State 1
Grassland State

The Grassland State defines the ecological potential and natural range of variability resulting from the natural disturbance regime of the Saline Lowland ecological site. This state is supported by empirical data, historical data, local expertise, and photographs. It is defined by a suite of native plant communities that are the results of periodic fire, drought, and grazing. These events are part of the natural disturbance regime and climatic process. The Reference Plant Community consists of warm-season tall- and midgrasses, cool-season and sod-forming grasses, forbs, and shrubs. The Midgrass Plant Community is made up primarily of warm-season midgrasses, with an interspersed cool-season component, forbs and tallgrasses. The Midgrass/Shortgrass Plant Community is dominated by midgrasses, shortgrasses, and cool-season midgrasses.

Characteristics and indicators. Tallgrasses and midgrasses are dominant in the Grassland State.

Resilience management. Management strategies that will sustain this state include monitoring key forage species and providing a forage and animal balance.

Community 1.1
Reference Plant Community

Figure 9. MLRA 74 Reference Plant Community.

The interpretive plant community for this site is the Reference Plant Community. This plant community represents the original plant community that existed prior to European settlement. The site is characterized as a grassland that is essentially free of trees and large shrubs. Salt marsh is a common term to describe this site. It is dominated by warm-season grasses including prairie cordgrass, alkali sacaton, switchgrass, big bluestem, and inland saltgrass. Major cool-season grasses and grass-like plants include western wheatgrass, prairie wedgescale, rushes, sedges, and foxtail barley. Other grasses and grass-like plants include little bluestem, buffalograss, common spikerush, cosmopolitan bulrush, Scribner’s rosette grass, and composite dropseed. These grasses and grass-like plants will account for about 70 percent of vegetation produced annually. The Saline Lowland ecological site has alkaline and sodic conditions that affect the kinds and amounts of vegetation present. The site supports a scattered population of legume species which are sparsely interspersed throughout the grass sward. Of these, prairie bundleflower is the most notable. Many legumes have a low tolerance to salt and occur in areas of low salt concentrations. Important forbs include broadleaf cattail, Maximilian sunflower, curly dock, common milkweed, Baldwin's ironweed, and giant ragweed. The most abundant shrub on this site is desert false indigo which is commonly present along incised areas. Small, green trees may be observed sparsely scattered over the site. Many of these are green ash trees apparently stunted in size by the saline-alkali soils. Small eastern cottonwood and black willow trees may also be noted along incised areas. Growth of warm-season grasses on this site typically begins during the period of May 1 to May 15 and continues until mid September. Cool-season grasses, sedges, and rushes generally have two primary growth periods, one in the fall (September and October) and again in the spring (April, May, and June). Some growth may occur in winter months during periods of unseasonably warm temperatures (Indian summers). As a general rule, 75 percent of total production is completed by mid-July. This varies only slightly from year to year depending upon temperature and precipitation patterns.

Resilience management. This is a stable plant community when grazing and fire are adequately managed. A prescribed grazing program that incorporates periods of rest and recovery during the growing season benefits the tallgrasses and even the more palatable forb species.

Community 1.2
Midgrass Plant Community

Figure 12. MLRA 74 Midgrass Plant Community.

This plant community developed as a result of many years of continuous overgrazing. Midgrasses and grass-like plants dominate the site and produce 40 to 60 percent of the vegetation. Remnant colonies of prairie cordgrass remain, but they are greatly reduced in size and vigor. The most abundant midgrasses include alkali sacaton, western wheatgrass, composite dropseed, several rush species, and tall sedges. Shortgrasses such as inland saltgrass, buffalograss, foxtail barley, Kentucky bluegrass, smoooth brome and sedges produce 20 to 30 percent of the vegetation. Remnant plants of big bluestem, switchgrass, and sideoats grama are often found sparsely scattered throughout the site. These plants are usually grazed repeatedly and remain in a low state of vigor. These remnants respond favorably to periods of rest from grazing and may regain vigor in two to three years. Forb production is variable and may range from 10 to 25 percent of the total vegetation depending upon the amounts and timing of rainfall and flooding. Perennial forbs include common milkweed, white sagebrush, red sorrel, curly dock, giant ragweed, and Cuman ragweed. Annual forbs common on the site include common sunflower and annual ragweed. Desert false indigo is the dominant shrub on this site and normally makes up less than five percent of the vegetation. Small amounts of green ash, eastern cottonwood, osage orange, and black willow may be scattered throughout the site.

Resilience management. Periods of rest and recovery from grazing are essential in maintaining this as a stable plant community. When the site is grazed continuously throughout the growing season, prairie cordgrass is usually overgrazed and exists in a state of low vigor. Over time this results in a gradual reduction in abundance.

Community 1.3
Midgrass/Shortgrass Plant Community

This plant community developed as a result of many years of heavy grazing without rest and recovery of the key forage species. Midgrasses and shortgrasses dominate the site and comprise 50 to 70 percent of the annual production. Most abundant midgrasses include inland saltgrass, composite dropseed, and western wheatgrass. Hairy grama, buffalograss, Kentucky bluegrass, smooth bromegrass, and blue grama produce 20-30 percent of the vegetation. Forb production is quite variable and may range from 10 to 30 percent of the total vegetation depending upon amounts and timing of rainfall events.

Resilience management. Remnant plants of prairie cordgrass, although sparse, are often found scattered throughout the site. These plants are usually grazed repeatedly and remain in a low state of vigor. Prescribed grazing with adequate rest and recovery periods during the growing season will shift this plant community to include more productive midgrasses. With continued management the taller grasses will gradually increase in abundance.

Pathway 1.1 to 1.2
Community 1.1 to 1.2

Reference Plant Community

Midgrass Plant Community

These mechanisms include management controlled by repetitive heavy use, no rest or recovery of the key forage species, and no forage and animal balance for many extended grazing seasons. This type of management lasting for periods greater than 10 years will shift functional and structural plant group dominance toward a midgrass plant community.

Context dependence. Plant community composition shifts from tallgrass- to midgrass-dominant.

Pathway 1.2 to 1.1
Community 1.2 to 1.1

Midgrass Plant Community

Reference Plant Community

Causes of plant community shift include management (10-15 years) with adequate rest and recovery of the key forage species (prairie cordgrass, big bluestem, switchgrass, Indiangrass, and inland saltgrass) within the Reference Plant Community. If woody species are present, prescription fires every 6-8 years will be necessary for their removal and/or maintenance.

Pathway 1.2 to 1.3
Community 1.2 to 1.3

These mechanisms include management controlled by repetitive heavy use, no rest or recovery of the key forage species, and no forage and animal balance for many extended grazing seasons. This type of management lasting for periods greater than 20 years will shift functional and structural plant group dominance toward a Midgrass/Shortgrass Plant Community.

Pathway 1.3 to 1.2
Community 1.3 to 1.2

Causes of plant community shift include management (10-15 years) with adequate rest and recovery of the key forage species (little bluestem, sideoats grama, big bluestem, switchgrass, and Indiangrass) within the Tallgrass/Midgrass Plant Community. If woody species are present, prescription fires every 6-8 years will be necessary for their removal and maintenance.

State 2
Shortgrass State

With heavy, continuous grazing, blue grama and buffalograss will become the dominant species and have a sod-bound appearance. Unable to withstand the grazing pressure, only a remnant population of western wheatgrass remains.

Characteristics and indicators. The Shortgrass State is characterized with specific dynamic soil property changes. Changes between the Grassland State and the Shortgrass State have been documented. As plant community cover decreases from bunchgrasses to more of the sod grasses there is a decrease in infiltration and interception and an increase in surface runoff (Thurow, T., 2003).

Resilience management. This is a resistant and resilient state. Grazing management practice should include a forage and animal balance.

Community 2.1
Shortgrass Plant Community

Figure 13. MLRA 74 Shortgrass Plant Community.

This plant community developed as a result of many years of heavy, continuous grazing with no rest and recovery of the key forage species. Shortgrasses dominate the site and comprise 50 to 70 percent of annual production. Most abundant shortgrasses include inland saltgrass, sand dropseed, buffalograss, and numerous rushes and sedge species. Western wheatgrass, although considered a midgrass, is an important part of this shortgrass plant community and is included in the annual production as a dominant species. Remnant plants of prairie cordgrass, big bluestem, and switchgrass are very sparse and scattered. They persist in a low state of vigor, often being semi-dormant or dormant. A significant population of alkali sacaton may also be scattered through this community but is generally in a state of low vigor. Forb production is variable and normally ranges from 20 to 30 percent of the total production on the Saline Lowland ecological site. Perennial forbs include common milkweed, curly dock, Carruth’s sagewort, common yarrow, wavyleaf thistle, Canadian horseweed, Cuman ragweed, and giant ragweed. Annual forbs include common sunflower and annual ragweed. Where remnant tallgrasses persist, total rest from grazing or a prescribed grazing period can result in a significant increase in prairie cordgrass and switchgrass with lesser increases in big bluestem. Shrubs and trees tend to remain scattered in the shortgrass community and combined usually make up less than 10 percent of the total production. Scattered populations of desert false indigo and saltcedar may be observed along incised areas. Trees such as green ash, eastern cottonwood, black willow, eastern redcedar, and common hackberry may be sparsely scattered over the site.

Resilience management. If this plant community is grazed heavily, especially during hot, dry periods, it may result in large areas of bare alkaline ground which is very susceptible to wind erosion. With heavy rains following this condition, sheet erosion will occur within the site, making conditions ideal for large populations of forbs. Annual forbs such annual sunflower, annual ragweed, giant ragweed, curly dock, and others may dominate large portions of the site for one year or more.

State 3
Tillage State

There are areas of the historic Saline Lowland plant communities that were plowed and converted to production of cultivated crops by the early European settlers and subsequent generations. In addition to destroying the original plant community, repeated tillage commonly resulted in major changes in soil conditions. Reductions in organic matter, mineral levels, soil structure, oxygen levels, and water-holding capacity, along with increased runoff and erosion and shifts in the populations of soil-dwelling organisms, were common on these sites. The extent of these changes depended upon duration of cropping as well as crops grown and other management practices. The Tillage State consists of abandoned cropland that has been naturally revegetated (go-back) or planted or seeded to grassland. Many reseeded plant communities were planted with a local seeding mix under the Conservation Reserve Program (CRP) or were planted to a monoculture of sideoats grama. Go-back communities are difficult to define due to the variability of plant communities that can exist. Many of these communities are represented by the genus Aristida (threeawns).

Characteristics and indicators. This is an alternative state because the energy, hydrologic, and nutrient cycles are altered to that of the Reference State in its natural disturbance regime. Bulk density, aggregate stability, soil structure, and plant functional and structural groups are not fully restored to that of the Reference State. Mechanical tillage can destroy soil aggregation. Soil aggregates are an example of dynamic soil property change. Aggregate stability is critical for infiltration, root growth, and resistance to water and wind erosion (Brady and Weil, 2008).

Resilience management. This state is a result of a land use management decision.

Community 3.1
Reseed Plant Community

Figure 14. MLRA 74 Seeded Plant Community.

This plant community occurs on areas that were formerly farmed or tilled for the purpose of seeding what were considered improved grasses. The two grasses found to be seeded on outer areas of this site were tall wheatgrass (Thinopyrum ponticum) and smooth bromegrass (Bromus inermis). These were seeded into areas that may have been cultivated for a short period of time or on low-producing zones which were tilled and seeded to improve forage production. They appear to have been seeded in single-species plantings. Once these areas become fully established, production is comparable to that of the Reference Plant Community. Total annual production varies according to the species planted, established plants, and years of establishment. When reseeded areas and areas supporting native rangeland exist in the same pasture, they seldom are utilized at the same intensity because domestic livestock usually prefer plants growing on the native rangeland areas. When feasible, reseeded plant communities should be managed as separate pastures or units. Some seeded areas are invaded by trees and shrubs during the establishment period of the desired plants. These invader species commonly include elm, common hackberry, eastern redcedar, and eastern cottonwood. Occasional burning is effective in controlling establishment of these woody plants. These areas, when established, may produce 5,000 to 6,000 pounds of forage, similar to the Reference Plant Community. However, without intensive agronomic management practices they rapidly yield to the rushes, sedges, and salt-tolerant grasses adapted to the wet soils. Older seeded areas seem to take on the characteristics of the Midgrass Plant Community with a component of about 15 to 20 percent of the seeded grass.

Resilience management. Following termination of cultivation, total annual production is quite variable and full recovery of the original plant community, including forbs and legumes, may take many decades. Additions of organic matter and minerals, deferred grazing, prescribed burning, and related management practices described earlier for this ecological site can be beneficial to the rehabilitation.

Community 3.2
Go-back Plant Community

This plant community also occurs on areas that were formerly farmed. When tillage operations ceased, the areas were allowed to revegetate or “go back” naturally in contrast to artificial reseeding to a selected species or group of species. The go-back process is a slow, gradual transformation that requires many years and many successional changes or stages in the plant community. The speed and extent of revegetation depends on the size of the area, level of grazing management and the proximity of the area to existing seed sources. In the initial stages of revegetation the site is usually dominated by annual forbs such as annual ragweed, slender snakecotton, Canadian horseweed, prairie sunflower, common sunflower, Mexican fireweed, camphorweed, and annual buckwheat. Gradually these are replaced by annual grasses including prairie threeawn, mat sandbur, tumblegrass, little barley, cheatgrass, and witchgrass. As plant succession progresses the plant community gradually becomes dominated by perennials. The major grasses include sand dropseed, composite dropseed, thin paspalum, purple lovegrass, red lovegrass, Scribner’s rosette grass, Carolina crabgrass, silver beardgrass, and tumble windmillgrass. Common forbs are Cuman ragweed, white sagebrush, Carruth’s sagewort, white heath aster, Missouri goldenrod, and sand milkweed. Combinations of these plants can form a stable community. In time with prescribed grazing management, other perennial grasses and forbs common in the Reference Plant Community return to the site. Blue grama is a shortgrass that is very common to the native plant communities on this site. However, it seldom occurs in go-back communities, even after 40 to 50 years of plant succession. Some go-back areas are invaded by trees and shrubs. The more common include elm, common hackberry, eastern redcedar, eastern cottonwood, and roughleaf dogwood. Occasional burning is effective in controlling these woody plants. Total annual production varies by site. This depends upon seasonal precipitation and the stage of plant succession in the plant community.

Resilience management. Following termination of cultivation, total annual production is quite variable and full recovery of the original plant community, including forbs and legumes, may take many decades. Additions of organic matter and minerals, deferred grazing, prescribed burning, and related management practices described earlier for this ecological site can be beneficial to the rehabilitation.

Transition 1 to 2
State 1 to 2

Long-term management (approximately 30 years) without a forage and animal balance and heavy, continuous grazing without adequate recovery periods between grazing events will convert the Grassland State to a Shortgrass State made up of blue grama and buffalograss sod. Drought in combination with this type of management will quicken the rate at which this transition occurs.

Constraints to recovery. The ecological processes affected are the hydrologic and nutrient cycles. There is an increase in evaporation rate, runoff, and bulk density. There is a decrease in infiltration, a change in plant composition, and the functional and structural groups have changed dominance. These are all examples of the soil and vegetation properties that have compromised the resilience of the Grassland State and therefore transitioned to a Shortgrass State.

Transition 1 to 3
State 1 to 3

This transition is triggered by a management action as opposed to a natural event. Tillage, or breaking the ground with machinery for crop production, will move the Grassland State to a Tillage State.

Constraints to recovery. The resilience of the Reference State has been compromised by the fracturing and blending of the native virgin sod. The energy, hydrologic, and nutrient cycles are altered and vary from that of the Grassland State.