIS was a useful tool
to examine the soil types in each of the proposed cutting
units. From the digital soils and hydrologic data, predictive soil and water effects information was generated for
each proposed harvest unit. In addition, these data are
being used in the KWCEA cumulative effects model (Klock
1985) to address the potential harvest impacts on water
quality in one of the project watersheds.
Some of my earlier development work has shown that
GIS can be used as a tool to map the landscape position
of current and potential forest productivity. These maps
were achieved by extending information gained by plot
data across the landscape by the use of GIS modeling.
While developing an analysis and consequent map of current productivity from plot data is rather obvious, developing some spatial distribution of potential site productivity
by evaluating environmental factors becomes considerably
more difficult.
EXTRINSIC· INTRINSIC FACTORS
Environmental factors that affect potential site productivity can be separated into two groups-extrinsic factors
and intrinsic factors (Grier and others 1989). Extrinsic
181
Undoubtedly these studies will require good spatial soils
data. In turn, the products of this research can be expected
to provide more opportunities to enhance forest soil management in the future.
REFERENCES
Carmean, W. H. 1975. Forest site quality evaluation in the
United States. Advances in Agronomy. 27: 209-269.
Grier, Charles C.; Lee, Katharine, M.; Nadkarni, Nalini M.;
Klock, Glen 0.; Edgerton, Paul J. 1989. Productivity of
forests of the United States and its relation to soil and
182
site factors and management practices: a review. Gen.
Tech. Rep. PNW-222. Portland, OR: U.S. Department of
Agriculture, Forest Service, Pacific Northwest Research
Station. 51 p.
Klock, G. O. 1985. Modeling the cumulative effects of
forest practices on downstream aquatic ecosystems.
Journal of Soil and Water Conservation. 20(2): 237-241.
Ralston, Charles W. 1964. Evaluation of forest site productivity. In: Romberger, John A.; Peitsa, Mikola, eds.
International review offorestry research. v.I. New
York: Academic Press: 171-201.