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Conservation Service

Ecological site R081BY353TX

Very Shallow 19-23 PZ

Last updated: 9/19/2023
Accessed: 11/21/2024

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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.

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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): 081B–Edwards Plateau, Central Part

This area is entirely in south-central Texas. It makes up about 11,125 square miles (28,825 square kilometers). The towns of Fredericksburg, Junction, Menard, Rocksprings, and Sonora are in this MLRA. Interstate 10 crosses the middle part of the area. A few State parks and State historic sites are in this MLRA.

Classification relationships

USDA-Natural Resources Conservation Service, 2006.
-Major Land Resource Area (MLRA) 81B

Ecological site concept

The Very Shallow ecological site is located on uplands with soils less than 10 inches deep over a petrocalcic horizon.

Associated sites

R081BY323TX	Clay Flat 19-23 PZ The Clay Flat site is found on similar sites but deeper soils in depressions.
R081BY333TX	Loamy 19-23 PZ The Loamy site is found on deeper soils.
R081BY325TX	Clay Loam 19-23 PZ The Clay Loam site can be found on adjacent slopes or slightly downslope on terraces.
R081BY593TX	Limestone Hill 19-23 PZ The Limestone Hill site may be encountered upslope.

Similar sites

R081BY342TX	Shallow 19-23 PZ The Shallow Site is similar in that both sites are located on similar topography and parent material.

R081BY342TX

Shallow 19-23 PZ

The Shallow Site is similar in that both sites are located on similar topography and parent material.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Bouteloua curtipendula (2) Schizachyrium scoparium

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Physiographic features

Sites are on nearly level to gently sloping uplands with a petrocalcic horizon. They are formed in calcareous loamy alluvium derived from limestone. This site is usually found on stream terraces, alluvial fans, hills, ridges, divides, and foot slopes. The elevation ranges from 1,200 feet to 2,700 feet above sea level. Slope ranges from 1 to 8 percent. The majority of the site is used for rangeland. Runoff is medium to very high.

Table 2. Representative physiographic features

Landforms	(1) Plateau > Stream terrace (2) Plateau > Ridge (3) Plateau > Plain
Runoff class	Medium to very high
Flooding frequency	None
Ponding frequency	None
Elevation	1,200 – 2,700 ft
Slope	1 – 8%
Aspect	Aspect is not a significant factor

Climatic features

The climate in the MLRA 81B is subtropical subhumid on the eastern portion and subtropical steppe on the western portion of the MLRA. Winters are dry, and the summers are hot and humid. The precipitation increases from west to east and the temperatures increase from north to south. The area usually receives 65 to 70 percent sunshine each year. The majority of the rainfall occurs during the warm months of April to October. Most precipitation comes from thunderstorms that vary in the amount of water received and the areas covered. Spring is characterized by fluctuating patterns, but mild temperatures prevail. July and August are relatively dry and hot with little weather variability day-to-day. As summer progresses through fall, an increase of precipitation usually occurs in the eastern portions while a decrease of precipitation occurs to the west. Winter temperatures are mild, but polar Canadian air masses bring rapid drops in temperature. These cold spells last 2 or 3 days. Prevailing winds are southerly with March and April the windiest months.

Table 3. Representative climatic features

Frost-free period (characteristic range)	210-240 days
Freeze-free period (characteristic range)	240-280 days
Precipitation total (characteristic range)	19-24 in
Frost-free period (actual range)	210-240 days
Freeze-free period (actual range)	240-280 days
Precipitation total (actual range)	19-25 in
Frost-free period (average)	225 days
Freeze-free period (average)	260 days
Precipitation total (average)	22 in

Characteristic range

Actual range

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Figure 2. Monthly precipitation range

Characteristic range

Actual range

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Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 4. Monthly maximum temperature range

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Figure 5. Monthly average minimum and maximum temperature

Figure 6. Annual precipitation pattern

Figure 7. Annual average temperature pattern

Climate stations used

(1) OZONA [USC00416734], Ozona, TX
(2) CARTA VALLEY [USC00411492], Rocksprings, TX
(3) ELDORADO [USC00412809], Eldorado, TX
(4) SONORA [USC00418449], Sonora, TX
(5) BIG LAKE 2 [USC00410779], Big Lake, TX

Soil features

The soils are well drained and permeability is moderate. The parent material is loamy alluvium, derived from limestone and/or sandstone. The surface layer is dark grayish-brown, calcareous loam about 6 to 9 inches thick. Depth to the petrocalcic horizon is generally less than 10 inches. Cemented caliche fragments occur throughout the soil profile. Gravel and/or cobble occupy up 40 percent on the surface and as much as 50 percent in the subsoil. The available water capacity is low the soil profile can contain as much as 70 percent calcium carbonate. Soil series correlated to this site include: Cho and Mailtrail.

Table 4. Representative soil features

Parent material	(1) Alluvium – limestone and sandstone
Surface texture	(1) Gravelly loam (2) Very gravelly clay loam
Family particle size	(1) Loamy (2) Loamy-skeletal
Drainage class	Well drained
Permeability class	Moderate
Depth to restrictive layer	4 – 10 in
Soil depth	4 – 10 in
Surface fragment cover <=3"	20 – 40%
Surface fragment cover >3"	5%
Available water capacity (0-10in)	0.6 – 1.1 in
Calcium carbonate equivalent (0-10in)	40 – 85%
Electrical conductivity (0-10in)	2 mmhos/cm
Sodium adsorption ratio (0-10in)	1
Soil reaction (1:1 water) (0-10in)	7.4 – 8.4
Subsurface fragment volume <=3" (4-10in)	15 – 30%
Subsurface fragment volume >3" (4-10in)	5%

Ecological dynamics

The Very Shallow Ecological Site is a midgrass dominated prairie with widely scattered trees and understory shrubs. Historically, the site evolved under the influences of grazing and browsing by endemic pronghorn antelope, deer, and migratory bison, severe droughts, and frequent fires. Fires are estimated to have occurred at 7 to 12 year-intervals maintaining brushy and woody species at about five percent canopy. The frequent fires and droughts were postulated to be the major influences on developing the plant communities.

Midgrasses such as sideoats grama (Bouteloua curtipendula) and little bluestem (Schizachyrium scoparium) are the co-dominants, with sideoats grama becoming more prominent to the west. Other midgrasses, including several feathery bluestems (Bothriochloa spp.) and green sprangletop (Leptochloa dubia), make significant contributions to production. Blue grama (Bouteloua gracilis), black grama (Bouteloua eriopoda), buffalograss (Bouteloua dactyloides), and curlymesquite (Hilaria belangeri) are characteristic shortgrasses. Frequent fires favor grasses over woody plants and forbs, but a wide variety of both are present. Trees, primarily live oak (Quercus virginiana), occupied deeper soil pockets underlain by marl on areas protected from fires, covering less than two percent of the ground area. Shrubs occupy two to four percent canopy.

The Midgrass Prairie Community (1.1) was relatively stable and resilient within the climate, soil, grazing, and fire regime until settlement and the advent of fencing and animal husbandry in the late 1800’s. Not understanding the limits of rangeland productivity, European settlers overstocked livestock almost universally. As overgrazing by livestock and wildlife occurred, there was a reduction of palatable plants, a decline in plant cover, mulch, soil organic matter, and 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 herbaceous increasers were generally endemic species released from the effects of fire or from competition. The resultant plant community was a Mid/Shortgrass Savannah Community (1.2). In this phase, the more palatable midgrasses transition to less palatable, or more grazing resistant, shortgrasses and midgrasses like feathery bluestems and plains lovegrass (Eragrostis intermedia). The grassland component still dominated primary production, but the proportion of encroaching woody species, mainly shrubs, was increasing.

When the Mid/Shortgrass Savannah Community (1.2) was continually overgrazed and fire is excluded, the process of regression proceeded toward woody plant dominance and replacement of the midgrasses with more grazing resistant shortgrasses and less palatable forbs. As grass 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 (Prosopis glandulosa) and Ashe juniper (Juniperus ashei). Redberry juniper (Juniperus pinchotii) often invades from the west and north. Rest from grazing will generally not restore the grassland community when the woody plant community exceeds 15 percent canopy and/or the woody invaders become dense and large enough to resist fire (about three feet in height). When this plant composition and structure is reached, not enough fine fuel exists for fires to effectively control woody species and forbs. When this threshold is crossed, the site changes into the Mixed Brush/Shortgrass Community (2.1). This transition also marks the beginning of the Shrubland state. The transition is not reversible without considerable input of energy and expense in the form of brush control.

With overgrazing being persistent, mesquite, juniper and other shrubs continue to increase forming thickets in the Mixed Brush/Shortgrass Community (2.1). Buffalograss, curlymesquite, three-awns (Aristida spp.), and broomweed (Gutierrezia spp.) are the typical shortgrass vegetation. With continued overgrazing, the more palatable grasses will be replaced by less palatable shortgrasses and forbs. Cool-season grasses such as Texas wintergrass (Nassella leucotricha) and annual bromes (Bromus spp.) also increase.

In the Mixed-Brush/Shortgrass Community (2.1), the process of retrogression can be reversed with moderately intensive brush control and good grazing management that allows the application of prescribed burning. If these conservation practices are not applied, the woody canopy will continue to increase in dominance and ground cover, even without livestock grazing or deer browsing. Once brush cover exceeds 25 to 30 percent, understory herbage production is very limited and generally composed of unpalatable shrubs, grasses, and forbs in the woody interspaces. The resultant woody plant dominated community is the Mixed-Brush/Shrubland Community (2.2). Mesquite and/or juniper dominate the overstory, although occasionally oaks are present. Brushy species such as agarito (Mahonia trifoliata), prickly pear (Opuntia spp.), and javelinabush (Condalia ericoides) often form thickets. The remaining shortgrasses, cool-season grasses, and forbs are in weakened condition. Primary production is from lower successional trees, shrubs, forbs, and grasses.

The microclimate becomes drier as interception losses increase with brush canopy cover and more runoff occurs during rainfall. Litter amounts are greatly reduced exposing bare soil. The exposed soil crusts readily, creating opportunities for rill erosion to occur. Considerable litter and soil movement occur during heavy rainfall events. Until maximum ground cover by woody species is approached, desertification and erosion continue in the interspaces. Once shrub canopy cover is maximized, however, the hydrologic processes, energy flow, and nutrient cycling stabilize under the woodland/shrubland environment. This process may take many years to become stable.

Major expense and energy are required to restore the Mixed-Brush/Shrubland Community (2.2) back to the productive grassland community. Generally, expensive mechanical or herbicidal treatments (IPT) range planting, grazing deferment, and prescribed burning are required for restoration. Erosion and fertility losses during the retrogression process may preclude the plant community’s ability to be restored. Very little of the Very Shallow site has been plowed because the lack of soil depth is not well suited for cultivation. The site is highly erodible when exposed by overgrazing, cultivation, or crop production. There are, however, some areas of the site planted to pasture grasses, small grains, or wildlife food plots. Many of these are inclusions with adjacent Shallow or Clay Loam sites. Generally, most fields in the Very Shallow Site previously cultivated for crops have been returned to native grasses and managed as rangeland.

State and transition model

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Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Grassland

2. Shrubland

T1A	-	Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure
R2A	-	Reintroduction of historic disturbance return intervals

State 1 submodel, plant communities

1.1. Midgrass Prairie

1.2. Mid/Shortgrass Savannah

State 2 submodel, plant communities

2.1. Mixed-brush/Shortgrass

2.2. Mixed-brush/Shrubland

State 1
Grassland

Dominant plant species

sideoats grama (Bouteloua curtipendula), grass
little bluestem (Schizachyrium scoparium), grass

Community 1.1
Midgrass Prairie

The reference plant community is a fire-maintained prairie of midgrasses. Woody plants, mostly shrubs provided little canopy cover. Live oak, netleaf hackberry (Celtis laevigata var. reticulata), and other small trees are widely scattered in protected areas and along draws. Catclaw acacia (Acacia greggii), sumacs (Rhus spp.), Texas kidneywood (Eysenhardtia texana), elbowbush (Forestiera pubescens), ephedra (Ephedra spp.), and javelinabush are typical shrubs. Little bluestem occupies favorable micro-sites and is locally abundant. Sideoats grama is the dominant grass throughout. Also occurring in smaller amounts, are meadow dropseed (Sporobolus compositus var. asper), feathery bluestems (Bothriochloa spp.), Arizona cottontop (Digitaria californica), Canada wildrye (Elymus canadensis), Texas wintergrass (Nassella leucotricha), vine mesquite (Panicum obtusum), and a number of shortgrasses. Shortgrasses include blue grama, black grama, curly mesquite, buffalograss, tridens (Tridens spp.), and bristlegrass (Setaria spp.). Characteristic forbs are dotted gayfeather (Liatris punctata), trailing ratany (Krameria lanceolata), awnless bushsunflower (Simsia calva), Engelmann’s daisy (Engelmannia peristenia), wooly-white (Hymenopappus spp.), half-shrub sundrop (Calylophus serrulatus), catclaw sensitivebriar (Mimosa aculeaticarpa var. biuncifera), and bundleflower (Desmanthus spp.). Texas redbud (Cercis canadensis var. texensis) and mesquite (Prosopis glandulosa) are widely scattered tree species. Productivity of the site is limited by the very shallow soils with restrictive layers of caliche and limestone, coarse surface fragments, and very low water availability. In reference condition, annual production ranges from 500 to 2,000 pounds per acre annually, depending upon the particular soil series and amount of precipitation. Production declines from east to west in response to average annual precipitation. Grasses make up to 90 to 95 percent of the total herbage. The grass cover and accumulated mulch aide in the infiltration of rainfall into the slowly permeable soil and reduces runoff. The Midgrass Prairie Plant Community (1.1) furnishes good habitat for grazing livestock and wildlife. But, with overgrazing, decreases in fires, and no brush management, this plant community will transition very quickly to the Mid/Shortgrass Savannah Community (1.2).

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	450	1350	1800
Shrub/Vine	20	60	80
Forb	20	60	80
Tree	10	30	40
Total	500	1500	2000

Figure 9. Plant community growth curve (percent production by month). TX3614, Midgrass & Shortgrass Savannah Community. Warm-season rangeland with peaks in production from April, May and June and in September and October..

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	3	5	13	23	15	4	5	15	7	5	3

Community 1.2
Mid/Shortgrass Savannah

The Mid/Shortgrass Savannah Community is a grassland being invaded by indigenous or woody species that had been held at low densities by repeated fires or competition from a vigorous grass component. Numerous brushy species, plus juniper and mesquite, are increasing in density because overgrazing by livestock has reduced grass cover, increased soil exposure, and reduced fine fuel for fire. In this phase, 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 10 and 15 percent depending on severity of grazing, time since last burned, and availability of invading species. Besides juniper and mesquite, other brushy species include sumacs (Sumac spp.), agarito, javelinabush, condalia, elbowbush, and feather dalea (Dalea spp.). The prairie is converting into a savannah by encroaching woody species. The more grazing-resistant grasses are replacing the preferred grasses. Grasses still occurring are sideoats grama, tall dropseed (Sporobolus compositus var. drummondii), meadow dropseed, vine mesquite, plains lovegrass, Texas wintergrass, and Canada wildrye (Elymus canadensis). All but the least grazing resistant climax perennial forbs persist. Annual primary production ranges from 500 to 2,000 pounds per acre depending on precipitation and the soil series. Forage production is still predominantly grass. There could be some mulch and litter movement during rainfall events but due to gentle slopes little soil movement would take place during this vegetation phase. The changes in composition are small initially, but unless proper grazing and prescribed burning are initiated at this stage, the woody species would continue to increase in stature and density. When the canopy of the woody plants becomes dense enough (15 to 20 percent) and tall enough (more than three feet) to suppress grass growth and resist fire damage, a threshold in ecological regression is reached. The Mid/Shortgrass Savannah Community (1.2) becomes the Mixed-Brush/Shortgrass Plant Community (2.1).

Pathway 1.1A
Community 1.1 to 1.2

Overgrazing, lack of fire, and allowing woody species to proliferate will shift the reference community into a Mid/Shortgrass Savannah Community (1.2).

Pathway 1.2A
Community 1.2 to 1.1

Prescribed grazing, return of fire, and brush management can return the Mid/Shortgrass Savannah Community (1.2) to reference conditions.

State 2
Shrubland

Dominant plant species

mesquite (Prosopis), shrub
Pinchot's juniper (Juniperus pinchotii), shrub

Community 2.1
Mixed-brush/Shortgrass

The Mixed Brush/Shortgrass Community (2.1) is shrub invaded grassland with a 15 to 25 percent woody plant canopy of mixed-brush, mainly mesquite and juniper. It is the result of selective overgrazing and browsing resulting in a differential response of plants to defoliation. With continued overgrazing, the diversity of the grassland species declines, while woody species and unpalatable forbs increase. All but the most palatable woody species increase in density and size. Mesquite is an early increaser throughout the MLRA, while redberry juniper (Juniperus pinchotii) is found in the western section. Many of the reference shrubs are present and javelinabush, agarito, pricklypear, prickly ash (Zanthoxylum spp.), condalia (Condalia spp.), and sumac often form thickets. Remnants of reference grasses, 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 where they find protection from grazing. Because of pressure and competition for nutrients and water, the grassland component shows a lack of vigor and productivity. Characteristic herbaceous species are three-awns (Aristida spp.), hairy tridens (Erioneuron pilosum), hairy grama (Bouteloua hirsuta), sedges (Carex spp.), Queen’s delight (Stillingia sylvatica), prairie coneflower (Ratibida columnifera), Texas grama (Bouteloua rigidiseta var. rigidiseta), and red grama (Bouteloua trifida). Buffalograss (Buchloe dactyloides), curlymesquite (Hilaria belangeri), and tobosa (Phleuraphis muticus) are persistent increasers until shrub density reaches the maximum. As the grassland vegetation declines, more soil is exposed to crusting and erosion. During this phase, sheet and rill erosion can be high. Higher interception losses by the increasing woody canopy combined with evaporation and runoff can reduce the effectiveness of rainfall. Primary plant production has decreased due to the decline in soil structure and organic matter. Annual primary production is approximately 400 to 1,500 pounds per acre and is balanced between woody and herbaceous species. Browsing animals, such as goats and deer, find fair food value if browsing has not been excessive, but forage quality for cattle is low. Good grazing management alone cannot reverse the succession towards dense shrubland. Unless brush management practices are applied at this stage, the transition will continue. The trend can be reversed with intensive brush management such as individual plant treatments combined with prescribed grazing and burning.

Community 2.2
Mixed-brush/Shrubland

Juniper and/or mesquite dominate the Mixed-Brush/Shrubland Community (2.2). Common shrubs are pricklypear, agarita, sumacs, condalia, yucca, elbowbush, prickly ash (Zanthoxylum spp.), croton (Croton spp.) and tasajillo (Opuntia leptocaulis). The brushy shrubs can approach 50 percent ground cover with heavy abusive grazing. Shortgrasses and low-quality annual and perennial forbs occupy the woody interspaces. Characteristic grasses are Texas wintergrass, sedges (Carex spp.), hooded windmillgrass (Chloris cucullata), Hall’s panicum (Panicum hallii var. hallii), rough tridens (Tridens muticus var. muticus), slim tridens (Tridens muticus), and fall witchgrass (Digitaria cognata). Characteristic forbs include dotted gayfeather (Liatris punctata var. punctata), orange zexmania (Wedelia hispida), croton (Croton spp.), Western ragweed (Ambrosia psilostachya), prairie coneflower (Ratibida columnifera), and broomweed (Gutierrezia spp.). The shrub canopy acts to intercept rainfall and increase evapotranspiration losses, creating a more xeric microclimate. Soil organic matter and mulch are reduced, exposing more soil surface. The exposed soil crusts readily and becomes susceptible to wind and water erosion. Rill erosion, terracettes, and pedestaling are common under extreme conditions. Unless brush control and proper stocking are applied, the brush community will continue to thicken until it stabilizes with the climate and soil. Good cover for wildlife can still be found, but only limited preferred forage and browse are available for livestock or wildlife. Alternatives for restoration include brush control and range planting to return vegetation back to the desired plant community and then prescribed grazing and prescribed burning to maintain the desired plant community. Without major management inputs, this state cannot be reversed.

Pathway 2.1A
Community 2.1 to 2.2

Continued heavy grazing, lack of fire, and absence of brush management will transition the site into a Mixed-brush/Shrubland Community.

Transition T1A
State 1 to 2

Heavy abusive grazing, absence of fire, and lack of brush management transition this site to a Shrubland State (2).

Restoration pathway R2A
State 2 to 1

Prescribed grazing, prescribed burning, brush management, and possibly range planting are required to restore the Shrubland State (2) back to the reference state. Depending on previous land history, erosion and soil fertility may be so low that a full restoration is unattainable.

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1	Tallgrass			25–100
	little bluestem	SCSC	Schizachyrium scoparium	25–100	–
2	Midgrasses			150–600
	sideoats grama	BOCU	Bouteloua curtipendula	150–600	–
	beardgrass	BOTHR	Bothriochloa	150–600	–
3	Midgrasses			75–300
	green sprangletop	LEDU	Leptochloa dubia	75–300	–
	vine mesquite	PAOB	Panicum obtusum	75–300	–
	plains bristlegrass	SEVU2	Setaria vulpiseta	75–300	–
4	Shortgrasses			50–200
	black grama	BOER4	Bouteloua eriopoda	50–200	–
	blue grama	BOGR2	Bouteloua gracilis	50–200	–
5	Midgrasses			50–200
	plains lovegrass	ERIN	Eragrostis intermedia	50–200	–
	bush muhly	MUPO2	Muhlenbergia porteri	50–200	–
	composite dropseed	SPCOC2	Sporobolus compositus var. compositus	50–200	–
	Drummond's dropseed	SPCOD3	Sporobolus compositus var. drummondii	50–200	–
	white tridens	TRAL2	Tridens albescens	50–200	–
6	Shortgrasses			50–200
	buffalograss	BODA2	Bouteloua dactyloides	50–200	–
	curly-mesquite	HIBE	Hilaria belangeri	50–200	–
7	Shortgrasses			25–100
	threeawn	ARIST	Aristida	25–100	–
	hairy grama	BOHI2	Bouteloua hirsuta	25–100	–
	fall witchgrass	DICO6	Digitaria cognata	25–100	–
	tobosagrass	PLMU3	Pleuraphis mutica	25–100	–
	Reverchon's bristlegrass	SERE3	Setaria reverchonii	25–100	–
	sand dropseed	SPCR	Sporobolus cryptandrus	25–100	–
	slim tridens	TRMU	Tridens muticus	25–100	–
	slim tridens	TRMUE	Tridens muticus var. elongatus	25–100	–
8	Cool-season grasses			25–100
	cedar sedge	CAPL3	Carex planostachys	25–100	–
	Canada wildrye	ELCA4	Elymus canadensis	25–100	–
	Texas wintergrass	NALE3	Nassella leucotricha	25–100	–
Forb
9	Forbs			20–80
	Indian mallow	ABUTI	Abutilon	20–80	–
	white sagebrush	ARLUM2	Artemisia ludoviciana ssp. mexicana	20–80	–
	aster	ASTER	Aster	20–80	–
	milkvetch	ASTRA	Astragalus	20–80	–
	Drummond's clematis	CLDR	Clematis drummondii	20–80	–
	croton	CROTO	Croton	20–80	–
	prairie clover	DALEA	Dalea	20–80	–
	purple prairie clover	DAPU5	Dalea purpurea	20–80	–
	bundleflower	DESMA	Desmanthus	20–80	–
	Engelmann's daisy	ENPE4	Engelmannia peristenia	20–80	–
	beeblossom	GAURA	Gaura	20–80	–
	hoary false goldenaster	HECA8	Heterotheca canescens	20–80	–
	trailing krameria	KRLA	Krameria lanceolata	20–80	–
	dotted blazing star	LIPU	Liatris punctata	20–80	–
	menodora	MENOD	Menodora	20–80	–
	Nuttall's sensitive-briar	MINU6	Mimosa nuttallii	20–80	–
	Texas sacahuista	NOTE	Nolina texana	20–80	–
	Texas sage	SATE3	Salvia texana	20–80	–
	awnless bushsunflower	SICA7	Simsia calva	20–80	–
	globemallow	SPHAE	Sphaeralcea	20–80	–
	queen's-delight	STSY	Stillingia sylvatica	20–80	–
	creepingoxeye	WEDEL	Wedelia	20–80	–
Shrub/Vine
10	Shrubs/Vines			20–80
	acacia	ACACI	Acacia	20–80	–
	catclaw acacia	ACGR	Acacia greggii	20–80	–
	snakewood	CONDA	Condalia	20–80	–
	featherplume	DAFO	Dalea formosa	20–80	–
	jointfir	EPHED	Ephedra	20–80	–
	Texas kidneywood	EYTE	Eysenhardtia texana	20–80	–
	stretchberry	FOPU2	Forestiera pubescens	20–80	–
	snakeweed	GUTIE	Gutierrezia	20–80	–
	desert-thorn	LYCIU	Lycium	20–80	–
	algerita	MATR3	Mahonia trifoliolata	20–80	–
	pricklypear	OPUNT	Opuntia	20–80	–
	fragrant sumac	RHAR4	Rhus aromatica	20–80	–
	littleleaf sumac	RHMI3	Rhus microphylla	20–80	–
	evergreen sumac	RHVIV	Rhus virens var. virens	20–80	–
	yucca	YUCCA	Yucca	20–80	–
	Hercules' club	ZACL	Zanthoxylum clava-herculis	20–80	–
Tree
11	Trees			10–40
	eastern redbud	CECA4	Cercis canadensis	10–40	–
	netleaf hackberry	CELAR	Celtis laevigata var. reticulata	10–40	–
	juniper	JUNIP	Juniperus	10–40	–
	mesquite	PROSO	Prosopis	10–40	–
	oak	QUERC	Quercus	10–40	–

Interpretations

Animal community

This site is used to produce domestic livestock and to provide habitat for native wildlife. Cow-calf operations are the primary livestock enterprise, although stocker cattle are also grazed. Sheep, Angora goats, and Spanish goats were formerly raised in large numbers. Sheep are still present in reduced numbers, while meat goats are now present in fairly high numbers. Boer goats have been introduced, either purebred or crossed with Spanish goats, to obtain a larger meat animal. Reports indicate that Boers do not browse as heavily as earlier breeds.

Sustainable stocking rates have declined drastically over the past 100 years due to the 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 careful observation of the plant community’s response to animal foraging.

A large diversity of wildlife is native to this site. In the reference plant community, migrating bison, grazing primarily during wetter periods, pronghorn, white-tailed deer and turkey were the more predominant herbivore 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.

Except for a few domestic herds, bison have been eliminated. 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 the plant community.

Various species of exotic wildlife have been introduced on the site, including deer such as axis, sika, fallow, and red; antelope such as sable, oryx, blackbuck, and nilgai, and sheep such as barbados (mouflon) and aoudad with various degrees of success. Their numbers must be included along with livestock and native wildlife, primarily white-tailed deer, in any management plan. Feral hogs may feed on the site. They can be damaging to the plant community if their numbers are not managed. Smaller mammals include many kinds of rodents, jackrabbit, cottontail, raccoon, ringtail, skunk, 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 or ocelot 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 turkey, bobwhite quail, scaled (blue) quail, and mourning dove. Turkeys prefer plant communities with substantial amounts of shrubs and trees interspersed with grassland. Quail prefer a combination of low shrubs, bunch grass (critical for nesting cover), bare ground, and low successional forbs. 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. Different species of raptors benefit from a diverse plant community as well.

Hydrological functions

The site is a well-drained, very shallow upland with nearly level to gentle slopes. Most soils are six to nine inches deep with pockets of deeper soils included. The shallowness to a hard limestone or caliche layer limits water holding capacity. Runoff is slow due to gentle slopes if there is a good vegetative cover. Exposed soil crusts readily which allows the soil to become more susceptible to runoff and erosion. Under reference conditions, grassland vegetation intercepts and utilizes much of the incoming rainfall. Only during extended rains or heavy thunderstorms does runoff occur. 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 Mid/Shortgrass Savannah Community (1.2). These processes continue as the site transitions to the Mixed-Brush/Shortgrass Community (2.1), and finally the Mixed-Brush/Shrubland Community (2.2). As canopy surpasses 30 to 40 percent, the hydrological and ecological processes, nutrient cycling, and energy flow stabilize within the woody plant canopy. Evaporation and interception losses are higher, however, resulting in less moisture reaching the soil. If overgrazing continues, the plant community deteriorates further, and desertification processes continue. Decreased mulch and more bare ground allow erosion from soils in openings between trees until a mature shrubland state is reached.

Recreational uses

The Very Shallow site occurs in association with Limestone Hill 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 area provides diverse scenic beauty and many opportunities for recreation and hunting.

Wood products

Posts and specialty wood products are made from juniper, mesquite, oak, and many shrubs. Mesquite, juniper, and oak are used for posts and firewood.

Other products

Jams and jellies are made from many fruit-bearing species. Seeds are harvested from many plants for commercial sale. Grasses and forbs may be harvested by the dried-plant industry for sale in dried flower arrangements. Honeybees are utilized to harvest honey from the many flowering plants.

Supporting information

Inventory data references

Eight records were used from Sterling and Taylor Counties. Information presented here has been derived from the revised Very Shallow Range Site, literature, limited NRCS clipping data (417s), field observations, and personal contacts with range-trained personnel. Photos by J. L. Schuster.

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

Dr. Joseph Schuster, Range & Wildlife Habitat Consultants, LLC, Bryan, TX
Edits by Travis Waiser, MLRA Leader, NRCS, Kerrville, TX

Approval

Bryan Christensen, 9/19/2023

Acknowledgments

Technical Assistance:
Charles Anderson, RMS, NRCS, San Angelo, TX
Justin Clary, RMS, NRCS, Temple, TX
Carroll Green, RMS, NRCS, Eldorado, TX
Homer Sanchez, RMS, NRCS, Temple, 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	09/20/2023
Approved by	Bryan Christensen
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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:
Perennial plant reproductive capability:

Download reference sheet

Click on box and path labels to scroll to the respective text.

Ecosystem states

1. Grassland

2. Shrubland

T1A	-	Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure
R2A	-	Reintroduction of historic disturbance return intervals