Shallow Marsh

Description

This state represents the natural range of variability that dominated the dynamics of this ecological site prior to European settlement. Historically the primary disturbance mechanisms for this site in the reference condition were large fluctuations of the water table, water levels, soil saturation, and water chemistry (e.g. brackishness/ salinity/ alkalinity). Periodic fire and grazing by large herding ungulates were also historical disturbances that influenced this site but to a much lesser degree. Climate, spring snowmelt runoff and rainfall events, coupled with subsurface groundwater movement, combined with the timing of fires and grazing, dictated the dynamics that occurred within the natural range of variability.

Presently, the main disturbances are climate, weather events, water level fluctuations, lack of fire, concentrated livestock grazing, and agronomic activities on adjacent ecological sites (e.g. tillage, fertilizer and herbicide use, drainage). However, during drawdown phases, livestock grazing and a lack of fire impact this ecological site.

The Reference State is composed of four community phases. These phases are largely due to weather and climate factors resulting in considerable fluctuations in water levels and water chemistry (e.g. brackishness). Brackishness, along with water depth, is also a major factor influencing vegetation of the site. Brackishness can be natural due to the type of hydrology and soils of the site. Exotic perennial species do not exist in this state. Because of the changes in these and other environmental factors, the Reference State is becoming increasingly rare.

Characteristics and indicators

(i.e. characteristics and indicators that can be used to distinguish this state from others). Exotic species and hydrologic manipulation would not be present on this site when it is in State 1: Reference State

Resilience management

(i.e. management strategies that will sustain a state and prevent a transition). If intact, the reference state should be managed with current disturbance regimes which has permitted the site to remain in reference condition as well as maintaining the quality and integrity of associated ecological sites. Maintenance of the reference state is contingent upon a monitoring protocol to guide management.

Submodel

Description

This state is characterized by the colonization and establishment of minor amounts of exotic plants. Reed canarygrass is native to North America, but exotic strains (largely Eurasian) have been widely introduced and, along with their hybrids, can be quite invasive. Hybrid cattail, the hybrid between narrowleaf cattail and broadleaf cattail is also a common exotic. Canada thistle, and exotic strains of common reed may also invade the site. Although the site is still dominated by native plants, an increase in exotic plants can be expected. Unless a prescribed grazing and/or prescribed burning program is implemented, or an increase in water depth drowns out exotic species, a transition to State 3: Invaded State can be expected.

Three community phases have been identified for this state. The exotic species/hybrids can be expected to increase. Hybrid cattail and exotic strains/hybrids of reed canarygrass tend to form virtual monocultures and, as such, plants more desirable to wildlife and livestock decline.

Maintenance of communities on the periphery of the wetland (e.g. Wet Meadow ecological site, adjacent upland sites) are critical to the ecological integrity/functioning of the wetland ecosystem. If a buffer zone (50 feet minimum) is not maintained, an increase in eutrophication, sedimentation rate, and invasion by exotic species can be expected. For more information on buffer widths please refer to the Gilbert et.al. (2006) in the references section.

To slow or limit the invasion of these exotic species and their hybrids, it is imperative that managerial options (e.g. prescribed grazing, prescribed burning, maintaining intact buffers) be carefully constructed and evaluated with respect to that objective. If management does not include measures to control or reduce these exotic cool-season grasses, the transition to State 3: Invaded State should be expected (T2A).

Characteristics and indicators

The presence of trace amounts of exotic species/hybrids (e.g. cattail, reed canarygrass) indicates a transition from State 1 to State 2.

Resilience management

Implementation of management techniques and monitoring procedures designed to limit or control exotic species/hybrids.

Submodel

Description

This state occurs when the site becomes dominated by exotic plants. The threshold for this state may be reached when hybrid cattail or the exotic strains/hybrids of reed canarygrass exceed 30% of the plant community and native plants represent less than 40% of the community.

One plant community phase has been identified for this state. It is typically dominated by hybrid cattail or exotic strains/hybrids of reed canarygrass. Other exotic species may include Canada thistle, purple loosestrife, flowering rush, and exotic strains/hybrids of common reed. These species typically form virtual monocultures; as a result, plant diversity is low and habitat suitability for some wildlife species is low as well (e.g. hybrid cattail dominated wetlands may not provide waterfowl habitat but may provide white-tailed deer winter habitat). Once this state is established, restoration efforts have proven difficult.

Characteristics and indicators

(i.e. characteristics that can be used to distinguish this state from others). This site is characterized by exotic species/hybrids dominating the site and controlling the ecological processes (i.e. approximately 30 to 40%).

Resilience management

Once established, reed canarygrass and hybrid cattail are very resilient and will withstand grazing, haying pressure and non-use.

Submodel

Description

Go-Back State often results following cropland abandonment during periods of extended, below average precipitation or drought and consists of only one plant community phase which often is composed of a variety of annual forbs, grasses, spike rushes, etc. including noxious weeds (e.g. Canada thistle) which may need control. Over time, the site will likely become dominated by exotic strains or hybrids of reed canarygrass and/or hybrid cattail.

This state is highly variable depending on the level and duration of disturbance related to the T5A pathway. In this MLRA, the most probable origin of this state is plant succession following crop abandonment. This plant community will initially include a variety of annual forbs and grasses, some of which maybe noxious weeds.

Characteristics and indicators

Tillage has destroyed the native plant community, altered soil structure and biology, increased eutrophication, reduced soil organic matter, and results in the formation of a tillage induced compacted layer which is restrictive to root growth. Noxious weeds, if present, will need to be managed.

Submodel

Description

This state is the result of annual cropping.

Submodel