Alpine Sedge-Scrub Frozen Loamy Slopes
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Nonsorted circle creation
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Restoration pathway R2A
Cessation of microfeature freezing processes
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This reference state is developed and characterized using available vegetation models, most notably United States Department of Agriculture - Soil Conservation Service range surveys (SCS, 1984; Swanson et al., 1985).
The reference state describes one distinct vegetative community on frozen slopes. Exposure to wind and low annual temperatures restrict vegetation height. The reference state appears to be stable (Viereck et al., 1992) and does not appear to be susceptible to fire.
There is no indication of an alternate grazing state on this site. Targeted data collection may be able to address whether grazing or browsing in the reference state result in an alternate state.
Submodel
Description
This state is developed and characterized using available vegetation models and published literature and is supplemented with field experience.
This state describes two communities that make up nonsorted circles. The inner part of the circle is often unvegetated and is dominated by surface rock fragments and bare soil. The circle ring is comprised of similar vegetation to that of the reference state. This community does not appear to be susceptible to fire. Exposure to wind and low annual temperatures restrict vegetation height.
The historic and current use of introduced ungulates in MLRA 241X may have altered the potential natural vegetation on this ecological site. No data indicates an alternate grazing state on this site. Targeted data collection may be able to address whether grazing or browsing in the reference state result in an alternate state.
Submodel
Mechanism
The process that creates nonsorted circles creates communities 2.1 and 2.2 simultaneously. The creation dynamics of nonsorted circles are not fully understood. It is suggested that gaps in the insulation provided by the organic layer allow available water to freeze. Surface and subsurface freezing restrict plant roots and growth, eventually removing vegetation from the center. A ring of vegetation is created as water is pulled into the center of the bare circle (Daanen et al., 2008).
Mechanism
The full cycle of nonsorted circles is poorly understood. It is suggested that if the freeze/thaw process that creates and maintains nonsorted circles ends, then edge vegetation may colonize the circle, reestablishing the reference state across the microfeature.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.