Arctic Tussock Loamy Frozen 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
Frost heave mound formation
More details -
Restoration pathway R2A
Mound collapse
More details -
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 under a fire cycle regime. Along with a fire regime, soil wetness, caused by water perched by permafrost, is the major factor influencing vegetation.
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 characterized using available vegetation models, most notably United States Department of Agriculture - Soil Conservation Service range surveys (SCS, 1984; Swanson et al., 1985).
This alternate state describes a scrub community across frost heaved mounds. The conditions required for this microfeature to develop are not fully understood. Available water, an insulating organic horizon and an absence of fire are suspected to be factors needed for the necessary ice cores to form and for mounds to develop.
Submodel
Mechanism
Mounds develop when ice cores form under an insulating layer of organics. Ice cores pull in surrounding water via capillary action and push the overlying vegetation upwards. This process can only be initiated in ideal conditions. The normal fire regime typically favors cottongrasses. The absence of a fire disturbance can allow low shrubs to dominate (Landfire, 2009; Racine et al., 1987), which adds to the insulating effect.
Mechanism
Collapse of the ice core within the frost heave mound results in a return to a tussock tundra community. Frost heave mounds collapse when the insulating organic layer is no longer sufficient. This can be due to natural dieback of the moss layer due to overgrowth of the ice core. Fire can also remove the organic layer and melt the ice core. The post-mound collapse community composition will be dependent on the method of mound collapse, with fire leading to community 1.2, and natural die-back leading to either community 1.1 or 1.2.
Model keys
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