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Title: National assessment and critiques of state-and-transition models: The baby with the bathwater

item Bestelmeyer, Brandon

Submitted to: Rangelands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2015
Publication Date: 6/1/2015
Publication URL:
Citation: Bestelmeyer, B.T. 2015. National assessment and critiques of state-and-transition models: The baby with the bathwater. Rangelands. 37(3):125-129.

Interpretive Summary: Ecological site descriptions and state-and-transition models are national-level tools for organizing and delivering information about landscape dynamics and management. Recent papers criticized state and transition models because they overemphasize grazing, are inconsistently presented, and do not address climate change. I argue that the analysis of Twidwell et al. does not support an overemphasis on grazing, that inconsistent presentation is a necessary consequence of early model development efforts and immature science concepts, and that climate change effects should not be addressed in site-level models without evidence. Improving these important tools requires fair critique, but also the strong commitment of scientists and funders.

Technical Abstract: Ecological site descriptions (ESDs) have been characterized as the world’ s largest land management framework. They comprise a database and document collection used throughout the United States to provide management guidance in rangelands and, increasingly, in forests, wetlands, and croplands. ESDs are specific to fine-grained (1:12,000) land classes called ecological sites that differ in soil, landscape position, or climate, and therefore in potential plant communities. Different ecological sites call for differences in the details of management actions such as stocking rates, restoration seed mixes, and strategies for managing woody plants. The focus of ESDs is on vegetation and soils as primary elements governing ecosystem services including forage for livestock, erosion control, and wildlife habitat. A core part of ESDs is the state-and-transition model (STM) that describes how vegetation responds to management and natural processes. STMs replace older “range succession” models that represented vegetation change as reversible linear trajectories driven by grazing and weather. The STM format encourages inclusion of a broader array of drivers, interactions among drivers, and multiple possible trajectories, reflecting recent advances in ecological science.