Using state-and-transition models: Tools for prophylaxis, diagnosis, or autopsy?

Title	Using state-and-transition models: Tools for prophylaxis, diagnosis, or autopsy?
Publication Type	Conference Paper
Year of Publication	2003
Authors	Bestelmeyer BT, Brown JR, Herrick JE, Smith P, Havstad K
Conference Name	56th Annual Meeting of Society for Range Management
Date Published	February 1, 2003
Conference Location	Casper, Wyoming
ARIS Log Number	159368
Abstract	As range managers and ecologists proceed with creating state-and-transition models, it is important to ask how they can be used to maintain rangeland health. We explore this question by examining how the Bureau of Land Management has used models, and by considering field studies of transitions in New Mexico. Models are often used in a 'post-mortem' fashion to explain the existence of degraded states. It is difficult, however, to identify the ultimate causes of degradation. Another challenge is to identify indicators in models that can be used to alert managers to the initial stages of degradation and to guide management changes. This difficulty is illustrated by cases in which healthy-looking landscapes degrade without continued human impacts. In other cases, landscapes that exhibit clear warnings of an impending transition recover without grazing adjustments. A promising use of state-and-transition models is to illustrate how within- and among site variability in topography and inherent soil properties (e.g. texture and depth) predispose sites to transitions. In this application, emphasis is placed on the relative risks of an undesired transition associated with landscape position, soil properties and regional climate characteristics. Unrecorded, unpredictable, and interacting variables (such as climate and species introductions) restrict our ability to correctly interpret and predict transitions. Nonetheless, state-and-transition models provide a basis for prediction, management action, and tests of concepts. We will discuss research approaches to addressing the various uses of state-and-transition models.