State 1
Grassland

Community 1.1
Native Mid/Shortgrass Prairie

This Native Mid/Shortgrass Prairie Community (1.1) developed under natural disturbance regimes spanning thousands of years. Composition of midgrasses makes up about 60 percent of annual production, shortgrasses approximately 30 percent, and associated forbs and shrubs make up the remainder. Annual forbs occur in varying amounts in response to grazing intensity, fire, drought, or excessive precipitation. The herbaceous plant structure will vary depending mainly on weather conditions and grazing pressure, but a mix of healthy mid and shortgrass species will maintain enough ground cover to facilitate water infiltration into the soil and outcompete shrub species for light and nutrients. The differences in rainfall will cause subtle changes in plant community and overall productivity. 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

The Shortgrass Prairie Community (1.2) develops because of continued heavy grazing, an absence of the historic fire regime, and lack of brush management. The grass community in this phase is less productive and has less litter than the Mid/Shortgrass Prairie (1.1). Shortgrasses are very common and bare ground will increase and vary depending on grazing use and rainfall. The ability to support the historic fire regime is diminished and the shrub community will begin to increase over time. This plant community phase can quickly transition from a grass-dominated community to a shrub community if conditions do not favor herbaceous production. When this site occurs on water shedding positions the plant community will look similar to the Tight Sandy Loam ecological site because the soil surface can form a crust and runoff increases. In this phase, reduced rainfall and prolonged droughts will begin to have more of an impact on plant production. As midgrasses decrease, shortgrasses such as red grama, Hall’s panicum (Panicum hallii), and perennial threeawns increase. Annual and perennial forbs often increase as a result of decreased competition for sunlight and moisture. This phase will quickly transition to the Tree/Shrubland Complex (2) if herbaceous plant production does not increase and shrub density grows.

Pathway 1.1A
Community 1.1 to 1.2

The midgrasses that dominate the landscape are highly preferred by livestock and are easily eliminated from the plant community with heavy continuous grazing. Once shortgrass species begin to dominate the herbaceous community, environmental factors like an increase in bare ground and water runoff will begin to favor the invasion of woody species. The historic fire regime has also been changed so that intermittent fires every three to eight 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

The restoration to the Reference Plant Community (1.1) can be accomplished by 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. Mechanical or chemical brush management is also feasible and relatively economical because this community has less than a 20 percent shrub canopy. 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
Mesquite Prairie

Figure 12. 2.1 Mesquite Prairie Community

A threshold has been crossed between the Grassland State (1) and the Tree/Shrubland Complex (2). This Mesquite 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 also hasten this process. The shift from the Grassland Community (1) to the Mesquite Prairie Community (2.1) can happen within a period of 5 to 10 years under certain conditions. Mesquite will be the first woody species to invade this site, but other woody species, such as granjeno and lime pricklyash, will occur as part of the plant community. The woody species will begin to form mottes which will grow in size and density. In this state the herbaceous plant community is quickly becoming less productive and as a result bare ground increases. This can become a problem the soil surface begins to crust and creates conditions that are not conducive to grass or forb germination. Unpalatable perennial forbs like dogweed (Thymophylla penchaeta) and false broomweed will invade. During rainfall events, more water will runoff of the site depending on its landscape position and slope, instead of entering the soil and becoming available to the plants. This will favor the shrubby species and break the water and nutrient cycles that promote herbaceous production.

Community 2.2
Mixed Brush Shrubland

Figure 15. 2.2 Mixed Brush Shrubland

Figure 16. 2.2 Mixed Brush Shrubland

Over time, with continued heavy grazing, no fire, and no brush management the Sandy Loam ecological site will be transformed into a Mixed Brush Shrubland Complex (2.2) with canopies from 50 to 100 percent. Average canopy height in this state ranges from 10 to 20 feet with motte size and spacing varying from less than 2 feet to more than 30 feet depending on the age of the shrub community and the strength of the herbaceous plants. Shrub species like lotebush (Ziziphus obtusifolia), desert yaupon, agarito (Mahonia trifoliolata), and armagosa (Castela erecta) will increase and can create dense shrub mottes with very little understory herbaceous production. Extended droughts will hasten this process. In this state, grass production is severely limited, and no amount of deferred grazing will restore the plant community to the Grassland state. The herbaceous production is dominated by threeawn species, Hall’s panicum, red grama (Bouteloua trifida), and annual forbs and grasses. The same grass species present in the Grassland state (1) can be found in this community phase, but they will be much less productive and more infrequent. Livestock management also becomes problematic in this plant community because of drastically reduced grass production.

Pathway 2.1A
Community 2.1 to 2.2

Mesquite Prairie

Mixed Brush Shrubland

Without diligent brush management along with prescribed grazing and other conservation practices this phase will inevitably transition from a Mesquite Prairie Community (2.1) to a Mixed Brush Shrubland Complex (2.2). This transition can happen within a 10-year period and is based on an increase of woody canopy cover to more than 50 percent and a severe decrease in herbaceous plant production. An increase in shrub diversity will also occur. Shortgrasses and forbs will dominate the herbaceous vegetation and while this transition may be desirable for some wildlife, it will be detrimental for a cattle or livestock operation.

Pathway 2.2A
Community 2.2 to 2.1

Mixed Brush Shrubland

Mesquite Prairie

Major inputs, both chemical and mechanical, are often required to restore this community to the Mesquite Prairie Community (2.1). Often with this community, mechanical means such as root plowing and raking are utilized along with dozing and grubbing to create a mosaic of brush mottes that allow herbaceous plants to thrive. Species like mesquite and huisache will re-sprout if not removed completely from the ground. 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. Follow-up conservation practices such as Individual Plant Treatment (IPT) 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.

State 3
Converted Land

Community 3.1
Planted Pasture/Cropland

Figure 19. 3.1 Planted Pasture/Cropland

Figure 20. 3.1 Planted Pasture/Cropland

To go from the Mixed Brush Shrubland Complex (2.2) to the Converted Land State, (3) mechanical brush management must be applied. Typically, rootplowing and raking are utilized to remove the woody vegetation. A seedbed is then prepared, and the area is planted into grass or crops. Typical crops planted on this site include small grains, oats, or feed grains like sorghum and hay grazer. If introduced species are planted with the addition of moderate to high rates of commercial fertilizer this site can be productive. Because these soils are productive, this site has historically been planted to buffelgrass or introduced bluestems. Inputs such as fertilizer, herbicide, and adequate precipitation or irrigation 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 invade as soon as the pasture is established. Not only is there a long-lived seed source of mesquite, huisache, and other woody species, additional seed are brought in by grazing animals and domestic livestock.

Community 3.2
Go Back Land

Figure 23. 3.2 Go Back Land

This community develops after land has been cropped and left to fallow without management inputs. It can also develop after a mechanical brush management practice has been applied during poor weather conditions or not followed up with appropriate management practices. It is typified by the dominance of woody species, very little herbaceous grass production, high amounts of annual forbs and grasses, and large areas covered by tree-leaf litter, bare ground, and low plant diversity. Because of the seed bank present in the soil and the constant addition of new seed from grazing/browsing animals and seed eating birds, re-infestation of woody seedlings happens in a relatively short time period of two to five years. Typically, pastureland will transition to the Mesquite Prairie Community (2.1) and not to Go Back Land (3.2).

Pathway 3.1A
Community 3.1 to 3.2

Planted Pasture/Cropland

Go Back Land

The transition from Planted Pasture/Cropland (3.1) to Go Back Land (3.2) can occur when crop fields are left to fallow without management. Generally, pasture will transition to the Tree/Shrubland Complex (2) and not to the Go Back Land plant community.

Pathway 3.2A
Community 3.2 to 3.1

Go Back Land

Planted Pasture/Cropland

Many land managers may want to utilize this site as cropland or pastureland. To achieve this transition land clearing practices such as dozing and raking will be necessary. After the land has been cleared and an appropriate seedbed prepared, the crop or 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 5 to 10 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. This will create a more favorable environment with bare ground and open spaces for woody plants to germinate and grow. If the woody component is not managed it will begin to dominate the landscape and out-compete grasses and forbs for water, sunlight, and other resources.

Transition T1B
State 1 to 3

Land managers may want to utilize this site as cropland or 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 crop or pasture can be planted.

Restoration pathway R2A
State 2 to 1

Major inputs, both chemical and mechanical, are often required to restore the Tree/Shrubland Complex State (2) to the Grassland State (1). The same techniques used to transition to the Mesquite Prairie Community (2.1) are used, but much more brush is typically cleared, allowing the majority of the site to revert to a Mid/Shortgrass Prairie Community (1.1). Depending on local conditions, it may also be necessary to prepare an appropriate seedbed and re-introduce a seed source for desired native plant species through range planting.

Transition T2A
State 2 to 3

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

Transition T3A
State 3 to 2

If the Go Back Land Community (3.2) is left alone, eventually the woody plants will create a moderate to heavy canopy. At this point, the desired understory grasses, forbs, and/or crops will be shaded out and the site will transition into a Tree/Shrubland Complex (2).