Arctic scrub gravelly frozen slopes

Description

The reference plant community is open low mesic shrub birch-ericaceous shrub tundra (Viereck et al. 1992). There are two plant communities within the reference state related to wildfire.

All plant communities associated with the site have limited data, so the state-and-transition model is provisional.

Submodel

Description

Non-sorted circles are a type of patterned ground. On gentle slopes, these patterned features are roughly circular and as steepness increases these features become slightly elongated. In this area, the diameter of non-sorted circles commonly ranged from 1.5 to 10 feet and are mounded above the surrounding vegetation. These circles are considered nonsorted due to an absence of coarse rock fragments on their borders (Schoeneberger and Wysocki 2017). For this ecological site, these non-sorted patterned ground features form through the process of cryoturbation.

Cryoturbation is a collective term used to describe all soil movements due to frost action, characterized by folded, broken and dislocated beds and lenses of unconsolidated deposits (Schoeneberger and Wysocki 2017). In this instance, these patterned ground features result through differential heave of frost susceptible material resulting in mounds (Schoeneberger and Wysocki 2017). During active periods of cryoturbation, freshly churned up mineral soil and rock fragments were commonly observed on mounded surfaces. The formation of these nonsorted circles leads to a distinct mosaic of vegetation.

This vegetation mosaic has two distinct plant communities that are associated with different positions on or adjacent to the nonsorted circle. The first plant community occurs in adjacent areas that have not yet formed these nonsorted circles or is the community that occurs between the nonsorted circles (community 2.1). This community generally resembles the reference state vegetation. The second plant community occurs on the nonsorted circle (community 2.2), which supports a lichen dominant plant community. When compared to community 2.1 soils, the non-sorted circle soils are much drier and have much less organic matter.

Submodel