Natural Resources
Conservation Service
Ecological site R078BY089TX
Shallow 19-26" PZ
Last updated: 9/15/2023
Accessed: 11/13/2024
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.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 078B–Central Rolling Red Plains, Western Part
MLRA 78B is characterized by strongly dissected, rolling plains with prominent ridges and valleys and rolling to steep irregular topography. Loamy soils are generally well drained, range from shallow to deep, and developed in sediments of Triassic and 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
These sites occur on shallow loam soils on uplands. The reference vegetation includes midgrasses with forbs and few woody species. Abusive grazing practices can lead to a shift in the plant community. Without periodic fire or alternative brush management, woody species may increase on the site.
Associated sites
| R078BY071TX |
Clay Flat 19-26" PZ The Clay Flat site may be adjacent. |
|---|---|
| R078BY072TX |
Clay Loam 19-26" PZ The Clay Loam site is often down slope. |
| R078BY091TX |
Very Shallow 19-26" PZ The Very Shallow site is often adjacent to the site. |
Similar sites
| R078BY091TX |
Very Shallow 19-26" PZ The Very Shallow site is similar in that both are located on similar topography. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Bouteloua curtipendula |
Physiographic features
These soils are on two sets of landforms on this rolling plains landscape. Shallow soils with petrocalcic horizons are primarily on depositional landforms, including nearly level to gently sloping alluvial fans, broad plains, and high stream terraces. Shallow soils with sandstone bedrock are primarily on erosional landforms, including erosional remnants, ridges, knolls, and escarpments. Slopes range from 0 to 5 percent. Elevation ranges from 1000 to 2800 feet.
Landforms: Alluvial fan, broad plain, high stream terrace for soils with petrocalcic horizon. Erosional remnant, ridge, knoll, escarpment for soils with sandstone bedrock.
Table 2. Representative physiographic features
| Landforms |
(1)
Plains
> Ridge
(2) Plains > Terrace |
|---|---|
| Runoff class | Medium to very high |
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 1,000 – 2,800 ft |
| Slope | 45% |
| Aspect | Aspect is not a significant factor |
Climatic features
The climate of the western rolling plains is dry, sub-humid with hot summers and mild winters. Temperatures often reach 100 degrees F for several consecutive days during summer. Cold spells with temperatures less than 20 degrees F only last short periods of time. The soil is not frozen below the 3-inch depth for more than 2 to 3 days. Humidity is low during the winter and early spring months. Sometimes relative humidity is high enough to make summer days uncomfortable. Most of the precipitation comes in the form of rain and occurs during the spring and early summer principally. May is the wettest month followed by June. July and August are dryer and much hotter. Rainfall often comes as intense showers of relatively short duration. Rainfall rate per hour is often high and runoff is significant. Infiltration is diminished due to lack of opportunity time. The growing season begins in April and ends with the first killing frost in Nov. There is little snowfall with the average being about 10 inches. Rainfall averages about 22 inches.
There is a 70% chance that yearly precipitation will fall between 16 and 24 inches. About 55% of the time, the yearly rainfall is below the mean. Dry spells during the growing season are common and long-term droughts occur in cycles of about 20 years. Native vegetation is principally warm season.
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 189-194 days |
|---|---|
| Freeze-free period (characteristic range) | 204-222 days |
| Precipitation total (characteristic range) | 23-24 in |
| Frost-free period (actual range) | 184-201 days |
| Freeze-free period (actual range) | 202-223 days |
| Precipitation total (actual range) | 22-25 in |
| Frost-free period (average) | 192 days |
| Freeze-free period (average) | 213 days |
| Precipitation total (average) | 23 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly minimum temperature range
Figure 4. Monthly maximum temperature range
Figure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7. Annual average temperature pattern
Climate stations used
-
(1) PADUCAH [USC00416740], Paducah, TX
-
(2) WELLINGTON [USC00419565], Wellington, TX
-
(3) JAYTON [USC00414570], Jayton, TX
-
(4) SNYDER [USC00418433], Snyder, TX
-
(5) ROBERT LEE [USC00417669], Robert Lee, TX
Influencing water features
None.
Wetland description
NA
Soil features
This ecological site consists of soils that are shallow to a petrocalcic horizon or sandstone bedrock with siltstone or shale interbeds. They are well-drained, moderately permeable soils. Soils with petrocalcic horizons formed in loamy, calcareous alluvial and eolian sediments, while soils with sandstone bedrock formed in loamy residuum.
Major Soil Taxonomic Units correlated to this site include: Mereta and Quinlan soil series.
The parent material occurs from loamy, calcareous alluvial or eolian sediments or loamy residuum derived from sandstone with siltstone and shale interbeds. Parent material origin was derived from mixed sources for Quarternary sediments or Permian and Triassic sandstone for residuum.
Table 4. Representative soil features
| Parent material |
(1)
Alluvium
–
sandstone and siltstone
(2) Eolian deposits – shale |
|---|---|
| Surface texture |
(1) Loam (2) Clay loam (3) Very fine sandy loam |
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately slow to moderate |
| Depth to restrictive layer | 4 – 20 in |
| Soil depth | 10 – 20 in |
| Surface fragment cover <=3" | 5% |
| Surface fragment cover >3" | 4% |
| Available water capacity (0-40in) |
1.1 – 4.1 in |
| Calcium carbonate equivalent (0-40in) |
20% |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
4 |
| Soil reaction (1:1 water) (0-40in) |
6.6 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
10% |
| Subsurface fragment volume >3" (Depth not specified) |
2% |
Ecological dynamics
The reference plant community of the Shallow Ecological Site in the 19-26” PZ zone of MLRA 78B is a fire-influenced Midgrass Prairie Community (1.1) with scattered tallgrasses, occasional woody plants and a good variety of forbs. Pre-settlement influences included grazing or browsing by endemic pronghorn antelope, deer and migratory bison, severe droughts and frequent fires. Wildfires occurred at 7-12 years intervals or less (Frost 1994) maintaining woody species at less than five percent canopy on this relatively level site. The soils of the site vary from shallow clay to clay loams. The soils have good plant-soil-moisture relationships, but moisture-holding capacity is moderate, often limiting productivity. Long-term droughts, occurring three to four times per century, such as the one occurring in the 1950s, may cause shifts in vegetation by causing woody plant die-off.
Sideoats grama is the dominant species throughout the MLRA contributing as much as 25 percent of the plant production. Other characteristic midgrasses found in the reference community include cane and silver bluestem, Arizona cottontop and vine-mesquite. Tallgrasses such as little and sand bluestem and Indiangrass occur in small amounts in more favorable soil-moisture locations such as limestone outcrops and drains. Buffalograss and curlymesquite are common shortgrasses. Frequent fires favor grasses over woody plants and forbs, but there are a wide variety of forbs present. In reference condition, a few trees, primarily live oak and hackberry, occupy rock crevices and deeper soil pockets on areas protected from wildfires and shrubs provide an estimated two to three percent canopy cover.
The Midgrass Prairie Community (1.1) was relatively stable and resilient within the climate, soil and fire regime until the advent of animal husbandry and fencing in the late 1800s. Not understanding the limits of rangeland productivity, European settlers overstocked the area with domesticated livestock almost universally. As overgrazing occurred on the Shallow site, there was a reduction of the less grazing resistant tall and midgrasses, a decline in mulch and organic matter, and consequently a reduction in intensity and frequency of fires. The shift in plant cover and decline in soil properties favored woody plant encroachment. The woody and grassland vegetation invaders were generally endemic species released from competition. In the resulting Midgrass/Shortgrass Community (1.2) the more palatable tall and midgrasses gave way to less palatable midgrasses and shortgrasses. Grasses still dominated annual herbage production, but the encroaching woody species increased in the proportion of production compared to the Midgrass Community (1.1).
When the Midgrass/Shortgrass Community (1.2) is continually overgrazed and fire is excluded, the ecological succession transitions into a community that is dominated by woody plants. More grazing resistant, Texas wintergrass, buffalograss and less palatable forbs begin replacing the midgrasses. As the midgrass cover declines, litter, mulch and soil organic matter decline and bare ground, erosion and other desertification processes increase. The microclimate in the grassland areas becomes more arid. Increasing woody dominants are primarily mesquite and juniper. Rest from grazing will generally not restore the grassland community when the woody plant community exceeds 10 to 15 percent canopy on this site and/or the plants reach fire resistant size (about four feet in height). When this threshold crossing occurs, the site transitions into the Shortgrass/Mixed-Brush Community (2.1). This threshold also marks the beginning of a new state, the Shrubland State.
Mesquite and/or juniper dominate the Shortgrass/Mixed-Brush Community (2.1) and the shrubs begin to form thickets. The grass component is a mixture of low palatability midgrasses, shortgrasses and low quality forbs. With continued livestock overgrazing, the better midgrasses are replaced by grazing resistant shortgrasses, such as buffalograss, curlymesquite, threeawns and western ragweed. Cool-season grasses such as Texas wintergrass and annual bromes also increase.
During this stage, the process of retrogression can be reversed with relatively inexpensive brush control practices and good grazing management that allows the application of prescribed burning. If these practices are not applied, the woody canopy will continue to increase in dominance and ground cover and a woody-plant dominated community, the Mixed–Brush/Shortgrass Shrubland Community (2.2), occurs. Once the brush canopy exceeds 30 to 35 percent, annual production for the understory is very limited and is generally made up of unpalatable shrubs, grasses and forbs within tree/shrub interspaces. Brushy species such as mesquite, juniper, prickly pear, tasajillo and condalia often form thickets. Shortgrasses, cool-season grasses and annuals persist, but in weakened condition.
Until maximum ground cover by woody species is reached, erosion continues in the interspaces. Considerable litter and soil movement occurs during heavy rains. The exposed soil crusts readily, creating opportunity for further soil and wind erosion. The microclimate becomes drier as interception losses increase with canopy cover. Once canopy cover reaches potential however, the hydrologic processes, energy flow and nutrient cycling stabilize under the shrubland environment.
Major expense and energy inputs are required to restore the Mixed-Brush/Shortgrass Shrubland Community (2.2) back to the Grassland State. Generally, mechanical or herbicidal brush management practices such as dozing and individual plant treatments (IPT) along with other conservation practices such as range planting, grazing deferment, prescribed grazing and prescribed burning are necessary for the ecological site to return to the reference community. Severe erosion and soil fertility losses during the retrogression process may prohibit the site from returning to the reference community.
Very little of the Shallow site has been put to crop cultivation. The site is highly erodible and should be cultivated with care, if at all. Most fields previously cultivated for crops have been returned to native or introduced grass species. Various introduced grass species planted include old world bluestem or Kleingrass. Most areas of the Shallow site re-vegetated to these introduced grasses are managed as rangeland.
Rangeland Health Reference Worksheets have been posted for this site on the Texas NRCS website (www.tx.nrcs.usda.gov) in Section II of the eFOTG under (F) Ecological Site Descriptions.
The following State and Transition Diagram depicts the ecological dynamics described above.
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
The Midgrass Prairie Community (1.1) is the interpretive or "reference" plant community for the Shallow Ecological Site. Sideoats grama is the dominant or co-dominant grass throughout the site. Big bluestem, little bluestem and Indiangrass occupy favorable micro-sites and were locally dominant. Also occurring on the site, but in smaller amounts, are cane and silver bluestems, Arizona cottontop, Texas wintergrass, Texas cupgrass, vine mesquite and a number of shortgrasses. Live oak and hackberry trees are widely scattered in protected areas, but probably made up less than two percent of the plant canopy. Liveoak tends to decrease moving north through the site. Sumacs, elbowbush, ephedra, bumelia, lotebush, agarito and catclaw are typical, but infrequent, shrubs. Common forbs found on the site include awnless bushsunflower, Engelmann’s daisy, orange zexmenia, prairie clover, dotted gayfeather and bundleflower. The Midgrass Prairie Community produces from 1,500 to 3,000 pounds of biomass annually, depending upon the amount of precipitation. Grasses produced as much as 85 percent of the annual production. The Midgrass-Shortgrass Community (1.2) is the result of overgrazing by livestock over a long period of time. It is midgrass-shortgrass dominated grassland being encroached by indigenous or invading woody species that had been held at low densities by repeated fires and competition from a vigorous grass component. The preferred tall grasses and midgrasses are being replaced by the more grazing resistant midgrasses and shortgrasses. Numerous brushy species, including juniper and mesquite, are encroaching because overgrazing by livestock has reduced grass cover, exposed more soil and reduced fine fuel for fire. In this plant community type, the increasing woody species are generally less than three feet tall and still subject to control by fire and improved grazing management. The woody canopy varies between 5 and 15 percent depending on severity of grazing, time since burned and availability of invading species. Important grasses are sideoats grama, little bluestem, vine mesquite, cane or silver bluestem, Texas cupgrass, Arizona cottontop, Texas wintergrass and Canada wildrye. Most of the climax perennial forbs persist. Annual primary production ranges from 1500 to 3000 pounds per acre.
Dominant plant species
-
sideoats grama (Bouteloua curtipendula), grass
-
cane bluestem (Bothriochloa barbinodis), grass
Community 1.1
Midgrass Prairie Community
Figure 8. 1.1 Midgrass Prairie Community
The Midgrass Prairie Community (1.1) is the interpretive or "reference" plant community for the Shallow Ecological Site. It developed under a dry, sub-humid climate with hot dry summers and mild winters. Herbivory by migrating bison and indigenous antelope and deer influenced the plant composition and structure, but not as much as frequent and intense wild fires, which kept woody species in check. Live oak and hackberry trees are widely scattered in protected areas, but probably made up less than two percent of the plant canopy. Liveoak tends to decrease moving north through the site. Sumacs, elbowbush, ephedra, bumelia, lotebush, agarito and catclaw are typical, but infrequent, shrubs. Big bluestem, little bluestem and Indiangrass occupy favorable micro-sites and were locally dominant. Sideoats grama is the dominant or co-dominant grass throughout the site. Also occurring on the site, but in smaller amounts, are cane and silver bluestems, Arizona cottontop, Texas wintergrass, Texas cupgrass, vine mesquite and a number of shortgrasses. Common forbs found on the site include awnless bushsunflower, Engelmann’s daisy, orange zexmenia, prairie clover, dotted gayfeather and bundleflower. The Midgrass Prairie Community (1.1) produces from 1,500 to 3,000 pounds of biomass annually, depending upon the amount of precipitation. Grasses produce as much as 85 percent of the annual production. The vegetation of the site is seasonally well balanced for grazing because of the presence of cool-season species. A good cover of grasses and mulch aides in the infiltration of rainfall into the moderately slowly permeable soil and reduced runoff. The Midgrass Community furnishes 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 into a Midgrass/Shortgrass Community (1.2).
Figure 9. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 1275 | 1700 | 2550 |
| Forb | 150 | 200 | 300 |
| Shrub/Vine | 45 | 60 | 90 |
| Tree | 30 | 40 | 60 |
| Total | 1500 | 2000 | 3000 |
Figure 10. Plant community growth curve (percent production by month). TX2042, Midgrass Dominant Community. Cool and warm-season midgrasses with few 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 |
| 2 | 6 | 16 | 22 | 20 | 10 | 4 | 3 | 6 | 5 | 4 | 2 |
Community 1.2
Midgrass/Shortgrass Community
Figure 11. 1.2 Midgrass/Shortgrass Community
The Midgrass/Shortgrass Community (1.2) is the result of overgrazing by livestock over a long period of time. It is midgrass/shortgrass dominated grassland being encroached by indigenous or invading woody species that had been held at low densities by repeated fires and competition from a vigorous grass component. The preferred tall grasses and midgrasses are being replaced by the more grazing resistant midgrasses and shortgrasses. Numerous brushy species, including juniper and mesquite, are encroaching because overgrazing by livestock has reduced grass cover, exposed more soil and reduced fine fuel for fire. In this plant community type, the increasing woody species are generally less than three feet tall and still subject to control by fire and improved grazing management. The woody canopy varies between 5 and 15 percent depending on severity of grazing, time since burned and availability of invading species. Typically, oaks increase in size and mesquite and/or juniper increase in density. Less preferred brushy species such as bumelia, sumacs, lotebush, elbowbush and agarito increase in density. Important grasses are sideoats grama, little bluestem, vine mesquite, cane or silver bluestem, Texas cupgrass, Arizona cottontop, Texas wintergrass and Canada wildrye. Most of the perennial forbs persist. Annual primary production ranges from 1500 to 3000 pounds per acre, depending on precipitation and the soil series. Forage production is predominantly grass. Heavy continuous grazing has reduced plant cover, litter and mulch and has increased bare ground slightly exposing the soil to some erosion. There could be some mulch and litter movement during rainstorms but due to gentle slopes little soil movement would take place in this vegetation type. Unless proper grazing and prescribed burning are initiated at this stage the woody species continue to increase in size and density. When the canopy of the woody plants becomes dense enough (15-20 % canopy) and big enough (greater than four feet) to suppress grass growth and resist fire damage, a threshold in ecological succession is reached. The Midgrass/Shortgrass Community (1.2) becomes the Shortgrass/Mixed-Brush Community (2.1). Once this vegetation type occurs, normal range management practices, such as proper grazing and prescribed burning, cannot reverse the trend to woody plant dominance. Brush control practices are necessary to maintain this vegetation type or to return the community back to grassland.
Figure 12. Annual production by plant type (representative values) or group (midpoint values)
Table 6. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 1200 | 1600 | 2400 |
| Shrub/Vine | 150 | 200 | 300 |
| Tree | 75 | 100 | 150 |
| Forb | 75 | 100 | 150 |
| Total | 1500 | 2000 | 3000 |
Figure 13. Plant community growth curve (percent production by month). TX2040, Midgrass/Shortgrass Community with Forbs and Shrubs. Warm season mid and shortgrasses along with traces of tallgrasses, 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 | 4 | 8 | 25 | 25 | 14 | 6 | 8 | 5 | 2 | 1 |
Pathway 1.1A
Community 1.1 to 1.2
With heavy continuous grazing, no fires, brush invasion, and no brush management practices, the Midgrass Prairie Community will shift to the Midgrass/Shortgrass Community.
Pathway 1.2A
Community 1.2 to 1.1
With Prescribed Grazing and Prescribed Burning conservation practices, the Midgrass/Shortgrass Community can be reverted back to the Midgrass Prairie Community.
Conservation practices
| Prescribed Burning | |
|---|---|
| Prescribed Grazing |
State 2
Shrubland State
The Shortgrass/Mixed-Brush Community (2.1) presents a 20 percent or greater woody canopy of Mixed-Brush, including mesquite, juniper and rarely live oak, as the dominant species. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs. Sideoats grama is replaced by increases in buffalograss and Texas wintergrass. Remnants of other climax grasses and forbs and unpalatable invaders occupy the interspaces between trees and shrubs. Cool-season grasses such as Texas wintergrass, plus other grazing resistant species, can be found under and around woody plants. Annual primary production is approximately 1000 to 2500 pounds per acre. The Mixed-Brush/Shortgrass Shrubland Community (2.2) is the result of many years of overgrazing, lack of periodic fires and little brush management. Mesquite and/or juniper dominate the Mixed-Brush/Shortgrass Shrubland Community, which is essentially a dense shrubland state. Trees and shrubs can approach 70 percent ground cover. Shortgrasses and low quality annual and perennial forbs occupy the woody plant interspaces. Characteristic grasses are curlymesquite, buffalograss, hairy tridens, Texas grama, and fall witchgrass. Texas wintergrass and cool season annuals are found in and around tree/shrub cover. Grasses and forbs make up 25 percent or less of the annual herbage production.
Dominant plant species
-
mesquite (Prosopis), shrub
-
juniper (Juniperus), shrub
-
buffalograss (Bouteloua dactyloides), grass
Community 2.1
Shortgrass/Mixed-Brush Community
Figure 14. 2.1 Shortgrass/Mixed-Brush Community
The Shortgrass/Mixed-Brush Community (2.1) presents a 20 percent or greater woody canopy of Mixed-Brush, including mesquite, juniper and rarely live oak, as the dominant species. It is the result of selective overgrazing by livestock and deer and the differential response of plants to defoliation over a long period of time. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs. Annual herbage 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 and density. Mesquite is an early increaser throughout the MLRA. Ashe juniper invaded from the south and redberry juniper is found more frequently in the north of the MLRA. Many of the reference community shrubs are present. Typically, agarito, pricklypear, lotebush, tasajillo and sumac form thickets on this site. Sideoats grama is replaced by increases in buffalograss and Texas wintergrass. Remnants of other reference grasses and forbs and unpalatable invaders occupy the interspaces between trees and shrubs. Cool-season grasses such as Texas wintergrass, plus other grazing resistant species, can be found under and around woody plants. 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. Common herbaceous species include threeawns, hairy tridens, red grama, hairy grama, and prairie coneflower. Buffalograss, western ragweed and curlymesquite are persistent increasers until shrub density reaches maximum canopy. As the grassland vegetation declines, more soil is exposed leading to crusting and erosion. In this vegetation type, 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 improve under the woody plant cover. Some soil loss can occur during heavy rainfall events. Annual primary production is approximately 1000 to 2500 pounds per acre. In this plant community, annual production is balanced between herbaceous plants and woody plants. Browsing animals such as goats and deer can find fair food value if browse plants have not been grazed excessively. Forage quantity for cattle is low. Unless brush management and good grazing management are applied at this stage, the transition toward the Mixed-Brush/Shortgrass Shrubland Community (2.2) will continue. The trend cannot be reversed with good grazing management alone.
Figure 15. Annual production by plant type (representative values) or group (midpoint values)
Table 7. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 500 | 1000 | 1250 |
| Shrub/Vine | 250 | 500 | 625 |
| Tree | 150 | 300 | 375 |
| Forb | 100 | 200 | 250 |
| Total | 1000 | 2000 | 2500 |
Figure 16. Plant community growth curve (percent production by month). TX2059, Shortgrass-Mixed-Brush Community. Shortgrasses, annual grasses and invasive 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 | 5 | 8 | 24 | 25 | 12 | 7 | 10 | 5 | 2 | 0 |
Community 2.2
Mixed-Brush/Shortgrass Shrubland Community
Figure 17. 2.2 Mixed-Brush/Shortgrass Shrubland Community
The Mixed-Brush/Shortgrass Shrubland Community (2.2) is the result of many years of overgrazing, lack of periodic fires and little brush management. Mesquite and/or juniper dominate the Mixed-Brush/Shortgrass Shrubland Community, which is essentially a dense shrubland state. Common understory shrubs are pricklypear, agarito, sumacs, lotebush, yucca, elbowbush, pricklyash, croton and tasajillo. With continued heavy grazing and no brush control, the trees and shrubs can approach 70 percent ground cover. Shortgrasses and low quality annual and perennial forbs occupy the woody plant interspaces. Characteristic grasses are curlymesquite, buffalograss, hairy tridens, Texas grama, and fall witchgrass. Texas wintergrass and cool season annuals are found in and around tree/shrub cover. Grasses and forbs make up 25 percent or less of the annual herbage production. Forbs commonly found in this community include dotted gayfeather, orange zexmania, croton, western ragweed, prairie coneflower, Louisiana sagewort, and catclaw sensitivebriar. 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 few interstitial spaces. The exposed soil crusts readily. However, within the woody canopy hydrologic processes stabilize and soil organic matter and mulch begin to increase and eventually stabilize under the shrub canopy. The Mixed-Brush/Shortgrass Shrubland Community (2.2) provides good habitat cover for wildlife, but only limited preferred forage, or browse, is available for livestock or wildlife. Alternatives for restoration include brush control and range planting to return the shrubland to grassland. Proper stocking, prescribed grazing and prescribed burning would then be necessary to maintain the desired community.
Figure 18. Annual production by plant type (representative values) or group (midpoint values)
Table 8. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 650 | 1300 | 1625 |
| Tree | 400 | 1000 | 1250 |
| Grass/Grasslike | 250 | 500 | 625 |
| Forb | 40 | 100 | 125 |
| Total | 1340 | 2900 | 3625 |
Figure 19. Plant community growth curve (percent production by month). TX2026, Mesquite/Cool Season annual grasses. Mesquite and cool season annual grasses..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 3 | 4 | 12 | 17 | 20 | 15 | 3 | 3 | 8 | 4 | 6 | 5 |
Pathway 2.1A
Community 2.1 to 2.2
With heavy continuous grazing, no brush management and no fires, the Shortgrass/Mixed-brush Community will shift to the Mixed-brush/Shortgrass Shrubland Community.
Pathway 2.2A
Community 2.2 to 2.1
With the implementation of various conservation practices such as Prescribed Grazing, Brush Management, Range Planting, and Prescribed Burning, the Mixed-Brush/Shortgrass Shrubland Community can be shifted back to the Shortgrass/Mixed-Brush Community.
Conservation practices
| Brush Management | |
|---|---|
| Prescribed Burning | |
| Range Planting | |
| Prescribed Grazing |
Transition T1A
State 1 to 2
With heavy continuous grazing, no fires, and no brush management, the Grassland State will transition into the Shrubland State.
Restoration pathway R2A
State 2 to 1
Prescribed Grazing, Brush Management, Range Planting, and Prescribed Burning are various conservation practices that are required to restore the Grassland State from the Shrubland State.
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 (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Midgrass | 320–640 | ||||
| sideoats grama | BOCU | Bouteloua curtipendula | 320–640 | – | ||
| 2 | Tallgrasses | 225–510 | ||||
| big bluestem | ANGE | Andropogon gerardii | 0–510 | – | ||
| sand bluestem | ANHA | Andropogon hallii | 0–510 | – | ||
| little bluestem | SCSC | Schizachyrium scoparium | 0–510 | – | ||
| Indiangrass | SONU2 | Sorghastrum nutans | 0–510 | – | ||
| 3 | Midgrasses | 255–510 | ||||
| cane bluestem | BOBA3 | Bothriochloa barbinodis | 0–510 | – | ||
| silver beardgrass | BOLAT | Bothriochloa laguroides ssp. torreyana | 0–510 | – | ||
| Arizona cottontop | DICA8 | Digitaria californica | 0–510 | – | ||
| Texas cupgrass | ERSE5 | Eriochloa sericea | 0–510 | – | ||
| vine mesquite | PAOB | Panicum obtusum | 0–510 | – | ||
| 4 | Mid/Shortgrasses | 150–300 | ||||
| threeawn | ARIST | Aristida | 0–300 | – | ||
| buffalograss | BODA2 | Bouteloua dactyloides | 0–300 | – | ||
| hairy grama | BOHI2 | Bouteloua hirsuta | 0–300 | – | ||
| fall witchgrass | DICO6 | Digitaria cognata | 0–300 | – | ||
| slim tridens | TRMU | Tridens muticus | 0–300 | – | ||
| slim tridens | TRMUE | Tridens muticus var. elongatus | 0–300 | – | ||
| 5 | Cool-season grasses | 150–300 | ||||
| Canada wildrye | ELCA4 | Elymus canadensis | 0–300 | – | ||
| Texas wintergrass | NALE3 | Nassella leucotricha | 0–300 | – | ||
|
Forb
|
||||||
| 6 | Forbs | 150–300 | ||||
| Cuman ragweed | AMPS | Ambrosia psilostachya | 0–300 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 0–300 | – | ||
| aster | ASTER | Aster | 0–300 | – | ||
| milkvetch | ASTRA | Astragalus | 0–300 | – | ||
| croton | CROTO | Croton | 0–300 | – | ||
| prairie clover | DALEA | Dalea | 0–300 | – | ||
| purple prairie clover | DAPU5 | Dalea purpurea | 0–300 | – | ||
| bundleflower | DESMA | Desmanthus | 0–300 | – | ||
| Engelmann's daisy | ENPE4 | Engelmannia peristenia | 0–300 | – | ||
| beeblossom | GAURA | Gaura | 0–300 | – | ||
| hoary false goldenaster | HECA8 | Heterotheca canescens | 0–300 | – | ||
| trailing krameria | KRLA | Krameria lanceolata | 0–300 | – | ||
| dotted blazing star | LIPU | Liatris punctata | 0–300 | – | ||
| menodora | MENOD | Menodora | 0–300 | – | ||
| catclaw mimosa | MIACB | Mimosa aculeaticarpa var. biuncifera | 0–300 | – | ||
| yellow nailwort | PAVI4 | Paronychia virginica | 0–300 | – | ||
| smartweed leaf-flower | PHPO3 | Phyllanthus polygonoides | 0–300 | – | ||
| leafflower | PHYLL | Phyllanthus | 0–300 | – | ||
| groundcherry | PHYSA | Physalis | 0–300 | – | ||
| slimflower scurfpea | PSTE5 | Psoralidium tenuiflorum | 0–300 | – | ||
| white rosinweed | SIAL | Silphium albiflorum | 0–300 | – | ||
| awnless bushsunflower | SICA7 | Simsia calva | 0–300 | – | ||
| fanpetals | SIDA | Sida | 0–300 | – | ||
| queen's-delight | STSY | Stillingia sylvatica | 0–300 | – | ||
| vervain | VERBE | Verbena | 0–300 | – | ||
|
Shrub/Vine
|
||||||
| 7 | Shrubs/Vines | 45–90 | ||||
| acacia | ACACI | Acacia | 0–90 | – | ||
| snakewood | CONDA | Condalia | 0–90 | – | ||
| jointfir | EPHED | Ephedra | 0–90 | – | ||
| stretchberry | FOPU2 | Forestiera pubescens | 0–90 | – | ||
| algerita | MATR3 | Mahonia trifoliolata | 0–90 | – | ||
| fragrant sumac | RHAR4 | Rhus aromatica | 0–90 | – | ||
| littleleaf sumac | RHMI3 | Rhus microphylla | 0–90 | – | ||
| sumac | RHUS | Rhus | 0–90 | – | ||
| bully | SIDER2 | Sideroxylon | 0–90 | – | ||
| Hercules' club | ZACL | Zanthoxylum clava-herculis | 0–90 | – | ||
|
Tree
|
||||||
| 8 | Trees | 30–60 | ||||
| hackberry | CELTI | Celtis | 0–60 | – | ||
| live oak | QUVI | Quercus virginiana | 0–60 | – | ||
| elm | ULMUS | Ulmus | 0–60 | – | ||
Interpretations
Animal community
Many types of grassland insects, reptiles, birds and mammals use the plant community of the Shallow Ecological Site, either as their base habitat or from the adjacent sites. Small mammals include many kinds of rodents, jackrabbit, cottontail rabbit, raccoon, skunk, opossum and armadillo. Predators include coyote, red fox, gray 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, but white-tailed deer utilize the Shallow site in its various states. Deer, turkey and quail particularly favor the habitat provided by the Midgrass-Shortgrass Community (2) and Mixed-Brush/Shortgrass (3) plant communities. Deer, turkey, quail and dove hunting is an important sport, or commercial enterprise, providing considerable income to land owners.
The site in reference condition is very suited to primary grass eaters such as bison and cattle. As retrogression occurs, and woody plants invade, it becomes better habitat for sheep, goats, deer and other wildlife because of the browse and cool season grasses. Predators, however, may preclude sheep and goats. 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 Community (4) will have little to offer as habitat except cover.
Hydrological functions
The Shallow Ecological Site is a well-drained, moderately slowly permeable shallow upland with nearly level to gentle slopes. Runoff is negligible on 0 to 1 percent slopes, very low on 1 to 3 percent slopes, and low on 3 to 5 percent slopes. However, soil crusting can cause erosion from bare ground on steeper slopes if plant cover is removed.
In reference condition, the grassland vegetation intercepte and utilized much of the incoming rainfall in the soil solum. Only during extended rains or heavy thunderstorms is there much runoff. Litter and soil movement is slight. Standing plant cover, duff and organic matter decrease and surface runoff increases as the Midgrass Prairie Community (1.1) transitions to the Midgrass/Shortgrass Community (1.2). These processes continue in the interstitial spaces in the Shortgrass/Mixed-Brush Community (2.1). 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 HCPC and production has shifts from primarily grasses to primarily woody plants. The deeper-rooted woody plants are able to extract water from greater depths than the short grasses, so less water will be available for down-slope movement. The woody plants compete for moisture with the remaining grasses and forbs further reducing production and ground cover in openings. Openings in the advanced Mixed-Brush/Shortgrass (Shrubland state) occur only on very shallow soil areas. Decreased litter and more bare ground allow erosion from soils in openings between trees. Once the Mixed-Brush/Shortgrass Shrubland Community (2.2) canopy surpasses 70 percent the hydrological and ecological processes, nutrient cycling and energy flow, stabilize within the woody plant canopy.
Recreational uses
The Shallow site occurs in narrow bands with Very Shallow, Clay Flat and Clay Loam sites. Together, these sites are well suited for many outdoor recreational uses including recreational hunting, hiking, camping, equestrian and bird watching. The Shallow site, along with adjacent uplands, provides diverse scenic beauty and many opportunities for recreation and hunting.
Wood products
Posts and specialty wood products are made from juniper, mesquite, live oak and many shrubs. Mesquite and oak are use for firewood and charcoal.
Other products
Jams and jellies are made from many fruit bearing species, such as agarito. Seeds are harvested from many plants for commercial sale. Grasses and forbs are harvested by the dried-plant industry for sale in dried flower arrangements. Honeybees are utilized to harvest honey from the many flowering plants, such as mesquite.
Other information
None.
Supporting information
Inventory data references
Information presented was derived from the revised Shallow Range Site, literature, field observations and personal contacts with range-trained personnel. Photos by J.L. Schuster.
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. Archer, Steve and F.E. Smeins.1991. Ecosystem-level Processes, Chapter 5 in: Grazing Management: An Ecological Perspective edited by R. K. Heitschmidt and J.W. Stuth. Timber Press, Portland, Oregon.
3. Frost, C. C. 1998. Pre-settlement fire frequency regions of the United States: A first approximation. Tall Timbers Fire Ecology Conference Proceedings No. 20
4. Smeins, Fred, Sam Fuhlendorf and Charles Taylor, Jr. 1997. Environmental and Land Use Changes: A Long Term Perspective. Chapter 1 in: Juniper Symposium 1997. Texas Agricultural Experiment Station. Pp 1-21.
5. Thurow T.L., 1991. Hydrology and erosion. Chapter 6 in: Grazing Management: An Ecological Perspective Edited by: R.K. Heitschmidt and J.W. Stuth. Timber Press, Portland, Oregon.
6. USDA/NRCS Soil Survey Manuals for Runnels, Fisher and Nolan Counties.
7. Vines, RA. 1984. Trees of Central Texas. University of Texas Press. Austin, Texas.
8. Plant symbols, common names and scientific names according to USDA/NRCS Texas Plant List (Unpublished)
9. 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.
10. Hamilton W. and D.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.
Special thanks to the following NRCS personnel for assistance and/or guidance with development of this ESD: Clint Rollins NRCS Amarillo, Ronnie Vanicek NRCS Ballinger and Justin Clary NRCS Temple, Texas.
Additional data provided by:
Rusty Dowell, NRCS, Soil Scientist, San Angelo, Texas
Steve Glasgow, GLS, NRCS, Stillwater, Oklahoma
Susan Horton, NRCS, Soil Scientist, Temple, Texas
Contributors
Joe B. Norris
Joe Schuster, Range & Wildlife Habitat Consultants, 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) | Stan Bradbury, Zone RMS, NRCS, Lubbock, Texas |
|---|---|
| Contact for lead author | 806-791-0581 |
| Date | 09/04/2007 |
| Approved by | Bryan Christensen |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Slight to moderate. -
Presence of water flow patterns:
Slight to moderate. -
Number and height of erosional pedestals or terracettes:
Slight to moderate. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
35 to 40% bare ground. -
Number of gullies and erosion associated with gullies:
Slight to moderate. -
Extent of wind scoured, blowouts and/or depositional areas:
None to slight. -
Amount of litter movement (describe size and distance expected to travel):
Slight to moderate. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Water erosion hazards are moderate to severe. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Shallow clays and clay loam surface; weak fine granular structure; few fine roots; hard, friable; calcareous moderately alkaline; moderate permeability; well drained; good plant-soil moisture; moderate SOM. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Low vegetative cover and percent slopes makes this site susceptible to erosion. This site has very slow permeability, runoff is medium to high depending on slope and available water holding capacity is moderate to high. -
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 tallgrasses >Other:
Warm-season shortgrasses > Cool-season grasses > Forbs > Shrubs/Vines > TreesAdditional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Plant mortality and decadence is minimal. -
Average percent litter cover (%) and depth ( in):
Litter is dominantly herbaceous. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
1,500 to 3,000 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:
Mesquite, lotebush, tasajillo, and pricklypear can be invasive. -
Perennial plant reproductive capability:
All plant species should be capable of reproduction except during periods of prolonged drought conditions, heavy natural herbivory or intense 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 |