Natural Resources
Conservation Service
Ecological site R081AY566TX
Limestone Hill
14-19 PZ
Last updated: 9/19/2023
Accessed: 08/30/2026
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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.
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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): 081A–Edwards Plateau, Western Part
This area is entirely in Texas. It makes up about 16,550 square miles (42,885 square kilometers). The cities of San Angelo and Fort Stockton and the towns of Big Lake, McCamey, Ozona, and Sheffield are in this MLRA. Interstate 20 crosses the northern part of the area, and Interstate 10 crosses the middle of the area. The eastern part of Amistad National Recreation Area is in this MLRA.
Classification relationships
USDA-Natural Resources Conservation Service, 2006.
-Major Land Resource Area (MLRA) 81AEcological site concept
The Limestone Hills are comprised of shallow soils with lithic contact. The sites are filled with gravels, cobbles, and flagstones and occur on undulating hills with less than 20 percent slopes.
Associated sites
R081AY290TX Clay Flat 14-19 PZ
The Clay Flat ecological site has deeper soils and is more productive.
R081AY303TX Loamy 14-19 PZ
The Loamy ecological site has deeper soils and is more productive.
R081AY291TX Clay Loam 14-19 PZ
The Clay Loam ecological site has deeper soils lower in the landscape.
Similar sites
R081AY309TX Low Stony Hill 14-19 PZ
The Low Stony Hill ecological site is shallow to limestone bedrock with gravels, cobbles, and stones.
R081AY311TX Shallow 14-19 PZ
The Shallow ecological site is shallow to limestone bedrock with fewer fragments.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Acacia greggii
Herbaceous (1) Bouteloua curtipendula
(2) Bouteloua eriopodaPhysiographic features
The sites are on uplands that occur on gently sloping to steep, generally convex ridges or mesas. Slopes range from 1 to 15 percent. Elevation of the site ranges from 900 to 5,080 feet above mean sea level. In most locations, no runoff is received from other sites. The abundant herbaceous ground cover prevents, or at least moderates, erosion damage, while the problem is compounded as cover diminishes. Although annual production is comparatively low, the site supports a diverse plant community and will recover from abuse relatively quickly under good management.
Table 2. Representative physiographic features
Landforms (1) Plateau > Ridge
(2) Plateau > Mesa
Runoff class Medium to high Flooding frequency None Ponding frequency None Elevation 900 – 5080 ft Slope 1 – 15 % Aspect Aspect is not a significant factor Climatic features
The climate is semiarid and is characterized by hot summers and dry, relatively mild winters. The average relative humidity in mid-afternoon ranges from 25 to 50 percent. Humidity is higher at night, and the average at dawn is around 70 to 80 percent. The sun shines 80 percent of the time during the summer and 60 percent in winter. The prevailing wind is from the south-southwest. Approximately two-thirds of annual rainfall occurs during the May to October period. Rainfall during this period generally falls during thunderstorms, and fairly large amounts of rain may fall in a short time. The climate is one of extremes, which exert much more influence on plant communities than averages. Timing and amount of rainfall are critical. High temperatures and dry westerly winds have a tremendously negative impact on precipitation effectiveness, as well as length of time since the last rain. Records since the mid-1900’s, as well as geological and archaeological findings, indicate wet and dry cycles going back many thousands of years and lasting for various lengths of time with enormous influence on the flora and fauna of the area.
Table 3 Representative climatic features
Frost-free period (characteristic range) 210-270 days Freeze-free period (characteristic range) 240-300 days Precipitation total (characteristic range) 20-20 in Frost-free period (actual range) 210-270 days Freeze-free period (actual range) 240-300 days Precipitation total (actual range) 20-20 in Frost-free period (average) 230 days Freeze-free period (average) 260 days Precipitation total (average) 20 in Characteristic rangeActual rangeBarLineFigure 2. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 3. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 4. Monthly maximum temperature range
BarLineFigure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7 Annual average temperature pattern
Climate stations used
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(1) BAKERSFIELD [USC00410482], Iraan, TX
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(2) BIG LAKE 2 [USC00410779], Big Lake, TX
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(3) COPE RCH [USC00411974], Big Lake, TX
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(4) GARDEN CITY [USC00413445], Garden City, TX
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(5) MCCAMEY [USC00415707], Mc Camey, TX
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(6) PAINT ROCK [USC00416747], Paint Rock, TX
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(7) PANDALE 1 N [USC00416780], Comstock, TX
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(8) PANDALE 11 NE [USC00416781], Comstock, TX
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(9) SANDERSON [USC00418022], Dryden, TX
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(10) SHEFFIELD [USC00418252], Sheffield, TX
">Influencing water features
This is an upland site and is not influenced by water from a wetland or a stream.
Wetland description
N/A
Soil features
The site consists of very shallow or shallow, well drained, moderately permeable soils. They are composed of grayish-brown to dark grayish-brown very gravelly loams, very cobbly clay loams, and very cobbly silt loams formed in residuum from limestone and lying over limestone bedrock, usually unfractured. Available water capacity is very low. Shrink-swell potential is low. In the profile there are no saline horizons, and there are no sodic horizons. Soils associated with this site include: Ector, Langtry, Lozier, and Noelke.
Table 4. Representative soil features
Parent material (1) Residuum – limestone
Surface texture (1) Very gravelly loam
(2) Very cobbly silt loam
(3) Very cobbly clay loam
Family particle size (1) Loamy-skeletal
Drainage class Well drained Permeability class Moderate Depth to restrictive layer 4 – 20 in Soil depth 4 – 20 in Surface fragment cover <=3" 20 – 50 % Surface fragment cover >3" 5 – 30 % Available water capacity
(0-20in)0.3 – 1.2 in Calcium carbonate equivalent
(0-20in)40 – 80 % Electrical conductivity
(0-20in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-20in)Not specified Soil reaction (1:1 water)
(0-20in)7.4 – 8.4 Subsurface fragment volume <=3"
(4-20in)15 – 40 % Subsurface fragment volume >3"
(4-20in)5 – 40 % Ecological dynamics
The Limestone Hill site was is a mid and short grassland with scattered small shrubs and numerous perennial forbs. Mid-size bunchgrasses, shortgrasses, and perennial forbs probably covered most of the surface. This plant community was greatly influenced by grazing, climate (including periodic extended periods of drought) and, to a lesser degree, fire.
Extensive herds of pronghorns, large towns of black tailed prairie dogs, as well as smaller populations of elk, white-tailed deer, and desert mule deer were present and had an impact on the plant community. Bison, a migratory herd animal, would come into an area, graze on the move, and not come back for many months or even years. This long deferment period allowed the plants to recover from the heavy grazing. Bison grazing on this site was probably intermittent, occurring during wetter periods. Very few bison were reported in the area after 1830. There were no recorded sightings after 1860. Fire has an influence on plant community structure and was probably a factor in maintaining the original savannah vegetation. Mesquite were present on the site, but not at the level seen today. Periodic fires may have helped keep mesquite as a scattered savannah and other woody species a small part of the composition. Grazing patterns by native herbivores and prairie dog activities were probably more significant factors in maintaining a well-balanced plant community.
Reference community plants developed ways to withstand periods of drought. The midgrasses and forbs shaded the ground, reduced soil temperature, improved infiltration of what little moisture might fall and maintained soil moisture longer. Their roots reached deeper into the soil, utilizing deep soil moisture no longer available to short-rooted plants. In extreme cases many species could go virtually dormant, preserving the energy stored in underground roots, crowns and stems until wetter weather arrived. Their seeds could stay viable in the soil for long periods, sprouting when conditions improved.
While grazing is a natural component of this ecosystem, overstocking and thus overgrazing by domesticated animals has had a tremendous impact on the site. Early settlers, accustomed to farming and ranching in more temperate zones of the eastern United States or even Europe, misjudged the capacity of the site for sustainable production and expected more of the site than it could deliver. Moreover, there was a gap of time between the extirpation of bison and the introduction of domestic livestock which resulted in an accumulation of plant material. This may have given the illusion of higher production than was actually being produced. Overgrazing and fire suppression disrupted ecological processes that took hundreds or thousands of years to develop. Instead of grazing and moving on, domestic livestock were present on the site most of the time, particularly after the practice of fencing arrived. Another influence on grazing patterns was the advent of wells and windmills. They opened up large areas that were previously unused by livestock due to lack of natural surface water. The more palatable plants were selected repeatedly and eventually began to disappear from the ecosystem to be replaced by lower successional, less palatable species. As overgrazing continued, overall production of grasses and forbs declined, more bare ground appeared, soil erosion increased, and woody and succulent increasers began to multiply. The elimination of fire due to the lack of fine fuel or by human interference assisted the rapid encroachment of mesquite and other woody increasers and a concurrent reduction of usable forage.
Extremes in climate exerted tremendous influence on the site long before European man arrived. Geologic formations, archeological findings, and rainfall records since the mid-1900’s show wide variations in precipitation with cycles of long, dry periods going back thousands of years with corresponding variations in kind and amount of flora and fauna species. Although the limestone hill site has shallow soils with low moisture holding capacity, it can make good use of small rainfall events. The mineral content and reaction of the soils enable the site to produce diverse, highly nutritious forage. Loss of cover and soil robs the site the site of this capability and promotes rapid water shed, erosion and crusting. Pedestalling, terracetes, and water flow patterns are range health indicators that will be present if the site begins to deteriorate.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 textEcosystem states
T1A - Absence of disturbance with natural regeneration overtime. Maybe be coupled with prolonged excessive grazing. T2A - Removal of woody canopy followed by rangeland seeding T3A - Absence of disturbance with natural regeneration overtime. Maybe be coupled with prolonged excessive grazing. State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Open GrasslandDominant plant species
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sideoats grama (Bouteloua curtipendula), grass
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black grama (Bouteloua eriopoda), grass
Community 1.1
Mid and Short GrasslandThe reference plant community for this site is a grassland composed of mid and shortgrasses with scattered shrubs that evolved under the influence of grazing, periodic fire, and fluctuations between wet and dry periods that often last for years at a time. Fire effects are limited to areas with a dominance of midgrasses and annual rainfall over 15 inches, generally increasing from west to east. The overstory shades less than five percent of the site and consists of occasional shrubs such as catclaw acacia (Acacia greggii), Roemer’s acacia (Acacia roemeriana), Texas kidneywood (Eysenhardtia texana), ephedra (Ephedra spp.), and skeletonleaf goldeneye (Viguiera stenoloba). Midgrasses such as sideoats grama (Bouteloua curtipendula), black grama (Bouteloua eriopoda), cane bluestem (Bothriochloa barbinoides), green sprangletop (Leptochloa dubia), and plains bristlegrass (Setaria leucopila) along with shortgrasses such as buffalograss (Bouteloua dactyloides), Hall’s panicum (Panicum hallii), and burrograss (Scleropogon brevifolius) dominate the site. Other important grasses include Arizona cottontop (Digitaria californica), vine mesquite (Panicum obtusum), three-flower melic (Melica nitens), Texas wintergrass (Nassella leucotricha), sand dropseed (Sporobolus cryptandrus), slim tridens (Hilaria muticus), rough tridens (Hilaria muticus var. elongates), and three-awns (Aristida spp.). Perennial forbs such as awnless bushsunflower (Simsia calva), orange zexmenia (Wedelia hispida), low menodora (Menodora heterophylla), Mexican sagewort (Artemisia ludoviciana), and Indianmallow (Abutilon spp.) are a small but important component of the plant community. In wet years, annual forbs produce significant herbaceous vegetation. The site has few trees due to the shallow nature of the soils and impermeable, non-fractured underlying material. Plants are vigorous and reproduction is rapid during wet weather.
Bare ground is less than 25 percent. Interspaces between plants are slightly covered with litter. Soil erosion is little to none and infiltration is slow to moderate. Runoff occurs during heavier rainfall but is slowed down and dispersed by vegetative ground cover. Concentrated water flow patterns are rare. Recurrent periodic fire, climatic patterns, and grazing by herbivores were natural processes that maintained this reference plant community. Interruption of the ecological processes of a site brings about change. The reference plant community included large populations of important grasses and smaller but highly important numbers of perennial forbs. Extended drought, continued overuse and elimination of fire result in their decline or disappearance from large portions of the site. The more dominant, desirable grasses decrease as do palatable perennial forbs. Less palatable or productive midgrasses such as perennial three-awn (Aristida purpurea), sand dropseed, slim tridens, and hairy grama (Bouteloua hirsuta); shortgrasses like buffalograss, red grama (Bouteloua trifida), and burrograss; and less desirable forbs such as croton (Croton spp.), globemallow (Sphaearalcea spp.), verbena (Verbena spp.), and annuals begin to increase, filling in for the declining species. Small juniper (Juniperus spp.), mesquite, agarito (Mahonia trifoliata), and prickly pear (Opuntia spp.) begin to appear. More bare ground is evident. If the process is not halted or reversed, the community shifts toward the Short and Midgrass Community.Figure 8. 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 635 850 1065 Forb 80 100 125 Shrub/Vine 35 50 60 Tree 0 0 0 Total 750 1000 1250 Figure 9. Plant community growth curve (percent production by month). TX3251 , Mid&Shortgrasses Grassland Community. Warm season mid and shortgrasses with 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 4 6 10 20 10 15 20 10 1 1 Community 1.2
Short and MidgrassThis community represents a significant vegetational shift. Due to overstocking, elimination of fire, lack of brush management, and possibly changes in weather patterns, the population of juniper and other woody species has increased. Vigor and reproduction of the historically dominant grass species have declined and they are being replaced by threeawns, buffalograss, burrograss, hairy grama, slim tridens, Hall’s panicum, and other shortgrasses. Less palatable annual and perennial forbs have also increased. Ground cover by litter has decreased. Up to 50 percent of the ground is bare. Soil organic matter is low. Infiltration has dropped off and runoff is rapid. Signs of erosion are evident. The loss of topsoil and soil organic matter makes it very hard for these abused areas to return to the reference plant community within a reasonable period of time.
Figure 10. 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 550 700 800 Forb 100 150 200 Shrub/Vine 80 100 150 Tree 25 50 100 Total 755 1000 1250 Figure 11. Plant community growth curve (percent production by month). TX3260 , Short&Midgrass Community. Short and midgrass dominated community..
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 4 6 10 20 10 15 20 10 1 1 Pathway 1.1A
Community 1.1 to 1.2With heavy abusive grazing, no brush management, brush invasion, and no fires, the Mid and Short Grassland Community will transition to the Short and Midgrass Community.
Pathway 1.2A
Community 1.2 to 1.1With the institution of sound management practices, this trend can usually be reversed and a measure of productivity restored. Understanding the effects of climate, fire, and grazing on the ecology of the site combined with the use of sound grazing management, individual plant treatment, fine fuel accumulation and prescribed burning where practical are keys to any attempt to return to the reference plant community.
Conservation practices
Brush Management Prescribed Burning Prescribed Grazing State 2
ShrublandDominant plant species
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juniper (Juniperus), tree
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catclaw acacia (Acacia greggii), shrub
Community 2.1
Juniper-Threeawn ShrublandThe Juniper-Threeawn Shrubland Community is the result of an extreme shift of site characteristics from the original midgrass grassland. Juniper, catclaw acacia, cenizo, and other woody increasers dominate the slopes. Mesquite, prickly pear, and other woody/succulent invaders/increasers are established on benches and plateau tops. Stands of sotol, ocotillo, and lechuguilla may be present, particularly in the southwest ranges of the site. Canopy cover ranges from 20 percent upward. Their strong competition for water, sunlight, and nutrients has severely limited or eliminated shortgrass populations, let alone the original midgrass community. Various threeawns, hairy tridens, red grama, Texas grama, burrograss, and annuals dominate the grass plant population of this site. The forb component consists predominantly of annuals or unpalatable perennials. Up to 80 percent of the ground can be bare of grasses and forbs. Often most of the original, fertile topsoil has eroded away. Bare soil has crusted and is relatively impermeable. Very little rainfall infiltrates and runoff is rapid.
This community very likely cannot be restored to the reference plant community. Decades of transition from a Midgrass Grassland Community have negatively impacted soil properties, species diversity, site integrity, and hydrological features. It can, however, be improved through mechanical and chemical brush management and implementation of sound grazing management. Before beginning the management program, the land manager should decide the relative value of livestock and wildlife to the ranch and plan brush management goals and objectives accordingly.Figure 12. 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 200 300 400 Shrub/Vine 250 300 400 Tree 175 200 300 Forb 100 200 300 Total 725 1000 1400 Figure 13. Plant community growth curve (percent production by month). TX3261 , Juniper-Threeawn Shrubland Community. Juniper and Threeawn dominated Shrubland community..
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 5 8 10 15 15 10 5 15 10 2 2 Community 2.2
Threeawn DominatedThis site is the result of a brush control program applied to the Juniper-Threeawn Shrubland Community. The grass and forb components are initially the same as in that community. Removal of brush competition for water and nutrients can be performed by increasing ground disturbance and pitting while removing brush. This would allow the forage production to be increased and improvement of rangeland health due to increased management and periodic mechanical or chemical individual plant treatment of unwanted brush seedlings. In the absence of prescribed grazing and brush control maintenance, this plant community will eventually revert back to the Juniper-Threeawn Shrubland community, sometimes in as little as 5 years. Due to the arid nature of the site, range seeding has about a 10 percent chance of being successful on the average. However, during periods of above average rainfall the potential for reseeding disturbed areas with native grasses and forbs, and prescribed grazing is much greater.
Figure 14. 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)Grass/Grasslike 300 600 800 Forb 80 150 200 Shrub/Vine 35 50 60 Tree 0 0 0 Total 415 800 1060 Figure 15. Plant community growth curve (percent production by month). TX3262 , Threeawn Dominated Grassland Community. Threeawn dominated grassland community..
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 4 6 10 20 10 15 20 10 1 1 Pathway 2.1A
Community 2.1 to 2.2With a brush management conservation practice, the Juniper-Threeawn Shrubland Community is converted to the Threeawn Dominated Community.
Conservation practices
Brush Management Pathway 2.2A
Community 2.2 to 2.1If woody species are allowed to grow unabated, the community will eventually transition back to the Juniper-Threeawn Shrubland Community. Proper grazing and brush management are needed to prevent this transition.
State 3
ReclamationCommunity 3.1
Reclaimed GrasslandThis community is the product of efforts to reclaim the Juniper-Threeawn Shrubland community or the Threeawn Dominated Grassland community. Through brush management, reseeding of native species during periods of above average rainfall, and prudent grazing management, a land manager can possibly manipulate this site successfully towards a reference community appearance. But, the plant community will never be able to mirror the original site, mainly because of the loss of topsoil. However, utilizing native species as the reseeding source will greatly benefit wildlife species that occur on the site.
This open grassland community may also be comprised of seeded non-native species, which may occur as a monoculture community. This type of community may contain less cover or food for wildlife, often practically devoid of native grasses and forbs. The site’s capacity to produce forage must be determined over time under careful management. Maintenance through prescribed grazing and individual plant treatment can preserve the site’s sustained production indefinitely within the constraints of extended weather cycles. Without these measures, the site will experience renewed encroachment of juniper and other increasers and invaders.Figure 16. Annual production by plant type (representative values) or group (midpoint values)
Table 9. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Grass/Grasslike 600 700 800 Forb 50 100 150 Shrub/Vine 40 50 60 Tree 10 25 50 Total 700 875 1060 Figure 17. Plant community growth curve (percent production by month). TX3253 , Reclaimed Grassland Community. Reclaimed Grassland Community..
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 4 6 10 20 10 15 20 10 1 1 Transition T1A
State 1 to 2If proper management is not planned and implemented, the site will continue to degrade and shift toward a Shrubland State. By implementing conservation measures such as prescribed grazing, chemical/mechanical brush management, and prescribed burning where sufficient fine fuel can be accumulated, the land manager can reverse the retrogression and shift the trend back toward the reference plant community.
Transition T2A
State 2 to 3With prescribed grazing, brush management, IPT, and prescribed burning, the Shrubland State can be transitioned to a Reclamation State.
Conservation practices
Brush Management Prescribed Burning Prescribed Grazing Transition T3A
State 3 to 2With heavy abusive grazing, no brush management, brush invasion, and no fires, the Reclamation State is reverted back to the Shrubland State.
Additional community tables
Table 10. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Midgrasses 265–435 cane bluestem BOBA3 Bothriochloa barbinodis 265–435 – sideoats grama BOCU Bouteloua curtipendula 265–435 – black grama BOER4 Bouteloua eriopoda 265–435 – 2 Midgrasses 190–310 Arizona cottontop DICA8 Digitaria californica 190–310 – green sprangletop LEDU Leptochloa dubia 190–310 – vine mesquite PAOB Panicum obtusum 190–310 – plains bristlegrass SEVU2 Setaria vulpiseta 190–310 – 3 Midgrasses 75–125 threeawn ARIST Aristida 75–125 – muhly MUHLE Muhlenbergia 75–125 – tobosagrass PLMU3 Pleuraphis mutica 75–125 – slim tridens TRMU Tridens muticus 75–125 – slim tridens TRMUE Tridens muticus var. elongatus 75–125 – 4 Shortgrasses 35–60 buffalograss BODA2 Bouteloua dactyloides 35–60 – Hall's panicgrass PAHA Panicum hallii 35–60 – 5 Shortgrasses 30–60 hairy grama BOHI2 Bouteloua hirsuta 30–60 – red grama BOTR2 Bouteloua trifida 30–60 – hairy woollygrass ERPI5 Erioneuron pilosum 30–60 – burrograss SCBR2 Scleropogon brevifolius 30–60 – sand dropseed SPCR Sporobolus cryptandrus 30–60 – 6 Cool Season grasses 30–55 southwestern needlegrass ACEM4 Achnatherum eminens 30–55 – threeflower melicgrass MENI Melica nitens 30–55 – Texas wintergrass NALE3 Nassella leucotricha 30–55 – 7 Annual grasses 10–20 Grass, annual 2GA Grass, annual 10–20 – Forb8 Forbs 80–120 Forb, annual 2FA Forb, annual 80–120 – Indian mallow ABUTI Abutilon 80–120 – dozedaisy APHAN3 Aphanostephus 80–120 – low silverbush ARHU5 Argythamnia humilis 80–120 – white sagebrush ARLUM2 Artemisia ludoviciana ssp. mexicana 80–120 – croton CROTO Croton 80–120 – prairie clover DALEA Dalea 80–120 – false pennyroyal HEDEO Hedeoma 80–120 – Gregg's tube tongue JUPI5 Justicia pilosella 80–120 – trailing krameria KRLA Krameria lanceolata 80–120 – low menodora MEHE2 Menodora heterophylla 80–120 – skullcap SCUTE Scutellaria 80–120 – awnless bushsunflower SICA7 Simsia calva 80–120 – globemallow SPHAE Sphaeralcea 80–120 – vervain VERBE Verbena 80–120 – creepingoxeye WEDEL Wedelia 80–120 – Shrub/Vine9 Shrubs/Vine 35–65 guajillo ACBE Acacia berlandieri 35–65 – catclaw acacia ACGR Acacia greggii 35–65 – roundflower catclaw ACRO Acacia roemeriana 35–65 – javelina bush COER5 Condalia ericoides 35–65 – snakewood CONDA Condalia 35–65 – Texan hogplum COTE6 Colubrina texensis 35–65 – featherplume DAFO Dalea formosa 35–65 – sotol DASYL Dasylirion 35–65 – jointfir EPHED Ephedra 35–65 – Texas kidneywood EYTE Eysenhardtia texana 35–65 – Texas swampprivet FOAN Forestiera angustifolia 35–65 – stretchberry FOPU2 Forestiera pubescens 35–65 – littleleaf ratany KRER Krameria erecta 35–65 – Texas barometer bush LEFR3 Leucophyllum frutescens 35–65 – algerita MATR3 Mahonia trifoliolata 35–65 – Texas sacahuista NOTE Nolina texana 35–65 – resinbush VIST Viguiera stenoloba 35–65 – Table 11. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 13. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 14. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
This site is suitable to produce domestic livestock and to provide habitat for native wildlife. Cow-calf, stocker cattle, sheep, and goats can utilize this site. Carrying capacity has declined drastically over the past 100 years due to deterioration of the reference plant community. An assessment of vegetation is needed to determine the site’s current carrying capacity. Calculations used to determine livestock stocking rate should be based on forage production remaining after determining use by resident wildlife, then refined by frequent and careful observation of the plant community’s response to animal foraging.
A large diversity of wildlife is native to this site. In the historic plant community, migrating bison, grazing primarily during wetter periods, resident pronghorns and smaller populations of white-tailed deer, desert mule deer, quail, and prairie chickens were the more predominant species. With the subsequent transformation of the plant community, due primarily to the influence of man and climate change, the kind and proportion of wildlife species have been altered.
With the eradication of the screwworm fly, increase in woody vegetation and man-suppressed natural predation, deer numbers have increased and are often in excess of carrying capacity. Where deer numbers are excessive, overbrowsing and overuse of preferred forbs causes deterioration of the plant community. Progressive management of deer populations through hunting can keep populations in balance and provide an economically important ranching enterprise. Achieving a balance between brushy cover and more open plant communities on this and adjacent sites is important to deer management. Competition among deer, sheep, and goats must be a consideration in livestock and wildlife management to prevent damage to preferred vegetation.
Smaller mammals include many kinds of rodents, jackrabbit, cottontail rabbit, raccoon, skunks, possum, and armadillo. Mammalian predators include coyote, red fox, gray fox, bobcat, and mountain lion. Wolves were common in earlier times, bears resided in some areas, and an occasional jaguar was encountered. Many species of snakes and lizards are native to the site.
Many species of birds are found on this site including game birds, songbirds, and birds of prey. Major game birds that are economically important are bobwhite quail, scaled (blue) quail, and mourning dove. Quail prefer a combination of low shrubs, bunch grass (critical for nesting cover), bare ground, and low successional forbs. Turkeys visit the site to feed. The different species of songbirds vary in their habitat preferences. Habitat on this site that provides a large diversity of grasses, forbs, and shrubs will support a good variety and abundance of songbirds. Birds of prey are important to keep the numbers of rodents, rabbits, and snakes in balance.Hydrological functions
The site is well drained with low water holding capacity but is able to make good use of small rainfall events. It does not lend itself to aquifer recharge, especially with unfractured bedrock. The site is located at higher elevations with steeper slopes, so the potential for rapid runoff is high, particularly when in a denuded state during heavy rainfall. Erosion can be quite high on this site, and, as the erosion process continues, the hydrologic characteristics worsen.
When heavy grazing or prolonged drought occurs, the water cycle becomes impaired due to the loss or reduction of bunchgrass and ground cover. Infiltration is decreased and runoff is increased due to poor ground cover, rainfall splash, soil capping, low organic matter, and poor structure. With a combination of a sparse ground cover and intensive rainfall, this site can contribute to increased frequency and severity of flooding within a watershed. Soil erosion is accelerated; quality of surface runoff is poor, and sedimentation is increased. Organic matter is lost from the site with surface runoff and decrease of herbaceous recycling.
As the site becomes dominated by woody species, the water cycle is further altered. Interception of rainfall by tree and shrub canopies increases, thereby reducing the amount of rainfall reaching the surface. However, stem flow is greater due to the funneling effect of the canopy, which increases soil moisture at the base of the tree and infiltration under the canopy is increased due to the mulch effect of leaf litter. Increased transpiration, especially by evergreen species such as live oak and juniper, accelerates depletion of soil moisture. As woody species increase, grass cover declines, which causes some of the same results as heavy grazing. Brush management combined with effective grazing management can help restore the natural hydrology of the site. Grass recovery, however, is slow.Recreational uses
This site has the appeal of the wide-open spaces and a wide variety of plant and animal life. When winter and early spring moisture is available, colorful annual and perennial forbs will show well on this site. The area is also used for hunting, birding, and other eco-tourism related enterprises.
Supporting information
Inventory data references
Information provided here has been derived from limited NRCS clipping data, and from field observations of range trained personnel.
Other references
Archer, S. 1994. Woody plant encroachment into southwestern grasslands and savannas: Rates, patterns, and proximate causes. Ecological implications of livestock herbivory in the West, 13-68.
Archer, S. and F. E. Smeins. 1991. Ecosystem-level processes. Grazing Management: An Ecological Perspective. Edited by R.K. Heischmidt and J.W. Stuth. Timber Press, Portland, OR.
Bestelmeyer, B. T., J. R. Brown, K. M. Havstad, R. Alexander, G. Chavez, and J. E. Herrick. 2003. Development and use of state-and-transition models for rangelands. Journal of Range Management, 56(2):114-126.
Bracht, V. 1931. Texas in 1848. German-Texan Heritage Society, Department of Modern Languages, Southwest Texas State University, San Marcos, TX.
Bray, W. L. 1904. The timber of the Edwards Plateau of Texas: Its relations to climate, water supply, and soil. No. 49. US Department of Agriculture, Bureau of Forestry.
Briske, D. D., S. D. Fuhlendorf, and F. E. Smeins. 2005. State-and-transition models, thresholds, and rangeland health: A synthesis of ecological concepts and perspectives. Rangeland Ecology and Management, 58(1):1-10.
Brothers, A., M. E. Ray Jr., and C. McTee. 1998. Producing quality whitetails, revised edition. Texas Wildlife Association, San Antonio, TX.
Brown, J. K. and J. K. Smith. 2000. Wildland fire in ecosystems, effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: US Department of Agriculture, Forest Service, Rocky Mountain Research Station, 257:42.
Davis, W. B. 1974. The Mammals of Texas. Texas Parks and Wildlife Department, 41.
Foster, J. H. 1917. The spread of timbered areas in central Texas. Journal of Forestry 15(4):442-445.
Frost, C. C. 1998. Presettlement fire frequency regimes of the United States: A first approximation. Fire in ecosystem management: Shifting the paradigm from suppression to prescription. Tall Timbers Fire Ecology Conference Proceedings, 20:70-81.
Gould, F. W. 1975. The grasses of Texas. The Texas Agricultural Experiment Station, Texas A&M University Press, College Station, TX.
Hatch, S. L. and J. Pluhar. 1993. Texas Range Plants. Texas A&M University Press, College Station, TX.
Hamilton, W. and D. Ueckert. 2005. Rangeland woody plant control--past, present, and future. Texas A&M University Press. College Station, TX.
Hart, C. R., A. McGinty, and B. B. Carpenter. 1998. Toxic plants handbook: Integrated management strategies for West Texas. Texas Agricultural Extension Service, The Texas A&M University, College Station, TX.
Heitschmidt, R. K. and J. W. Stuth. 1991. Grazing management: An ecological perspective. Timberline Press, Portland, OR.
Loughmiller, C. and L. Loughmiller. 1984. Texas wildflowers. University of Texas Press, Austin, TX.
Milchunas, D. G. 2006. Responses of plant communities to grazing in the southwestern United States. Gen. Tech. Rep RMRS-GTR-169. Fort Collins, CO: US Department of Agriculture, Forest Service, Rocky Mountain Research Station, 126:169.
Niehaus, T. F. 1998. A field guide to Southwestern and Texas wildflowers (Vol. 31). Houghton Mifflin Harcourt, Boston, MA.
Ramsey, C. W. 1970. Texotics. Texas Parks and Wildlife Department, Austin, TX.
Roemer, F. translated by O. Mueller. 1995. Roemer’s Texas, 1845 to 1847. Texas Wildlife Association, San Antonio, TX.
Scifres, C. J. and W. T. Hamilton. 1993. Prescribed burning for brushland management: The South Texas example. Texas A&M Press, College Station, TX.
Smeins, F. E., S. Fuhlendorf, and C. Taylor, Jr. 1997. Environmental and land use changes: A long term perspective. Juniper Symposium, 1-21.
Taylor, C. A. and F. E. Smeins. 1994. A history of land use of the Edwards Plateau and its effect on the native vegetation. Juniper Symposium, 94:2.
Thurow, T. L. 1991. Hydrology and erosion. Grazing Management: An Ecological Perspective. Edited by R.K. Heitschmidt and J.W. Stuth. Timber Press, Portland, OR.
Tull, D. and G. O. Miller. 1991. A field guide to wildflowers, trees and shrubs of Texas. Texas Monthly Publishing, Houston, TX.
USDA-NRCS. 1997. National range and pasture handbook. Washington, DC: United States Department of Agriculture. Natural Resources Conservation Service, Grazing Lands Technology Institute.
Weniger, D. 1997. The explorers’ Texas: The animals they found. Eakin Press, Austin, TX.
Weniger, D. 1984. The explorers’ Texas: The lands and waters. Eakin Press, Austin, TX.
Vines, R. A. 1984. Trees of Central Texas. University of Texas Press, Austin, TX.
Vines, R. A. 1960. Trees, shrubs and vines of the Southwest. University of Texas Press, Austin, TX.Contributors
Bruce Deere
Edits by Travis Waiser, MLRA Leader, NRCS, Kerrville, TXApproval
Bryan Christensen, 9/19/2023
Acknowledgments
The following individuals assisted with the development of this site description: Gary Askins, DC, NRCS, Big Lake, TX Rusty Dowell, SS, NRCS, San Angelo, TX Dr. Jake Landers, RMS, Retired Agrilife, San Angelo, TX Ken Moore, RMS, UT Lands, Big Lake, TX Steve Nelle, Biologist, NRCS, San Angelo, TX Rudy Pederson, RMS, Retired NRCS, San Angelo, TX Darrel Seidel, DC, NRCS, Sanderson, TX Terry Whigham, DC, NRCS, Fort Stockton, TX Stephen Zuberbueler, DC, NRCS, Ozona, TX QC/QA completed by: Bryan Christensen, SRESS, NRCS, Temple, TX Erin Hourihan, ESDQS, NRCS, Temple, TX
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) Contact for lead author Date 08/30/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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