Physiographic features

The Very Shallow Ecological site occurs on nearly level to moderately sloping, outwash plains, stream terraces, alluvial fans, ridgetops and breaks of erosional uplands. The soils were formed in calcareous and loamy sediments several feet thick; either residuum from indurated limestone or loamy calcareous gravelly alluvium. Soils are very shallow and shallow to a petrocalcic horizon, well drained, and moderately permeable. The site generally will not receive runoff from adjacent ecological sites. Slopes are smooth to convex and range from 1 to 30 percent. Elevation of the site ranges from 1200 to 2400 feet above mean sea level.

Table 2. Representative physiographic features

Climatic features

The climate of MLRA 78A is subtropical subhumid, with hot, dry summers and mild, dry winters. The Precipitation is similar north to south throughout the area, but decreases slightly from east to west. Temperature is similar east to west, but warmer from north to south. The area is clear to partly cloudy 80 percent of the time during the summer and 60 percent during the winter. Prevailing winds usually occur from a southerly direction and from north to northwest during passage of fall and winter cool fronts. March and April are the windiest months of the year.

Most precipitation occurs during the warmer months from April to October, in the form of rainfall during thunderstorms, often of short duration and high intensity, with considerable variation in amounts of rain and the area covered. Lightening, strong winds and hail frequently accompany the thunderstorms. Occasional tornadoes are not uncommon. Precipitation distribution is bimodal, with peaks occurring in May-June and September-October. The annual precipitation is about 25 to 28 inches. Timeliness and amount of rainfall are critical to plant growth. Rainfall events of one-fourth inch or less have limited effectiveness. High temperatures and dry winds reduce precipitation effectiveness. Snowfall represents only a small part of the annual precipitation. Snowfall of one inch or more occurs about one in five years, while snowfall of greater than five inches occurs only about one in ten years. Snow cover generally is of short duration (i.e. one to three days). Probability of snowfall is greater in the northern part of MLRA 78A.

Rainfall in the region is highly erratic, usually with more years below than above average. Periodic droughts of both temporary and prolonged duration are common to the area, although not predictable. Some of the more severe droughts of the past century in this region occurred during 1918-1919, early 1930’s, early to mid 1950’s, and mid to late 1990’s. High temperatures and dry winds accentuate the effects of drought. The extremes in climate have greater influence on plant communities than averages. Historic wet and dry cycles of extended duration likely influenced the evolution of drought hardiness and other survival traits in the endemic flora and fauna of the area.

Temperatures range from 31 degrees F in January to 96 degrees F in July, based on the 30-year average from 1971-2000, although considerably lower and higher temperatures for these months, respectively, have been recorded for some years. Periods of excessive heat, exceeding 100 degrees F, are not uncommon during July and August. Temperatures in the winter are generally mild, but abrupt and large drops in temperature can occur when polar air masses plunge southward across the area. The duration of freezing temperatures usually does not last more than three to five days. Temperatures in the spring are mild, both daytime and nighttime. Summer temperatures are hot, with highs generally in the 80’s to mid 90’s during the daytime, cooling down to the upper 70’s during the night. Fall is usually pleasant with mild, sunny days and crisp, cool nights, as cool northers periodically begin moving south this time of year. The area has a frost-free period of approximately 225 to 233 days and a freeze-free period of about 248 to 259 days. The primary growing season for warm-season plants is approximately 233 to 246 days, increasing from north to south. The first frost generally occurs around November 15 and the last frost occurs around March 15. These dates will vary from north to south and from year to year.

The average relative humidity ranges from 35 to 50 percent in mid-afternoon as diurnal air temperature nears maximum. As nighttime air temperature drops, relative humidity rises, averaging 70 to 80 percent by dawn.

Table 3. Representative climatic features

Climate stations used

• (1) CONCHO PK/IVIE RSVR [USC00411934], Millersview, TX

• (2) COLEMAN [USC00411875], Coleman, TX

• (3) PUTNAM [USC00417327], Baird, TX

• (4) ALBANY [USC00410120], Albany, TX

• (5) THROCKMORTON 7NE [USC00419016], Throckmorton, TX

Influencing water features

There are no influences of water features on the Very Shallow site.

Wetland description

NA

Soil features

The soils of the Very Shallow Ecological Site are very shallow loam and clay loam uplands, with solums ranging in thickness from 7 to 20 inches deep over cemented or indurated caliche or limestone. The surface layer is brown, dark brown, grayish brown or dark grayish brown with loan or clay loam soil surface texture. Gravel and channers of caliche make up 5 to 30 percent by volume along with up to 15 percent cobbles and flagstones. Calcium carbonate makes up 40-60 percent of the soil profile. Scattered hard caliche or limestone fragments are present on the surface. Available water capacity is very low and the soils are droughty. Rainfall intake is moderate. Permeability is moderate to slow in surface layers, depending upon depth and amounts of hardened layers beneath the surface. Surface runoff is medium to rapid, depending upon amount of cover and degree of slope. Plant-soil-air-moisture relationships are fair to poor. In healthy condition, rills, ephemeral gullies, wind scoured areas, and pedestals are present in moderate quantities on the site. Shallow depth to cemented pans, large percentage of fragments, high lime content, and very low water capacity are the most limiting features for intensive agricultural uses, such as cropland or tame pasture.

Soil surveys often delineate two or more kinds of soil in a single mapping unit, due to their geographical association in the landscape, intricate patterns, or size, making it is impractical to map them separately at the selected scale for a given soil survey. Such groupings of soils are referred to as either associations or complexes. Ecological sites may or may not correspond to the all soil series contained in the association or complex.

The Very Shallow Ecological Site is associated with the following soil series and/or associations and complexes in MLRA 78A: Cho gravelly loam, Lueders very cobbly clay loam, Pitzer gravelly clay loam, and Talpa stony clay loam.

Table 4. Representative soil features

Animal community

The animal community, like the plant community, is a component of a larger and more complex ecosystem. The animal community includes the primary consumer organisms, which interface directly with the vegetative component of the ecological site, as well as the secondary and tertiary consumers (carnivores and scavengers). All play a vital role in maintaining the cycling of nutrients and flow of energy in the ecosystem. Some animal species were site-specific, but many species common to the region used various ecological sites in association with one-another.

The animal community changed dramatically from the mid 1800s to early 1900s, as a result of overexploitation of various wildlife species through unregulated market hunting, trapping, poisoning, and wanton destruction. Some of the most drastic changes in animal communities include the extinction of populations, species, and subspecies, changes in geographical distribution, and the introduction of non-endemic species. In the past century, changes in animal populations have been more related to loss or fragmentation of critical habitat. Loss of habitat is usually the major cause of population declines or even extinction of some species. Cultivation has been the demise of many wildlife species, such as the prairie chicken and certain kinds of waterfowl, while still other species, such as the pronghorn, have been displaced geographically. However, the problem does not always result from total destruction of habitat, but often involves the loss of one or more critical habitat components, such as mating and nesting habitat for certain birds, or in other cases the reduction in area or continuity of desirable habitat.

The major problem affecting many wildlife species of the Very Shallow Ecological Site was and continues to be degradation of the plant community and soils. As the site changed from a midgrass dominant plant community to a shortgrass and shrub dominant plant community, the animal community has also changed. The true grassland animal species decreased their use of the site with loss of the prairie midgrasses and increase of woody cover. The site would have become less desirable for species, such as pronghorn, lesser prairie chicken and certain species of grassland sparrows. Some of the mice and other small rodents migrated into the Shortgrass/Shrubland Plant Community, as well as the Broom Snakeweed Plant Community, because they were more adapted to such brushy habitats. Conversion of the natural plant communities of the Very Shallow Ecological Site to seeded states would result in major habitat destruction and fragmentation. However, the Very Shallow Ecological Site is not arable, so its natural habitat would be less likely to be destroyed by cultivation. Species having limited tolerance to habitat change might abandon certain plant communities for more suitable habitat in another community, or in some cases extirpated from the area.

The reference plant community of the Very Shallow Ecological Site was used by a diversity of indigenous wildlife, which preferred grassland habitat. The larger grazing and browsing herbivores included bison, elk, pronghorn and white-tailed deer. The smaller mammals included prairie dog, black-footed ferret, badger, jackrabbit, cottontail rabbit, skunk, ground squirrel and various other species of small rodents. Transient species, such as bats, occasionally used the site intermittently or incidental to more preferred or associated sites. Carnivores included the wolf, coyote, bobcat, fox and mountain lion. Birds included lesser prairie chicken, wild turkey, bobwhite quail, scaled quail, doves, nighthawk, roadrunner, and numerous species of sparrows, eagles, hawks and vultures. Various snakes and lizards, including the rattlesnake and horned lizard, also occurred in the historic climax plant community.

The migratory bison was the largest herbivore grazing the historic climax plant community. Bison probably grazed the Very Shallow Ecological Site intermittently in association with surrounding sites. They were selective grazers, preferring primarily grasses, while utilizing only a few forbs and very little woody browse. Bison often grazed an area heavily, but it was primarily during winter dormancy of the warm-season prairie grasses, and long deferment periods occurred before the next migration into the area. Unlike bison grazing, earlier domestic livestock grazing was both heavy and continuous. Domestic cattle eventually replaced the endemic bison and became the principal larger grazing herbivore, after 1860.

The elk, another large migratory herbivore, used the Very Shallow Ecological Site on an intermittent basis during the winter. The elk was primarily a grazer, using grasses and forbs in this wintering location, although newer leader growth of some shrubs would have been used. The elk probably did not impact the plant community to the extent of the bison. Like the bison, elk were eventually extirpated from this region, due to over exploitation, competition with domestic livestock, and land use practices after European settlement.

Local populations of pronghorn occupied the area year-round, prior to European settlement. The pronghorn was primarily a grazer, with strong preference for forbs, while using considerably less woody browse and grasses. Pronghorn populations are believed to have decreased in the Rolling Plains, due to extirpation of the larger predators, the increase of brush on the prairies, competition with domestic sheep and the introduction of netwire fencing. The pronghorn has been displaced geographically and no longer inhabits the immediate region. Individuals or small groups of pronghorn may occasionally wander into this region from farther west.

White-tailed deer was another non-migratory herbivore with a considerably smaller home range than the antelope. The white-tailed deer is considered to be primarily a browser but also utilizes large quantities of forbs, including cool-season annuals, and some cool-season grasses in winter and early spring, while using very limited amounts of warm-season grasses in any season. The Very Shallow Ecological Site provided a wide variety of preferred food items of the white-tailed deer, and scattered woody shrubs and motes provided edge-effect and screening cover. The site was used in association with other sites in the area. Since European settlement, the white-tailed deer population has increased dramatically. The increase in the white-tailed deer population may be attributed to extirpation of the wolf and mountain lion, primary predators of the deer, increase of woody vegetation, eradication of the screwworm fly, and intensive predator control, as well as early regulatory restrictions on harvest of does. During the past three decades (1970-2004), great progress has been made in wildlife management, through habitat improvement, as well as selective population controls (primarily through hunting), including harvest of does and manipulation of buck:doe ratios. The white-tailed deer has become the most popular large game species in the region, and contributes immensely to local economies.

The reference plant community of the Very Shallow Ecological Site was marginally suitable to the javelina. Javelina prefer habitat with dense woody cover and cacti. The site actually became more favorable to the javelina, following retrogression of the plant community, in which woody species and cacti increased in abundance. Prickly pear and mesquite beans are highly preferred dietary items. Interest in the javelina as a game species has grown in recent years, especially among bow hunters.

Smaller herbivores of the Very Shallow Ecological Site include: jackrabbits, cottontail rabbits, black-tailed prairie dogs, Mexican ground squirrels and many species of smaller rodents having diets of herbage, seeds, and mast. Also occurring on the site, usually in association with other sites, were the striped skunk, raccoon, and opossum, which are omnivorous with mixed diets of insects, arthropods, roots, tubers, mast, fish, occasional rodents and carrion. Small carnivores included black-footed ferret, badger and ringtail with diets of rodents and insects. The black-footed ferret, which preyed primarily on the prairie dog when it was abundant, has been extirpated from the region and is near extinction.

The prairie dog was despised by European settlers, leading to large-scale control of the rodent by shooting and poisoning along with natural die-offs from disease. These events led to major reductions in prairie dog populations throughout the region. Very few active prairie dog towns remain in the region. These relict prairie dog towns are small and very sparsely dispersed throughout the region. The vegetative state of the prairie dog towns represented degraded plant communities from higher seral stages. Since abandonment of prairie dog towns, the sites have been undergoing long-term secondary plant succession.

Lesser prairie chickens used the Very Shallow Ecological Site for feeding, nesting and brood rearing as long as the taller midgrasses were plentiful. The vegetative structure was more important than plant species for the life cycle of this species and many other bird species. The taller, standing dry grasses from previous year’s growth are important to nesting success. Openings among the taller bunchgrasses provided ease of movement by young chicks and protection from avian predators. The chicks and juveniles fed primarily on protein-rich insects, which were abundant and easily accessible on recently burned areas. Male prairie chickens used open shortgrass land, bare areas and recently burned areas for leks, where their courtship ritual was performed. Even after loss of midgrass dominance, the prairie chicken continued to use the same historical plant community until rendered undesirable by excessive brush encroachment. The lesser prairie chicken no longer occurs in this immediate region, now relegated to only isolated populations farther north and northwest of the Major Land Resource Area. All prairie chicken species and subspecies were true prairie birds. They have been so strongly affected by loss and fragmentation of grassland habitat that some species are rare or on the brink of extinction.

Many other species of birds still inhabit the Very Shallow Ecological Site in the alternate vegetative states, although plant species composition differs considerably from that found in the reference plant community. The gallinaceous birds, including wild turkey, bobwhite quail, and scaled quail still occur in one or more of the communities, but the lesser prairie chicken has been extirpated. Many species of grassland passeriformes, including songbirds such as larks and sparrows, have been displaced due to increase in woody cover and cacti. The community has become more desirable for other species, such as wrens and thrashers, which prefer habitat with more woody cover. The roadrunner is a unique bird from the past, which thrives in vegetative states with abundance of woody vegetation and cacti such as the Shortgrass/Shrubland Plant Community. It feeds upon a variety of items including lizards, snakes, insects and prickly pear tunas, common to such plant communities. The roadrunner nests in thorny shrubs and sometimes in larger pricklypear plants. Numerous species of hawks, many migratory, still use this site due to the abundance of rodents and rabbits.

Birds of prey associated with the Very Shallow Ecological Site, included eagles, hawks, and falcons. Some of the common hawks include Swainson’s hawk, red-tailed hawk and Harris’ hawk. The American kestrel, a small falcon, is one of the smaller avian predators occurring in the area. The golden eagle was common and fed mostly on jackrabbits and other small mammal, as well as young lambs and kid goats. After European settlement of the area, the golden eagle population was extirpated from this ecosystem and now only infrequently ventures into this region from farther west. The bald eagle occurred primarily around perennial streams and lakes, since their primary prey was fish. The bald eagle became endangered during the mid-twentieth century. Although still rare, the bald eagle has recovered sufficiently enough to be removed from the endangered species list. Federal law now protects all eagles and hawks.

Both turkey vulture and black vulture were and still are common to the Very Shallow Ecological Site and surrounding sites in the area. They are not site specific. Vultures are scavengers, feeding primarily on dead animals and birds. These tertiary consumers are important in accelerating nutrient cycling and flow of energy in the ecosystem. The vultures are protected by federal law.

Snakes, lizards and tortoise are still important components of the Very Shallow Ecological Site. Many of the reptiles are important prey species of predators and omnivores. The rattlesnake, a remnant from the reference plant community or far beyond, was the only poisonous snake endemic to the site. Occasional rock outcrops on this site provided dens for the rattlesnake and its prey. The unique horned lizard, another remnant species from past eras, also occurred on this site. It preferred bare or sparsely vegetated areas, especially where its primary dietary item, the red harvester ant, was abundant. The horned lizard has become rare during the late twentieth century, due to reduction of major dietary items within its very small home range, increased predation and human activities.

Larger mammalian predators using the Very Shallow Ecological Site include the gray wolf, coyote, red fox, gray fox, ocelot, bobcat and occasional mountain lion. Wolves and ocelot were common to the area before European settlement, but declined rapidly thereafter and no longer occur in the area. All of these species did not coexist in harmony, but from time to time each found a survival niche in the community. The wolf and mountain lion preyed primarily on deer and antelope, but also took some of the smaller mammals, including other predators. After ranching was begun in the area, all of the larger predators preyed upon domestic livestock. The gray fox population tends to increase as the coyote population declines and visa versa. The Very Shallow Ecological Site was used for denning by coyote and fox, but not simultaneously at the same location. The wolf and ocelot have been extirpated the entire state, and the mountain lion now is only as an occasional transient in this region. Viable populations of coyote, gray fox, and bobcat still exist in the area, while the red fox occurs occasionally. Coyote and bobcat predation on domestic livestock can be a problem, especially where sheep and goats are raised.

The animal component of the plant community has changed drastically since settlement and the introduction of domestic livestock, including cattle, sheep, and goats. All current vegetative states of the Very Shallow Ecological Site are now used for the production of domestic livestock, as well as native wildlife. Domestic livestock have largely replaced the endemic large herbivores, with the exception of white-tailed deer. Cattle have replaced bison as the principal grazers, utilizing approximately 85 % grass, 10 % forbs and 5 % woody plants. Sheep have replaced the pronghorn, with their strong preference for forbs, approximately 85 % while using only about 10 % grasses and 5% browse. There is strong competition between sheep and deer for forbs, especially during late winter and spring. Spanish goats are heavy browsers with diets consisting of approximately 80% woody plants, 10% forbs and 10 % grasses. This places them in strong competition with white-tailed deer for woody browse. Angora goats and Borer goats utilize considerably less browse than the Spanish goat, with the balance of their diets consisting of about equal proportions of forbs and grass. Both Spanish and Angora goats have been used for biological control of certain woody species, especially in conjunction with mechanical brush management and prescribed burning. Tables of plant preferences for the major kinds of animals are provided following this section.

The Very Shallow Ecological Site is one of the lower producing sites with considerable amounts of woody plants, especially in the Shrubland State. Plant communities in this vegetative state would be less desirable for cattle, but highly desirable for Spanish goats and white-tailed deer, since both are strong browsers. The abundance of pricklypear in these communities provides large amounts of pricklypear tunas, which deer and other animals utilize in large amounts when available from late summer to winter. The wide variety of forbs preferred by deer would be desirable during winter and early spring, thus placing deer and sheep in strong competition. Areas with large amounts of catclaw and catclaw mimosa are undesirable for Angora goats, and to a lesser degree for sheep, due to snagging of mohair and wool. Kid goats sometimes become entangled in these shrubs and die from overexposure to heat or cold, starvation, or predation. The site also provides cover for white-tailed deer, in conjunction with other sites.

Numerous exotic herbivores have been introduced to this region, primarily from Africa and Asia. They now graze and browse the Very Shallow Ecological Site, in association with other sites, usually confined by high fences. Some of the more common exotic animals include axis deer, blackbuck antelope, gazelle, red deer, fallow deer, ibex and eland. Some of the exotics compete directly with the native white-tailed deer, as well as domestic livestock. The feral hog is an exotic, invader species sometimes associated with this site. It often is destructive to rangeland, due to its feeding habits, which cause major soil disturbance and damage to perennial vegetation. The feral hog is considered to be omnivorous and sometimes preys on young lambs and kid goats, as well as ground nests of birds.

Recreational hunting is a decimating factor of wildlife species, considered to be game animals. Game hunting substitutes for natural predation of earlier times. Hunting can be a useful management tool when based upon sound ecological principles. On the contrary, it can be detrimental to wildlife populations, if not based upon sound principles. Hunting can be used for population control, to manipulate sex ratios, and to enhance quality of certain attributes within a population. State game laws regulate seasons and bag limits of non-migratory species while federal game laws take precedent over state laws in regulating the harvest of migratory species. Most exotic wildlife species using this site are hunted as an economic enterprise and are not regulated by law as to seasons or bag limits. White-tailed deer, a non-migratory species, is the only native big game animal hunted in association with the Very Shallow Ecological Site. Non-migratory game birds of this site are the Rio Grande wild turkey, bobwhite quail and scaled quail. Migratory game birds using this site include the mourning dove, and more recently the white-winged dove. Wildlife management takes the form of habitat conservation and habit manipulation, as well as balancing populations with available habitat. It requires knowledge of the natural history of individual species and their specific habitat requirements. Brief statements follow, regarding some of the preferences and habitat requirements for principle native game species using the Very Shallow Ecological Site.

White-tailed deer prefer edge-effect, but will readily adapt to other vegetation types or plant community states. They require cover for protection from predators (including hunters), bedding areas, travel corridors, and thermoregulation. White-tailed deer are strong browsers, utilizing large amounts of certain woody plants on a seasonal basis. White-tailed deer also utilize large amounts of forbs and some cool-season grasses, especially during late fall, winter, and early spring. Some perennial forbs also are used during the summer and fall. White-tailed deer are, however, very selective as to species preference (see table of preference ratings).

The Rio Grande turkey prefers to locate in the vicinity of roost trees, but they range over large areas while feeding. They would use this site in conjunction with others for feeding and cover. The wild turkey feeds on seeds and mast of many plants occurring on the Very Shallow Ecological Site. They also use large amounts of herbaceous plant material, including lush green grass, especially Texas wintergrass, during fall, winter, and spring. Turkeys would nest among the taller midgrasses of this site when it is in a higher stage of plant succession. Structure is the key vegetation attribute for most ground nesting birds, with the exception of the nighthawk and killdeer.

Bobwhite quail prefer edge-effect and scattered shrubs with underspace, such as lotebush and littleleaf sumac, which provide loafing areas and cover from raptors. Combinations of bunchgrasses and low shrubs provide good nesting cover. The Very Shallow Ecological Site supports many plants, especially the leguminous forbs and shrubs, which produce hard seeds preferred by quail. Quail diets also include many of the annual forbs produced on this site. The scaled (blue) quail prefers the more regressed plant communities of this site to higher seral stages of dense grass cover. It prefers openness in the understory, bare ground, and shortgrasses, which facilitates their running nature and their preference or tolerance for more woody cover and cacti. They use many of the same foods as bobwhites, in addition to fruits of the tasajillo and pricklypear. Both species of quail also use considerable amounts of leafy herbage in their diets.

Additional information on both game and non-game species is available from local offices of Natural Resources Conservation Service, Texas Agricultural Extension Service, Texas Parks and Wildlife Department, or range, wildlife, and biology departments of various universities.

Hydrological functions

The reference plant community of the Very Shallow Ecological Site, with its abundance of deep-rooted bunchgrasses, good surface mulch, moderately high soil organic matter, and limited erosion, contributed to optimum hydrologic functions, within limitations of the prevailing climate, geology, and soils. Infiltration and percolation of water to plant root zones was moderate. Permeability was moderate to slow in surface layers, depending on depth and amounts of hardened layers beneath the surface. The soils are well drained, but have very low available water capacity and medium to rapid runoff, causing this to be a droughty site. Precipitation effectiveness is low, so more frequent rainfall is required to maintain adequate moisture for plant growth. Light showers are ineffective in benefiting the deeper-rooted midgrasses, although the short grasses and annuals may have short-term benefits. Deep percolation beyond the root zone is limited, due to low annual precipitation and hardened subsurface layers of caliche or limestone. However, where limestone is fractured, some water would reach greater depths during higher rainfall events, provided adequate surface cover is available to reduce runoff. The Very Shallow Ecological Site is probably less significant in recharging underground aquifers or water tables, than most other sites with deeper soils, lacking restrictive subsurface layers and having better infiltration rates and less runoff. The Very Shallow Ecological Site supports various woody shrubs, having limited effect on deep percolation, and supports very few deep-rooted trees, which could channel water to greater depths.

Loss of vegetative cover, especially the larger bunchgrasses, as well as mulch and soil organic matter, reduces infiltration and increases runoff. This occurs under heavy continuous grazing, prolonged drought, or untimely fire. As the deep-rooted midgrasses, such as little bluestem, sideoats grama, and cane bluestem, decrease, the shortgrasses, such as buffalograss, curlymesquite, and slim tridens, tend to increase. The shallow-rooted, sod-forming grasses, such as buffalograss and curlymesquite, are less effective than bunchgrasses in promoting good water infiltration and reducing runoff. Under these conditions woody plants, such as catclaw, lotebush, and juniper, also increase in density and canopy cover. Increased runoff results in less water for plants and accelerates soil erosion. Under intensive rainfall, the degraded site can contribute to down slope flooding, sedimentation, and poor water quality in streams and rivers. Regression of the plant community to stages 2 and 3 farther accentuates these conditions. Degradation of the plant community and soils disrupts the normal water dynamics of the site, consequently impairing the water cycle.

Brush management and prescribed grazing will help improve hydrologic function over a period of several years, through increase of deep-rooted midgrasses and surface cover, which will improve water infiltration and percolation to the root zone; also reduce raindrop splash and soil erosion. Woody plants use larger amounts of water than grasses per unit of biomass produced and usually outcompete grasses for available water. Reduction of woody plants through chemical versus mechanical methods will give grasses a competitive advantage for limited moisture. Reduction of woody canopy will reduce evaporation of precipitation intercepted by woody canopies, thus allowing more water to reach the soil surface and infiltrate. Although, hydrologic functions can be improved, along with improvement in the plant community, it would not return to that of the reference plant community if excessive soil loss has occurred in associated with site degradation leading to the crossing of ecological thresholds.

Soil Surveys of Concho County (1988) and Tom Green County (1976) placed the principal soils of the Very Shallow Ecological Site in Hydrologic Groups C and D.

Recreational uses

The Very Shallow Ecological Site generally occupies a higher position in the landscape, providing opportunity to enjoy panoramic vistas of surrounding landscapes, as well as plant and animal life. In some locations the site contains artifacts and other historical evidence of past civilizations. The site provides aesthetic appeal from colorful wildflowers, produced in the spring. This site is used for hunting, birding, hiking, camping, and horseback riding.

Wood products

Most woody species of the Very Shallow Ecological Site are shrubs, having limited value for wood products. Blueberry juniper is used for fence posts and stays but redberry juniper is less desirable.

Other products

The Very Shallow Ecological Site contains large amounts of caliche, which is mined for roadfill and construction of ranch roads. Occasional boulders and flagstone occurring on the site are used in landscaping. The site may be used for honey production from some of the woody shrubs, such as catclaw, which produces blooms favored by honeybees.

Other information

None.

Other references

Davis, W.B., and D.J. Schmidly. 1994. The mammals of Texas. Texas Parks and Wildlife Press, Austin. 338 pp.
Gould, F. W. 1975. Texas plants a checklist and ecological summary. Texas Agricultural Experiment Station, MP-585 revised.119 pp.
Hatch, S.L., K.N. Gandhi, and L.E. Brown. 1990. Checklist of the vascular plants of Texas. Texas Agricultural Experiment Station, MP-1655.
Matthews, S.R. Interwoven – a pioneer chronicle. Texas A&M University Press, College
Station, TX.
Oberholser, H. C. 1974. The bird life of Texas. Vol. 1 and Vol. 2. University of Texas Press,
Austin. 1069 pp.
Pederson, R.J. 1965- 1976. Range site descriptions of western Texas, SCS (NRCS) Field
Office Technical Guide, rangeland interpretations; and rangeland interpretations for Soil Surveys of Coke and Tom Green Counties, Texas.
Sibley, Marilyn McAdams. 1967. Travelers in Texas 1761-1860. University of Texas Press,
Austin, TX.
Thomas, G. W. 1975. Texas plants – an ecological summary. In: Gould, F. W. 1975.
Texas plants a checklist and ecological summary. Texas Agricultural Experiment Station, MP-585 revised. pp. 7-14.
USDA, Natural Resources Conservation Service. 1974. Soil survey of Coke County, Texas, in
cooperation with Texas Agriculture Experiment Station. 49 pp., plus maps.
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and composition record for native grazing lands.
USDA, Natural Resources Conservation Service. 1988. Soil survey of Concho County, Texas,
in cooperation with Texas Agriculture Experiment Station and Texas Soil and Water Conservation Board. 117 pages, plus maps.
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Vines, R.J. 1960. Trees, shrubs, and vines of the Southwest. University of Texas Press,
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Weniger, Del. 1984. The Explorers’ Texas – The lands and waters. Eakin Publications Inc.
Weniger, Del. 1997. The Explorers’ Texas, Volume 2 – The animals. Eakin Press.

Other Contributors Assisting With Development of This Site Description:
Homer Sanchez, State Rangeland Management Specialist, NRCS, Temple, Texas
Justin Clary, Rangeland Management Specialist, NRCS, Temple, Texas
Charles Anderson, Rangeland Management Specialist, NRCS, San Angelo, Texas
Bruce Deere, Range and Wildlife Mgt. Consultant, San Angelo, Texas
Dr. Bob Steger, Range Consultant, Mertzon, Texas
Rusty Dowell, Soil Scientist, NRCS, San Angelo, Texas
Gary Bates, District Conservationist, NRCS, Menard, Texas
Brad Teplicek, District Conservationist, NRCS, Eden, Texas
Ronald Crumley, District Conservationist, NRCS, San Angelo, Texas
Kyle Wright, Soil Conservationist, NRCS, San Angelo, Texas
Michael Votaw, Environmental Resource Specialist, USACE, Fort Worth, Texas
Marty Underwood, Biologist, U.S. Fish and Wildlife Service, Austin, Texas
Tim Schumann, Biologist, U.S. Fish and Wildlife Service, Austin, Texas
Rudy Pederson, SCS Range Conservationist, Retired, San Angelo, Texas
Steve Nelle, Biologist, NRCS, San Angelo, Texas
Kurt Kemp, Manager, San Angelo State Park, Texas Parks and Wildlife Department, San Angelo, TX
Pat Bales, Assistant Manager, San Angelo State Park, Texas Parks and Wildlife Department, San Angelo, TX

Contributors

Dean Chamrad
PES Edits by Tyson Morley, MLRA Soil Scientist, Altus, Oklahoma

Approval

Bryan Christensen, 9/15/2023

Acknowledgments

Site Development and Testing Plan:

Future work, as described in a Project Plan, to validate the information in this Provisional
Ecological Site Description is needed. This will include field activities to collect low,
medium and high intensity sampling, soil correlations, and analysis of that data. Annual
field reviews should be done by soil scientists and vegetation specialists. A final field review, peer review, quality control, and quality assurance reviews of the ESD will be needed to produce the final document.

Annual reviews of the Project Plan are to be conducted by the Ecological Site Technical
Team.