Developing Ecological Site Description State and Transitions Models for Great Basin Rangeland Plant Communities
Great Basin Rangelands Research
Project Number: 2060-13610-001-07
Start Date: Sep 25, 2011
End Date: Dec 31, 2014
The USDA, Natural Resource Conservation Service is the agency tasked with the development and maintenance of ecological sites and for providing ecological site descriptions (ESDs) to stakeholders. The ecological dynamics associated with natural disturbances and / or management actions within an ecological site are described through a state-and-transition model. State-and-transition models describe the disturbances or combination of disturbances leading to the ecological degradation of an ecological site and the management or conservation practices necessary to rehabilitate a degraded site. In order to quantify the impact of prescribed conservation practices on degraded rangelands it is necessary to identify the ecological site and the current state and plant community phase associated with the location receiving a conservation practice. Identification of the current functional level of the ecological processes driving site degradation enhances management’s ability to determine the appropriate conservation practice and to predict the probability of success. Ecological sites descriptions are not complete without a state-and-transition model. Expediting the process of developing the state-and-transition models for describing the ecological dynamics associated with natural disturbances and / or management actions within an ecological site will enhance NRCS's ability to provide private land owners and land managers with the tools necessary to determine their land's current ecological condition and to make informed management decisions. In addition, quantification of the impact of the Conservation Effects Assessment Project (CEAP) requires an ecological site approach while simultaneously the data derived from the effort to quantify CEAP impacts allows improvement of the state-and-transition model for each ecological site.
In order to expedite the development of second generation ecological site descriptions and the CEAP quantification project the Ely District of the Bureau of Land Management has provided funding to ARS and NRCS, Nevada for the development of state-and-transition models for Major Land Resource Area (MLRA) 28 within Nevada. The Ely District encompasses approximately 12 million acres in eastern Nevada including White Pine County, Lincoln County and a small portion of Nye County with an estimated 200 ecological sites. Much of the District is representative of the Great Basin with large expanses of sagebrush, pinyon and juniper rangelands. ARS scientists will work with University of Nevada Reno, scientists and NRCS on the development of the State and Transition Models for MLRA 28 utilizing a process they have developed for expediting state-and-transition model development. The ARS Rangeland Hydrology and Erosion Model will be applied to new State and Transition models to provide first time estimates of changes in hydrologic processes as a state changes as a means of quantifying environmental benefits of conservation. This project is closely aligned with existing agreements with NRCS, BLM, University of Nevada-Reno and Society for Range Management to develop technology to define and monitor changes in Great Basin rangeland ecosystem processes.