Wet Meadow

Description

This site developed under Northern Great Plains climatic conditions which included frequent droughts and wide fluctuations in temperature and precipitation which can result in both short-term and long-term changes in water levels and water chemistry (e.g. alkalinity/salinity). Hydrology, water chemistry, grazing, and fire can all serve as important drivers of this site. Hydrology is mainly a factor of landscape position, including the size of the contributing watershed, connectivity to other basins and, whether the basin has an outlet. Water chemistry is influenced by soil chemistry and whether the site is a recharge, flow-through, or discharge site.

This state is typically co-dominated by a mixture of cool-season and warm-season graminoids, mainly woolly sedge, wheat sedge, and Sartwell’s sedge, along with prairie cordgrass and northern reedgrass. Prior to European influence the primary disturbance mechanisms for this site in the reference condition included water level fluctuations, periodic fire, and grazing by large herding ungulates. Spring snowmelt runoff and rainfall events, coupled with timing of fires and grazing events, dictated the dynamics that occurred within the natural range of variability. Along with water level fluctuations and water chemistry, present day primary disturbances are from concentrated livestock grazing and a lack of fire. Under these conditions, vegetation for livestock and wildlife can be expected to decline along with a corresponding increase in less desirable vegetation.

Wet Meadow ecological sites are highly influenced by water levels (including saturated soil), water movement, and water chemistry (i.e. discharge and recharge hydrology). Water levels influence fire effectiveness and livestock use. Water levels also influence exotic species invasion. As Wet Meadow sites draw down, drying and losing soil moisture, they transition to functioning as an upland ecological site and can increase in salinity/alkalinity. Exotic cool-season grasses and forbs begin to invade starting from the upland edge of the Wet Meadow ecological site moving toward the deeper portion of the wetland. Many factors will dictate the speed of exotic species invasion including duration of draw-down phase, management of the sites during the draw-down phase, changes in soil chemistry, and availability of exotic species seed or plants parts (e.g. propagules). During extended periods of draw-down, presence of exotic species adjacent to the site and lack of fire or heavy season-long livestock grazing can speed up the invasion of cool-season exotic grasses or forbs such as Canada thistle or sow thistle.

Once the site is invaded, increased water depth can begin to reverse the invasion of exotic species. However, the increase in salt accumulation will be difficult to reverse back to levels prior to extended periods of draw-down. In addition, exotic grasses (such as quackgrass and foxtail barley) can tolerate extended periods of inundation or saturation, never totally drowning out along the outer margins of the Wet Meadow site. The continued presence of cool-season exotic grasses prevents the site from transitioning back to State 1: Reference State.

Submodel

Description

This State may be characterized as consisting of similar community phases as found in the Reference State (e.g. Community Phase 1.1 and 1.2), but the site has now been colonized by exotic plants, mainly cool-season grasses such as Kentucky bluegrass, quackgrass, smooth brome, or exotic strains/hybrids of reed canarygrass. Canada thistle is also a frequent exotic on the state. Although the state is still dominated by native cool-season grasses and graminoids, an increase in the exotic cool-season grasses can be expected.

These exotic cool-season grasses have been particularly and consistently invasive under extended periods of non-use and no fire. To slow or limit the invasion of these exotic grasses it is imperative that managerial options (e.g. prescribed grazing, prescribed burning, other) 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.

Restoration of State 2: Native/Invaded State back to State 1: Reference State is not considered to be achievable. It should be noted, however, that if the major invader is reed canarygrass, prescribed grazing techniques that target reed canarygrass may be a good choice for restoration efforts because the species is not very tolerant of heavy grazing.

Submodel

Description

This state occurs throughout the MLRA and can result from the colonization by willows during extended period of no disturbance.

Submodel

Description

This state is similar to Community Phase 2.1, but exotic species now dominate the site. Foxtail barley is a conspicuous component of the community; however, the exotic grasses make up the bulk of the vegetation. Several exotic grasses may be present (alone or in combination) and include barnyardgrass, quackgrass, smooth brome, redtop, and/or exotic strains or hybrids of reed canarygrass. Common exotic forbs include Canada thistle, kochia, lambsquarters, and field sowthistle. Marsh fleabane (aka swamp ragwort) is also occasionally abundant on the site during draw-downs.

Submodel

Description

This community is the freshwater phase of the Invaded State and appears similar to Community Phase 2.2. Exotic grasses dominate the site and may consist of quackgrass, smooth brome, and barnyardgrass (alone or in combination). Although foxtail barley may be present, it is much reduced compared to that of State 4: Invaded/Saline State. Canada thistle, field sowthistle, and lambsquarters are common forbs.

Submodel

Description

This state results from eutrophication and sedimentation of the site, often due to tillage on or adjacent to the site. Depending upon what seeds, rhizomes, and propagules are present in the substrate, monotypic stands of hybrid cattails or exotic strains/hybrids of reed canarygrass generally develop.

Submodel

Description

This state is highly variable depending on the level and duration of disturbance related to the T8A 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.

Submodel

Description

This plant community generally results from annual cropping.