State and Transition Model Library
Level 1 Users are users with little GIS and remote sensing experience or access to specialized GIS or remote sensing software or hardware. Level 1 users will mostly interact with Toolbox-generated products and web applications and may work with level-2 or level-3 users to use other Toolbox tools for their management information needs.
Level 2 Users have an understanding of GIS and rangeland monitoring data and have experience with GIS software. Level 2 users can do some minor data creation (e.g., creating layers to define new management scenarios) or edit existing layers (e.g., correcting and updating polygons in the vegetation maps). They will use Toolbox tools and products to aid analyses for their management questions and may also run new scenarios based on existing state and transition models and vegetation maps. These users may provide outputs to level 1 users but may also require assistance from level 3 users to set up datasets for some tools.
Level 3 Users have a highly-developed skill set for manipulating and analyzing GIS, remote sensing, and assessment/monitoring data. They will have access to specialized software and hardware for creating new data layers (e.g., creating image objects from new imagery) and would set up the data layers that level 1 and 2 users would have access to. These users could also lead the process of creating new state and transition models or vegetation maps for new areas. Use of Landscape Toolbox tools in major planning efforts (e.g. RMP) would rely heavily on level 3 users.WHAT ARE THEY?
State and Transition (S/T) models are a way of documenting our understanding of how processes create patterns we observe in an ecosystem. They define the different discrete types of vegetation – called “states” – that occur as a result of an area’s characteristics like climate, soils, history, or disturbances. States vary in their ability to resist change and one state can “transition” to another as a result of natural processes - like succession or wildfire - or management practices – like grazing or juniper removal.
The S/T models in the Landscape Toolbox were modified from existing sagebrush community models from the LANDFIRE program and based on the NRCS ESD conceptual models. We followed the procedure of modifying existing S/T models for the Landscape Toolbox case studies by working with groups of rangeland experts over the course of many workshops. Each model in the Landscape Toolbox library has been reviewed by rangeland ecosystem experts for completeness and accuracy.
HOW DO YOU USE THEM?
By themselves, S/T models are useful because they quantify what is known about the vegetation states of a rangeland ecosystem and what events may lead to changes in the states and how likely those events are to occur. This kind of information, gleaned from the model documentation, can be useful when considering management regimes to maintain or improve rangeland condition or developing restoration activities.
A set of S/T models that describe an entire landscape, though, can be used together in a scenario-modeling program to look at the cumulative impact of many events over a long time period. However, because scenario models are quantitative they require describing all of the possible transition pathways and states in the S/T models and assigning a likelihood to each transition. For example, S/T pathway diagrams must be created with succession, management, and disturbance pathways as well as disturbance probabilities, all of which should be based on empirical data. It is rarely the case, though that data will be available to quantify many S/T model parameters, and expert opinion must be used to supply missing values. In such cases, sensitivity analysis can be used to determine the influence expert-opinion values may have on the scenario outcomes. The S/T models in the Landscape Toolbox were modified from existing sagebrush community models, starting with landfire models (http://www.landfire.gov) as a base, and then integrating the NRCS ESD conceptual models in order to create quantitative simulation models that could be used with the Cumulative Effects Analysis (CEA) Tool. The CEA Tool allows users to alter the processes (e.g. transitions, disturbance pathways and management actions) to create different scenarios, and the potential long-term outcomes of these scenarios can be evaluated.
To get started you will need four things:
First, you will need to obtain the S/T models pertinent to your area. Models created as part of the Landscape Toolbox project are available below for download. These models may be applicable to other areas with minor modifications. To obtain the NRCS S/T models for other areas not included on this site see the “where do you get them” section below for details on how to obtain them).
Second, you will need simulation modeling software. The S/T models in this library were developed using ESSA Technologies' Vegetation Dynamics Database Tool (VDDT) software. We have worked closely with ESSA Technologies in creating the CEA Tool as an easy way to create and run different scenarios with S/T models and datasets from the Landscape Toolbox. See the VDDT/TELSA Scenario Modeling Tools page for more information on how to get and use this software.
Third, you need information on the existing condition of your landscape with regard to the states in your models. The CEA Tools were designed to use outputs of the Landscape Toolbox’s Multi-scale Landscape Assessment Tools. The data layers we developed for the Landscape Toolbox case studies can be downloaded from the Data Center.
Finally, you will need some basic training in running the models and interpreting the simulation outputs. As part of the Landscape Toolbox project, we are developing documentation and training materials to help you implement the CEA Tool. More information is available on the Training and User Support page.
WHERE DO YOU GET THEM?
The S/T models that were developed as part of the Landscape Toolbox project can be downloaded from the links below. Available are the original VDDT S/T models with a document describing each of the states and transitions, and the CEA Tool projects containing the models and the management scenarios developed for the Landscape Toolbox case studies. See the VDDT/TELSA Scenario Modeling Tools page for more information on how to use these models.
For S/T models not provided in the Landscape Toolbox S/T Model Library, ESDs and associated S/T models will need to be obtained from the NRCS. The NRCS is currently updating the ESDs and associated S/T models. Older ESDs or ESDs that have already been updated can be obtained from their website at http://esis.sc.egov.usda.gov/. If the ESDs are not available for your area of interest you can obtain information on when they are expected to be finalized by contacting your local NRCS office. As stated above, the S/T models will then need to be modified to varying degrees to use as part of the VDDT and TELSA modeling programs through rangeland expert workshops.