State 1
Grassland

Community 1.1
Midgrass

The Midgrass Community (1.1) developed under natural disturbance regimes spanning thousands of years. Composition of grasses makes up over 90 percent by weight of annual production while forbs, shrubs, and woody species make up the remainder. Shrubs and trees may be found scattered throughout, and without disturbance will grow very large, but will not create a significant canopy cover. Annual forbs occur in varying amounts in response to grazing intensity, fire, drought, or excessive precipitation. This community is greatly affected by variations in plant available water in the soil. This sometimes extreme fluctuation is reflected in the herbaceous plant community and along with grazing may be the most important factor driving species composition within the Grassland State (1). Tall and midgrasses dominate this site under favorable growing conditions and bare ground is limited due to the multi-layered structure of the grass and forb community. The herbaceous cover produces a thermal insulation which reduces evaporation of soil water and greatly reduces ground temperatures. These factors promote the midgrass and forb community. During drought conditions shortgrasses will increase and become larger components of the herbaceous community and bare ground will slightly increase. Differences in rainfall across the region 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

Figure 11. 1.2 Shortgrass Community

The Shortgrass Community (1.2) develops because of continued heavy grazing, an absence of the historic fire regime, and lack of brush management. This community could also be driven by precipitation and may have been more common than the reference plant community (1.1) in drier parts of the region. The Shortgrass Prairie Community (1.2) has reduced biomass production and litter accumulation which causes subtle impacts to the water, mineral, and energy cycles. 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, brownseed paspalum, plains bristlegrass, and perennial three awns increase. Reduced fuel loads result in reduced fire frequency and intensity. Annual and perennial forbs often increase as a result of decreased competition for sunlight and moisture. Introduced grass species such as Kleberg bluestem (Dicanthium annulatum) and other introduced bluestems may start to invade. For the first time on this site, woody invader seedlings, such as mesquite and huisache, gain considerable height and density. This phase will quickly transition to the Shrubland State (2) if herbaceous plant production does not increase and shrub density grows. While the appearance of introduced plants may prevent a full restoration to the reference 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

The midgrasses are highly preferred by livestock and are easily eliminated from the plant community with heavy continuous grazing. This is because less palatable plants are left ungrazed and will eventually be able to out-compete the dominant grasses for resources and space. Rainfall patterns and subsoil moisture variations drive the diversity of the herbaceous component on this site, but prolonged drought and continuous grazing will create conditions that increase bare ground and shortgrass dominance. Invasive shrub species, like mesquite, will begin to encroach. 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 Midgrass Community (1.1) to a Shortgrass 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. 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 rates, 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
Shrubland

Community 2.1
Midgrass/Shrubland

Figure 14. 2.1 Midgrass/Shrubland Community

A threshold has been crossed between the Grassland State (1) and the Shrubland State (2). This Midgrass/Shrubland 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 can happen within a period of 5 to 10 years under certain conditions. Mesquite will be the dominate woody species on this site, but other woody species such as lime pricklyash, granjeno, desert yaupon (Schaefferia cuneifloia), prickly pear (Opuntia engelmannii), and algerita (Mahonia trifoliolata) will begin to increase as part of the plant community. Herbaceous production in this state is lower than in the Grassland State (1) and because of an increase in bare ground and shrub canopy cover, the resilience of the grass community is negatively affected. The more productive midgrasses will begin to fade from the plant community while less palatable shortgrasses increase. Plants that will increase in this state include red grama (Bouteloua trifida), three awn species (Aristida spp.), brownseed paspalum, and forbs like false broomweed (Haploesthes greggii) and dogweed. Grazing management on this site plays an important role in maintaining healthy grass communities that can take advantage of rainfall events and are more capable of withstanding drought conditions. In this state, forbs will respond quickly to rainfall events and can also out-compete grasses for resources, causing an overall decrease in grass production.

Community 2.2
Shrubland

Figure 17. 2.2 Shrubland Community

Over time, with continued heavy grazing, no fire, and no brush management the Tight Sandy Loam ecological site will be transformed into a Shrubland Community (2.2) with canopies from 50 to 100 percent. Average shrub canopy heights can vary from 10 to 20 feet depending on the age of the plants and local rainfall history. Extended droughts will hasten this transition process. Once the mesquite community begins to mature, mixed shrubs will begin to increase underneath the canopy creating mottes that will increase in size and density. Shrub species like desert yaupon (Schaefferia cuneifloia), catclaw acacia (Acacia gregii), elbowbush (Forestiera pubescens), and the other species already mentioned, will increase in density. At this point, no amount of deferred grazing will restore the plant community to the Grassland State (1). The herbaceous production is dominated by threeawn species, red grama, annual grasses, and annual forbs. 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. Because of the higher amounts of bare ground, opportunistic forbs like western ragweed (Ambrosia psilostachya), annual broomweed (Amphiachyris amoena), and dogweed will be able to quickly take advantage of timely rain events. Livestock management becomes problematic in this plant community because of drastically reduced grass production. The community may be much better wildlife habitat than the previous state because of the increased amount of woody cover and the increased production of both perennial and annual forbs. With increased emphasis on white-tailed deer and bobwhite quail, many landowners choose to manage their land in this condition to enhance wildlife populations.

Pathway 2.1A
Community 2.1 to 2.2

Midgrass/Shrubland

Shrubland

Without diligent brush management, prescribed grazing, and other conservation practices, this phase will inevitably transition to a Shrubland Community (2.2). This transition is relatively long-term, but can begin within 5 to 10 years. This transition is based on an increase of woody canopy cover and a severe decrease in herbaceous plant production. Shortgrasses and forbs will dominate the herbaceous vegetation. This transition may be desirable for some wildlife, but it will be detrimental for a cattle operation.

Pathway 2.2A
Community 2.2 to 2.1

Shrubland

Midgrass/Shrubland

Major inputs, both chemical and mechanical, are often required to restore this community to the Mesquite Prairie Community (2.1). Prescribed burning is an effective tool to control the mixed brush community if weather conditions are good and the plant community can produce enough fine fuel to carry a burn. Often with this community, mechanical means such as root plowing and raking are utilized along with dozing and grubbing. Species like mesquite will re-sprout if not removed completely from the ground. Chaining and roller chopping are short-lived mechanical practices typically resulting in thicker, harder to manage brush stands that encourage brush seedlings. Follow-up conservation practices such as Individual Plant Treatment (IPT) for woody re-growth 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 replant seeds for desired native plants.

State 3
Converted Land

Community 3.1
Converted Land

Figure 20. 3.1 Converted Land Community

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. Crops planted on this site include small grains like oats or feed grains. Inputs such as fertilizer, herbicide, and adequate 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. Not only is there a long-lived seed source of mesquite and other woody species, additional seeds are brought in by grazing animals and domestic livestock.

Community 3.2
Abandoned Land

Figure 23. 3.2 Abandoned Land Community

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 but not followed up with appropriate management practices. It is typified by the dominance of mesquite, very little herbaceous grass production, high amounts of annual forbs and grasses, large areas covered by tree leaf litter, and/or bare ground. This phase does not have a diverse plant community and the shrub canopy cover can be up to 100 percent mesquite. 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, planted pasture will transition directly to the Shrubland State (2).

Pathway 3.1A
Community 3.1 to 3.2

Converted Land

Abandoned Land

The transition from the Converted Land Community (3.1) to the Abandoned Land Community (3.2) can occur when crop fields are left to fallow without management. Shrub species, like mesquite, will begin to grow and dominate the plant community. Generally, planted pasture will transition to the Shrubland State (2).

Pathway 3.2A
Community 3.2 to 3.1

Abandoned Land

Converted Land

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 Shrubland State (2) can happen within 5 to 10 years. This transition is driven by persistently dry weather conditions, grazing management, and the lack of fire and brush management practices. Overstocking 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

Brush management, either mechanical or chemical, is necessary to restore the site to the Grassland State. Removal of woody species to reduce canopy cover will allow light to the herbaceous species. Prescribed grazing and fire will also help.

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.

Restoration pathway R3A
State 3 to 1

The transition from the Converted Land State (3) to the Grassland State (1) will take time and patience. If practices such as fertilizer application and weed control are stopped, prescribed grazing is applied, woody seedlings are managed, and prescribed burning is applied, this state will begin the reversion back to the Grassland State (1). Introduced grass species are very resilient and competitive. They can maintain dominance in a pasture for a very long time after they are planted even without careful management. In these cases, management practices such as disking or applying herbicide to kill or suppress introduced species will be necessary to achieve the transition from an introduced pasture to a native pasture. This transition may occur very slowly because introduced grasses will remain competitive and will probably always be present. This transition may also require brush management practices and the re-introduction of desirable native species through range planting.

Transition T3A
State 3 to 2

In time, this site will revert to the Shrubland State (2) on its own. If no brush management occurs, woody species will occupy the overstory canopy and shad out herbaceous species.