Hazardous Fuels and Vegetation Treatment Tools and Models
Under Development by PNW and RM Research Stations
OUTLINE FOR DOCUMENTATION OF MODELS/TOOLS
1. Tool Name : Vegetation Development Dynamics Tool (VDDT)
2. Brief Description of Tool : VDDT is a relatively easy-to-use state and transition model that can be
used to model the short- and long-term interactions of vegetation, management, and disturbance. Most
analysts use it to depict vegetation as structure (e.g. grass/shrub, seedling, sapling, pole, etc.) and
cover (e.g. dominant species group) classes connected by growth, succession, management activities,
and natural disturbances. The tool is substantially more flexible than that, however, and could be used
for any system that connects state classes through probabilities of different kinds of changes. VDDT
is not spatial. It produces a variety of database and graphical outputs, but not maps.
3. Scale Tool is Applicable: VDDT can be used at any scale through the appropriate choice of state
classes (usually vegetation types). VDDT is often used a mid- and broad spatial scales where other
modeling systems tend to become difficult to assemble, very data intensive, and time-consuming to
run.
4. Analyst Requirement: Low to moderate. VDDT is becoming increasingly easy to use through the
development of user interfaces that use EXCEL spreadsheets and ACCESS databases, but still requires
thoughtful assembly and local expertise in vegetation types, disturbances, and management activities.
5. Data Inputs: VDDT models are generally built by an analyst, resource specialist, or planner using
local expert opinion, existing data, and available literature. The process requires developing
vegetation state classes that are useful in addressing important issues (e.g. fire risks, wildlife habitats,
forest products, recreation, and others); developing growth, succession, reaction to management, and
reaction to natural disturbance timelines or probabilities (expert opinion, literature, FVS or other
models); and reviewing model outputs. The current vegetation condition is generally taken from GIS
layers (pixel or polygon) and used to supply current condition by vegetation state class. Potential
vegetation is often used to stratify models and account for differing environments, disturbance
regimes, and productivity. Several different management allocations can be used by adjusting
disturbance probabilities, so an allocation and land ownership GIS coverage is useful.
6. Model Outputs: VDDT produces graphic displays of state class conditions, disturbances,
management activities, and calculated or other assigned attributes over time. It can generate time stepby-time step output of percentages and area of the landscape in vegetation state classes, management
activities, and natural disturbances. Output can be easily imported to spreadsheets or databases for
further analyses. Model runs of several hundred years typically require only a few minutes and many
runs using randomly chosen initial probability seeds can be run for statistical analysis.
7. Application of Model for Fuel Treatment work: VDDT can be and has been used to examine
changes in vegetation/fuels conditions given different management scenarios, natural disturbance
Disclaimer: The views in this report (presentation) are these of the author(s) do not necessarily represent the views of the
Forest Service.
regimes, and assumed long-term trends (e.g. global warming). Results are not spatial, so spatial
strategies for fuel treatments cannot be examined. However, the model can be very useful for
estimating vegetation, fuel, and fire trends given different management approaches.
8. Linkage to Other Models/Tools: VDDT models feed directly into the TELSA modeling process,
which is spatial. FVS and other stand to landscape simulation tools can be used to develop VDDT
pathways and probabilities. Any other model or tool that uses vegetation state classes (e.g.
FRAGSTATS, Bayesian Belief Network, INFORMS, others) can supply input to or use data from
VDDT. This is especially easy when spreadsheets or databases are used to supply or analyze output.
9. Partners: VDDT was jointly developed by the USDA Forest Service and ESSA Inc., Vancouver,
B.C. Canada.
10. Current Status: VDDT is available for FS/BLM use without charge and can be downloaded from
www.essa.com. A password to unzip the downloaded file can be obtained free of charge from ESSA’s
website. The model is currently being used for Forest Planning in many places across the nation.
11. Example of Model/Tool Application: Example graphical output for a 300 year run of an aggressive
fuels treatment scenario in the upper Grande Ronde area. Extensive tabular and other graphic output is
available.
Disclaimer: The views in this report (presentation) are these of the author(s) do not necessarily represent the views of the
Forest Service.
1. Tool Name : Tool for Exploratory Landscape Scenario Analysis (TELSA)
2. Brief Description of Tool : TELSA is a spatially explicit state and transition model that can be used
to model the short- and long-term interactions of vegetation, management, and disturbance. Most
analysts use it to depict vegetation as structure (e.g. grass/shrub, seedling, sapling, pole, etc.) and
cover (e.g. dominant species group) classes connected by growth, succession, management activities,
and natural disturbances. TELSA produces a variety of GIS, database, and graphical outputs.
3. Scale Tool is Applicable: TELSA can be used at stand to watershed or larger scales through the
appropriate choice of state classes (usually vegetation types). TELSA is limited by the maximum size
of Access97 databases (1GB), though the DB is being converted to a newer version of Access and
maximum size limits will become 2 GB or more. This limitation makes TELSA difficult to run on
very large landscapes or where the number of simulated vegetation polygons exceeds 75,000 to
100,000.
4. Analyst Requirement: Moderate. TELSA requires thoughtful assembly and local expertise in
vegetation types, disturbances, and management activities. VDDT models are used as the basis for
TELSA, but additional expertise in GIS and Access DB analysis is required.
5. Data Inputs: TELSA models are generally built by an analyst, resource specialist, or planner using
local expert opinion, existing data, and available literature. The process is easiest if VDDT models are
built and tested first. GIS coverages of vegetation state classes, management allocations or zones,
potential vegetation type groups, roads (optional), proposed management units (optional), and other
attributes are either required or optional.
6. Model Outputs: TELSA produces graphic displays and GIS (ArcGIS shapefiles and databases) of
state class conditions, disturbances, management activities, and calculated or other assigned attributes
over time. It can generate time step-by-time step output of percentages and area of the landscape in
vegetation state classes, management activities, and natural disturbances. Output can be easily
imported to spreadsheets or databases for further analyses. Model runs of several hundred years
typically require several hours and several runs using randomly chosen initial probability seeds can be
run for statistical analysis.
7. Application of Model for Fuel Treatment work: TELSA can be and has been used to examine
changes in vegetation/fuels conditions given different management scenarios, natural disturbance
regimes, and assumed long-term trends (e.g. global warming). Spatial strategies for fuel treatments
can be examined, but the model does not project actual fire weather and burning conditions. Fire
contagion is a relatively simple process based on the susceptibility of adjacent polygons to fire.
However, the model can be very useful for examining landscape vegetation, fuel, and fire trends given
different management approaches.
8. Linkage to Other Models/Tools: TELSA models feed directly from VDDT and can be used to
examine the spatial implications of VDDT models. FVS and other stand to landscape simulation tools
can be used to develop TELSA pathways and probabilities. Any other model or tool that uses
vegetation state classes (e.g. GIS, FRAGSTATS, Bayesian Belief Network, INFORMS, others) can
Disclaimer: The views in this report (presentation) are these of the author(s) do not necessarily represent the views of the
Forest Service.
supply input to or use data from TELSA. This is especially easy when spreadsheets or databases are
used to supply or analyze output.
9. Partners: TELSA was developed ESSA Inc., Vancouver, B.C. Canada.
10. Current Status: TELSA is available for research or education use without charge and can be
downloaded from www.essa.com. A password to unzip the downloaded file can be obtained free of
charge from ESSA’s website.
11. Example of Model/Tool Application: Example map output for a 100 year run of an natural
disturbance regime scenario in the upper Grande Ronde area. Extensive tabular and other graphic
output is available.
100 year fire probability
1100 year insect/disease probability
year insect and disease probability
Disclaimer: The views in this report (presentation) are these of the author(s) do not necessarily represent the views of the
Forest Service.