Natural Resources
Conservation Service
Arctic silty polygon complex
Scenario model
Current ecosystem state
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Management practices/drivers
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-
Transition T1
thermal erosion of ice wedges
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This state relates to low-centered ice wedge polygon, which are polygon whose center is depressed relative to its boundary. There are three associated plant communities related to polygon microtopography in this state: low-center of the polygon (community 1.1), adjacent rim (community 1.2), and the ice wedge trough (community 1.3). The polygon center and trough are often perennially ponded with shallow water and supports a wet graminoid herbaceous community dominated by various sedges. The polygon center is surrounded by a raised rim that supports open low scrub communities dominated by scrub birch, various ericaceous scrubs, willow, and various sedges.
The depth of ponded water in the polygon center likely plays a critical role in plant species composition but was not accounted for during development of this provisional state and transition model.
Dominant plant species
water sedge (Carex aquatilis), grass
tall cottongrass (Eriophorum angustifolium), grass
round sedge (Carex rotundata), grass
creeping sedge (Carex chordorrhiza), grass
limprichtia moss (Limprichtia), grass
sphagnum (Sphagnum), grass
meesia moss (Meesia), grass
yellow marsh saxifrage (Saxifraga hirculus), grass
Submodel
Description
This state relates to high-centered ice wedge polygon, and these are polygon whose center is raised relative to its boundary. There are two associated plant communities related to polygon microtopography in this state: domed center of the polygon (community 1.1) and ice wedge trough (community 1.2). The troughs are often perennially ponded with shallow water and supports a wet graminoid herbaceous community dominated by various sedges. The polygon dome supports ericaceous dwarf scrub communities dominated by lingonberry, marsh Labrador tea, various sedges, and various moss.
Dominant plant species
lingonberry (Vaccinium vitis-idaea), shrub
marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
dwarf birch (Betula nana), shrub
white arctic mountain heather (Cassiope tetragona), shrub
entireleaf mountain-avens (Dryas integrifolia), shrub
Bigelow's sedge (Carex bigelowii), grass
tussock cottongrass (Eriophorum vaginatum), grass
turgid aulacomnium moss (Aulacomnium turgidum), grass
dicranum moss (Dicranum), grass
splendid feather moss (Hylocomium splendens), grass
meadow bistort (Polygonum bistorta), grass
Submodel
Mechanism
Thermal erosion of ice wedges and/or infilling of low-center results in the transformation of low-center polygon to high-center polygon. This is a natural process that can take thousands of years. Climate change and anthropogenic disturbances to associated soils can much more rapidly cause thermal erosion of ice wedges and cause this transformation.
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.
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