State 1
Grassland State

The Grassland State defines the ecological potential and natural range of variability resulting from the natural disturbance regime of the Sandy Loam 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 community is made up primarily of warm-season midgrasses with an interspersed cool-season component and decreasing amounts of forbs and tallgrasses. The Midgrass Plant Community is dominated by less desirable midgrasses, shortgrasses, and cool-season midgrasses.

Characteristics and indicators. This state is distinguished from other states by the tall- and midgrass native species that that dominate the site.

Resilience management. The Grassland State is defined by a suite of native plant communities that are a result of periodic fire, drought, and grazing.

Community 1.1
Reference Plant Community

The interpretive plant community for this site is the Reference Plant Community. This community represents the original plant community that existed prior to European settlement. The site is characterized as a grassland essentially free of trees and large shrubs. It is dominated by tall, warm-season grasses, including sand bluestem, switchgrass, and Indiangrass. These tallgrasses have extensive root systems that penetrate the soil profile to depths of 10 to 12 feet. The major midgrass species is little bluestem. Combined, the sand bluestem, switchgrass, Indiangrass, and little blusestem will account for approximately 80 percent of the vegetation produced annually. Other prevalent midgrasses include Canada wildrye, sideoats grama, sand lovegrass, purple lovegrass, western wheatgrass, composite dropseed, and sand dropseed. Scattered throughout are minor amounts of shortgrasses consisting of blue grama, hairy grama, thin paspalum, and Carolina crabgrass.

The Sandy Loam ecological site supports a wide variety of legume species which are intermixed throughout the sward. The most abundant are Nuttall’s sensitive-briar, roundhead lespedeza, sessileleaf ticktrefoil, golden prairie clover, silky sophora, and prairie bundleflower. Other important forbs include Maximilian sunflower, scaly blazing star, stiff goldenrod, and pitchersage. A small amount of annual plants are common most years. They often occur as a result of soil disturbances by rodents and other digging animals. They may also be abundant in years when normal precipitation returns after an extended drought period.

Leadplant and Jersey tea are low-growing shrubs that occur over the site. Unlike many shrubs, these plants are both quite tolerant to fire and are readily grazed by livestock. A few small clumps of Chickasaw plum and fragrant sumac may be found on slope exposures, where they partially escape the effects of intense fires. Sand sagebrush occurs in some of the extreme western portions of MLRA 79.

The Reference Plant Community is stable when properly managed. A prescribed grazing program that incorporates periods of deferment during the growing season benefits tallgrasses and even the more palatable forb species. Soils are susceptible to wind erosion and excessive grazing. Trailing by livestock can impair the stability of the site.

Growth of warm-season grasses on this site typically begins during the period of April 25 to May 10 and continues until late September. As a general rule, 75 percent of total production is completed by mid-July. This varies only slightly from year to year depending on temperature and precipitation patterns. There are exceptions. For example, some plants of sand bluestem will occasionally initiate spring growth in early April 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 and grass-like plants 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. Numerous forbs and a few cool-season grasses form leaf rosettes in the fall that remain green throughout the winter. These plants then initiate rapid growth in early spring.

Total annual production ranges from 2,000 to 4,000 pounds of air-dry vegetation per acre and averages about 3000 pounds.

Resilience management. A prescribed grazing program that incorporates periods of deferment during the growing season benefits tallgrasses and even the more palatable forb species.

Community 1.2
Midgrass/Tallgrass Community

Figure 10. Midgrass/Tallgrass Plant Community

The composition of this plant community resembles that of the Reference Plant Community. Comparatively, there has been a decrease in the amount of the more palatable tallgrasses and forbs and a subsequent increase in midgrasses.

The dominant grasses are little bluestem and sand bluestem with lesser amounts of switchgrass and Indiangrass. A number of midgrasses have increased in abundance as the taller grasses have been reduced by overgrazing. These include sand dropseed, sand lovegrass, purple lovegrass, western wheatgrass, and composite dropseed. Other secondary grasses are Carolina crabgrass, red lovegrass, thin paspalum, tumble windmill grass, Texas bluegrass, hairy grama, blue grama, and Scribner’s rosette grass. Combined these secondary grasses now comprise 20 to 30 percent of the total herbage produced annually.

Forbs such as Maximilian sunflower, roundhead lespedeza, prairie bundleflower, and golden prairie clover have largely been replaced by white sagebrush, Cuman ragweed, Missouri goldenrod, Fendler’s aster, redroot buckwheat, and tenpetal blazingstar. Forbs produce 10 to 12 percent of the total herbage.

This site supports a few shrubs. Leadplant and Jersey tea may be scattered throughout the site. Chickasaw plum, smooth sumac, and fragrant sumac are usually found in small, single-species clumps or mottes. On pastures where only summer grazing is practiced, there is often an increase of soapweed yucca. Shrubs will usually not comprise over 10 percent of the total production.

Total annual production ranges from 2,000 to 3,600 pounds of air-dry vegetation per acre and averages about 2,600 pounds.

Prescribed grazing that incorporates periods of deferment during the growing season will improve the vigor and gradual recovery of the more palatable tallgrasses and forbs.

Resilience management. Periods of deferment from grazing are essential in maintaining this as a stable plant community. Sand bluestem is preferred and readily grazed by cattle. When the site is grazed continuously throughout the growing season, sand bluestem is usually overgrazed and thus maintained in a state of low vigor. This results in a gradual reduction in its abundance over time. Even under moderate continuous stocking, livestock tend to locate and severely overgraze the tops or crests of mounded areas or low sand dunes. Where this occurs, sand dropseed, thin paspalum, red lovegrass, and mat sandbur replace the taller grasses. Such grazing concentrations in some areas have eventually lead to wind erosion and even the establishment of small blowouts.

Community 1.3
Midgrass Community

Figure 11. Midgrass Plant Community

This plant community developed as a result of many years of continuous overgrazing. Midgrasses dominate the site and comprise 50 to 70 percent of the annual production. The most abundant midgrasses include sand dropseed, composite dropseed, western wheatgrass, sand lovegrass, and purple lovegrass. Shortgrasses such as Carolina crabgrass, red lovegrass, tumble windmill grass, purple threeawn, hairy grama, and blue grama produce 10 to 15 percent of the vegetation.

Remnant plants of sand bluestem, Indiangrass, switchgrass, and little bluestem, although sparse, are often found scattered throughout the site. These plants are usually grazed repeatedly and remain in a low state of vigor. Of these remnants, sand bluestem is generally the most abundant. It has rhizomes that can persist for many years in a weakened condition. When in this state, new growth consisting of three to five leaves will emerge in a prostate position rather than upright. This allows the plants to partially escape grazing. These remnants respond favorably to periods of rest from grazing, and may regain vigor in two to three years.

Forb production is quite variable and may range from 10 to 30 percent of the total vegetation depending on amounts and timing of rainfall events. Perennial forbs include Carruth’s sagewort, white sagebrush, redroot buckwheat, tenpetal blazingstar, bush morning-glory, queen’s-delight, and Cuman ragweed. Annual forbs common on the site include prairie sunflower, fourpoint evening-primrose, camphorweed, sleepingplant, annual ragweed, and annual buckwheat. In some locations shrubs such as fragrant sumac and Chickasaw plum comprise 10 to 20 percent of the vegetation. Where past grazing has usually been only during the summer months there may be an increase in the abundance of soapweed yucca. Usually this species is grazed primarily during the period of February and March.

Total annual production ranges from 1,600 to 3,200 pounds air dry vegetation per acre and averages about 2,300 pounds.

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.

Resilience management. 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

The following describes the mechanisms of change from Plant Community 1.1 to Plant Community 1.2. These mechanisms include management controlled by repetitive heavy use, no rest or recovery of the key forage species, and/or no forage and animal balance for many extended grazing seasons. This type of management for periods greater than 10 years will shift functional and structural plant group dominance toward Plant Community 1.2.

Pathway 1.2 to 1.1
Community 1.2 to 1.1

The following describes the mechanisms of change from Plant Community 1.2 to Plant Community 1.1. Management (10-15 years) that includes adequate rest and recovery of the key forage species (sand bluestem, switchgrass, and Indiangrass) within the Reference Plant Community; and, 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

Midgrass/Tallgrass Community

Midgrass Community

The following describes the mechanisms of change from Plant Community 1.2 to Plant Community 1.3. Long-term (>10 years) management that includes continuous, heavy use of the native vegetation; management that is void of a forage and animal balance; inadequate rest and recovery of native grasses during the growing season.

Pathway 1.3 to 1.2
Community 1.3 to 1.2

Midgrass Community

Midgrass/Tallgrass Community

The following describes the mechanisms of change from Plant Community 1.3 to Plant Community 1.2. Management (approximately 10 years) that includes adequate rest and recovery of the key forage species in the Midgrass Community 1.2 (little bluestem, sand bluestem, switchgrass, Indiangrass). Implement prescription fires at a frequency of 6-8 years. Dependent upon the level of woody vegetation encroachment, the fire return interval might need to be adjusted to two consecutive years of prescribed fires.

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.

Species diversity has been reduced further. Water infiltration is reduced and runoff is increased due to the sod nature of the blue grama and buffalograss.

Specific dynamic soil property changes between the Grassland State and the Sod-bound 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).

Characteristics and indicators. Plant community functional and structural group shift from a midgrass community to a shortgrass dominant community.

Resilience management. Maintaining a forage and animal balance will sustain this plant community.

Community 2.1
Shortgrass Plant Community

Figure 12. Shortgrass Plant Community

This plant community is dominated by shortgrasses. It develops following many years of continuous heavy grazing, generally in small pastures associated with a farming-oriented enterprise. Such pastures are often used as holding areas in anticipation of seasonal wheat pasture or other cropland forages. Major grasses are blue grama, hairy grama, Carolina crabgrass, thin paspalum, red lovegrass, sand dropseed, composite dropseed, and silver beardgrass. Annual grasses including Japanese brome, cheatgrass, tumblegrass, prairie threeawn, purple threeawn, and witchgrass are common during seasons of normal or above-normal precipitation. Major forbs are camphorweed, Cuman ragweed, redroot buckwheat, slender snakecotton, firewheel, Rocky Mountain beeplant, Canadian horseweed, and blackeyed susan.

In a few isolated areas where overgrazing was primarily done by sheep, the resulting plant community is completely dominated by shortgrasses, as essentially all tallgrasses and midgrasses have been eliminated. The major perennial grasses are blue grama, red lovegrass, foxtail barley, tumblegrass, Fendler threeawn, and, in some locations, false buffalograss. With normal or above-normal precipitation, numerous annual grasses including prairie threeawn, little barley, sixweeks fescue, and cheatgrass will occur.

Although productivity is significantly reduced when compared to the Reference Plant Community, this plant community can be managed as a stable shortgrass community. Restoration to tallgrasses in a reasonable period of time would require range seeding.

Total annual production ranges from 1,100 to 2,800 pounds of air-dry vegetation per acre, and averages about 1,900 pounds.

Resilience management. Although productivity is significantly reduced when compared to the Reference Plant Community, this plant community can be managed as a stable shortgrass community. Prescribed grazing that includes a forage and animal balance and periodic rest will sustain this plant community.

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 1percent increase on burned areas (Bragg and Hulbert, 1976). Periodic burning tends to hinder the establishment of most woody species and favors forbs and grasses. However, it should be pointed out that not all unburned areas have a woody plant invasion.

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.

Birds, small mammals, and livestock are instrumental in the distribution of seed and accelerating the spread of most tree 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 base 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. The Woody State is maintained by the absent of fire and mechanical and/or chemical control of woody species.

Community 3.1
Shrub and/or Tree Community

This plant community is dominated by shrubs consisting primarily of Chickasaw plum, fragrant sumac, and smooth sumac. Sand sagebrush occurs in some locations in the extreme western portion of MLRA 79. Trees such as honeylocust and eastern redcedar have invaded and become established in isolated areas. Chickasaw plum is generally the most abundant shrub, and typically forms large mottes or thickets scattered over the site. Shrubs and trees may produce 30 to 60 percent of the total vegetation.

The spread of shrubs and trees results in the absence of fire. Periodic burning tends to hinder the establishment of most of these woody species and favor forbs and grasses. However, it should be pointed out that not all unburned areas have a woody plant problem. Birds and small mammals are instrumental in the distribution of seed and accelerating the spread of most shrubs common to this site. The speed of encroachment varies considerably and can occur on both grazed and non-grazed pastures. When encroachment occurs on areas that have been subjected to long-term continuous overgrazing, the associated grasses will usually consist of sand dropseed, sand lovegrass, purple lovegrass, Texas bluegrass, and Scribner’s rosette grass. When both grazing and fire have been excluded for many years, associated grasses generally are sand bluestem, little bluestem, Indiangrass, switchgrass, sedges, and Canada wildrye.

Grass production is significantly reduced because of the shrub competition. Grass yields vary from 30 to 50 percent of the total vegetative production. Forbs generally produce 10 to 20 percent of the total vegetation production. Major forbs include white sagebrush, Carruth’s sagewort, redroot buckwheat, Cuman ragweed, lemon scurfpea, camphorweed, and tenpetal blazingstar.

Usually a prescribed burning program accompanied with prescribed grazing will gradually return the plant community to one dominated by grasses and forbs. Special planning will be necessary to assure that sufficient amounts of fine fuel are available to carry fires with enough intensity to control the woody species. In some locations use of chemicals as a brush management tool will be necessary to initiate and accelerate this transition.

Many species of wildlife, especially bobwhite quail and whitetail deer, benefit from the growth of shrubs for both food and as cover. When wildlife populations are a desirable component, this should be a considered in any brush management plans.

Resilience management. Sustaining this plant community entails the absence of fire as a natural disturbance.

State 4
Tillage State

The Tillage State consists of abandoned cropland that has been naturally revegetated (go-back) or planted/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 since 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. Until further evidence is fulfilled the tillage state does not have a restoration pathway.

Community 4.1
Reseed Community

This plant community occurs on areas that were formerly farmed and reseeded with a mixture of native species common in the Reference Plant Community. Most seeding mixtures consisted of a blend of grasses that include sand bluestem, Indiangrass, switchgrass, little bluestem, sideoats grama, blue grama, and western wheatgrass. In some locations, seeds from legumes and forbs such as prairie bundleflower and Maximilian sunflower were included in the mixture.

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.

Resilience management. Once these areas become fully established, production is comparable to that of the Reference Plant Community. Total annual production ranges 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.

Community 4.2
Go-back 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.

Resilience management. 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 will become 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 windmill grass. 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.

Transition 1.3 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. Ecological processes affected are the hydrologic and nutrient cycles. There is an increase in evaporation rate, runoff, and in bulk density. There is a decrease in infiltration, plant composition changes, 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.

Constraints to recovery.Due to species composition change there is an increase in evaporation rate, runoff, and in bulk density. There is a decrease in infiltration, plant composition changes, 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

Lack of prescribed fire and brush management cause this transition. Tree and shrub establishment becomes increasingly greater while fine fuel loads decrease. As trees and shrubs increase at levels of greater than 20 percent canopy cover, the processes and functions that allow the Woody State to become resilient are active and dominate over the processes and systems inherent of the Grassland State. Using prescribed fire as a standalone management tool is unsuccessful to eradicate the trees and shrubs due to a lack of fine fuel loads.

Constraints to recovery.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 a reduction 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, with desirable forage grasses often most severely reduced (Eddleman, 1983). As vegetation cover changes from grasses to trees, a greater proportion of precipitation is lost throughout interception and evaporation; therefore, less precipitation is available for producing herbaceous forage or for deep drainage or runoff (Thurow and Hester, 1997).

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. 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.

Constraints to recovery.Soil structure and aggregate stability are soil properties that have changed as a result of mechanical tillage. These properties affect the infiltration and percolation of water in the soil profile which affects the hydrology on the landscape.

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 necessary 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).