Ecological dynamics
The dominant visual aspect of this site is sedges and rushes with scattered forbs. If shrubs are present, they occur in small amounts. The site usually occurs within a complex of wetland sites. The soil surface of the area where the site is found is typically slightly undulating causing small depressions and high spots with variable soil moisture characteristics. The plant communities found on these areas are sites within the complex. Characteristics of these sites are as follows:
1. Deep depressions with the water table at or near the surface or slightly above the surface for the entire growing season are co-dominated by cattails and Schoenoplectus spp. This is the Lakeshore Marsh site.
2. Slightly higher areas that have the water table at the end of the growing season at 20 to 40 inches are drier during the growing season. The plant community may have tufted hairgrass, Nebraska sedge and Baltic rush. This is the Semiwet Fresh Meadow site.
Composition by weight is 80 to 90 percent sedges and rushes, 5 to 15 percent forbs, and 0 to 5 percent shrubs.
In the last few thousand years, this site has evolved in an arid climate characterized by dry summers and cold, wet winters. The site has evolved on deep alluvial soils that are saturated to the surface in the beginning of the growing season to about 10 to 30 inches at the end of the growing season and seasonal flooding. Herbivory has historically occurred on this site at low levels of utilization. Herbivores include pronghorn antelope, mule deer and moose.
Fire has had little influence on the development of the site. Rare wildfires can occur following consecutive drought years.
The conditions for the plant community of this site are highly variable due to a wide variation of soils, flooding frequency and duration, water table fluctuations, air and soil temperatures and competition between plants that are mostly rhizomatous. These conditions can vary within the site at any given location. At any one point within the site, one species can occupy nearly 100 percent of a small area. Another point nearby, may have another species fully occupying that area. Due to these situations, the plant community in this ESD is written broadly.
The soils within any complex of meadow sites are highly variable. Factors that affect the determination of the site include depth to water table at end of growing season, micro-topography and drainage class. Depth to water table and micro-topography are measurable features. Determination of drainage class requires the use of soil interpretation tables. Other interpretive factors that may be used for site determination are ponding frequency, depth and duration and flooding frequency, timing and duration.
Micro-topography is a feature that has a dramatic effect on depth to water table and the resulting plant communities. A few inches of change in surface elevation changes species composition and/ or production. Slightly undulating topography is common in meadow complexes, therefore, more than one site should be expected.
An infinite number of combinations of factors that influence the ecology of potential plant communities exist. For practical purposes, four plant communities where the depth to the water table drives the vegetative composition have been described. They are:
Semiwet Fresh Meadow Water table at 20-40” at end of growing season
Wet Fresh Meadow Water table at 10-20” at end of growing season
Lakeshore Marsh Water at surface to <10” at end of growing season
Influence of fire:
This site usually does not burn from wildfire. If a fire occurs, it usually does not affect the plant community adversely. Most plants including shrubs sprout back after sufficient moisture and the next growing season.
Influence of improper grazing management:
Season-long grazing can be very detrimental to this site. Excessive utilization is also detrimental. The rhizomatous sedges in the reference community will decline in the stand and unpalatable sedges, rushes and forbs will increase. Continued improper grazing management will result in a stand of forbs and Kentucky bluegrass with unpalatable sedges and rushes. The reduced ability of the community to withstand seasonal flooding is reduced and down cutting of adjacent streams can result or headcut initiation can occur. This down cutting will lower the water table and thus reduce the potential of the site.
Good grazing management that addresses frequency, duration, and intensity of grazing can maintain the integrity of the plant community and the water table on which it is dependent.
Weather influences:
Because of the deep soils, the influence of the water table, seasonal flooding and run-on, the production of this site changes little during wet or dry precipitation years. The plant overall production can be influenced adversely with prolonged drought. Overall plant composition is normally not effected when perennials have good vigor.
Below normal temperatures in the spring can have an adverse impact on total production regardless of the precipitation. A hard, early freeze can kill some plants occasionally.
Insects and disease outbreaks:
Periodic disease and insect outbreaks can affect health of vegetation. Mormon cricket and grasshopper outbreaks occur periodically. Outbreaks seldom cause plant mortality since defoliation of the plant occurs only once during the year of the outbreak. An outbreak of a particular insect is usually influenced by weather but no specific data for this site is available.
Influence of noxious and invasive weeds:
Annual and perennial weeds can compete with desirable plants for moisture and nutrients. The result is reduced production and change in composition of the understory. The plants on this site are very good competitors to most potential weeds.
Influence of wildlife:
This site is important for many species of mammals for food and life cycles. The site is primarily used in the late spring, summer, and fall by big game. Many birds use the site for food, nesting or brood raising in the late spring, summer, and fall. Sage grouse use the site for brood rearing and forage.
Total numbers are seldom high enough to adversely affect the plant community.
Watershed:
The largest threat to degradation of the Wet Fresh Meadow site is the lowering of the water table. Off-site conditions can affect the gradient of adjacent stream channels that can affect the water table. If the perennial sedge and rush cover is depleted, down cutting can be accelerated within the site. High run-off events from the adjacent uplands can severely damage or change the normal stream channel on the site. As the water table is lowered, productive potential is lost. Eventually the water table is below the reach of the roots of the adapted sedges and rushes. These are ultimately replaced by perennial forbs and shallow rooted grasses. Extreme down cutting and lowering of the water table can move the site across the threshold to a new, less productive site. Severe down-cutting can result in a plant community that resembles an upland site.
State 1
Reference State
The Reference State represents the plant communities that are adapted to a high water table under a natural disturbance regime. There are two community phases in this state. Community Phase 1.1 is dominated by rhizomatous sedges, like Nebraska sedge (Carex nebracensis) or northwest territory sedge (Carex utriculata) and rushes, like Baltic rush (Juncus arcticus). The sedges in this community are tolerant to saturated soil conditions. Community Phase 1.2 is still dominated by sedges and rushes, but the species of sedge is shifted to a more grazing tolerant sedge, like Nebraska sedge. Northwest territory sedge is less tolerant to grazing pressure and Nebraska sedge often becomes dominant when wet meadows are grazed.
Community 1.1
Northwest territory sedge/Nebraska sedge/rush
The general view of this site is Nortwest territory sedge, Nebraska sedge and arctic rush. These will occur in variable amounts at any one location due to variations in soil and water conditions as stated above. A variety of forbs also occur in the plant community in minor amounts. Willows and shrubby cinquefoil may occur in small amounts. Northwest territory sedge (Carex utriculata), also known as beaked sedge, and Nebraska sedge are common riparian plants and is considered one of the wettest plant associations (Crowe et al. 2004; Hoag and Zierke 1998). Both sedges are capable of growing in areas with a fluctuating water table and tolerant of flooding (Hultgren 1988). They are both a rhizomatous, sod forming sedge (Ewing 1996, Hoag and Zierke 1998). These sedges can be found growing together or dominating the site individually. Shoots from their rhizomes are produced throughout the growing season into late fall. Both sedge shoots can live on average for two growing seasons (Bernard 1976; Bernard 1990, Ratliff 1983; Ratliff 1992). Shoots may remain vegetative or they may develop reproductive structures (Ratliff 1992). The primary mechanism for reproduction in sedges is through vegetative growth in rhizomes (Ratliff 1983; van der Valk et al. 1999). Disturbance is often needed for seedlings to establish in the clonal plant communities (Eriksson 1989). Nebraska sedge is rarely found where the water table drops more than 1 meter below the rooting zone and can tolerate inundation up to 3 months (Carex nebrascensis Wetland Plant Sheet). The composition by air-dry weight is approximately 90 percent perennial graminoids, 5 percent forbs, and 5 percent shrubs.
Table 5. Annual production by plant type
| Plant type |
Low
(lb/acre) |
Representative value
(lb/acre) |
High
(lb/acre) |
| Grass/Grasslike |
900 |
2475 |
7650 |
| Forb |
45 |
138 |
425 |
| Shrub/Vine |
45 |
138 |
425 |
| Total |
990 |
2751 |
8500 |
Table 6. Ground cover
| Tree foliar cover |
0%
|
| Shrub/vine/liana foliar cover |
1%
|
| Grass/grasslike foliar cover |
70-80%
|
| Forb foliar cover |
1-5%
|
| Non-vascular plants |
0%
|
| Biological crusts |
0%
|
| Litter |
0%
|
| Surface fragments >0.25" and <=3" |
0%
|
| Surface fragments >3" |
0%
|
| Bedrock |
0%
|
| Water |
0%
|
| Bare ground |
0%
|
Table 7. Canopy structure (% cover)
| Height Above Ground (ft) |
Tree |
Shrub/Vine |
Grass/
Grasslike |
Forb |
| <0.5 |
– |
– |
– |
– |
| >0.5 <= 1 |
– |
– |
– |
0-10% |
| >1 <= 2 |
– |
– |
75-85% |
– |
| >2 <= 4.5 |
– |
0-5% |
– |
– |
| >4.5 <= 13 |
– |
– |
– |
– |
| >13 <= 40 |
– |
– |
– |
– |
| >40 <= 80 |
– |
– |
– |
– |
| >80 <= 120 |
– |
– |
– |
– |
| >120 |
– |
– |
– |
– |
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
Community 1.2
Nebraska sedge/Rushes
As the sedge community is disturbed, either through grazing or a lower water table, Nebraska sedge and Baltic rush dominate the site while Northwest territory sedge decreases. Baltic rush is adapted to both flooding and drought and is also tolerant of a range of soil conditions, including mild to moderate salinity and alkaline to calcareous soils.
Pathway 1.1a
Community 1.1 to 1.2
Develops with improper grazing management.
Pathway 1.2a
Community 1.2 to 1.1
Results from prescribed grazing or no grazing.
State 2
Current Potential State
The Current Potential State is similar to the Reference State except the plant communities have non-native species present. The presence of non-native species, especially those that are invasive, lowers the resistance and resiliency of the state. Invasive/non-native plants that can come in with a high water table are meadow foxtail (Alopecurus arundinaceus), quackgrass (Elymus repens), reed canarygrass (Phlaris arundinacea), and Kentucky bluegrass (Poa pratensis). These species are also more tolerant of grazing and can increase and may become dominant.
Community 2.1
Northwest territory sedge/Nebraska sedge/rushes/non-native species
Community phase 2.1 is similar to Community Phase 1.1 with the exception of non-native species present in the community.
Community 2.2
Nebraska sedge/Rushes/non-native species
Community phase 2.2 is similar to Community Phase 1.2 with the exception of non-native plant species present.
Pathway 2.1a
Community 2.1 to 2.2
Improper grazing decreases Northwest territory sedge, while non-native plants, Nebraska sedge, and Baltic rush increase.
Pathway 2.2a
Community 2.2 to 2.1
Lack of disturbance, such as grazing, or prescribed grazing applied.
State 3
Degraded/Lowered water table State
The Degraded/Lower water table State develops after a permanent lowering of the water table. This can occur from excessive grazing that can cause meadow downcutting or through artificial meadow drainage to decrease soil saturation. State 1 and State 2 can transition to this state, however State 2 is more likely to transition to State 3 through improper grazing management. This state can be similar to the Semiwet Fresh Meadow site in early seral status. The site has crossed the threshold. This state cannot be returned to State 1 without raising the water table.
Community 3.1
Sedges/Rushes/non-native species
The plant community is dominated by Nebraska sedge and Baltic rush, but the overall production potential of the site is much lower than State 1. There is an increase in forbs and grasses that require less soil moisture. Kentucky bluegrass, redtop bentgrass and meadow foxtail may have invaded the community.
Transition T1A
State 1 to 2
This transition occurs after the introduction of non-native species.
Transition T1B
State 1 to 3
This transition can occur with artificial drainage of the site.
Transition T2A
State 2 to 3
This transition develops through permanently lowering the late growing season water table to 20-40 inches. This can occur with continued improper grazing management. It may also occur with proper grazing on the site, but channel erosion may continue if poor off-site conditions cause more frequent and/or severe flooding.
