Recommendations for Development of Resilience-Based State-and-Transition Models

Abstract

The objective of this paper is to recommend conceptual modifications for incorporation in state-and-transition models (STMs) to link this framework explicitly to the concept of ecological resilience. Ecological resilience describes the amount of change or disruption that is required to transform a system from being maintained by one set of mutually reinforcing processes and structures to a different set of processes and structures (e.g., an alternative stable state). In light of this concept, effective ecosystem management must focus on the adoption of management practices and policies that maintain or enhance ecological resilience to prevent stable states from exceeding thresholds. Resilience management does not exclusively focus on identifying thresholds per se, but rather on within-state dynamics that influence state vulnerability or proximity to thresholds. Resiliencebased ecosystem management provides greater opportunities to incorporate adaptive management than does threshold-based management because thresholds emphasize limits of state resilience, rather than conditions that determine the probability that these limits will be surpassed. In an effort to further promote resilience-based management, we recommend that the STM framework explicitly describe triggers, at-risk communities, feedback mechanisms, and restoration pathways and develop process-specific indicators that enable managers to identify at-risk plant communities and potential restoration pathways. Two STMs representing different ecological conditions and geographic locations are presented to illustrate the incorporation and application of these recommendations. We anticipate that these recommendations will enable STMs to capture additional ecological information and contribute to improved ecosystem management by focusing attention on the maintenance of state resilience in addition to the anticipation of thresholds. Adoption of these recommendations may promote valuable dialogue between researchers and ecosystem managers regarding the general nature of ecosystem dynamics. Resumen El objetivo de este documento es recomendar las modificaciones conceptuales para la incorporación en los modelos estado-ytransición (STMs) para ligar explícitamente este marco con el concepto de resistencia ecológica. La resistencia ecológica describe la cantidad de cambio o de interrupción que se requiere para transformar un sistema mantenido con sus procesos y estructuras mutuas a un sistema diferente (ej. un estado estable alternativo). Basándose en esta idea, el manejo eficaz del ecosistema debe centrarse en la adopción de prácticas de manejo y reglamentos que mantengan o promuevan la resistencia ecológica para evitar que los estados estables excedan los umbrales. El manejo de la resistencia no se centra exclusivamente en la identificación de umbrales por sí mismo, sino en las dinámicas dentro del-estado que influencian vulnerabilidad o proximidad del estado a los umbrales. El manejo del ecosistema basado en la resistencia proporciona mayores oportunidades de incorp...

Sagebrush steppe recovery after fire varies by development phase of Juniperus occidentalis woodland

“…To assist in predicting potential vegetation changes and identifying the driving factors, state-and-transition models (STMs), proposed by Westoby et al (1989), have been increasingly refined and employed in ecological research. In the United States federal land agencies have accepted STMs for vegetation and habitat management where they serve as integral parts in the development of ecological site descriptions (ESDs) (Papanastasis and Chouvardas 2005;Chartier and Rostagno 2006;Briske et al 2008;Petersen et al 2009;Holmes and Miller 2010). STMs describe alternative plant community states and community transitions resulting from disturbance or management, for related vegetation associations or ESDs that can occur over time.…”

“…Changes in disturbance regimes and introduction of exotic species can cause plant communities to decline in resilience and become unstable, with the potential for crossing a threshold to a new state(s) that differs in plant composition, structure and function. Once a threshold is crossed, a return to the former state is often difficult because of changes in species composition and site attributes (Westoby et al 1989;Laycock 1991;Briske et al 2008).…”

“…The development of threshold and resilience concepts and STMs for categorising woodland expansion and evaluating natural disturbances or management applications has been a building process since the late 1980s (Archer 1994;Milton et al 1994;Briske et al 2008;Petersen et al 2009). Several detailed STMs have been proposed for describing the expansion of J. occidentalis Hook.…”

“…Several detailed STMs have been proposed for describing the expansion of J. occidentalis Hook. (western juniper) woodlands Briske et al 2008;Petersen et al 2009 developed STMs for A. t. ssp. vaseyana steppe with increasing western juniper dominance including multiple transitions and thresholds.…”

“…vaseyana steppe with increasing western juniper dominance including multiple transitions and thresholds. However, the point at which thresholds are crossed during woodland development is yet to be specifically identified or tested (Briske et al 2008 Our objective was to compare recovery of mountain big A. t. ssp. vaseyana steppe after prescribed fire in Phase 2 and Phase 3 J. occidentalis woodlands.…”