Utah’s
Forest Stewardship Spatial Analysis Project
Methodology
2007
Project Overview
This project analyzed and ranked the potential for benefits of forest stewardship practices
on private lands in Utah. A way to prioritize and maximize benefits from forest stewardship
practices was needed. This project generated the information needed by foresters and land
managers as they plan and implement forest stewardship practices within Utah. Benefits can be
maximized as forest stewardship practices can now more effectively be prioritized and linked..
During 2006 the Utah Division of Forestry, Fire and State Lands (the Division) weighted
and combined the common data layers suggested by the national Spatial Analysis Project (SAP)
to analyze the forest stewardship potential in Utah. Utah State University (USU) and Utah’s
Forest Stewardship Coordinating Committee (FSCC) participated in the project.
The outputs of this project are a GIS data layer containing the potential forest
stewardship benefit rankings of private lands, seven maps, and this report.
Although the project is now completed, with useful outputs, the project is intended to be a
starting point. Updates, improvements, or additions will be made to the model or to the input
layers as the Division determines prudent.
Project Methodology and Participants
Guidelines and funding for Utah’s project came from the national SAP program within
the US Forest Service. Utah’s Division of Forestry, Fire and State Lands ran the project which
had four phases: data preparation, model creation, running the model, and preparing output for
consumption. Throughout the project the Division reported progress to and received suggestions
from the Forest Stewardship Coordinating Committee.
Data Preparation
The RS/GIS Lab at Utah State University participated extensively in data preparation.
The national program suggested twelve common data layers to be included in each participating
state’s analysis. Existing data needed to be located, sometimes combined or otherwise adjusted,
and then converted to rasters. The RS/GIS Lab at Utah State located and prepared most of the
data layers used in the model. For more information about the input layers see the Model and
Data Layers section in this document.
The Division also digitized the location of existing Forest Stewardship Plans for use in
the final maps.
Model Creation
The GIS Lab at Utah State University also created a potential model for the analysis that
included data preparation as part of the model. The Division decided to not have data
preparation as part of the model so that the model could be reused when improved data layers
became available. The Division created a model using ESRI ArcGIS tools. It is an easy to use,
easy to change model. For more information about the model see the Model and Data Layers
section in this document.
Running the Model
The Division conducted four preliminary runs of the model using varying weighting
schemes for the model and input layers. The weighting schemes and the output from the
preliminary runs were used by the Forest Stewardship Coordinating Committee to understand
the model. The committee discussed the importance of each input layer in an open format with
lots of participation by those in attendance. The committee agreed upon ranking values within
each data layer and a weighting scheme for combining the layers. The final weighting scheme
contained parts of the four preliminary schemes, but it was different from each preliminary
scheme.
The Division used the agreed upon weighting scheme and ran the model. Two other
small models were run. One model simply combined the nine data layers that contribute to
resource richness; the other combined the three layers that contribute to resource threats.
Preparing Output for Consumption
The Division used the Forest Stewardship Potential output layer, the resource richness
layer, and the resource threats layer to create the seven maps suggested by the national program.
The Division has also clipped the Forest Stewardship Potential layer by counties for ease of use
on a county scale.
Project Outputs
The analysis’s main output is a GIS data layer that categorizes Utah’s private land’s forest
stewardship potential within the range 0 to 10. This data layer will mostly be used by the
Division in planning projects, map making, or as input for further analysis. The layer is available
to others by contacting the Division.
Seven maps, using guidelines from the national SAP project, were created as project
outputs. These maps show and the forest stewardship potential benefits within Utah, the location
of existing Forest Stewardship Plans, and some summary statistics. The maps may be
downloaded from the national Forest Stewardship SAP project’s web page:
http://www.fs.fed.us/na/sap.
This report is also an output of the project. The report may be downloaded from the
national SAP web page already given.
Analysis Model and Data Layers
The Division used the Weighted Overlay tool in ArcGIS’s model builder to create the
model (see Figure 1). The Division used the 12 common data layers suggested by the national
Forest Stewardship Spatial Analysis Project as inputs to the model. Each input layer contained a
scaling value from 0 to 12 for each data component within the layer. The model has an analysis
mask layer that includes private and tribal lands available for forest stewardship practices by
masking public lands, municipalities, and water.
The USU RS/GIS Lab help locate and prepare the data layers. Utah’s Forest Stewardship
Coordinating Committee helped scale and weight the layers. The basic rational for the scaling
within each layer was this: the higher the impact of the component the higher the scaling value,
using a 0 to 12 scale. Three main ideas controlled the weighting values for the data layers in the
model. First, Utah’s forests are by far the most important factor for benefits from forest
stewardship practices. Thus, if forests exist they were given a very high weight. Second, water
is the next most important factor. Riparian areas, wetlands, and watersheds got the second
highest weights. Third, threats to forests were given some of the third highest weights.
Figure 1 contains a diagram of the model. Also, a description of each data layer is given,
with the nine layers that contribute to resources richness listed first followed by the three layers
that constitute resource threats.
Figure 1 Utah’s SAP Model
Following are the nine data layers that contribute to resource richness.
Private Forests Layer
Name: forestpriv12
Weight: 40%
Scale within layer:
Forest Type
Scale Value
Aspen
12
Aspen - Mixed Conifer 12
Mixed Conifer
12
Spruce - Fir
12
Ponderosa Pine
12
Lodgepole Pine
12
Limber - Bistlecone Pine 8
Pinyon - Juniper
10
Bigtooth Maple
6
Gambel Oak
8
No Data
0
Description: Forest lands were extracted from the 2004 Southwest Regional Gap analysis
Project layer utlandcover using the values 22-26, 28, 29, 30, 32, 34, 36-38 and 124 then
clipped by private lands.
Riparian Areas Layer
Name: riparian12
Weight: 9%
Scale within layer:
Field
Scale Value
Present
12
Not Present
0
No Data
0
Description: used 1:24,000 stream data from Utah’s Automated Geographic Reference
Center (AGRC), intermittent streams not used. A 200 foot buffer was created. The
buffer was rasterized as the final riparian raster
Wetlands Layer
Name: wetlands12
Weight: 9%
Scale within layer:
Nearness to
Populated Areas Scale Value
Near
12
Farther Away
10
Farthest Away
8
No Data
0
Description: wetlands were extracted from the 2004 Southwest Regional Gap analysis
Project layer utlandcover using the values 85 and 86.
Watersheds Layer
Name: watersheds12
Weight: 9%
Scale within layer:
Nearness to
Populated Areas Scale Value
Near
12
Farther Away
10
Farthest Away
8
No Data
0
Description: 8 digit HUC watersheds were given priorities of high, main Utah mountain
watersheds near cities; medium, not high mountain watersheds nor near cities, and low,
west desert watersheds.
Forest Health Layer
Name: forhealth12
Weight: 8%
Scale within layer:
Insect or
Disease Pest Scale Value
Present
12
Not Present
0
No Data
0
Description: Used data layer prepared by USU RS/GIS Lab from forest health aerial
survey data obtained from the US Forest Service.
Public Water Supplies Layer
Name: pubwatsup12
Weight: 6%
Scale within layer:
Supply Points Scale Value
0
0
Present
12
No Data
0
Description: water use points were obtained from Utah’s Department of Water Rights.
The water use points became an attribute of the 11digit HUC watershed layer from
AGRC, and then rasterized.
Forest Patches Layer
Name: forestptch12
Weight: 1%
Scale within layer:
Patch Size
Scale Value
0 - 40 acres
6
40 - 160 acres
7
160 - 640 acres
8
640 - 1,280 acres
9
1,280 - 5,000 acres
10
5,000 - 10,000 acres
11
> 10, 000 acres
12
No Data
0
Description: Used a model similar to the USU forest patches model. The model clips
forest by roads and reclassifies patches by size.
Figure 2 Forest Patches Model
Topology/Slope Layer
Name: slope12
Weight: 1%
Scale within layer:
Percent Slope Scale Value
< 30%
12
30 - 40%
10
40 - 60%
8
> 60%
0
No Data
0
Description: slope was calculated using a statewide 30m DEM from AGRC.
Distance to Public Land Layer
Name: dist2pub12
Weight: 1%
Scale within layer:
Field
< 1 mile
1 - 2 miles
2 - 3 miles
> 3 miles
Scale Value
10
8
6
0
.
No data
0
Description: Used ArcGIS distance tool to calculate Distance to public land with a limit
of 3 miles. Reclassified to an integer raster: 1 - 0 to 1 mile, 2 - 1 to 2 miles, 3 - 2 to 3
miles.
Following are the three layers that are contribute to resource threats.
Wildfire Assessment Layer
Name: fireassess12
Weight: 8%
Scale within layer:
Risk Level
Scale Value
3
5
4
6
5
7
6
8
7
9
8
10
9
11
10
12
No Data
0
Description: used a 1998 assessment that was done by the BLM using data from the
BLM, the USFS, and the State of Utah.
Threatened and Endangered Species Layer
Name: t_e12
Weight: 4%
Scale within layer:
Field
Scale Value
Present
12
Not Present
0
No Data
0
Description: The USU RS/GIS lab created this layer using data obtained from the Utah
Division of Wildlife Resources. The data set contains a buffer since it is not desirable to
let the specific location of these species known.
Change in Households Layer
Name: chghouse12
Weight: 4%
Scale within layer:
Change Units/
Kilometer sq
<=0
1
2
3
Scale Value
0
2
4
6
4
8
5
10
>5
12
No Data
0
Description: Used 1990 and 2000 census housing data by census blocks, units per
kilometer squared. Subtracted the 1990 values from the 2000 values, rasterized the layar
to 30m and reclassified.
Summary
This has been a successful cooperative project that generated a valuable data layer that
shows the potential for forest stewardship benefits within Utah. Foresters and land managers can
use the data layer in planning and practice implementation to prioritize and maximize benefits
from projects.
The model is easy to use, easy to update, easy to expand. It is expected that the Division
will continue to use the model, making improvements as deemed prudent.
One interesting final note. This project inspired a similar project that the Division is now
undertaking: analyzing the potential for benefits from Urban and Community Forest practices.