How does TELSA work?
TELSA is a toolbox of models and programs. Together, the tools help users to:
- prepare spatial and other model input data;
- define various management and natural disturbance scenarios;
- simulate these scenarios; and
- analyse compare and display simulation results.
TELSA combines commercial software products (a Microsoft Access™ database and the ArcView / Spatial Analyst™ GIS) with a custom simulation model and interfaces to the database and GIS systems. TELSA runs on high-end PC platforms with Windows 2000 or XP operating systems.
TELSA divides the landscape into simulation polygons. This map shows the original forest cover polygons (black lines), riparian areas (red and tan) and the resulting tessellation (green lines) into the simulation units that are explicitly simulated.
The practical limitations to the size of landscape units that can be simulated with TELSA are determined by the available computing resources and the spatial resolution employed in the analysis. TELSA is designed to simulate landscapes that are up to approximately 800,000 ha, although larger landscapes have been simulated. The model has been successfully applied to a number of different ecosystem types including:
- the southern interior of British Columbia;
- the northern coastal region of British Columbia;
- the boreal forest of northern Alberta;
- rangeland in Idaho, Nevada, Montana and Utah;
- national parks in Utah, California, Oregon, and Montana;
- grasslands in Saskatchewan; and
- forests in Ontario.
Studies in other ecosystem types are currently underway.
What are the data requirements?
TELSA requires the following input data from the user:
- transition pathway diagrams with succession, management, and disturbance pathways and transition probabilities (these diagrams can be developed using VDDT and imported to TELSA);
- landscape cover maps showing the distribution of vegetation cover and structure;
- maps of zones with different management constraints (such as parks, watersheds, riparian zones);
- management information (management limits, size classes of management units, age and order of activities); and
- disturbance size distributions, between-year variation and temporal trends.
What results are produced?
TELSA results can be viewed as maps, graphs, or tables, for the entire landscape or for strata within the landscape, using user-friendly interfaces. Since all results are stored in an Access database, users can compare results of different scenarios or multiple Monte Carlo runs of one or more scenarios. Basic information such as area disturbed (including the range of area disturbed or the frequency of disturbance for different polygons), age-class distribution (figure on left below), and seral stage distribution, can be graphed and mapped. Additional spatial information such as count and area distribution of patch size classes and interior habitat (figure on right below), and the length of edge between different seral stages or age classes are also calculated. Because the state of every polygon is known for every reporting time-step, further post-processing for wildlife habitat interpretation or other analyses is also possible.
A comparison of layout and age class distribution of two landscapes with different management and disturbance histories.
A portion of a landscape showing areas of interior habitat.
What are the system requirements?
TELSA is designed to run on high-end personal computers with the following minimum hardware requirements:
- a Pentium-class processor of 500 MHz or faster;
- a monitor capable of 1024 X 768 resolution – small fonts highly recommended;
- at least 64 megabytes of RAM (128 megabytes is ideal); and
- 1 gigabyte or more of available hard drive space.
The amount of free disk space needed will vary according to the type of analysis and the number of simulation runs that are conducted. More powerful systems will result in increased performance of the software and, as with all spatially-explicit models, a large amount of free disk space is highly recommended.
The model runs under a 32-bit operating system such as Windows NT 4.0, 2000 or XP, and you must have the following software installed on your system:
- ArcView GIS (version 3.1 or higher);
- ESRI Spatial Analyst (version 1.1 or higher);
- Microsoft Excel (97 or 2000);
- the Vegetation Dynamics Development Tool (version 3.0 or higher); and
- the software included in the TELSA toolbox.