State 1
Grassland

Community 1.1
Native Mid/Shortgrass Prairie

Figure 8. 1.1 Mid/Shortgrass Prairie Community

This Mid/Shortgrass Prairie Community (1.1) developed under natural disturbance regimes spanning thousands of years. Composition of grasses makes up 90 percent of annual production. Late succession plants such as false rhodesgrass, Arizona cottontop (Digitaria californica), and tanglehead make up about 25 percent of this community. Increaser plants, or more resilient species, make up 65 percent. These grasses include plains bristlegrass, pink pappusgrass, silver bluestem, and hooded windmillgrass along with threeawns and other shortgrasses. Perennial forbs, shrubs, and woody species make up the remainder. Annual forbs occur in varying amounts in response to grazing intensity, fire, drought, or excessive precipitation. The occurrence of annual forbs is sporadic and usually short-lived, mostly depending on rainfall events. This community is productive and can be managed to attain many landowner goals for livestock, wildlife, or recreation. The droughty nature of this site increases competition between species for water and nutrients; this tends to promote a high diversity in species composition because no one species can easily dominate the plant community. Rainfall differences across the region will cause subtle changes in plant community and overall productivity, which is displayed as high and low values in the annual production tables. Although the values provided in this report are representative, doing an onsite inventory of plant community and production when planning management decisions will help land managers make sound decisions based on actual conditions on the ground.

Community 1.2
Shortgrass Prairie

Figure 11. 1.2 Shortgrass Prairie Community

The Shortgrass Prairie Community (1.2) developed as a result of continued heavy grazing, an absence of the historic fire regime, and lack of brush management. This community would also be driven by weather conditions and be more common on sites that have higher slopes and in areas of decreased rainfall. In comparison to the Reference Plant Community (1.1) the Shortgrass Prairie Community (1.2) has reduced biomass production and litter accumulation which causes subtle impacts to the water, mineral, and energy cycles. The loss of thermal protection and increased water runoff potential will start to negatively affect the plant available water in the soil. In this situation reduced rainfall and prolonged droughts will begin to have more of an impact on plant production. As midgrasses such as false rhodesgrass, plains bristlegrass, and tanglehead decrease, grasses such as hooded windmillgrass, red grama (Bouteloua trifida), and three awn species increase. As competition for resources from taller grasses decreases, curly mesquite will also begin to increase. Reduced fuel loads result in reduced fire frequency/intensity. Annual and perennial forbs often increase as a result of decreased competition for sunlight and moisture. Introduced grass species like Kleberg bluestem (Dichanthium annulatum) start to invade. Woody species such as lotebush, granjeno, blackbrush, brasil, and mesquite will begin to establish dominance and as their canopy cover increases herbaceous production will decrease. While the appearance of introduced plants prevents a full restoration to the Reference Plant Community, some of these plants do perform the same functions as native species. Management activities can slow down the increase of introduced plants if this is the management goal.

Pathway 1.1A
Community 1.1 to 1.2

Native Mid/Shortgrass Prairie

Shortgrass Prairie

The Mid/Shortgrass Prairie Community (1.1) is the reference plant community that would have dominated the Gray Sandy Loam ecological site for thousands of years. Because of human influence this community is rarely found today. The midgrasses that dominated the landscape are highly preferred by livestock and are easily eliminated from the plant community with heavy continuous grazing. Climate also plays a large role on this site. During drought conditions, increaser plants continue growing while more productive plants are less able to thrive. The site will begin to be dominated by shortgrasses and increased bare ground. The historic fire regime has also been changed so that intermittent fires every three to seven years, which would decrease woody plant encroachment and encourage midgrass dominance, have been prevented to protect livestock and societal interests. These factors cause a shift from a Native Mid/Shortgrass Prairie Community (1.1) to a Shortgrass Prairie Community (1.2).

Pathway 1.2A
Community 1.2 to 1.1

Shortgrass Prairie

Native Mid/Shortgrass Prairie

The restoration to the Reference Plant Community (1.1) can be accomplished by installation of prescribed grazing with appropriate stocking rates. If the herbaceous component of this community remains healthy and maintains at least 85 to 90 percent ground cover, including live plants and litter, the woody component of this site will remain stable and new seedling growth will be inhibited. Individual Plant Treatment (IPT) and prescribed burning will be the most efficient and economical ways to manage brush species encroachment. The use of prescribed fire in conjunction with prescribed grazing enhances the recovery process, but because of the droughty nature of this site timing and weather conditions are critical to successful restoration efforts. Mechanical or chemical brush management is also feasible and relatively economical because this community has less than a 30 percent canopy of woody species. Once initial woody plant management has been achieved, periodic burning, reduced stocking, and prescribed grazing will cause a transition towards the Reference Plant Community over time. If the landowner wants to speed this transition, some range planting can be done to increase the number of desired species.

State 2
Tree/Shrubland

Community 2.1
Mixed Brush Prairie

Figure 14. 2.1 Mixed Brush Prairie Community

Figure 15. 2.1 Mixed Brush Prairie Community

A threshold has been crossed between the Grassland State (1) and the Tree/Shrubland Complex (2). This Mixed Brush Prairie Community (2.1) has developed because of continuous heavy grazing, loss of fire as a management tool, greatly altered water and energy cycles, and invasion of woody plants. Episodic droughts will hasten this process. The shift from the Shortgrass Prairie Community (1.2) to the Mixed Brush Prairie Community (2.1) can happen within a period of three to seven years under certain conditions. In most cases the shrub community is diverse and no one species will account for more than 20 percent of the shrub canopy, but occasionally guajillo, blackbrush, cenizo, or mesquite can create nearly 100 percent canopy cover. Other woody species such as lotebush, granjeno, guajillo, desert yaupon (Schaefferia cuneifloia), prickly pear (Opuntia engelmannii), elbowbush, brasil, lime pricklyash (Zanthoxylum fagara), guayacan (Guaiacum angustifolium), and shrubby blue sage will occur as part of the plant community. Shrubby blue sage and cenizo are very common invaders on this site and will dominate open areas between shrub mottes; this reduces or even prevents herbaceous production. Average shrub canopy cover in this state is about 60 percent, but can range from 30 to 100 percent. The amount of bareground and herbaceous production will vary with weather conditions, grazing pressure, and as the grass community diminishes. Soils with a more developed argillic horizon will support a denser shrub community. Shrub canopy height typically ranges from 6 to 10 feet, but in areas with relatively old plants mesquite trees can be more than 15 feet tall with dense understory of mixed brush creating large mottes. Grass production is severely reduced in this state and shortgrasses like perennial three awn, Hall’s panicum (Panicum hallii), red grama (Bouteloua trifida), and lovegrass tridens (Tridens eragrostoides) will be most common. On the northeastern range of this ecological site, live oak trees (Quercus virginiana) will become part of the landscape and may make up a small portion of the plant community. This community may be much better wildlife habitat than the previous state because of the increased amount of woody cover and browse. With increased emphasis on white-tailed deer and bobwhite quail, many landowners choose to manage their land in this condition to enhance wildlife populations.

State 3
Converted Land

Community 3.1
Planted Pasture

Figure 18. 3.1 Planted Pasture

Typically dozing and raking or Rhome disking is utilized to remove the woody vegetation in transition from State 1 and 2. A seedbed is then prepared, and the area is planted into grass, or rarely will it be planted into crops or wildlife food plots. This site does not generally receive enough rainfall to create successful crops year after year, so cash crops are not typical. If introduced species are planted this site may be more productive than the original plant community. Inputs such as fertilizer, herbicide, and adequate precipitation may be necessary to maintain high productivity. Now, because of the availability of seed, landowners can also replant with native species. To maintain this seeded state, herbicides must be used to control woody seedlings that seek to invade as soon as the pasture is established. Not only is there a long-lived seed source, additional seeds are brought in by grazing animals and domestic livestock.

Community 3.2
Go Back Land

Figure 21. 3.2 Go Back Land

This community develops after land has been left to fallow without management inputs or after unsuccessful brush management practices. It is typified by the dominance of woody species, very little herbaceous grass production, and large areas covered by tree-leaf litter or bare ground. This plant community has low species diversity and is commonly dominated by mesquite, cenizo, or guajillo. Re-infestation of woody seedlings happens in a relatively short time period of two to five years on abandoned cropland or pastures.

Pathway 3.1A
Community 3.1 to 3.2

Planted Pasture

Go Back Land

The transition from Planted Pasture (3.1) to Go Back Land (3.2) occurs when fields or pastures are left to fallow without management. Woody species begin to invade the site and will continue to grow and eventually dominate the plant community. Generally, pastureland will transition to the Tree/Shrubland Complex (2) and not to the Go Back Land plant community, but this depends on pasture management and the amount of time the grass community is healthy and dominant.

Pathway 3.2A
Community 3.2 to 3.1

Go Back Land

Planted Pasture

Many land managers may want to utilize this site as pastureland. To achieve this transition practices such dozing and raking will be necessary. After the land has been cleared and an appropriate seedbed prepared the pasture can be planted.

Transition T1A
State 1 to 2

The transition from the Grassland State (1) to the Tree/Shrubland Complex (2) can happen within three to seven years. This transition can be driven by persistently dry weather conditions, grazing management, and the lack of fire and brush management practices. Overstocking the site with grazing animals will put pressure on the herbaceous plant component of the community. Increased bare ground becomes a large problem affecting the hydrologic cycle. As herbaceous ground cover decreases runoff and evaporation during rainfall events will increase, causing less water to infiltrate into the soil available for plant use. If the woody component is not managed, it will begin to dominate the landscape and out-compete grasses and forbs for water, sunlight, and resources.

Transition T1B
State 1 to 3

Land managers may want to utilize this site as pastureland. To achieve this transition from the Grassland State (1) brush management and heavy disking with a Rhome disk, or other heavy implement, will be necessary to incorporate the vegetation into the soil. Prescribed burning can also be used prior to the disking operation to eliminate excessive vegetation. After the land has been cleared and an appropriate seedbed prepared the pasture can be planted. This site is not typically used as cropland.

Restoration pathway R2A
State 2 to 1

Major inputs are required to restore this community to the Grassland State (1). Mechanical brush management practices such as dozing or using a Rhome disk are the most common options. Chaining and roller chopping are mechanical practices which will be short-lived and will typically result in thicker, harder to manage brush stands and will encourage brush seedlings. Chemical brush management is more difficult because of the highly diverse mixed brush community. Follow-up conservation practices such as Individual Plant Treatment for woody re-growth and new seedlings and prescribed grazing will be necessary for several years after the initial brush management to maintain an improved plant community. Depending on local conditions it may also be necessary to re-introduce a seed source for desired native plant species through range planting. Successful restoration of the Mid/Shortgrass Prairie Community (1.1) is highly dependent on rainfall and follow up management activities which promote the establishment of native grasses and forbs.

Transition T2A
State 2 to 3

Land managers may want to utilize this site as pastureland. To achieve this transition from the Mixed Brush Prairie Community (2.1) brush management and heavy disking with a Rhome disk, or other heavy implement, will be necessary to incorporate the vegetation into the soil. Prescribed burning can also be used prior to the disking operation to eliminate excessive vegetation. After the land has been cleared and an appropriate seedbed prepared, the pasture can be planted.

Transition T3A
State 3 to 2

In time, this site will revert to the Tree/Shrubland Complex (2) on its own, but usually this timeline is impractical for landowners. Prescribed grazing along with various brush management practices will be necessary to achieve this transition. This phase is very unproductive for herbaceous plants and it could take years for desirable plant species to begin to re-establish.