State 1
Grassland State

The Grassland State defines the ecological potential and natural range of variability resulting from the natural disturbance regime of the Loamy Terrace 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 a result 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/Tallgrass Plant Community is made up primarily of warm-season midgrasses, with an interspersed cool-season component and decreasing amounts of 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 11. Reference Plant Community in MLRA 74.

The interpretive plant community for this site is the Reference Plant Community. It represents the original plant community that existed prior to European settlement. The site is characterized as a grassland with only occasional trees and shrubs. It is dominated by warm-season tallgrasses including big bluestem, Indiangrass, switchgrass, and eastern gamagrass. All of these grasses and most of the dominant forbs have extensive rhizomes. These underground stems often form a dense, intertwined mass throughout the upper four or five inches of the soil profile. Combined these tallgrasses—along with the major midgrass little bluestem—will account for about 70 percent of the total vegetation produced annually. Other prevalent midgrasses and grass-like plants are sideoats grama, blue grama, buffalograss, western wheatgrass, composite dropseed, and several species of sedges. Only a trace amount of prairie cordgrass is present. The Loamy Terrace ecological site supports a wide variety of legume species interspersed throughout the grass sward. The most abundant are slimflower scurfpea, Nuttall’s sensitive-briar, prairie bundleflower, and American licorice. Other important forbs include compassplant, white heath aster, dotted blazing star, pitcher sage, upright prairie coneflower, and Cuman ragweed. American plum, coralberry, and pricklypear may occur in scattered clumps on this site. This is a stable plant community when adequately managed. A prescribed grazing program that incorporates periods of deferment during the growing season benefits the tallgrasses and more palatable forbs. Soils are susceptible to excessive grazing and livestock trailing, which can quickly impact on the soil stability and lead to sheet and gully erosion. Long-term grazing can lead to the reduction of tallgrasses and palatable forbs. Growth of warm-season grasses on this site typically begins during the period of May 1 to May 15 and continues until mid-September. 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. There are exceptions as big bluestem, eastern gamagrass, and prairie cordgrass will occasionally initiate spring growth as early as April 5 following mild winter temperatures. Also, it is not unusual for other warm-season grasses such as Indiangrass and little bluestem to have some new leaf growth arising from basal buds in late October following moderate fall temperatures. 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).

Resilience management. This is a stable plant community when adequately managed. A prescribed grazing program that incorporates periods of deferment during the growing season benefits the tall-grasses and even the more palatable forb species. Soils are susceptible to excessive grazing and livestock trailing which can quickly impact soil stability and lead to sheet and gully erosion. Long-term heavy, continuous grazing can lead to the reduction of the tall-grasses and palatable forbs on terraces as livestock often concentrate there.

Community 1.2
Midgrass/Tallgrass Plant Community

Composition of this plant community is dominated by a mixture of tallgrasses and midgrasses. Compared with the Reference Plant Community, there has been a decrease in the more palatable tallgrasses and forbs and a subsequent increase in midgrasses. Although reduced by overgrazing, tallgrasses such as big bluestem, Indiangrass, and switchgrass remain dominant. The increased proportion of midgrasses include composite dropseed, little bluestem, western wheatgrass, and sideoats grama. Other secondary grasses that have increased are Texas bluegrass, Kentucky bluegrass, blue grama, and plains muhly. Combined, these plants now comprise 30 to 40 percent of the total herbage produced annually. Forbs such as Maximilian sunflower, wholeleaf rosinweed, compassplant, and prairie bundleflower have decreased and largely been replaced by white heath aster, white sagebrush, Cuman ragweed, Baldwin's ironweed, and Canada goldenrod. Forbs produce 10 to 20 percent of the total herbage. In some locations the Loamy Terrace ecological site supports an increasing amount of shrubs and trees. The common shrubs are American plum, roughleaf dogwood, smooth sumac, and coralberry. Common hackberry, American elm, Siberian elm, Osage-orange, and eastern redcedar are the major tree species that can be found invading the site. Shrubs and trees together can comprise 5 to 10 percent of the total production. Periodic rest and recovery from grazing pressure is necessary to maintain production of some of the major grasses found in this plant community. Eastern gamagrass and big bluestem are especially preferred and selectively grazed by cattle. When the site is grazed continuously throughout the growing season, these grasses are usually overgrazed and thus maintained in a lower state of vigor. When continued for many years, overgrazing results in a gradual reduction in their abundance. However, prescribed grazing that incorporates periods of rest and recovery during the growing season will improve the vigor and gradual recovery of the more palatable tallgrasses and forbs.

Resilience management. The plant community is relatively stable with moderate grazing unless adversely affected by drought or other major stress factors. With heavy, continuous overgrazing it can deteriorate to a Midgrass/Shortgrass community over a period of many years. However, with a significant component of tallgrass remnants it can also be restored to near the Reference Plant Community in a few years by moderate grazing with use of timely rest periods during the growing season.

Community 1.3
Midgrass/Shortgrass Plant Community

This plant community results from many years of overgrazing. The amount of tallgrasses has decreased significantly and the site is dominated by midgrasses and shortgrasses. Major midgrasses are little bluestem, composite dropseed, sideoats grama, and western wheatgrass. Shortgrasses include Kentucky bluegrass, Texas bluegrass, smooth bromegrass, buffalograss, and blue grama. Major forbs on the site are Cuman ragweed, Canada goldenrod, Missouri goldenrod, white sagebrush, white heath aster, and annual ragweed. In some locations the site supports an increasing amount of shrubs and trees. The most common shrubs are American plum, roughleaf dogwood, smooth sumac, and coralberry. American elm, eastern redcedar, and Osage-orange are the major trees found on the site. Shrubs and trees combined usually will not comprise over 10 percent of the total production. Remnant plants of big bluestem, Indiangrass, switchgrass, prairie cordgrass, eastern gamagrass, and Maximilian sunflower are often found scattered throughout the site. These plants are usually grazed repeatedly and maintained in a low state of vigor. They respond favorably to periods of rest from grazing during the growing season and often regain vigor in a few years.

Resilience management. Remnant plants of big bluestem, Indiangrass, and switchgrass are commonly found only in protected locations. These plants are usually grazed repeatedly and remain in a low state of vigor. Of these remnants, big bluestem is generally the most abundant. It has rhizomes that can persist for many years in a weakened condition. When in this state of vigor, new growth consisting of three to five leaves will emerge in a prostrate position rather than upright. This allows the plants to partially escape grazing. These remnant plants respond favorably to periods of rest from grazing and may regain vigor in two to three years. However, if their numbers or percentage of composition is greatly reduced, it may take many years to regain a large role in the plant community. Prescribed grazing with adequate rest and recovery periods during the growing season will shift this plant community to include more productive tallgrasses. With continued management the taller grasses will gradually increase in vigor and abundance to dominate the landscape.

Pathway 1.1 to 1.2
Community 1.1 to 1.2

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

Causes of plant community shift include management (10-15 years) with adequate rest and recovery of the key forage species (big bluestem, switchgrass, Indiangrass, and little bluestem) within the Reference Plant Community . If woody species are present, prescription fires every 6-8 years will be necessary for their removal and 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 towards 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 Midgrass/Tallgrass 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 has 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 14. MLRA 74 Shortgrass Plant Community.

This plant community is dominated by a mixture of shortgrasses and occurs after many years of continuous overgrazing. Usually pastures are small and associated with farming enterprises. In the past they were often used as holding areas in anticipation of seasonal wheat pasture or other cropland forages. Dominant grasses are blue grama, buffalograss, Carolina crabgrass, sideoats grama, composite dropseed, and western wheatgrass. Annual grasses including, Japanese brome, cheatgrass, little barley, tumblegrass, prairie threeawn, purple threeawn, and fall panicgrass are common during seasons of normal or above-normal precipitation. Major forbs are Cuman ragweed, Missouri goldenrod, crested pricklypoppy, hoary verbena, prairie broomweed, Baldwin's ironweed, and white sagebrush. A number of thistles both native and introduced are common in this plant community and may include such varieties as wavyleaf, yellowspine, tall, Canada, bull, and nodding pumeless thistles. Common shrubs found are American plum, smooth sumac, roughleaf dogwood, and coralberry. Areas that have experienced a major disturbance will generally support a large number of annual forbs. These may include snow on the mountain, cocklebur, annual ragweed, and common sunflower. Although productivity is significantly reduced when compared to the Reference Plant Community, this plant community can be managed as a stable shortgrass plant community. Restoration to a tallgrass plant community is not well documented. Further research and observations are necessary in order to understand restoration potential.

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

State 3
Woody State

This state is dominated by a shrub and/or tree plant community. The increase and spread of shrubs and trees results from an absence of fire. Woody plants can increase up to 34 percent from a lack of fire according to a study from 1937 to 1969, in contrast to a 1 percent increase on burned areas (Bragg and Hulbert, 1976). Periodic burning will hinder the establishment of most woody species and favor forbs and grasses. However, it should be pointed out that not all unburned areas have a woody plant invasion. Birds, small mammals, and livestock are instrumental in the distribution of seed and accelerating the spread of most trees and shrubs common to this site. The speed of encroachment varies considerably and can occur on both grazed and non-grazed pastures. Many species of wildlife, especially bobwhite quail, turkey, and white-tailed deer, benefit from the growth of trees and shrubs for both food and cover. When management for specific wildlife populations is desirable, these options should be considered in any brush management plan.

Characteristics and indicators. Hydrologic function is affected by the amount of vegetative cover. Canopy interception loss can vary from 25.4 percent to 36.7 percent (Thurow and Hester, 1997). A small rainfall event is usually retained in the foliage and does not reach the litter layer at the base of the tree. Only when canopy storage is reached and exceeded does precipitation fall to the soil surface. Interception losses associated with the accumulation of leaves, twigs, and branches at the bases of trees are considerably higher than losses associated with the canopy. The decomposed material retains approximately 40 percent of the water that is not retained in the canopy (Thurow and Hester, 1997). Soil properties affected include biological activity, infiltration rates, and soil fertility.

Resilience management. Special planning will be necessary to assure that sufficient amounts of fine fuel are available to carry fires with enough intensity to control woody species. In some locations the use of chemicals as a brush management tool may be desirable to initiate and accelerate this transition.

Community 3.1
Shrubs and/or Trees

This plant community is dominated by shrubs consisting primarily of American plum, coralberry, fragrant sumac, roughleaf dogwood, and smooth sumac. Trees including American elm, common hackberry, Osage-orange, Siberian elm, and eastern redcedar have invaded and become established in some areas. American plum, coralberry, roughleaf dogwood, and smooth sumac are generally the most abundant shrubs and often form low, dense thickets throughout the site. Shrubs and trees may produce 40 to 60 percent of the total vegetation. The spread of shrubs and trees results from the absence of fire. Periodic burning tends to hinder the establishment of most of these woody species and favor grasses and forbs. Not all unburned areas have a woody plant problem, however. The speed of woody encroachment varies considerably depending upon seed availability in surrounding areas. Numerous birds are instrumental in the distribution of seed and accelerating the spread of shrub and tree species over the site. Woody encroachment may also occur on areas subjected to longtime continuous overgrazing. In these situations the associated grasses will usually consist of composite dropseed, purple lovegrass, Kentucky bluegrass, smooth bromegrass, and Scribner’s rosette grass. Shrubs also will invade and spread on areas where both grazing and fire have been excluded for many years. Heavy accumulation of plant mulch and litter retards herbage growth and provides a favorable habitat for seed germination and establishment of many woody species. The associated grasses in this situation are usually big bluestem, little bluestem, Indiangrass, switchgrass, and a few sedges. Competition from forbs and woody species significantly reduces grass production which accounts for only 40 to 50 percent of total vegetative production. Forbs often produce up to 15 to 20 percent of the total and include white sagebrush, Cuman ragweed, Baldwin ironweed, and common yarrow. In this plant community, the amount of available forage is heavily dependent upon the predominant woody species and the kind(s) of livestock and wildlife utilizing the site. Usually a prescribed burning program accompanied by prescribed grazing will gradually return the plant community to one dominated by grasses and forbs. Longer periods will be needed where tall and midgrasses have been greatly reduced or eliminated. Special planning will be necessary to assure that sufficient amounts of fine fuel are available to carry fires with enough intensity to control woody species. Use of labeled herbicides as a brush management tool will usually be necessary to reduce populations of fire resistant species like Osage-orange and accelerate the recovery of the desired vegetative cover. Many species of wildlife, especially northern bobwhite quail and white-tailed deer, benefit from the growth of shrubs for both food and as cover. When wildlife populations are a desirable component, this should be considered in any brush management plan.

Resilience management. The shrub and tree plant community is sustained by the absence of fire and brush control.

State 4
Tillage State

Extensive areas of the historic Loamy Terrace plant communities 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/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. The Tillage State is a result of a land use management decision.

Community 4.1
Reseed Community

This plant community occurs on areas that were formerly farmed. When farming operations ended, the area was seeded and established to a mixture of plants, usually native species common in the Reference Plant Community. Most seeding mixtures consisted of a blend of grasses that included big bluestem, Indiangrass, switchgrass, and little bluestem. In some locations seed of additional plants such as eastern gamagrass, prairie bundleflower, and Maximilian sunflower were included in the mixture. When reseeded areas and areas supporting native rangeland exist in the same pasture, they seldom are grazed at the same intensity. There is usually a preference by domestic livestock for plants on the native rangeland areas. When feasible, reseeded plant communities should be managed as separate pastures or units. These areas are generally productive when managed for hay production. Some seeded areas are invaded by trees and shrubs during the establishment period of the desired plants. These invader species commonly include Siberian elm, common hackberry, eastern redcedar, and roughleaf dogwood. Occasional burning is effective in controlling the establishment of these woody plants.

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 for this ecological site can be beneficial to the rehabilitation.

Community 4.2
Go-back Plant Community

This plant community occurs on areas that were formerly farmed. When tillage operations were discontinued, the areas were allowed to revegetate or “go back” naturally. This was in contrast to artificial reseeding with a selected species or group of species. Go-back is a slow, gradual process that entails 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, Canadian horseweed, common sunflower, field horsetail, and golden tickseed. Gradually these are replaced by annual grasses including prairie threeawn, prairie cupgrass, little barley, Japanese brome, and cheatgrass. Usually plant succession will progress until the plant community is dominated by perennial grasses and grass-like plants including composite dropseed, foxtail barley, silver beardgrass, buffalograss, and Torrey’s rush. These plants can form a stable community. In time and with prescribed grazing management, other perennial grasses and forbs common in the Reference Plant Community return to the site. Some go-back areas are invaded by trees and shrubs. The more common species include Siberian elm, common hackberry, eastern redcedar, and roughleaf dogwood. Occasional burning is effective in controlling these woody plants.

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 are increases 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

Changes from a Grassland State to a Woody State lead to changes in hydrologic function, forage production, dominant functional and structural groups, and wildlife habitat. Understory plants may be negatively affected by trees and shrubs by reductions in light, soil moisture, and soil nutrients. Increases in tree and shrub density and size have the effects of reducing understory plant cover and productivity, and desirable forage grasses often are most severely reduced (Eddleman, 1983). As vegetation cover changes from grasses to trees, a greater proportion of precipitation is lost through interception and evaporation; therefore, less precipitation is available for producing herbaceous forage or for deep drainage or runoff (Thurow and Hester, 1997).

Constraints to recovery. Recovery is possible through management.

Transition 1 to 4
State 1 to 4

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.

Restoration pathway 3 to 1
State 3 to 1

Restoration efforts will be costly, labor-intensive, and can take many years, if not decades, to return to a Grassland State. Once canopy levels reach greater than 20 percent, estimated cost to remove trees is very expensive and includes high energy inputs. The technologies needed in order to go from an invaded Woody State to a Grassland State include but are not limited to: prescribed burning—the use of fire as a tool to achieve a management objective on a predetermined area under conditions where the intensity and extent of the fire are controlled; brush management—manipulating woody plant cover to obtain desired quantities and types of woody cover and/or to reduce competition with herbaceous understory vegetation, in accordance with overall resource management objectives; and prescribed grazing—the controlled harvest of vegetation with grazing or browsing animals managed with the intent to achieve a specified objective. In addition, to grazing at an intensity that will maintain enough cover to protect the soil and maintain or improve the quantity and quality of desirable vegetation. When a juniper tree is cut and removed, the soil structure and the associated high infiltration rate may be maintained for over a decade (Hester, 1996). This explains why the area near the dripline usually has substantially greater forage production for many years after the tree has been cut. It also explains why runoff will not necessarily dramatically increase once juniper is removed. Rather, the water continues to infiltrate at high rates into soils previously ameliorated by junipers, thereby increasing deep drainage potential. In rangeland, deep drainage amounts can be 16 percent of the total rainfall amount per year (Thurow and Hester, 1997).