Arctic Scrub Loamy Hillslopes
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
More details -
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 two distinct vegetative communities supported by a fire cycle regime. Vegetation height is restricted by shallow to moderately deep permafrost.
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.
Gaps in the insulation provided by the organic layer allow available water to freeze. Surface and subsurface freezing and cryoturbation of the soil restrict plant roots and growth, eventually removing vegetation from the center. A ring of vegetation is created as the circle center is cryoturbated and vegetation is restricted (Daanen et al., 2008). The formation of these nonsorted circles leads to a distinct mosaic of vegetation.
Mechanism
The conditions required for nonsorted circles to disappear 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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Ecological sites
Major Land Resource Areas
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.