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Conservation Service

Ecological site R081BY354TX

Very Shallow 23-31 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 or bedrock.

Associated sites

R081BY326TX	Clay Loam 23-31 PZ The Clay Loam may be encountered down slope.
R081BY324TX	Clay Flat 23-31 PZ The Clay Flat may be encountered on adjacent slopes.

R081BY326TX

Clay Loam 23-31 PZ

The Clay Loam may be encountered down slope.

R081BY324TX

Clay Flat 23-31 PZ

The Clay Flat may be encountered on adjacent slopes.

Similar sites

R081BY343TX	Shallow 23-31 PZ The Shallow site is similar in that both sites are located on similar topography and parent material.

R081BY343TX

Shallow 23-31 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 steep sloping uplands. 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 1,000 feet to 2,500 feet above sea level. Slope ranges from 1 to 40 percent. The majority of the site is used for rangeland. Runoff is low to very high depending on slope and vegetative cover.

Table 2. Representative physiographic features

Landforms	(1) Plateau > Ridge (2) Plateau > Plain (3) Plateau > Stream terrace
Runoff class	Low to very high
Flooding frequency	None
Ponding frequency	None
Elevation	1,000 – 2,500 ft
Slope	1 – 40%
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)	25-28 in
Frost-free period (actual range)	210-240 days
Freeze-free period (actual range)	240-280 days
Precipitation total (actual range)	24-30 in
Frost-free period (average)	225 days
Freeze-free period (average)	260 days
Precipitation total (average)	27 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) BRADY [USC00411017], Brady, TX
(2) FREDERICKSBURG [USC00413329], Fredericksburg, TX
(3) FT MCKAVETT [USC00413257], Fort Mc Kavett, TX
(4) HUNT 10 W [USC00414375], Hunt, TX
(5) JUNCTION 4SSW [USC00414670], Junction, TX
(6) JUNCTION KIMBLE CO AP [USW00013973], Junction, TX
(7) MENARD [USC00415822], Menard, TX
(8) ROCKSPRINGS 1S [USC00417706], Rocksprings, TX
(9) SAN SABA [USC00417992], San Saba, TX
(10) EDEN [USC00412741], Eden, TX

Soil features

The soils are well drained and permeability is moderately slow to moderately rapid. The parent material is loamy alluvium or residuum derived from limestone. The surface layer is dark grayish-brown, calcareous loam about 6 to 9 inches thick. Depth to the petrocalcic horizon or bedrock 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 95 percent calcium carbonate. Soil series correlated to this site include: Cho, Eckert, Eola, Mailtrail, and Yates.

Table 4. Representative soil features

Parent material	(1) Residuum – limestone (2) Alluvium – limestone and sandstone
Surface texture	(1) Very cobbly loam (2) Very gravelly clay loam (3) Very flaggy fine sandy loam
Family particle size	(1) Loamy (2) Loamy-skeletal
Drainage class	Well drained
Permeability class	Moderately slow to moderately rapid
Depth to restrictive layer	4 – 10 in
Soil depth	4 – 10 in
Surface fragment cover <=3"	2 – 30%
Surface fragment cover >3"	5 – 40%
Available water capacity (0-10in)	0.3 – 1.8 in
Calcium carbonate equivalent (0-10in)	40 – 95%
Electrical conductivity (0-10in)	2 mmhos/cm
Sodium adsorption ratio (0-10in)	Not specified
Soil reaction (1:1 water) (0-10in)	7.4 – 8.4
Subsurface fragment volume <=3" (4-10in)	35%
Subsurface fragment volume >3" (4-10in)	40%

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), little bluestem (Schizachyrium scoparium), feathery bluestems (Bothriochloa spp.), and green sprangletop (Leptochloa dubia) dominated the vegetation in the early 1800’s. Buffalograss (Bouteloua dactyloides) and curlymesquite (Hilaria belangeri) were characteristic shortgrasses. Frequent fires favored grasses over woody plants and forbs, but there were a wide variety of forbs present. Trees, primarily live oak (Quercus virginiana), occupied deeper soil pockets underlain by marl on areas protected from wildfires, shading less than three percent of the site. Because of the effects of infrequent fires, some of the fire resistant woody species existed as shrubs giving the site a shrubby or “shinnery” appearance. Shrubs provided only two to four percent woody plant 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 resulting plant community was a Midgrass Savannah Community (1.2). In this transitional phase, the more palatable midgrasses transition to less palatable, or more grazing resistant, shortgrasses and midgrasses like feathery bluestems, vine mesquite (Panicum obtusum), and curlymesquite. The grassland component still dominated the annual primary production, but the proportion of encroaching woody species, mainly shrubs, was increasing.

When the Midgrass Savannah Community is continually overgrazed and fire is excluded, the process of ecological succession proceeds toward woody plant dominance. The more palatable midgrasses and forbs are replaced by more grazing resistant shortgrasses and less palatable forbs. As grass cover declines, litter, mulch, and soil organic matter decrease and bare ground, erosion, and other desertification processes increase. This is a very fragile site in that small soil losses have a significant impact and the loss is essentially irreversible. The microclimate in the grassland areas becomes more arid. The site becomes favorable to the invasion of species previously repressed by fire or herbaceous competition. Mesquite (Prosopis glandulosa), Ashe juniper (Juniperus ashei), and pricklypear (Opuntia spp.) are early increasers. Redberry juniper (Juniperus pinchotii) often invades the area from the west and north. When the woody plant community exceeds 15 percent canopy and/or the woody invaders become dense enough and large enough to resist fire (about five feet in height), rest from grazing pressure will generally not restore the grassland community. When this plant composition and structure is reached, not enough fine fuel exists for fires to effectively control woody species and forbs. As this threshold is crossed, the plant community transitions into the Mixed-Brush/Shortgrass Community (2.1). This threshold also marks the beginning of the Shrubland State. Until this threshold is breached, the change from grassland to shrubland can be reversed, or halted, with proper grazing management and appropriate prescribed burning practices. Individual plant treatments can also be effective to remove the unwanted woody plants before they become too dense to treat individually.

With continued overgrazing, mesquite and/or juniper continue to increase, and other shrubs begin forming thickets. Buffalograss, curly mesquite, three-awns (Aristida spp.) and broomweed (Gutierrezia spp.) are representative shortgrasses and forbs found in this community. In time, the less palatable or more grazing resistant shortgrasses and forbs will replace the more palatable shortgrasses. Cool-season grasses such as Texas wintergrass (Nassella leucotricha) and annual bromes (Bromus spp.) also increase in the protection and shading of shrubs.

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), wolfberry (Lycium spp.), and javelinabush (Condalia ericoides) often form thickets. The remaining shortgrasses, cool-season grasses, and forbs are in weakened condition. Primary production is from low-quality 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 a 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

More interactive model formats are also available. View Interactive Models
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. Midgrass 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

Figure 8. Midgrass Prairie Community

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), Texas mulberry (Morus microphylla,) and shrubs 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 microsites and is locally abundant. Sideoats grama is the dominant midgrass throughout the site, but Texas cupgrass, green sprangletop, vine mesquite, meadow dropseed (Sporobolus asper var. asper), feathery bluestems, Canada wildrye (Elymus canadensis), and Texas wintergrass (Nassella leucotricha), are also abundant. Shortgrasses included blue grama (Bouteloua gracilis), curlymesquite, 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.). Live oak, hackberry (Celtis spp.) and mesquite are widely scattered tree species. Productivity is limited by the very shallow soils having restrictive layers of caliche and limestone, course surface fragments, and very low water availability. In reference condition, the site produces from 800 to 2,500 pounds per acre annually, depending upon the particular soil series and amount of precipitation. Annual forbs add to the annual production in favorable moisture years. Grasses make up 85 to 90 percent of the annual production. The abundant grass cover and considerable accumulated mulch aide in the infiltration of rainfall and reduces runoff in all but heavy rains. The Midgrass Prairie Community furnishes good habitat for grazing livestock and wildlife. With continued overgrazing, a decrease in intensity and frequency of fires, and no brush management, this plant community transitions very quickly into the Midgrass Savannah 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	680	1700	2125
Forb	56	140	175
Shrub/Vine	40	100	125
Tree	24	60	75
Total	800	2000	2500

Figure 10. 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
Midgrass Savannah

Figure 11. Midgrass Savannah Community

The Midgrass 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 the severity of grazing, time since last burned, and availability of invading species. Typically, mesquite and/or juniper, sumacs (Sumac spp.), agarito, javelinabush, condalia and feather dalea (Dalea spp.) have increased in density and size. The prairie is converting into a savannah by encroaching woody species. Most of the reference grasses are present, although in lesser amounts. Important grasses for this community are sideoats grama, little bluestem, feathery bluestems, tall dropseed, (Sporobolus compositus var. drummondii), meadow dropseed, vine mesquite, plains lovegrass (Eragrostis intermedia), Texas wintergrass, and Canada wildrye. White tridens (Tridens albescens), buffalograss, and curlymesquite are representative shortgrasses. All but the least grazing resistant perennial forbs persist. Annual primary production ranges from 700 to 2,300 pounds, depending on precipitation and the soil series. Forage production is still predominantly grass. 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 on gentle slopes, little soil movement will take place in this vegetation phase. The changes in composition are small initially, but unless proper grazing and prescribed burning are initiated, the woody species continue to increase in size and density. When the canopy of the woody plants becomes dense enough (15 to 20 percent) and tall enough (more than five feet) to suppress grass growth and resist fire damage, a threshold is reached. The Midgrass Savannah Community transitions into the Mixed-Brush/Shortgrass Community (2.1).

Pathway 1.1A
Community 1.1 to 1.2

Midgrass Prairie

Midgrass Savannah

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

Pathway 1.2A
Community 1.2 to 1.1

Midgrass Savannah

Midgrass Prairie

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

State 2
Shrubland

Dominant plant species

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

Community 2.1
Mixed-brush/Shortgrass

Figure 12. Mixed-brush/Shortgrass Community

The Mixed-Brush/Shortgrass Community (2.1) is a shrub invaded grassland with 15 to 30 percent woody plant canopy of mixed-brush. Brush density has increased and shortgrasses have largely replaced midgrasses. This plant community 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 and Ashe juniper are common increasers throughout the MLRA, while redberry juniper (Juniperus pinchotii) is found in the western section. Many of the reference shrubs are present. Javelinabush, agarito, prickly ash (Zanthoxylum spp.), condalia (Condalia spp.), shin oak (Quercus sinuata), 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 lack of vigor and productivity. Characteristic herbaceous species are buffalograss, curlymesquite, three-awns (Aristida spp.), hairy tridens (Erioneuron pilosum), hairy grama (Bouteloua hirsuta), and sedges (Carex spp.), although remnants of the reference midgrasses remain. Representative forbs include dalea (Dalea spp.), gray goldaster (Heterotheca canescens), croton (Croton spp.), verbena (Verbena spp.), Queen’s delight (Stillingia sylvatica), prairie coneflower (Ratibida columnifera), and Western ragweed. As the grassland vegetation declines, more soil is exposed to crusting and erosion. During this phase, sheet and rill erosion can be high, especially on steeper slopes. 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 decline in soil structure and organic matter. Annual primary production is approximately 500 to 2,000 pounds and is balanced between woody and herbaceous species. Browsing animals, such as goats and deer, find fair food value if browsing by sheep or deer 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

Figure 13. Mixed-brush/Shrubland Community

Live oak, juniper and/or mesquite dominate the Mixed-Brush/Shrubland Community (2.2). Common shrubs are pricklypear, agarita, sumacs, condalia, elbowbush, prickly ash (Zanthoxylum spp.), and tasajillo (Cylindropuntia leptocaulis). Brush cover is greater than 30 percent and can exceed 50 percent ground cover. Only remnants of reference grasses, forbs, and unpalatable invaders occupy the interspaces. Characteristic grasses found in this plant community are Texas wintergrass, sedges (Carex spp.), tumble windmillgrass (Chloris verticellata), Hall’s panicum (Panicum hallii var. hallii), rough tridens (Tridens muticus var. muticus), slim tridens (Tridens muticus), fall witchgrass (Digitaria cognata), Texas grama (Bouteloua rigidiseta var. rigidiseta), and red grama (Bouteloua trifida). Characteristic forbs include dotted gayfeather (Liatris punctata var. punctata), orange zexmenia (Wedelia hispida), croton (Croton spp.), Western ragweed (Ambrosia psilostachya), prairie coneflower (Ratibida columnifera), gray goldaster, 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

Mixed-brush/Shortgrass

Mixed-brush/Shrubland

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			80–250
	little bluestem	SCSC	Schizachyrium scoparium	80–250	–
2	midgrasses			240–750
	sideoats grama	BOCU	Bouteloua curtipendula	240–750	–
	blue grama	BOGR2	Bouteloua gracilis	240–750	–
	beardgrass	BOTHR	Bothriochloa	240–750	–
	green sprangletop	LEDU	Leptochloa dubia	240–750	–
3	midgrasses			200–625
	plains lovegrass	ERIN	Eragrostis intermedia	200–625	–
	bush muhly	MUPO2	Muhlenbergia porteri	200–625	–
	vine mesquite	PAOB	Panicum obtusum	200–625	–
	Reverchon's bristlegrass	SERE3	Setaria reverchonii	200–625	–
	plains bristlegrass	SEVU2	Setaria vulpiseta	200–625	–
	composite dropseed	SPCOC2	Sporobolus compositus var. compositus	200–625	–
	Drummond's dropseed	SPCOD3	Sporobolus compositus var. drummondii	200–625	–
	white tridens	TRAL2	Tridens albescens	200–625	–
4	shortgrasses			80–250
	buffalograss	BODA2	Bouteloua dactyloides	80–250	–
	curly-mesquite	HIBE	Hilaria belangeri	80–250	–
5	shortgrasses			40–125
	threeawn	ARIST	Aristida	40–125	–
	hairy grama	BOHI2	Bouteloua hirsuta	40–125	–
	Texas grama	BORI	Bouteloua rigidiseta	40–125	–
	red grama	BOTR2	Bouteloua trifida	40–125	–
	fall witchgrass	DICO6	Digitaria cognata	40–125	–
	Scribner's rosette grass	DIOLS	Dichanthelium oligosanthes var. scribnerianum	40–125	–
	hairy woollygrass	ERPI5	Erioneuron pilosum	40–125	–
	sand dropseed	SPCR	Sporobolus cryptandrus	40–125	–
	slim tridens	TRMU	Tridens muticus	40–125	–
	slim tridens	TRMUE	Tridens muticus var. elongatus	40–125	–
6	cool-season grasses			40–125
	sedge	CAREX	Carex	40–125	–
	Canada wildrye	ELCA4	Elymus canadensis	40–125	–
	Texas wintergrass	NALE3	Nassella leucotricha	40–125	–
Forb
7	forbs			56–175
	Indian mallow	ABUTI	Abutilon	56–175	–
	onion	ALLIU	Allium	56–175	–
	Cuman ragweed	AMPS	Ambrosia psilostachya	56–175	–
	white sagebrush	ARLU	Artemisia ludoviciana	56–175	–
	aster	ASTER	Aster	56–175	–
	milkvetch	ASTRA	Astragalus	56–175	–
	Drummond's clematis	CLDR	Clematis drummondii	56–175	–
	croton	CROTO	Croton	56–175	–
	prairie clover	DALEA	Dalea	56–175	–
	purple prairie clover	DAPU5	Dalea purpurea	56–175	–
	bundleflower	DESMA	Desmanthus	56–175	–
	blacksamson echinacea	ECAN2	Echinacea angustifolia	56–175	–
	Engelmann's daisy	ENPE4	Engelmannia peristenia	56–175	–
	beeblossom	GAURA	Gaura	56–175	–
	false goldenaster	HETER8	Heterotheca	56–175	–
	trailing krameria	KRLA	Krameria lanceolata	56–175	–
	dotted blazing star	LIPU	Liatris punctata	56–175	–
	menodora	MENOD	Menodora	56–175	–
	catclaw mimosa	MIACB	Mimosa aculeaticarpa var. biuncifera	56–175	–
	Texas sacahuista	NOTE	Nolina texana	56–175	–
	Texas sage	SATE3	Salvia texana	56–175	–
	awnless bushsunflower	SICA7	Simsia calva	56–175	–
	globemallow	SPHAE	Sphaeralcea	56–175	–
	queen's-delight	STSY	Stillingia sylvatica	56–175	–
	vervain	VERBE	Verbena	56–175	–
	creepingoxeye	WEDEL	Wedelia	56–175	–
Shrub/Vine
8	shrubs/vines			40–125
	acacia	ACACI	Acacia	40–125	–
	catclaw acacia	ACGR	Acacia greggii	40–125	–
	snakewood	CONDA	Condalia	40–125	–
	featherplume	DAFO	Dalea formosa	40–125	–
	jointfir	EPHED	Ephedra	40–125	–
	Texas kidneywood	EYTE	Eysenhardtia texana	40–125	–
	stretchberry	FOPU2	Forestiera pubescens	40–125	–
	snakeweed	GUTIE	Gutierrezia	40–125	–
	desert-thorn	LYCIU	Lycium	40–125	–
	algerita	MATR3	Mahonia trifoliolata	40–125	–
	pricklypear	OPUNT	Opuntia	40–125	–
	fragrant sumac	RHAR4	Rhus aromatica	40–125	–
	littleleaf sumac	RHMI3	Rhus microphylla	40–125	–
	evergreen sumac	RHVIV	Rhus virens var. virens	40–125	–
	greenbrier	SMILA2	Smilax	40–125	–
	yucca	YUCCA	Yucca	40–125	–
Tree
9	trees			24–75
	eastern redbud	CECA4	Cercis canadensis	24–75	–
	netleaf hackberry	CELAR	Celtis laevigata var. reticulata	24–75	–
	juniper	JUNIP	Juniperus	24–75	–
	littleleaf leadtree	LERE5	Leucaena retusa	24–75	–
	Texas mulberry	MOMI	Morus microphylla	24–75	–
	mesquite	PROSO	Prosopis	24–75	–
	oak	QUERC	Quercus	24–75	–

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 6 to 9 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 allow 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 Midgrass 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 40 to 50 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

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

Information presented was 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 Review:
Charles Anderson, RMS, NRCS, San Angelo, TX
Justin Clary, RMS, NRCS, Temple, TX
Carol Green, RMS, NRCS, Eldorado, TX
Mark Moseley, RMS, NRCS, Boerne, 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	09/21/2023
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