Clayey Overflow

Description

This State represents what is believed to exist prior to European settlement In Reference, this site is dominated by cool- and warm-season season grasses, and various shrub and tree species that are scattered across the site. Grazing or the lack of grazing, flooding or lack of flooding, salt accumulation, fire, excessive haying and invasion of non-native cool-season grasses are the major drivers of State.

Submodel

Description

This State developed because of management induced salt accumulation. The State is dominated by salt tolerant, warm- and cool-season grasses. Salt sensitive species have decreased significantly in the plant community. The major drivers of this state are grazing, wetter than normal climatic conditions and land management on adjacent sites that cause a change in hydrology that resulted in increased salinity. Cropping of adjacent sites, saline seeps, water impoundment and excessive grazing on uplands will potential cause salts to accumulate on this site.

Submodel

Description

This State has a significant amount of Kentucky bluegrass or smooth brome in the plant community, but they have not become the dominate species. Kentucky bluegrass makes up less than 30 percent of the plant community composition (by weight). This State is at risk of transitioning to a bluegrass dominated state (Invaded State 4.0).

Submodel

Description

This state is the result of invasion and dominance of introduced species. This state is characterized by the dominance of Kentucky bluegrass and smooth brome, and an increasing thatch layer that effectively blocks introduction of other plants into the system. Plant litter accumulation tends to favor the more shade tolerant, introduced grass species. The nutrient cycle is also impaired, and the result is typically a higher level of nitrogen which also favors the introduced species. Increasing plant litter decreases the amount of sunlight reaching plant crowns thereby shifting competitive advantage to shade tolerant, introduced grass species. Studies indicate that soil biological activity is altered, and this shift apparently exploits the soil microclimate and encourages growth of the introduced grass species. Once the threshold is crossed, a change in grazing management alone cannot cause a reduction in the invasive grass dominance. Preliminary studies would tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species (Toledo, D. et al., 2014).

Submodel