Utilizing State and Transition Models to Aid in the Decision Making Process

Updated 06/09/2006

George Peacock, USDA-Natural Resources Conservation Service
Grazing Lands Technology Institute,
Fort Worth, Texas

Traditional range site descriptions described a single persistent vegetation state referred to as the climax plant community. Range condition was determined by comparing the species composition of present vegetation to the climax vegetation for the site. Ecological site descriptions will utilize the state and transition model to describe the dynamics of rangeland vegetation associated with each site. State and transition model offers a method to organize and communicate complex vegetation management information. Lack of common understanding as to what constitutes a state, transition and threshold has resulted in a tremendous variability in state and transition models that are being developed. A couple of examples of state and transition models that have been developed will be reviewed. One model was developed utilizing a broad approach in defining the different states and the other model was developed with a more detailed approach describing states that were important from a management point of view.

As state and transition models are being developed, need to remember for whom we are developing these models and what information we want the model to provide. We need to agree on common definition for state, transition and threshold. We also need to develop a method to describe those plant communities that are important from a management point of view.

State and transition models provide a repository for all of the information that we know about the ecological dynamics of the site. They are excellent communication tools to discuss the dynamics of the site with a land manager. Once developed, the state and transition model will assist land managers in making timely, well informed management decisions.

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Utilizing State and Transition Models to Aid in the Decision Making Process

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