Major Land Resource Areas (MLRA) Reports

What are Ecological Site Descriptions & State-and-Transition Models

Ecological Site Descriptions (ESD) synthesize information concerning soils, hydrology, ecology, and management into a user friendly document. A crucial component of an ESD is the state-and- transition model (STM) that identifies the different vegetation states, describes the disturbances that caused vegetation change, and the restoration activities needed to restore plant communities. State-and-transition models are powerful tools that utilize professional knowledge, data and literature to describe the resistance and resilience of an ecological site to various disturbances, the triggers leading to ecological thresholds, the feedback mechanisms maintaining ecological states and the restoration techniques required for moving from one ecological state to another

Many ecological sites are similar in their plant composition and other important physical attributes such as soils but may differ in total production or landscape setting. Thus, often these similar ecological sites will respond to the same disturbance in a similar manner. The rate of response to disturbance may be different but the endpoint of the change will be very similar. In order to expedite development of STMs a process developed by Experiment Station's Tamzen Stringham and referred to as Disturbance Response Grouping was utilized on this project. The Disturbance Response Group process is conducted at the Major Land Resource Area (MLRA) scale making it a highly efficient method for STM development. The process requires a team of experts with years of experience working in the area of interest.