Natural Resources
Conservation Service
Ecological site R078CY114TX
Shallow Red Clay 23-31" PZ
Last updated: 9/15/2023
Accessed: 12/22/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 078C–Central Rolling Red Plains, Eastern Part
MLRA 78C is characterized by moderately dissected, rolling plains with prominent ridges and valleys and numerous terraces adjacent to dissecting streams. Loamy and clayey soils are generally deep, well drained, and developed in calcareous and gypsiferous sediments of Permian age.
LRU notes
NA
Classification relationships
This ecological site is correlated to soil components at the Major Land Resource Area (MLRA) level which is further described in USDA Ag Handbook 296.
Ecological site concept
This site occurs on shallow and very shallow clay soils. The reference vegetation consist of midgrasses and shortgrasses with scattered forbs and few shrubs. These areas are often intermixed with “badlands” areas where vegetation may be sparse with high amounts of bare ground. While grazing and fire impact these sites, often the vegetation may be more affected by precipitation patterns and slope aspect.
Associated sites
| R078CY112TX |
Red Clay (South) 23-30" PZ Sites are often adjacent, but the shallow site has somewhat deeper soils. |
|---|
Similar sites
| R078CY112TX |
Red Clay (South) 23-30" PZ Both sites have similar physiographic positions on the landscape but the Shallow site is somewhat less productive. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Bouteloua curtipendula |
Physiographic features
This site was formed in residuum over dense non-cemented clay stone red bedrock of Permian age. These soils are on very gently sloping to very steep ridges, side slopes and erosional footslopes on uplands of the Central Rolling Red Plains – Eastern Part (MLRA-78C). Slopes range from less than 1 to 50 percent. Elevation ranges from 900 to 2250 feet.
Table 2. Representative physiographic features
| Landforms |
(1)
Plains
> Ridge
(2) Plains > Hill |
|---|---|
| Runoff class | Very high |
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 274 – 686 m |
| Slope | 1 – 50% |
| Water table depth | 183 – 203 cm |
| Aspect | Aspect is not a significant factor |
Climatic features
MLRA 78C lies within the subtropical sub-humid climate regime, which typically has dry winters with hot and not as humid summers. MLRA 78C extends north and south from Coldwater, Kansas to just northeast of San Angelo, Texas (Ballinger, Texas), and east to west from Weatherford, Oklahoma to west of Shamrock, Texas. This regime is characterized by rapid changes in temperature; marked extremes, both daily and annual; and rather erratic rainfall. The weather is alternately influenced by cold dry air from the Arctic Circle, and warm moist air from the Gulf of Mexico.
Seasonal changes are gradual. Spring is a season of variable weather and relatively high precipitation with prevailing winds from the southwest. Summers are generally hot with low humidity. Fall has long periods of pleasant weather interspersed with moderate to heavy rains. Winter is open and moderate to cold with winds from the north and infrequent snows.
Wind speeds average more than eleven miles an hour with prevailing southern winds. Rather strong winds can occur in all months of the year. While strong gusty winds occur, severe dust storms are rare.
Approximately 75 percent of the rainfall occurs during the warm season, and much of it comes in storms of high intensity and short duration in May and June. These rains can be particularly erosive on sites where vegetation is sparse. Occasional droughts are to be expected. Lack of rainfall and hot, dry winds often curtail forage production during July and August.
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 173-199 days |
|---|---|
| Freeze-free period (characteristic range) | 191-223 days |
| Precipitation total (characteristic range) | 660-686 mm |
| Frost-free period (actual range) | 166-201 days |
| Freeze-free period (actual range) | 190-227 days |
| Precipitation total (actual range) | 635-737 mm |
| Frost-free period (average) | 188 days |
| Freeze-free period (average) | 209 days |
| Precipitation total (average) | 686 mm |
Figure 1. Monthly precipitation range
Figure 2. Monthly minimum temperature range
Figure 3. Monthly maximum temperature range
Figure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6. Annual average temperature pattern
Climate stations used
-
(1) MEDICINE LODGE [USW00003957], Medicine Lodge, KS
-
(2) MUTUAL [USC00346139], Mutual, OK
-
(3) CLINTON SHERMAN AP [USW00003932], Dill City, OK
-
(4) ALTUS AFB [USW00003981], Frederick, OK
-
(5) MUNDAY [USC00416146], Munday, TX
-
(6) ABILENE RGNL AP [USW00013962], Abilene, TX
Influencing water features
None.
Wetland description
NA
Soil features
Soils are mapped for each county within the MLRA. Mapunits are representations of the major soil series component(s) and named accordingly. Each Mapunit is spatially represented on a digital soils map as polygons of different shapes and sizes. Within these Mapunits, there are often minor soil series components included. These minor components are soils that occur within a Mapunit polygon but are of small extent (15% or less of the Mapunit area). However, it is difficult to separate these minor soils spatially due to the scale of soil mapping.
Ecological sites are correlated at the component level of the soil survey. Therefore, a single Mapunit may contain multiple Ecological Sites just as it may contain multiple soil components. This is important to understand when investigating soils and Ecological Sites. A soil survey Mapunit may be correlated to a single Ecological Site based on the major component; however, there may be inclusional areas of additional Ecological Sites which are correlated to the minor components of that particular soil Mapunit.
Representative soil components for this site include:
Knoco
The soils are very shallow to shallow, well drained, and permeability is impermeable to very slow. Runoff is high on 0 to 1 percent slopes, and very high on slopes greater than 1 percent.
Table 4. Representative soil features
| Parent material |
(1)
Residuum
–
claystone
|
|---|---|
| Surface texture |
(1) Clay (2) Silty clay |
| Family particle size |
(1) Clayey |
| Drainage class | Well drained |
| Permeability class | Very slow to slow |
| Depth to restrictive layer | 8 – 51 cm |
| Soil depth | 8 – 51 cm |
| Surface fragment cover <=3" | 0 – 15% |
| Surface fragment cover >3" | 0 – 10% |
| Available water capacity (0-101.6cm) |
1.27 – 9.14 cm |
| Calcium carbonate equivalent (0-101.6cm) |
1 – 20% |
| Electrical conductivity (0-101.6cm) |
1 – 8 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 – 8 |
| Soil reaction (1:1 water) (0-101.6cm) |
7.4 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
1 – 10% |
| Subsurface fragment volume >3" (Depth not specified) |
0 – 7% |
Ecological dynamics
The information contained in the State and Transition Diagram (STD) and the Ecological Site Description was developed using archeological and historical data, professional experience, and scientific studies. The information presented is representative of a very complex set of plant communities. Not all scenarios or plants are included. Key indicator plants, animals and ecological processes are described to inform land management decisions.
The Shallow Red Clay Ecological Site is found on uplands. The soils vary from very shallow clays to silty clays of varying thickness. Slopes vary from gently sloping to very steep ridges and side slopes. Badlands are generally mixed in this site and can occupy as much as 15 to 20 percent of the area. Plant rooting depth is restricted and moisture holding capacity is low and often limiting productivity. Productivity of the site varies with these fluctuations. It is also influenced by aspect. North and east facing slopes will generally have higher production and diversity than south and west facing slopes. This site is characterized by low production as compared to surrounding sites and considerable bare ground which crusts easily.
The reference plant communty is assumed to have been an open Mixed-grass Prairie Community (1.1) with few forbs and only scattered shrubs. Pre-settlement influences included grazing or browsing by endemic pronghorn antelope, deer and migratory bison, severe droughts and infrequent fires. Fires, set by lightening or by Native American Indians, undoubtedly had some impact on the community structure. Studies show that fires, often severe, occurred at 7 to 12 year intervals in this region (Frost 1998). The fires would favor grass vegetation and keep woody plants and forbs in check. The sparse fuel on the site may have reduced the frequency and intensity compared to adjacent sites, however, and fire may not have been the dominant disturbance.
The herbaceous vegetation included a mix of mid and shortgrasses along with limited forbs. The dominant grass species at the time of European settlement was sideoats grama , but little bluestem was often dominant, or co-dominant on north-facing slopes. Characteristic shortgrasses included buffalograss and blue grama. Curlymesquite was also characteristic in the southern portions of the MLRA. Alkali sacaton and silver bluestem were common throughout. The site produced a limited amount and diversity of forbs. Shrubs occupied deeper soil pockets on areas protected from wildfires, contributing three percent, or less, of the annual production. Characteristic shrubs were lotebush, pricklypear and four-winged saltbush. See the Species Composition List below for composition and production estimates of the species believed to have been present when European settlers first arrived.
The Mixed-grass Prairie Community (1.1) was relatively stable and resilient within the climate, soil and fire regime. Nutrient cycling, energy flow and water cycling were in harmony with the climate, grazing and fire regime of the time. With the arrival of European settlers in the mid 1800’s and the invention of wire fencing and windmills in the 1870’s overstocking of the area became widespread. The settlers had little understanding of rangeland productivity and generally overstocked all ranges with livestock. As continuous overgrazing occurred, there was a reduction of the less grazing resistant midgrasses, a decline in mulch and organic matter, and a reduction in intensity and frequency of fires. This shift in plant community composition changed the Mixed-grass Prairie Community into a Shortgrass/Midgrass Community (1.2). Sideoats grama and little bluestem, although persistent under moderate grazing, decrease under continuous overgrazing. In the Shortgrass/Midgrass Community they are being replaced by buffalograss or curlymesquite, alkali sacaton, silver bluestem, dropseeds, hairy grama, other short grasses along with annuals and woody shrubs. Nutrient cycling, watershed protection and energy flow have been somewhat reduced. The shift in plant cover and decline in soil properties favor woody plant encroachment. The woody and herbaceous invaders are generally endemic species releases from competition or fire suppression. Woody plant production will range from 3 to 15 percent. Mesquite and/or juniper are common invaders. Careful grazing management, chemical and/or mechanical brush control of invading woody/cacti competition can restore the Shortgrass/Midgrass Community (1.2) to near reference conditions. If, however, heavy grazing continues without control of shrub invasion the plant community transitions into a Shortgrass/Mixed-brush Community (2.1). The transition from Grassland (1) to Shrubland (2) is complete when shrub canopies (production) exceed 15 percent and the shrub cover becomes resistant to control with prescribed burning. Naturally low biomass production will reduce the effectiveness of prescribed burning on this site.
In the Shortgrass/Mixed-brush Community (2.1), shortgrasses dominate forage production. Increasing amounts of bare ground will be found throughout the site and erosion can occur on steeper slopes. The bare spaces are often occupied by annuals. Grass production will still dominate the site, but encroaching woody species have begun to compete for nutrients and water. This type is still somewhat productive for livestock, but the browse and cover provided by the woody species favor deer and other wildlife. Nutrient cycling, energy flow and watershed protection is reduced as shrubs displace grasses, grazing reduces plant production and ground cover and more soil surface is exposed. The plant community is so degraded that it cannot reverse retrogression without considerable energy and management inputs. Restoration of the Shortgrass/Mixed-brush Community (2.1) will require prescribed grazing with rest periods during the growing season for several years. Brush control and re-seeding bare areas with adapted native species will be necessary although soil limitations may make reseeding impractical.
Heavy livestock grazing over a long period of time, combined with periodic droughts and no burning will cause the Shortgrass/Mixed-brush Community (2.1) to transition into a Mixed-brush/Shortgrass/Annuals Community (2.2). Woody plants, especially mesquite and/or juniper, will continue to increase in size and density until they dominate the community. This generally occurs when the woody plant cover exceeds 15 percent and shrubs dominate the ecological processes. Annuals will occupy many of the bare areas throughout the site during wet seasons, while only low vigor shortgrasses will persist in shrub interspaces. As grass cover declines, litter, mulch and soil organic matter decline and bare ground, erosion and other desertification processes increase in the spaces between shrubs. The site is so degraded at this stage that little forage of value is produced. The Mixed-brush/Shortgrass/Annuals community is of little forage value for livestock and rather poor habitat for deer and browsing animals. Desirable forage production is low and variable.
Restoration of the Mixed-brush/Shortgrass/Annuals community to grassland is possible, but expensive. The dense brush cover and very limited seed source will require both brush control and re-seeding to restore a grassland state. The shallow fine textured soils and steep slopes limit the use of mechanical treatments and care must be taken in restoration efforts. Following brush management, re-seeding the site to adapted native mixture will be arduous, but necessary. Several years of limited grazing will be necessary. Severe erosion and fertility losses during retrogression may prohibit the site to returning to reference conditions.
State and Transition Diagram:
A State and Transition Diagram for the Shallow Red Clay (R078CY114TX) site is depicted below. Thorough descriptions of each state, transition, and pathway follow the model. Experts base this model on available experimental research, field observations, professional consensus, and interpretations. It is likely to change as knowledge increases.
Plant communities will differ across the MLRA because of the natural variability in weather, soils, and aspect. The Reference Plant Community is not necessarily the management goal; other vegetative states may be desired plant communities as long as the Range Health assessments are in the moderate and above category.
The biological processes on this site are complex. Therefore, representative values are presented in a land management context. The species lists are representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.
Composition by dry weight and percent canopy cover are provided to describing the functional groups. Most observers find it easier to visualize or estimate percent canopy for woody species (trees and shrubs).
The following diagram suggests some pathways that the vegetation on this site might take. There may be other states not shown on the diagram. This information is intended to show what might happen in a given set of circumstances. It does not mean that this would happen the same way in every instance. Local professional guidance should always be sought before pursuing a treatment scenario.
State and transition model
More interactive model formats are also available.
View Interactive Models
Click on state and transition labels to scroll to the respective text
Ecosystem states
| T1A | - | Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure |
|---|---|---|
| R2A | - | Adequate rest from defoliation and removal of woody canopy, followed by reintroduction of historic disturbance regimes |
State 1 submodel, plant communities
State 2 submodel, plant communities
State 1
Grassland State
This is the reference or diagnostic community for the site. The description is based on early range site descriptions, clipping data, professional consensus of experienced range specialists, and analysis of field work. The interpretive plant community is assumed to have been a Mixed-grass Prairie Community (1.1). Shrubs were widely scattered in protected areas and along draws, but made up less than three percent of the total annual production. The clay soils and droughty conditions apparently also kept forb diversity and production low. Sideoats grama was the dominant grass throughout the site, although little bluestem was occasionally co-dominant on in the more northern latitudes and north facing slopes. Also occurring on the site, but in smaller amounts, were meadow dropseed, silver bluestem, alkali sacaton and a number of shortgrasses. Common shortgrasses included buffalograss, blue grama, threeawns, tridens and sand dropseed. Characteristic forbs were western ragweed, dotted gayfeather, dalea and Indian rushpea. Lotebush, four-winged saltbush, tasajillo, vine ephedra and pricklypear were common woody plants. The Mixed-grass Prairie Community produced from 400 to 1400 pounds of biomass annually The Shortgrass/Midgrass Prairie Community represents the last grassland phase in the transition of the Mixed-grass Prairie Community (1.1) toward a Shrubland state (2.). Woody species, especially juniper, mesquite, pricklypear, tasajillo and lotebush are encroaching, but are not seriously impacting forage production. Invading brushy species are generally less than four feet tall and provide less than 15 percent of the annual production. The dominants of the reference community are being replaced by less palatable grasses, such as silver bluestem, and sand dropseed, tobosa, where present. Less palatable forbs such as dalea, dotted gayfeather and western ragweed are also increasing and replacing the palatable forb dominants of the reference community.
Community 1.1
Mixed-grass Prairie Community
Figure 7. 1.1 Mixed-grass Prairie Community
The interpretive plant community is assumed to have been a Mixed-grass Prairie Community (1.1). Shrubs were widely scattered in protected areas and along draws, but made up less than three percent of the total annual production. Apparently recurring fires and occasional long-term droughts had interacted with migrating buffalo and other wildlife grazing to keep shrubs in check and favor a mixture of mid and short grasses. The clay soils and droughty conditions apparently also kept forb diversity and production low. Sideoats grama was the dominant grass throughout the site, although little bluestem was occasionally co-dominant on in the more northern latitudes and north facing slopes. Also occurring on the site, but in smaller amounts, were meadow dropseed, silver bluestem, alkali sacaton and a number of shortgrasses. Common shortgrasses included buffalograss, blue grama, threeawns, tridens and sand dropseed. Curlymesquite was common only in the southern portion of the MLRA while tobosa occurred in significant amounts only in the western portion with less than 25 inches annual rainfall. Characteristic forbs were catclaw sensitivebriar, plains blackfoot daisy, western ragweed, dotted gayfeather, dalea and Indian rushpea. Lotebush, four-winged saltbush, tasajillo, vine ephedra and pricklypear were common woody plants. The Mixed-grass Prairie Community produced from 400 to 1400 pounds of biomass annually, depending upon the amount of precipitation. Grasses made up to 90 to 95 percent of species composition and production. The midgrasses aided in the infiltration of rainfall into the slowly permeable soil and reduced runoff, although considerable bare ground existed. The droughty characteristics of the site kept forage production and forb diversity low. The Mixed-grass Prairie plant community furnished good habitat for grazing type wildlife such as bison and pronghorn antelope. With continuous overgrazing, decrease in intensity and frequency of fires and no brush management, this plant community transitions very quickly to the Shortgrass/Midgrass Prairie Community (1.2). The plant community responds to selective grazing by differential responses of the plants to defoliation and selective use of the individual species. Sideoats grama and little bluestem although generally preferred by cattle are initially resistant to grazing and persist, but in weakened condition. The shortgrasses, although they might be preferentially grazed also are generally more resistant to grazing because of their short stature and lower growing points. This allows them to replace species that are weakened by continued overgrazing. At the same time those species, generally called weeds, that are avoided or only grazed when the more palatable species are depleted will increase in density and stature. The resulting reduction in plant cover allows indigenous noxious species to increase or others to invade from off-site. Mesquite and juniper are common invaders. The Mixed-grass Prairie is resilient and stable but continued overgrazing and reduction in frequency and intensity of fires allows the above process to cause retrogression so that the plant community transitions into a Shortgrass/Midgrass Prairie Community (1.2) with shrubs invading.
Figure 8. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 412 | 1049 | 1350 |
| Forb | 22 | 45 | 67 |
| Shrub/Vine | 13 | 27 | 40 |
| Tree | – | – | – |
| Total | 447 | 1121 | 1457 |
Figure 9. Plant community growth curve (percent production by month). TX2276, Mid/Shortgrasses with Forbs. Warm-season mid and shortgrasses, cool-season grasses, and forbs..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 2 | 4 | 8 | 25 | 25 | 14 | 6 | 8 | 5 | 2 | 1 |
Community 1.2
Short/Midgrass Prairie Community
Figure 10. 1.2 Short/Midgrass Prairie Community
This community represents the last grassland phase in the transition of the Mixed-grass Prairie Community (1.1) toward a Shrubland state (2.). It is the result of continued overgrazing of the site and reduction in frequency and intensity of fires. Woody species, especially juniper, mesquite, pricklypear, tasajillo and lotebush are encroaching, but are not seriously impacting forage production. Invading brushy species are generally less than four feet tall and provide less than 15 percent of the annual production. This phase may, in fact, present more desirable conditions for livestock husbandry, wildlife and recreational use than the reference community phase because forage production for browsing animals is enhanced. Overgrazing has reduced the more palatable species and opened up the grass and litter cover for the invasion of the woody species that had been held in check by competition and fire. The reference community dominants are being replaced by less palatable grasses, such as silver bluestem, and sand dropseed, tobosa, where present. Less palatable forbs such as dalea, dotted gayfeather and western ragweed are also increasing and replacing the palatable forb dominants of the reference community. The dominant grasses, such as sideoats grama, little bluestem, meadow dropseed and alkali sacaton, persist in this phase but make up a smaller part of the plant composition. Nutrient cycling and energy flow are shifting toward woody plants. Herbage production is slightly less than in the reference community, averaging from 350 to 1100 pounds of annual production. The herbaceous component still dominates herbage production. Litter and ground cover are beginning to decrease, however, exposing more soil to erosion and plant encroachment by previously suppressed species, such as annuals. Proper grazing and prescribed burning can easily improve or maintain this plant community and reverse the transition toward the Shortgrass/Mixed-brush Community (2.1). Without brush management and proper grazing, the woody species will continue to encroach until the woody species dominate. This threshold occurs when woody plant cover exceeds 15 to 20 percent and/or limited grass production will not allow effective prescribed burning. When this occurs the transition to a Shortgrass/Mixed-brush (2.1) is complete and irreversible without extensive accelerating cultural practices followed by prescribed grazing and proper stocking.
Figure 11. Annual production by plant type (representative values) or group (midpoint values)
Table 6. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 314 | 673 | 986 |
| Shrub/Vine | 39 | 84 | 123 |
| Tree | 19 | 41 | 62 |
| Forb | 20 | 43 | 62 |
| Total | 392 | 841 | 1233 |
Figure 12. Plant community growth curve (percent production by month). TX2292, Shortgrass/Midgrass Community. Warm-season shortgrasses and midgrasses with some forbs and shrubs..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 2 | 7 | 15 | 25 | 20 | 5 | 5 | 15 | 5 | 1 | 0 |
Pathway 1.1A
Community 1.1 to 1.2
Without proper grazing management and judicious prescribed burning, the Mixed-grass Prairie Community will transition (regress) to a Short/Midgrass Prairie Community (1.2).
Pathway 1.2A
Community 1.2 to 1.1
With the implementation of Prescribed Grazing and Prescribed Burning conservation practices, the Short/Midgrass Prairie Community can be reverted back to the Mixed-grass Prairie Community.
Conservation practices
| Prescribed Burning | |
|---|---|
| Prescribed Grazing |
State 2
Shrubland State
The Shortgrass/Mixed-Brush Community exceeds 15 percent woody plant canopy of mixed-brush, depending on how long the site has been overgrazed and brush not controlled. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs. All, except the more palatable woody species, have increased in size. Mesquite is generally dominant on the site throughout the MLRA. However, redberry juniper has increased considerably in recent years. Many of the climax shrubs are present. Typically, agarito, pricklypear, and lotebush form mixed-brush complexes with mesquite and juniper. Mesquite and/or juniper dominate the Mixed-brush/Shortgrass/Annuals Community production. Even though the canopy remains approximately 15 - 25 percent, the trees and shrubs can exceed 65 percent of the annual production. Common understory shrubs are pricklypear, agarito, lotebush, vine ephedra and tasajillo. Shortgrasses and low quality annual grasses and forbs occupy the woody plant interspaces. Characteristic grasses are buffalograss, rough tridens, threeawns, hairy grama, Texas grama and red grama. Forbs found in this community include dotted gayfeather, croton, western ragweed, gaura and broomweed.
Community 2.1
Shortgrass/Mixed-brush Community
Figure 13. 2.1 Shortgrass/Mixed-brush Community
The Shortgrass/Mixed-brush Community exceeds 15 percent woody plant canopy of mixed-brush, depending on how long the site has been overgrazed and brush not controlled. It is the result of selective overgrazing by livestock, the differential response of plants to defoliation and lack of fire as a deterrent to woody plant encroachment. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs. Primary production has decreased due to decline in soil structure and organic matter and has shifted toward the woody component. All, except the more palatable woody species, have increased in size. Mesquite is generally dominant on the site throughout the MLRA. However, redberry juniper has increased considerably in recent years. Many of the climax shrubs are present. Typically, agarito, pricklypear, and lotebush form mixed-brush complexes with mesquite and juniper. Remnants of climax grasses and forbs and unpalatable invaders occupy the interspaces between trees and shrubs. As further regression occurs, sideoats grama is replaced with buffalograss, or curly-mesquite in the southern portions of the MLRA. Tobosa may also be common west of the 25-inch rainfall line. Buffalograss or curlymesquite and alkali sacaton are persistent increasers. Other characteristic grasses include silver bluestem, sand dropseed, threeawns, hairy tridens, hairy grama and rough tridens. Indian rushpea, dotted gayfeather, dalea, western ragweed, gaura and prairie clover are common forbs. Filaree is common following wet winters. Many annuals such as croton and annual broomweed occupy bare areas and weak grassland. Because of grazing pressure and competition for nutrients and water from the woody plants, the grassland component shows general lack of plant vigor and productivity. As the grassland vegetation declines, more soil is exposed leading to soil crusting and erosion. During this phase, erosion can be severe. Higher interception losses by the increasing woody canopy combined with evaporation and runoff can reduce the effectiveness of rainfall. Soil organic matter and soil structure decline within the interspaces but soil conditions are improved under the woody plant cover. Some soil loss can occur during heavy rainfall events. In this plant community, annual production is balanced between herbaceous plants and woody plants (See Annual Production table below). Browsing animals such as goats and deer can find fair food value if browse plants have not been grazed excessively. Forage quality for cattle is low. Unless accelerated brush management and good grazing management are applied at this stage, the transition toward the Mixed-brush/Shortgrass/Annuals Community (2.2) will continue. The trend cannot be reversed with good grazing management alone.
Figure 14. Annual production by plant type (representative values) or group (midpoint values)
Table 7. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 196 | 420 | 616 |
| Shrub/Vine | 118 | 252 | 370 |
| Tree | 39 | 84 | 123 |
| Forb | 39 | 84 | 123 |
| Total | 392 | 840 | 1232 |
Figure 15. Plant community growth curve (percent production by month). TX2277, Shortgrasses/Mixed-Brush Community. Shortgrasses, annual grasses, and forbs..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 2 | 5 | 8 | 24 | 25 | 12 | 7 | 10 | 5 | 2 | 0 |
Community 2.2
Mixed-brush/Shortgrass/Annuals Community
Figure 16. 2.2 Mixed-brush/Shortgrass/Annuals Community
The Mixed-brush/Shortgrass/Annuals Community occurs when the site is overgrazed for many years, fires are excluded and woody plants are not controlled. With continued overgrazing, the site becomes a shrubland with its interstitial areas occupied by a degraded herbaceous community of shortgrasses and annuals. The shrub canopy acts to intercept rainfall and increase evapotranspiration losses, creating a more xeric microclimate. Soil fauna and organic mulch are reduced exposing more soil surface to erosion in the shortgrass interspaces between shrubs/trees. The exposed soil crusts readily and erosion can be a problem. However, within the woody canopy hydrologic processes stabilize and soil organic matter and mulch begin to increase and ecological processes eventually stabilize under the shrub canopy. Mesquite and/or juniper dominate the Mixed-brush/Shortgrass/Annuals Community production. Even though the canopy remains approximately 15 - 25 percent, the trees and shrubs can exceed 65 percent of the annual production. Common understory shrubs are pricklypear, agarito, lotebush, vine ephedra and tasajillo. Shortgrasses and low quality annual grasses and forbs occupy the woody plant interspaces. Characteristic grasses are buffalograss, rough tridens, threeawns, hairy grama, Texas grama and red grama. Forbs found in this community include dotted gayfeather, croton, western ragweed, gaura and broomweed. Annual forbs and grasses invade the bare ground if moisture is available in spring and summer. Grasses and forbs make up 35 percent or less of the annual biomass production and production varies considerably with seasonal moisture. The Mixed-brush/Shortgrass/Annuals Community provides good habitat cover for wildlife but limited preferred forage, or browse, is available for livestock or wildlife. The woody plants are generally of low value as browse and forage production being mostly annuals is highly variable. So, the Mixed-brush/Shortgrass/Annuals Community is considerably degraded compared to the reference community, or other community types found on the site. Without considerable energy inputs in brush control and range planting plus proper grazing management, the shrubland will continue to thicken until the site stabilizes with the climate and soil factors. Restoration to the reference community may not be possible if erosion has depleted the historic soil properties.
Figure 17. Annual production by plant type (representative values) or group (midpoint values)
Table 8. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Shrub/Vine | 168 | 392 | 560 |
| Grass/Grasslike | 84 | 196 | 280 |
| Tree | 50 | 118 | 168 |
| Forb | 34 | 78 | 112 |
| Total | 336 | 784 | 1120 |
Figure 18. Plant community growth curve (percent production by month). TX2291, MixedBrush/Shortgrass/Annuals Community. Spring & Fall growth of grasses, annuals and woody shrubs..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 1 | 2 | 6 | 10 | 20 | 22 | 6 | 8 | 12 | 10 | 2 | 1 |
Pathway 2.1A
Community 2.1 to 2.2
With heavy continuous grazing pressure, no fires, and no brush management practices implemented, the Shortgrass/Mixed-brush Community can shift to the Mixed-brush/Shortgrass/Annuals Community.
Pathway 2.2A
Community 2.2 to 2.1
With Brush Management and Prescribed Grazing, the Mixed-brush/Shortgrass/Annuals Community can be shifted back to the Shortgrass/Mixed-brush Communities.
Conservation practices
| Brush Management | |
|---|---|
| Prescribed Grazing |
Transition T1A
State 1 to 2
Due to heavy continuous grazing, no brush management, and no fires to keep the brush species in check, the Grassland State will transition into the Shrubland State.
Restoration pathway R2A
State 2 to 1
Converting the Woodland State back to the Grassland state requires extensive and expensive reclamation practices. Without major brush control and management inputs, this plant community cannot be returned to grassland. Range planting, prescribed grazing and prescribed burning, must follow intensive mechanical brush control.
Conservation practices
| Brush Management | |
|---|---|
| Prescribed Burning | |
| Prescribed Grazing | |
| Range Planting |
Additional community tables
Table 9. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 0 | Midgrasses | 179–583 | ||||
| 1 | Midgrasses | 90–359 | ||||
| tobosagrass | PLMU3 | Pleuraphis mutica | 0–247 | – | ||
| alkali sacaton | SPAI | Sporobolus airoides | 45–90 | – | ||
| silver beardgrass | BOLAT | Bothriochloa laguroides ssp. torreyana | 45–90 | – | ||
| 2 | Shortgrasses | 135–404 | ||||
| buffalograss | BODA2 | Bouteloua dactyloides | 90–135 | – | ||
| curly-mesquite | HIBE | Hilaria belangeri | 0–67 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 22–45 | – | ||
| hairy grama | BOHIH | Bouteloua hirsuta var. hirsuta | 22–45 | – | ||
| 3 | Shortgrasses/Midgrasses | 9–27 | ||||
| tumblegrass | SCPA | Schedonnardus paniculatus | 2–6 | – | ||
| Drummond's dropseed | SPCOD3 | Sporobolus compositus var. drummondii | 2–6 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 2–6 | – | ||
| slim tridens | TRMU | Tridens muticus | 2–6 | – | ||
| slim tridens | TRMUE | Tridens muticus var. elongatus | 2–6 | – | ||
| 4 | Shortgrasses | 0–1 | ||||
| purple threeawn | ARPU9 | Aristida purpurea | 0–1 | – | ||
| Wright's threeawn | ARPUW | Aristida purpurea var. wrightii | 0–1 | – | ||
|
Forb
|
||||||
| 5 | Forbs | 22–67 | ||||
| Cuman ragweed | AMPS | Ambrosia psilostachya | 3–10 | – | ||
| prairie clover | DALEA | Dalea | 3–10 | – | ||
| Indian rushpea | HOGL2 | Hoffmannseggia glauca | 3–10 | – | ||
| trailing krameria | KRLA | Krameria lanceolata | 3–10 | – | ||
| dotted blazing star | LIPU | Liatris punctata | 3–10 | – | ||
| plains blackfoot | MELE2 | Melampodium leucanthum | 3–10 | – | ||
| Nuttall's sensitive-briar | MINU6 | Mimosa nuttallii | 3–10 | – | ||
|
Shrub/Vine
|
||||||
| 6 | Shrubs/Vines | 13–40 | ||||
| fourwing saltbush | ATCA2 | Atriplex canescens | 1–7 | – | ||
| Christmas cactus | CYLE8 | Cylindropuntia leptocaulis | 1–7 | – | ||
| featherplume | DAFO | Dalea formosa | 1–7 | – | ||
| black prairie clover | DAFR2 | Dalea frutescens | 1–7 | – | ||
| prairie clover | DALEA | Dalea | 1–7 | – | ||
| clapweed | EPAN | Ephedra antisyphilitica | 1–7 | – | ||
| algerita | MATR3 | Mahonia trifoliolata | 1–7 | – | ||
| pricklypear | OPUNT | Opuntia | 1–7 | – | ||
| yucca | YUCCA | Yucca | 1–7 | – | ||
| lotebush | ZIOB | Ziziphus obtusifolia | 1–7 | – | ||
Interpretations
Animal community
The Shallow Red Clay Ecological Site wis used by a diversity of wildlife that preferred grassland habitat. Grassland insects, reptiles, birds and mammals frequented the site, either as their base habitat or in conjunction with the adjacent sites. The large grazing and browsing animals included bison, elk, pronghorn, white-tailed and mule deer. Small mammals include many kinds of rodents, jackrabbit, cottontail rabbit, raccoon, skunk, opossum and armadillo. Predators include coyote, fox, bobcat and occasionally mountain lion. Game birds, songbirds, and birds of prey were indigenous or frequent users. Most are still plentiful. Bison and pronghorn antelope, however, are no longer present. White-tailed and Mule deer utilize the site in its various states. Deer, turkey and quail particularly favor the habitat provided by the Shortgrass/Midgrass Prairie (1.2) and Shortgrass/Mixed-brush (2.1) communities. Deer, turkey, quail and dove hunting is an important sport, or commercial enterprise, providing considerable income to land owners.
The site is suitable for production of livestock, primarily cattle. In reference conditions it was very suited to primary grass eaters such as cattle. As retrogression occurs and woody plants invade it becomes better habitat for goats, deer and other wildlife because of the browse. Sheep and goats were also once common in the southern portion of the site but are seldom pastured now because of predation and economics. Any livestock should be stocked in proportion to the available grass, forb and browse forage, keeping deer competition for forbs and browse in mind. If the animal numbers are not kept in balance with herbage and browse production through grazing management and good wildlife population management, the late Mixed-brush/Shortgrass/Annuals phase will have little to offer as habitat except cover. The naturally low and variable production of the site should be kept in mind when calculating stocking rates.
Hydrological functions
The Shallow Red Clay Ecological Site is a well-drained, very shallow upland with slow permeability and poor plant-soil-moisture relationships. Runoff is fast and the site is erosion prone if vegetative cover is sparse and slopes are steep. Exposed surface soils crust readily.
Some runoff and erosion probably existed under reference condition, but the Mixed-grass Prairie Community (1.1) vegetation intercepted and utilized much of the incoming rainfall in the soil profile. Only during extended rains or heavy thunderstorms was runoff excessive. Litter and soil movement occurred on steeper slopes but otherwise was slight. Standing plant cover, duff and organic matter decrease and surface runoff increases as the Mixed-grass Prairie Community (1.1) transitions to the Shortgrass/Midgrass Prairie Community (1.2). These processes continue in the interstitial spaces in the Shortgrass/Mixed-brush Community (2.1) phase. Evaporation and interception losses are higher, resulting in less moisture reaching the soil. If overgrazing continues, the plant community deteriorates further and desertification processes continue. Biomass production is reduced relative to the reference community and production has shifted from primarily grasses to primarily woody plants. The woody plants compete for moisture with the remaining grasses and forbs further reducing production and ground cover in openings. Decreased litter and more bare ground allow erosion from soils in openings between shrubs. Once the woody canopy surpasses 15 percent, the hydrological and ecological processes, nutrient cycling and energy flow stabilize within the woody plant canopy and the community functions as a shrubland community.
Recreational uses
The Shallow Red Clay Site is moderately suited for outdoor recreational uses including hunting, hiking, camping, equestrian use and bird watching in conjunction with adjacent sites. Deer, turkey, quail and dove hunting is an important sport, or commercial enterprise, providing considerable income to land owners. This site along with adjacent sites provides diverse scenic beauty.
Wood products
None.
Other products
None.
Other information
None.
Supporting information
Inventory data references
Information presented here has been derived from the Very Shallow Clay Range Site 33-44 dated 3/25/1985, literature, limited NRCS clipping data (417s), field observations and personal contacts with range-trained personnel. Photos by J.L. Schuster.
Special thanks to the following NRCS personnel for assistance and guidance with development of this ESD: Reggie Quiett and Cody Bauman NRCS Vernon, TX, Mark Moseley, NRCS San Antonio, TX, Justin Clary NRCS Temple, Texas.
Other references
1. Archer S. 1994. Woody plant encroachment into southwestern grasslands and savannas: rates, patterns and proximate causes. In Ecological implications of livestock herbivory in the West, pp.13-68. Edited by M. Vavra, W. Laycock, R. Pieper, Society for Range Management Publication. , Denver, CO.
2. Bestelmeyer, B. T., J.R. Brown, K. M. Havsted, R. Alexander, G. Chavez and J. E. Hedrick. 2003. Development and use of state-and-transition models for rangelands. J. Range Management. 56(2): 114-126.
3. Brown J.K. and J.K. Smith (ed.). 2006. Wildland Fire in Ecosystems: Effects of fire on Flora. Gen. Tech. Rep. RMRS-GTR-42, Vol.2. Ogden, UT. USDA-Forest Service, 257p.
4. Frost, C. C. 1998. Pre-settlement fire frequency regions of the United States: A first approximation. Tall Timbers Fire Ecology Conference Proceedings No. 20
5. Hamilton W. and Darrell Ueckert. 2005. Rangeland Woody Plant Control--Past, Present, and Future.Ch 1 in: Brush Management-Past, Present, and Future. Texas A & M University Press. Pp.3-16.
6. Milchunas, D.G. 2006. Responses of Plant Communities to grazing in the southwestern United States. USDA-Forest Service. Rocky Mtn. Sta. GTR. 169
7. Plant symbols, common names and scientific names according to USDA/NRCS Texas Plant List (Unpublished)
8. Thurow T.L., 1991. Hydrology and erosion. Chapter 6 in: Grazing Management: An Ecological Perspective Edited by: R.K. Heischmidt and J.W. Stuth. Timber Press, Portland, Oregon.
9. USDA/NRCS Soil Survey Manuals for Jones, Wilbarger and Haskell Counties, Texas.
Reviewers:
Lem Creswell, RMS, NRCS, Weatherford, Texas
Reggie Quiett, DC, NRCS, Vernon, Texas
Lee Knox, RMS, NRCS, Abilene, Texas
Steve Glasgow, GLS, NRCS, Stillwater, Oklahoma
Dr. Jack Eckroat, RMS, NRCS, Stillwater, Oklahoma
Contributors
Dan Caudle, RMS, NRCS, Abilene, Texas
Joseph Schuster, Range & Wildlife Habitat Consultants, LLC Bryan Texas
PES Edits by Tyson Morley, MLRA Soil Scientist, Altus, Oklahoma
Approval
Bryan Christensen, 9/15/2023
Acknowledgments
Site Development and Testing Plan
Future work, as described in a Project Plan, to validate the information in this Provisional Ecological Site Description is needed. This will include field activities to collect low, medium and high intensity sampling, soil correlations, and analysis of that data. Annual field reviews should be done by soil scientists and vegetation specialists. A final field review, peer review, quality control, and quality assurance reviews of the ESD will be needed to produce the final document.
Annual reviews of the Project Plan are to be conducted by the Ecological Site Technical Team.
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
| Author(s)/participant(s) | Lem Creswell, Zone RMS, NRCS, Weatherford, Texas |
|---|---|
| Contact for lead author | 817-596-2865 |
| Date | 01/28/2008 |
| Approved by | Bryan Christensen |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
None to slight. -
Presence of water flow patterns:
Water flow patterns are common and follow old stream meanders. Deposition or erosion is uncommon for normal rainfall. -
Number and height of erosional pedestals or terracettes:
None to slight. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Expect no more than 20% bare ground randomly distributed throughout. -
Number of gullies and erosion associated with gullies:
Some gullies may be present on side drains into perennial and intermittent streams. Gullies should be vegetated and stable. -
Extent of wind scoured, blowouts and/or depositional areas:
None. -
Amount of litter movement (describe size and distance expected to travel):
Under normal rainfall, little litter movement should be expected; however, litter of all sizes may move long distances depending on obstructions under intense storm events. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface is resistant to erosion. Stability class range is expected to be 5-6. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
0-5" red clay, light gray spots in places, weak, medium blocky structure, very hard, very firm, very sticky, very plastic, few roots, calcareous, moderately alkaline; clear smooth boundary. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
The prairie of grasses and forbs along with adequate litter and little bare ground provides for maximum infiltration and little runoff under normal rainfall events. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. -
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Warm-season midgrasses >>Sub-dominant:
Warm-season shortgrasses >Other:
Forbs > Shrubs/VinesAdditional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Slight mortality and decadence is expected for this site. -
Average percent litter cover (%) and depth ( in):
Litter is dominately herbaceous. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
400 to 1200 pounds per acre. -
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Honey mesquite, pricklypear, lotebush, yucca, japanese bromegrass, annual broomweed, broom snakeweed. -
Perennial plant reproductive capability:
All plants are capable of reproducing except during periods of prolonged drought conditions, heavy natural herbivory, and natural wildfires.
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
Click on box and path labels to scroll to the respective text.
Ecosystem states
| T1A | - | Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure |
|---|---|---|
| R2A | - | Adequate rest from defoliation and removal of woody canopy, followed by reintroduction of historic disturbance regimes |