State and transition modeling: An ecological process approach

Abstract

State-and-transition models hold great potential to aid in understanding rangeland ecosystems' response to natural and/or management-induced disturbances by providing a framework for organizing current understanding of potential ecosystem dynamics. Many conceptual state-and-transition models have been developed, however, the ecological interpretation of the model's primary components, states, transitions, and thresholds, has varied due to a lack of universally accepted definitions. The lack of consistency in definitions has led to confusion and criticism indicating the need for further development and refinement of the theory and associated models. We present an extensive review of current literature and conceptual models and point out the inconsistencies in the application of nonequilibrium ecology concepts. The importance of ecosystem stability as defined by the resistance and resilience of plant communities to disturbance is discussed as an important concept relative to state-and-transition modeling. Finally, we propose a set of concise definitions for state-and-transition model components and we present a conceptual model of state/transition/threshold relationships that are determined by the resilience and resistance of the ecosystems' primary ecological processes. This model provides a framework for development of process-based state-and-transition models for management and research. ResumenLos modelos de estados-y-transicion presentan un gran potencial para ayudar a entender la respuesta de los ecosistemas de pastizal a los disturbios naturales y/o inducidos por el manejo al proveer una estructura para organzzar el conocimiento presente de las dinamicas del potential del ecosistema. Muchos modelos conceptuales de estados-y-transicion han sido desarrollados, sin embargo, la interpretacion ecologica de los componentes principales del modelo: estados, transiciones y umbrales han variado debido a la carencia de definiciones universalmente aceptadas. La falta de consistencia en las definiciones ha conducido a confusion y critica indicando la necesidad de un mayor desarrollo y refinamiento de la teoria y los modelos asociados. Nosotros presentamos una revision extensiva de la literatura actual y modelos conceptuales y puntualizamos las inconsistencias en la aplicacion de los conceptos de la ecologia de no equilibrio. La importancia de la estabilidad del ecosistema, detinida como la resistencia y resilencia de las comunidades vegetales a los disturbios, se discute como un concepto importante relativo al modelaje de estados-y-transicion. Finalmente, proponemos un grupo de definiciones concisas para los componentes del modelo de estados-y-transicion y presentamos un modelo conceptual de las relaciones de estados/transiciones/umbrales que estan determinadas por la resilensia y resistencia de los principales procesos ecologicos del ecosistema. Este modelo provee un marco para el desarrollo de modelos de estados-y-transicion basados en procesos para manejo a investigacion.1986, Tausch et al. 1993). After 50 y...

China's Grassland Contract Policy and its Impacts on Herder Ability to Benefit in Inner Mongolia: Tragic Feedbacks

“…On arid rangelands, spatial and temporal variation in water and forage resources is high, annual production is as unpredictable as rainfall and temperature patterns, and extremes of precipitation or temperature are not uncommon. Nonequilibrium models also posit the existence of multiple stable (within a management time frame) vegetation states maintained largely by abiotic factors, rather than a single endpoint climax or stable equilibrium state (Westoby et al 1989, Stringham et al 2003) created mostly by biotic interactions.…”

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

“…State-and-transition models (Westoby et al 1989) hold great potential to aid in understanding rangeland ecosystems' response to natural and/or management-induced disturbances by providing a framework for organizing current understanding of potential ecosystem dynamics (Bestelmeyer et al 2003;Stringham et al 2003). Thresholds have become a focal point in the development and application of state-and-transition models.…”

State and Transition Models: Theory, Applications, and Challenges

“…To this end, it is important to distinguish transient dynamics from persistent transitions between alternative states (Bestelmeyer et al 2003;Stringham et al 2003). Transient dynamics, driven by disturbance or weather events, produce significant but temporary changes in vegetation composition or production that can be reversed in a few years to several decades (e.g., via moderation of disturbance, succession, or weather events).…”

“…9.1c). Weather variations or disturbances can cause transient dynamics within a historical or "reference" state resulting in two (or more) distinct communities (Bestelmeyer et al 2003;Stringham et al 2003). Certain of these communities may have low resilience and be susceptible to a state transition (called an "at-risk community"; Briske et al 2008).…”