Nevada
Spatial Analysis Project
Nevada Division of Forestry
August 2007
Table of Contents
Executive Summary.......................................................................................................................... 5
Stewardship Analysis Project (SAP) Introduction, Purpose, and Background.................................. 7
SAP Implementation.................................................................................................................... 7
Stewardship Potential Suitability Analysis......................................................................................... 8
Data Layer Development and Geoprocessing............................................................................. 8
1. Private Forestland .............................................................................................................. 9
2. Forest Patches.................................................................................................................... 9
3. Riparian River Areas............................................................................................................ 9
4. Wetlands . ........................................................................................................................... 9
5. Slope .................................................................................................................................. 9
6. Proximity to Public Lands.................................................................................................. 10
7. Priority Watersheds........................................................................................................... 10
8. Public Water Supply ......................................................................................................... 10
9. Threatened and Endangered Species............................................................................... 10
10. Soil................................................................................................................................... 10
11. Wildfire Risk..................................................................................................................... 10
12. Forest Health (Insects and Diseases) ............................................................................ 11
13. Development Level......................................................................................................... 11
14. Cheatgrass...................................................................................................................... 11
Analysis Masks . ....................................................................................................................... 11
Weighting................................................................................................................................... 11
Overlay Analysis........................................................................................................................ 11
Analysis Calculations and Results............................................................................................ 12
Appendices...................................................................................................................................... 13
Appendix A: Final Maps............................................................................................................. 16
Appendix B: Graph of Cells and Values.................................................................................... 24
Executive Summary
Nevada Division of Forestry (NDF) conducted an assessment of private forestland in Nevada in 2007. This
state-wide assessment was accomplished using geographic information system (GIS) analytic techniques and involved developing three spatial layers—Forest Resource Richness, Forest Resource Threat, and Critical Private
Forestland. Results of the analysis will be used to direct future technical assistance and educational activities
and may be used to demonstrate the value of forests and forestry to the regional economy, environmental health,
and quality of life. This analysis provides insight where future stewardship education and technical assistance
opportunities may be most beneficial. It also captures where past activity (i.e. Forest Stewardship management
plans) has occurred. The project began in June 2007 and ended in August 2007 with approval by the Forest
Stewardship Steering Committee. During the analysis process, the GIS Specialist from the Nevada Division of
Environmental Protection and NDF staff met to assess whether the process was heading in the correct direction.
During these discussions, several modifications were made to data set structure and its relation to the overall
project.
“Stewardship potential” in Nevada is non-industrial private forest (NIPF) that defines acreage prioritized for
educational and technical assistance. The final results for critical forest stewardship potential on critical private lands indicate slightly more than 9 million acres of stewardship potential in Nevada, with approximately
750,000 acres holding high potential. About 2.4 million acres are low potential. Slightly more than 8 million
acres of land with stewardship potential are on currently non-forested land. Certain areas of Nevada forests are
undergoing rapid change primarily due to population growth and associated subdivision development.
In addition, it is increasingly difficult to promote sound forest management as NIPF landowners are steadily
increasing in number and their individual ownership parcel size are becoming smaller as forest tracts are subdivided into multiple smaller parcels with a greater number of owners. This challenge is exacerbated by weak
funding, shifting priorities, and greater demands for accountability. Key stakeholders, forest resources, and
threats to the resource vary across the state. Because of this variation, information designed to portray the region
must be developed with an understanding of the differing pressures within the region. NDF does not have a
source of information that adequately shows the pattern and distribution of critical forestland. This Assessment
provides this understanding and a strong foundation for better forest management decisions. The users of the
Assessment include NDF and USDA Forest Service (USFS) regional and national programs.
The Assessment results in GIS layers and maps showing forest resource richness and threat on a State-wide
basis, with enough detail that sub-county assessments are meaningful. The merging of resource richness and
resource threat show the distribution of critical (or priority) forestland. The results of the analysis provide a
new way to describe the region’s distinctiveness; they can be used to inform policymakers, stakeholders and
concerned groups, empower the region to communicate its distinctiveness, and better quantify its management
challenges. Knowing where the forest resources are, where they are most vulnerable, and where they are most
valuable will be indispensable as NDF positions itself as the lead stakeholder of forestry issues in the state.
The Assessment can help meet the challenge of diminishing funds and increasing customer base by facilitating strategic outreach. Because the capacity to promote forest management to landowners is limited, it is more
effective to focus energy in places where it will provide the highest return. In addition, as Nevada develops its
strategy for market competitiveness, it will need to know where the opportunities lie to sustain its most valuable and lucrative assets. The state-wide Assessment will be invaluable for NDF as it strives to sustain healthy,
productive forests, and protect the economic viability of its private forests.
The Assessment analyzes where best to focus forest management resources, and therefore is a perfect complement to the Nevada Wildfire Risk Assessment, whose output will help focus fire suppression, prevention, and
mitigation resources. These two data sets together will empower the state to market its identity more comprehensively.
The resulting output will be useful and relevant at many spatial scales, from regional down to sub-county. As
a result, the model outputs will help Nevada address critical resource management issues within the state, be it
with state and county policy makers or as a tool for agency foresters.
A GIS modeling methodology has already been developed to identify resource richness and resource threat
on NIPF as part of the Spatial Analysis Project (SAP) of the Forest Stewardship Program. The USFS developed
the SAP model primarily to address the efficacy of Forest Stewardship Plans and to promote strategic program
delivery. NDF recognizes additional benefits beyond meeting the standard goals of the project. Spatial analysis
can assist states in managing their private forest programs and can help as an analytical tool when addressing
forest policy issues. A national objective was to have a country-wide analysis completed state by state. Participating states are being asked to use a given set of twelve data layer themes and to follow an establish set of procedures and standards for displaying results. States have the freedom to add additional GIS data layers needed
to describe local conditions, and to weight each data layer to best reflect its level of importance. Nevada used
two additional layers: Cheatgrass (weeds) and Soils. The standard data layer themes include Riparian Corridors,
Forest Patches, Public Water Supply Areas, Priority Watersheds, Threatened & Endangered Species, Proximity
to Public Forestlands, Wetlands, Topographic, Wildfire Risk, Insect and Disease Risks, and Change in Household.
The Nevada Division of Forestry worked with the Forest Stewardship Committee in establishing weighting
factors for each data layer. These data layers and weighting factors focus on NIPF issues. The analysis provides
a priority value for each 30 meter by 30 meter piece of non-industrial private forest land across the state. These
cells were then grouped into high, medium, or low categories. Nevada’s weighting strategy included differences
from the National model, and differences with other states that have completed their SAP analysis.
Stewardship Analysis Project (SAP)
Introduction, Purpose and
Background
USDA Forest Service and State Forestry agencies
have a long standing partnership that began in the
late 1940s promoting the protection and improvement of private forestland. Current efforts are defined
in the Cooperative Forestry Assistance Act of 1978;
the Forest Stewardship Program (FSP) of 1990 is the
primary tool for assisting non-industrial forest landowners. The focus of this Spatial Analysis project
is to assist the Forest Service and State Forestry
agencies in administering and monitoring the FSP.
Nevada Division of Forestry (NDF) fully supports a
national spatial analysis effort.
The FSP has been very successful as a national
program promoting sustainable forest management.
Comparing today’s national and state strategies for
assisting non-industrial private forest (NIPF) landowners with those of 1990 when FSP was first introduced clearly demonstrates the evolution of the program. Multi-resource management planning is now
an accepted standard. It is by far the exception that
timber production is the primary goal when considering forest planning. Efforts such as spatial analysis
strengthen the FSP and other assistance efforts, and
benefit landowners, states, and the nation.
NIPF landowners are defined as private individuals, group association, corporation, Indian tribe or
other private legal entity. NIPF lands may have existing forest cover or may be suitable for growing trees.
Forestland was identified using the National Land
Cover Database (NLCD).
The USDA Forest Service Northeast Area, in partnership with four state forestry agencies, developed
a GIS process for mapping lands eligible for the FSP,
prioritizing them, and overlaying these lands with existing forest stewardship plans. After these four states
completed their spatial analysis project in 2003-04,
the Forest Service offered incentive grants to several
Western states in order to complete spatial analysis
projects. In 2005 and 2006, Nevada received grants
to initiate the analysis on a statewide basis.
benefit most from educational and technical assistance. Through a series of work sessions, 14 overall
data sets were selected and individually evaluated
for their specific application to the Nevada SAP. At
several milestones in the analysis process, the GIS
specialist from the Nevada Division of Environmental Protection and the NDF staff met to assess whether the process was heading in the correct direction.
During these discussions, several modifications were
made to data set structure and its relation to the overall project. Each of these modifications are covered
in individual data set summaries.
SAP Implementation
The SAP will provide Nevada with the ability
to track and display FSP activities over a statewide
landscape now and in the future. Through continual
GIS analysis, resource data dealing with multiple
issues can be mapped and planned. The Nevada FSP
will benefit from knowing more about the actual location of stewardship plans across the landscape and
identifying potential opportunities where individual
landowner planning can address key larger scale
resource needs. SAP will also assist regional and
national FSP managers to address program effectiveness and public funds accountability.
The FSP Spatial Analysis Project (SAP) is providing a consistent methodology across the country to
evaluate and prioritize natural resource issues and,
at the same time, offer states the ability to customize
collection and analysis of pertinent spatial data. The
analysis will provide insight into:
• important forest lands (rich in natural resources,
vulnerable to threat, or both),
• existing stewardship tracts (properties under management plans), and
• areas of opportunity to focus future FSP efforts
(stewardship potential).
Nevada’s SAP will also address the following
questions, as they relate to the FSP.
• Where are the state’s NIPF lands?
• Where are the management plans?
• Where are the state’s priority NIPFs (those lands
of highest potential to benefit from active forest
management)?
• What percentage of existing NIPF management
plans are on the state’s priority forest lands?
The initial scoping of the SAP process was coordinated through the Forest Stewardship Committee.
For the purpose of this exercise, Forest Stewardship
potential was defined as NIPF acreage that would
• Are there opportunities to implement forestry education or technical assistance to increase forest
management activities in high priority areas?
With additional GIS data layers, spatial analysis can
also be used to:
• assess program effectiveness in serving stateidentified critical resource management needs;
• relate factors such as completed cost/share practices, landowner activities, and monitoring data to
help determine program strategies and effectiveness;
• establish future practices that can improve effectiveness in addressing priority needs based on
landscape scale resource issues;
• determine the economic, environmental and social
importance of NIPFs; and
• provide additional information and clarity when
addressing a broad range of forest policy issues.
Three primary directions will evolve out of Nevada’s
SAP:
• Develop a historic management plan database and
associated geo-referenced map of existing forest
stewardship plans.
•Assess how the state can use the results of these
analyses to guide future landowner assistance activities in conjunction with other NIPF programs.
• Recommend modifications to the future spatial
analysis efforts to evolve with the current FSP.
Stewardship Potential Suitability
Analysis
The statewide stewardship suitability analysis is
comprised of fourteen data layers and an analysis
mask. The layers used are
Input Layers
Private forestland
Forest patches
Riparian river areas
Wetlands
Slope
Proximity to public lands
Priority watersheds
Public water supply
Threatened and Endangered Species
Wildfire risk
Forest health (insects and diseases)
Change in Household
Cheatgrass
Soil
Analysis Masks
Private lands
Data Layer Development and Geoprocessing
The 14 data layers used for this analysis are described in this section. Twelve of these layers were
mandated by the Federal SAP requirements. Two additional layers were added within the SAP flexibility
scope to localize the process for Nevada. The Forest
Stewardship Committe ranked the 14 layers based on
relative importance for delivering stewardship education and technical assistance.
Data sources are from Nevada Division of Environmental Protection (NDEP), U.S. Geological
Survey (USGS), Nevada Natural Heritage Program,
Bureau of Land Management (BLM), Landfire
National Data, U.S. Forest Service, and the National
Resource Conservation Service (NRCS) were identified to meet the project requirements.
All data sets (raster and vector) were compiled and
stored in a geodatabase file format. ESRI’s ArcGIS
9.2 software was used to manage, create, and manipulate data.
All data sets were checked for attribute completeness and correct projection parameters. The projection used UTM Zone 11, with NAD 83 as the datum.
All vector data sets were converted to a raster
format using the POLYGONRASTER tool. The
POLYGONRASTER tool default cell size or a selected increment divided by 30 was used to get the
best representation of the data. This was a two step
process due to vector-to-raster conversion issues. All
rasters that were not a 30 m cell size were resampled
to a 30 m cell size.
Layers were resampled so that data was given a
value of 1 and no data was given a value of 0. The
exception was the layer for Forest Patch Size (Nevada Landuse, 2000). All values except 41, 42 and 43
along with no data were classified as 0. Values 41, 42
and 43 were classified as 1.
All data was added together using the WEIGHTED SUM tool. The weights or ranking came from
the Forest Stewardship Committee. The original
value for the rankings were in a decimal format. The
WEIGHTED SUM tool can not use decimal values
as the input. The weights were adjusted to an integer
value so the values would add up to 100.
2. Forest Patches
The forest patches layer
was derived from the private forestland layer. This
is a raster data set.
The private lands were then extracted for the statewide output using the EXTRACTION BY MASK
tool. The mask was created by taking BLM landownership data and selecting the private land holdings.
This vector coverage was manipulated with the DISSOLVE command on the boundaries to create larger
polygons. This data set was converted to a raster data
set.
Final input raster included
a value of 1 for forest
patches and a 0 for no data,
with a weighted overlay
value of 3 percent.
The resulting extracted raster data was copied to
create an integer grid instead of a floating point grid.
This helped in the classification of the data in addition to displaying the data on a map.
A brief summary of each layer is described below.
The description includes where the data set originated and what the final weighted value was for each
layer.
1. Private Forestland
The forest cover used in this project was extracted
from the National Land Cover Dataset (NLCD). The
1992 NLCD was derived from early to mid-1990s
Landsat 5 Thematic Mapper satellite data and is a
21-class land cover classification scheme applied
consistently over the United States. The spatial
resolution of the data is 30 m. NLCD is provided on
a state-wide basis. NLCD was updated in 2000 and
was used for this project. This is a raster data set. The
forest cover layer was
derived by combining
three NLCD classes:
Deciduous Forest
Evergreen Forest
Mixed Forest
The final input raster
included a value of 1 for
private forestland and
a 0 for no data, with a
weighted value of 10
percent.
3. Riparian River Areas
All perennial streams and
major rivers in the 1:100,000
scale Digital Line Graph
(DLG) were buffered by 300
feet on each side. The resulting perennial streams and
rivers were converted to a
raster data set with a value of
1 for riparian corridors.
The final input raster included a value of 1 for riparian
areas and a 0 for no data,
with a weighted overlay
value of 10 percent.
4. Wetlands
The data for the wetlands
layer came from the National Wetland Inventory
(NWI) data maintained by
the U.S. Fish and Wildlife
Service and is based on the
1:250,000 scale data in the
National Wetlands Inventory. This is a vector data
set that was converted to a
raster data set.
The final input raster included a value of 1 for wetlands and a 0 for no data, with a weighted overlay
value of 7 percent.
5. Slope
The statewide 30 ­meter digital elevation model
(DEM) was used to develop a topographic slope
layer. The forest stewardship potential on critical private forestlands mask was used to select only slope
values for the areas that fell within private forest
lands. This data originally existed as a raster data set.
layer to the general public directly or through other
agencies or entities was not authorized by the NDEP.
The final input raster included a value of 1 for all
lands and a 0 for no data, with a weighted overlay
value of 4 percent.
The final input raster included a value of 1 for the
data and a 0 for no-data, with a weighted overlay
value of 7 percent.
6. Proximity to Public Lands
The proximity to public lands layer was created by
combining a ½ mile buffer of public lands based
on BLM Landownership
data. This is a vector data
set and was converted to a
raster format.
9. Threatened and Endangered Species
Data for the threatened and endangered species
layer was obtained from Nevada’s Natural Heritage
Program. The information provided by Nevada’s
Natural Heritage Program is intended for distribution
or use only within the
requesting department,
agency, or business. A
generalized composite
summary was created of
all the data from Nevada’s Natural Heritage
Program for threatened
and endangered species.
It cannot be reversed
engineered to identify
individual species locations.
The final input grid included a grid value of 1
for all lands in proximity
to forested public lands
and a 0 for no data, with a
weighted overlay value of
4 percent.
7. Priority Watersheds
The priority watersheds were taken from the
1:2,000,000 USGS Hydrologic Unit Data Set. All
Hydrologic Units were included in the analysis because of the small amount of private land. This is a
vector data set that was converted to a raster data set.
Final input raster included a value of 1 for priority
watersheds and a 0 for no data, with a weighted overlay value of 11 percent.
8. Public Water Supply
The public water supply layer included community
surface water intake locations from the Bureau of
Safe Drinking Water, NDEP. This data was the result
of a query of the SDWIS data base in 2006 for a
Drinking Water Protection Area. The wells and
intakes had a 6000 ft
buffer drawn around the
well or intake. This data
set is a vector data set that
was converted to a raster
format. The buffer size
was selected on the advice
of the Bureau of Water
Pollution Control to minimize any affects on a well
or intake. Release of this
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The final input raster
included a value of 1
for threatened and endangered species and a 0 for no
data, with a weighted overlay value of 8 percent.
10. Soil
The soil data set is from NRCS. The data is a generalized state soil map. This data set was downloaded
from the NRCS website as a vector format and converted to a raster data set.
The final input raster included a value of 1 for soils
and a 0 for no data, with a weighted overlay value of
1 percent.
11. Wildfire Risk
The wildfire risk layer used the fire regime condition
classes from the National Landfire Program.
LANDFIRE fire regime condition classes (FRCC)
delineate a standardized, interagency index to
measure the departure of current conditions from
reference conditions. FRCC is defined as a relative
measure describing the degree of departure from
the reference fire regime. This departure results in
changes to one (or more) of the following ecological
components: vegetation characteristics (species
composition, structural stages, stand age, canopy
closure, and mosaic pattern); fuel composition; fire
frequency, severity, and pattern; and other associated
disturbances (such as insect and disease mortality,
grazing, and drought). This data came in a raster
format.
The final input raster included a value of 1 for all
areas defined with wildfire risk and a 0 for no data,
with a weighted overlay value of 12 percent.
12. Forest Health (Insects and Diseases)
This raster data set was
obtained from the U.S.
Forest Service.
The final input grid included a grid value of 1
and a 0 for no data, with a
weighted overlay value of
13 percent.
Landownership coverage
Dissolve all polygons
Convert all polygons to raster
Weighting
To produce the composite layers, each input layer
was given a weight according to its relative importance. The Forest Stewardship Committee derived
the weighting scheme for the individual suitability
layers based on relative importance for delivering stewardship education and technical assistance.
Once all data layers were assigned a percentage, the
percentages were converted to weighting values; that
is, 10 percent became a value of 10 and the sum of
the maximum points for all 14 layers equaled 100.
Several of the values were rounded to whole numbers in order to work within the parameters of the
WEIGHTED SUM tool. The final weighted values
for each layer are
Private forestland10%
Change in household 4%
Forest health13%
Wildfire risk
12%
Soil1%
Cheatgrass 6%
Proximity to public lands
4%
Forest patches
3%
Priority watersheds
11%
Riparian river areas
10%
Public water supply
7%
Threatened and Endangered Species
8%
Slope
4%
Wetlands
7%
13. Change of Household.
This data set was created by joining the 2000 census data with a shapefile of Nevada’s Counties. The
join was done with the county name attribute. The
shapefile was converted to a raster data set using the
change population from 1990 to 2000 attribute field.
Final input ratser included a value of 1 for counties
and a 0 for no data, with a weighted overlay value of
4 percent.
14. Cheatgrass
This raster data set came from Nevada’s Natural
Heritage Program. This layer was used as a weed
layer because of the incompleteness of a noxious
weed data set. Nevada’s Natural Heritage Program
is working on updating the noxious weed layer but
it won’t be finished within the time frame of this
project.
Final input raster included a value of 1 for cheatgrass
and a 0 for no data, with a weighted overlay value of
6 percent.
Analysis Masks
The analaysis mask was created using the following steps:
Select all private lands from the BLM
Overlay Analysis
The GIS data representing each of the layers was
converted to the ESRI raster format with a cell size
of 30 m, an area representing approximately onequarter acre. For example, all the 30-m grid cells
that fall within the riparian river buffers were coded
as “1,” while all cells outside the riparian buffers
were coded as “0” in that layer. Each grid cell was
multiplied by its weighted value so that cells coded
as “1” took on the weighted value while all “0” cells
retained a value of 0. The final result contained cells
whose values equaled the sum of the values in the
same location (on the same quarter-acre) from all
included layers in each composite layer.
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The ESRI Spatial Analyst extension allowed for the
specification of an analysis mask. The analysis mask
described above was used to exclude areas that did
not meet eligibility requirements for inclusion in the
Forest Stewardship Program.
Analysis Calculation and Results
The data is displayed in ArcMap with several other
data sets such as cities, counties, roads, streams,
waterbodies and existing stewardship plans. The
data is displayed using a classification scheme based
on 3 intervals (low-medium-high) based on Natural
Breaks (Jenks).
The acreage was calculated the following way: the
number of cells that had values in the low group (23
to 46) were added together (see graph, Appendix B)
and that value was then multiplied by 900 (30 m by
30 m cell is 900 square meters). The result of that
mathematical equation was plugged into a conversion
tool that converted square meters to acres. The same
process was done for the medium and high classifications.
The process and results mentioned above were crosschecked by taking the total number of cells and multiplying the cells by 900 (area of a 30 m cell). That
result was plugged into the same conversion tool that
converted square meters to acres. The values from
this mathematical operation and the one mentioned
above came out to match. When the number of acres
were converted to square miles, the value represented
12.8% of Nevada land that is private.
The amount of forested land was calculated by
extracting the state landuse/landcover layer (forest
patch size) with the mask used for the analysis. The
number of cells was multiplied by 900 and converted
to acres. The result of this calculation gives us the
amount of forested lands. The non-forested value was
calculated by taking the total number of acres and
subtracting the forested area.
Each category (low-middle-high) of forested lands
acres were calculated by taking the total acres of forested land multiplied by the percentage of total acres
for the specific category. The percentage was calculated by dividing the acreage for each catagory by the
total number of forested acres. The same process is
done for non-forested areas.
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The value for acres capable of stewardship plans vs.
acres that have plans were calculated this way: the
total stewardship plans acreage was calculated using
the statistics tool in ArcGIS on the acreage field then
divided by the total number of acres to get the percentage. The stewardship plan acres were calculated
the following way: for every location with a valid
coordinate, the cell value of the weighted layer was
queried and the value was added to the stewardship
shapefile; the select by attribute tool was used to
query for values that are less than 46 (low), 47 to 56
(middle), and greater than 57 (high); for each category (low, middle, or high), the acreage field is added
together and calculates the total of all acres. Sites
that do not have coordinates were not added to the
stewardship plan acres. This methodology took into
account plans that were both active and cancelled.
Appendices
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Appendix A: Final Maps
Map 1 – Classified Forest Stewardship Potential on Critical Private Lands for Nevada
Map 2 - Classified Forest Stewardship Potential on Critical Private Lands and Existing Stewardship Plans for Nevada
Map 3 - Classified Forest Stewardship Potential on Critical Private Forestlands and
Existing Stewardship Plans for Nevada
Map 4 - Resource Richness in Nevada
Map 5 - Resource Threats in Nevada
Map 6 - Classified Forest Stewardship Potential on Critical Non-Forestlands &
Non-Developed Lands and Existing Stewardship Plans for Nevada
Map 7 - Private and Public Landownership
Appendix B: Graph showing values and cell count.
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