TELSA – Tool for Exploratory Landscape Scenario Analyses
The Tool for Exploratory Landscape Scenario Analyses (TELSA) is a spatially explicit, GIS-based landscape-level model for simulating terrestrial ecosystem dynamics. It helps resource managers and planners assess the consequences of alternative management scenarios at the landscape scale. Unlike many other strategic planning models of landscape dynamics, TELSA takes into account natural disturbances so that users can explore how their proposed management strategies will interact with vegetation succession and disturbances to alter landscape composition and structure.
TELSA can be used as a tool for landscape modelling, for adaptive management, or for any other planning process that involves different groups of experts and stakeholders who need to compare and assess the outcomes of different assumptions across space and time. At the core of the process is a tool with which to simulate multiple scenarios, each characterised by different assumptions about management actions and natural disturbances. The results of scenarios are compared in terms of several indicators relevant to the stakeholders in the planning process. Since wildfires and other natural disturbance events that affect vegetation dynamics are inherently unpredictable, the model can use multiple stochastic simulations of each scenario to provide estimates of the mean, range and variability of future values of the selected performance indicators.
TELSA represents ecological succession and the impacts of management and natural disturbances as changes in species composition and structural stage. Diagrams developed with the Vegetation Dynamics Development Tool (VDDT) define the transition times between various state classes (combinations of species composition and structural stage) and the probabilities and impacts of disturbance by insects, fire or other agents. These diagrams also define the impacts of landscape management actions on structure and composition. The area disturbed annually, and the sizes, types, and locations of disturbances respond to landscape changes from past disturbances, succession or management.
Management activities (for example, salvage logging in forests) can also be defined by specifying which actions to schedule based on the condition of individual polygons and of the landscape. TELSA includes an automated approach to designing management units based on user-specified criteria. It can therefore be used to assess alternative size ranges for management units and mixtures of management systems.
TELSA uses numerous customized ArcView tools to automate the preparation of spatial files for use with the model and to facilitate the spatial display of output data from the database. Specialized graphing routines allow users to quickly view and compare the results from one or more simulations.