Physiographic features

This site is classified as upland. Slope gradient is mostly from 1 to 12 percent but range up to 20 percent. It is presumed that this site was formed in residuum from weathered limestone. Elevation for this site ranges from 1000 to 2000 feet above sea level.

Table 2. Representative physiographic features

Table 3. Representative physiographic features (actual ranges)

Climatic features

The climate is humid subtropical and is characterized by hot summers and relatively mild winters. The average first frost should occur around November 15 and the last freeze of the season should occur around March 19.

The average relative humidity in mid-afternoon is about 50 percent. Humidity is higher at night, and the average at dawn is about 80 percent. The sun shines 70 percent of the time possible during the summer and 50 percent in winter. The prevailing wind direction is southeast.

Drought is calculated as 75% below average rainfall. It should be noted that timing of rainfall may be more significant than average rainfall.

Approximately two-thirds of annual rainfall occurs during the April to September period. Rainfall during this period generally falls during thunderstorms, and fairly large amount of rain may fall in a short time. Hurricanes provide another source of extremely high rains in a short time. A review of the rainfall records suggest that rainfall is below “normal” at least 60 percent of the time. Therefore, the erratic nature of the rainfall should be considered when developing any land management plans.

The impact of droughts in the Edwards Plateau cannot be under-estimated. Not only are droughts devastating to the land but also to those that manage the land. Droughts occur roughly every 20 years but not always. A severe drought in 2012 coupled with extreme heat resulted in a die off of juniper over millions of acres as well as other native plants.

Table 4. Representative climatic features

Climate stations used

• (1) MEDINA 1NE [USC00415742], Medina, TX

• (2) SAN ANTONIO/SEAWORLD [USC00418169], San Antonio, TX

• (3) KERRVILLE 3 NNE [USC00414782], Kerrville, TX

• (4) BLANCO [USC00410832], Blanco, TX

• (5) CANYON DAM [USC00411429], Canyon Lake, TX

• (6) BURNET MUNI AP [USW00003999], Burnet, TX

• (7) AUSTIN GREAT HILLS [USC00410433], Austin, TX

• (8) GEORGETOWN LAKE [USC00413507], Georgetown, TX

• (9) PRADE RCH [USC00417232], Leakey, TX

Influencing water features

This is an upland site and is not influenced by water from a wetland or stream. These upland sites may shed some water via runoff during heavy rain events. The presence of good ground cover and deep rooted grasses can help facilitate infiltration and reduce sediment loss.

Wetland description

N/A

Soil features

In a representative profile for the Adobe ecological site, the soils are shallow to moderately deep, usually gravelly, light-colored loam or clay loam over weakly or moderately cemented limestone with thin beds of indurated limestone. Rock fragments in the surface horizons are about 20 percent and up to 70 percent in the subsoil. There are gravelly to extremely gravelly or paragravelly to extremely paragravelly texture modifiers throughout the soil profile. The permeability of the soil is moderate and the permeability of the paralithic material is very slow to slow. On erosional sideslope positions, the organic matter development in the topsoil is low. Because of high runoff and high calcium carbonate content, the soils are droughty. They do not support a dense cover of plants, which require high amounts of water and plant nutrients. Runoff is rapid, even under good plant cover. Forage grown on the site is usually low in nutritive value and must be supplemented, especially with phosphorus as the high calcium levels tie up the phosphorus. Soils on the lower slopes of the site have organic material in the soil surface and are often characterized by the presence of Texas oaks. These sites occur on sideslopes of ridges on dissected plateaus.

Because of the scale of mapping, there are inclusions of minor components of other soils within these mapping units. Before performing any inventories, conduct a field evaluation to ensure the soils are correct for the site.

The following representative soil series associated with the Adobe ecological site are Brackett, Kerrville, and Real.

Table 5. Representative soil features

Animal community

The site is usable by cattle, sheep, Angora goats and meat goats. The high pH in the soil may tie up some of the phosphorus rendering plants like little bluestem more unpalatable than on other sites. Wildlife species utilizing this site for at least a portion of their habitat needs include white-tailed deer, raccoon, cottontail rabbit, jackrabbit, Rio Grande turkey, bobwhite quail, mourning dove, mountain lion, bobcat and other wildlife species. A field assessment of vegetation is needed to calculate carrying capacity for the animals of interest. Traditional regional average stocking rates should not be used and can be misleading because of differences in plants utilized.

With the eradication of the screwworm fly (Cochilomyia hominivorax), the increase in woody vegetation and insufficient natural predation, white-tailed deer numbers have increased drastically 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 woodland and more open plant communities on this site is an important key to deer management. Competition among deer, sheep and goats can cause damage to preferred vegetation and is an important consideration in livestock and wildlife management. Maintaining cover and food for wildlife on the steeper slopes is extremely important to the wildlife ecology of this site and associated sites below or above it.

Smaller animals using the site include rodents, jackrabbit, cottontail rabbit, raccoon, skunks, possum and armadillo. Mammalian predators include coyote, red fox, gray fox, bobcat, and mountain lion. Many species of snakes and lizards are also native to this site.

A diversity of birds is found on this site including game birds, songbirds and birds of prey. The different species of songbirds vary in their habitat preferences. Prairie chickens (Tympanuchus spp.) were also recorded in the general area. In general, a habitat that provides a large variety of grasses, forbs, shrubs, vines and trees and a complex of grassland, savannah, shrubland and woodland will support a variety and abundance of songbirds. Birds of prey are important to keep the numbers of rodents, rabbits and snakes in balance. The different plant communities of the site will sustain different species of raptors.

Various kinds of exotic wildlife have been introduced on the site including axis, sika, fallow and red deer, auodad sheep and blackbuck antelope. Axis deer are extremely competitive with the native white-tailed deer as they have the ability to shift their diets to several different plant groups while the white-tails do not. Their numbers should be managed in the same manner as livestock and white-tailed deer to prevent damage to the plant community. Feral hogs are present and can cause damage when their numbers are not managed.

Hydrological functions

The soils on this site are well drained with very low water holding capacity. Surface runoff can be rapid because of the slope and physiography of the site. Soils correlated with this site are in Hydrologic Groups C and D. The reference plant community (1.1) is dominated by tall bunchgrass species that are correlated with high hydrologic function. When conditions degrade into States 2 and 3, the composition of desirable tall grasses decreases and mid and short grasses become more dominant. If soil conditions also degrade and management is consistent with overuse, hydrologic function decreases significantly. Hydrology and erosion dynamics are discussed below for States 1, 2, and 3.

The Savannah State, representative of the historic community, is the most productive of the plant community phases. With reference to the state and transition model, state 1 is the most hydrologically stable with the lowest runoff and soil loss. This is because of the prominence of tall grass cover. The greater foliar and basal plant cover of big and little bluestem creates many raindrop interception layers. In addition, many lower statured forbs are located in the understory. Litter cover accumulating during the winter months can provide protection from raindrop impact. The morphology of big bluestem roots is characterized by thick coarse vertical and lateral roots. Rhizomes form a rigid, coarse, open network in the upper 2 inches of soil with branching roots arising from them. Where fractures occur in the underlying rock, roots can penetrate into deeper strata. Infiltration studies have shown the bluestem, Indian grass, and switchgrass are associated with higher infiltration capacity compared to other short-statured grasses which tend to have thicker fibrous surface roots (e.g., gramas, buffalograss, dropseeds, and three-awn grasses).

Where the geologic substrate is fractured (commonly associated with oat mottes), infiltration is rapid and immediate. This water percolates deep into the substrate and largely escapes the evapotranspiration (ET) process. In the non-oak mott portions of this site, runoff often occurs during high intensity, short duration storms. This is a common occurrence, even when Similarity Index is high. In this state, runoff, on the average, displaces and erodes little soil. Water quality is high with little or no sediment. Intermittent channels and water flow paths carry runoff water without appreciable degradation in the channels. Seeps and spring flow are common on this site after high rainfall periods and may last several weeks. If adequate rainfall is received throughout the growing season, spring flow may last throughout the year. Stream channels and intermittent adjacent channels serve as recharge areas--water can percolate via fractures in the geologic substrate. As this water moves downward, it contributes to the recharge of aquifers and provides a constant source of subsurface water for sustained base flow to creeks and streams.

State 1: Savannah State

Model Predictions return periods based on 50 years climate data.
(Return)(Precip)(Runoff) (Erosion)
(Period)(in) (in) (t/ac)
---------------------------------
(50 yr) (52.7) (9.6) (2.3)
(25 yr) (49.5) (3.8) (2.0)
(10 yr) (44.5) (2.9) (1.4)
(5 yr) (40.1) (1.5) (0.7)
(2.5 yr)(35.6) (0.4) (0.2)
---------------------------------
(50 yr) (32.9) (0.8) (0.4)
(avg.)

Based on 50 years of climate data, there is an 85 percent chance there will be runoff and delivered sediment for these conditions. [Rangeland Hydrology and Erosion Model (RHEM) predictions—model calibrated from field data]. The average sediment to runoff ratio is (0.4/0.8 = 0.5). For every 1.0 inch of runoff, 0.5 tons/acre soil erosion.

Return Period Analysis
To help interpret the table, note that a 5-year value will be exceeded, on the average, about once every five years, or twice every ten. There is a one in 5 or 20 percent chance that a value equal to or greater than the 5-year value will occur in a given year. There is a (100 - 20), or 80 percent, chance that the precipitation, runoff, erosion, or sediment yield will be less than the 5-year value. In the results shown in the table, the average 50-year erosion rate is 0.4 tons/acre. There is a 20 percent chance that the annual erosion will exceed about 0.7 tons per acre. At best, any predicted runoff or erosion value, by any model, will be within plus or minus 50 percent of the true value. Erosion rates are highly variable.

Plant Community 1.2: Savannah shrubland community
This community is in an intermediate state of flux i.e., combinations of lack of fire, times of overuse, subsequent wood invasion, and increases in less desirable grasses. Grasslike vegetation is significantly reduced when Ashe juniper and other woody species preempt sunlight and moisture. Seepy areas and /or spring flows are reduced by more than 20 percent over the reference state (1). Less desirable midgrasses such as hairy grama, hairy tridens, Texas grama, red threeawn, and puffsheath dropseed (Sporobolus neglectus) predominate the stand. The rooting systems of these grasses are more fibrous with a majority of the roots in the upper 4 inches of the soil surface. Infiltration capacity is less in this state and can be viewed as significantly different compared to the reference state (1).

Model Predictions return periods based on 50 years climate data
(Return)(Precip)(Runoff)(Erosion)
(Period)(in) (in) (t/ac)
---------------------------------
(50 yr)(52.7) (9.2) (7.4)
(25 yr)(49.5) (5.8) (4.5)
(10 yr)(44.5) (3.6) (3.8)
(5 yr) (40.1) (2.5) (2.0)
(2.5 yr)(35.6) (1.1) (0.9)
---------------------------------
(50 yr) (32.9) (1.30 (1.2)
(avg.)

Based on 50 years of climate data, there is a 98 percent chance there will be runoff and delivered sediment for these conditions. [Rangeland Hydrology and Erosion Model (RHEM) predictions—model calibrated from field data]. The average sediment to runoff ratio is (1.2/1.3 = 0.92. For every 1.0 inch of runoff, 0.92 tons/acre soil erosion. This ratio is almost 2 times higher than state 1.

State 2: Oak Juniper State
The Oak juniper woodland State (2) is associated with a substantial shift to woody plants. As the juniper overstory matures, these trees can grow 20 feet or taller. Grasses and forbs in the understory are shaded and conditions gradually become depauperate as tree overstory and shading increases. Understory vegetation can be dominated by weedy forbs which generally provide less protection to the soil surface compared to grasses. The hydrologic effect is significant from a runoff and accelerated soil loss point of view. Compared to State 1, the Reference State, average runoff and erosion are 1.5 and 3 times higher, respectively.

(Return)(Precip)(Runoff)(Erosion)
(Period)(in) (in) (t/ac)
(50 yr) (52.7) (11.9) (10.5)
(25 yr) (49.5) (6.5) (5.9)
(10 yr) (44.5) (4.9) (5.4)
(5 yr) (40.1) (2.7) (3.0)
(2.5 yr)(35.6) (1.3) (1.7)
(50 yr) (32.9) (1.6) (1.8)
(avg.)

Based on 50 years of climate data, there is a 98 percent chance there will be runoff and delivered sediment for these conditions. [Rangeland Hydrology and Erosion Model (RHEM) predictions—model calibrated from field data]. The average sediment to runoff ratio is (1.8/1.6 = 1.1. For every 1.0 inch of runoff, 1.1 tons/acre soil erosion. This ratio is 2.2 times higher than that of State 1.

Recreational uses

This site has the potential for recreational use due to the diversity of wildlife, which can inhabit ecological sites above and below this site. The tall and mid grasses and scattered oaks produce beautiful fall color variations. Many native plants valuable for landscape may be found on sites nearer to climax. The area is used for hunting, hiking, birding and other nature tourism related enterprises.

The open grassland with widely scattered oaks has an open-space appeal. The mixture of live oak and Texas oak adds to the fall color variations. Early spring rains will produce a variety of flowering annual and perennial forbs.

Wood products

Oaks and Ashe juniper may be used for firewood, fencing material, and/or in the specialty wood industry.

Other information

Plant Preference by Animal Kind:
This rating system provides general guidance as to animal forage preference for plant species. It also indicates possible competition and diet overlap between kinds of herbivores. Grazing preference changes from time to time, especially between seasons, and between animal kinds and classes. An animal’s preference or avoidance of certain plants is learned over time through grazing experience and maternal learning (http://extension.usu.edu/behave/Grazing). Preference does not necessarily reflect the ecological status of the plant within the plant community. For wildlife, plant preferences for food are rated. Refer to detailed habitat guides for a more complete description of a species habitat needs.

Legend: P=Preferred D=Desirable U=Undesirable N=Not Consumed T=Toxic X=Used, but not degree of utilization unknown
Preferred – Percentage of plant in animal diet is greater than it occurs on the land
Desirable – Percentage of plant in animal diet is similar to the percentage composition on the land
Undesirable – Percentage of plant in animal diet is less than it occurs on the land
Not Consumed – Plant would not be eaten under normal conditions. It is only consumed when other forages not available. This can also include plants that are unavailable during parts of the year.
Toxic – Rare occurrence in diet and, if consumed in any tangible amounts results in death or severe illness in animal (Hart, 2003). (Note: many plants can be good forage but toxic at certain doses or at certain times of the year. Animals in poor condition are most susceptible.)

Inventory data references

Information provided here has been derived from limited NRCS clipping data, and from field observations of range trained personnel.

Other references

Anderson, J.R., C.A. Taylor, Jr., C.J. Owens, J.R. Jackson, D.K. Steele, and R. Brantley. 2013. Using experience and supplementation to increase juniper consumption by three different breeds of sheep. Rangeland Ecol. Management. 66:204-208. March.

Archer S. 1994. Woody plant encroachment into southwestern grasslands and savannas: rates, patterns and proximate causes. in: Ecological implications of livestock herbivory in the West, pp.13-68. Edited by M. Vavra, W. Laycock, R. Pieper, Society for Range Management Publication. , Denver, Colorado.

Bestelmeyer, B.T., J.R. Brown, K.M. Havsted, R. Alexander, G. Chavez, and J.E. Hedrick. 2003. Development and use of state-and-transition models for rangelands. Journal of Range Management. 56(2): 114-126.

Bushland, R.C. 1985. Eradication program in the southwestern United States. Symposium on eradication of the screwworm from the United States and Mexico. Misc. Pub. Entomol. Soc. Am., 62:12-15.

Foster, J.H. 1917. The spread of timbered areas in central Texas. Journal of Forestry 15:442-445.

Frost, C. C. 1998. Presettlement fire frequency regimes of the Unites States: a First Approximation. Tall Timbers Fire Ecology Conference Proceedings. No. 20. Tall Timbers Research Station. Tallahassee, FL.

Fuhlendorf, S. D., and Engle D.M., Kerby J., and Hamilton R. 2008. Pyric Herbivory: rewilding Landscapes through the Recoupling of Fire and Grazing. Conservation Biology. Volume 23, No. 3, 588-598.

Hamilton W. and D. Ueckert. 2005. Rangeland Woody Plant Control--Past, Present, and Future. Chapter 1 in: Brush Management-Past, Present, and Future. Texas A & M University Press. Pp.3-16.

Hanselka, W., R. Lyons, and M. Moseley. 2009. Grazing Land Stewardship – A Manual for Texas Landowners. Texas AgriLife Communications, http://agrilifebookstore.org.

Hart, C., R.T. Garland, A.C. Barr, B.B. Carpenter, and J.C. Reagor. 2003. Toxic Plants of Texas. Texas Cooperative Extension Bulletin B-6103 11-03.

Inglis, J. M. 1964. A History of Vegetation on the Rio Grande Plains. Texas Parks and Wildlife Department, Bulletin No. 45. Austin, Texas.

Massey, C.L. 2009. The founding of a town – The Gugger and Benke families. Helotes Echo, July 1, 2009.

Natural Resources Conservation Service. 1994. The Use and Management of Browse in the Edwards Plateau of Texas. Temple, Texas.

Plant symbols, common names, and scientific names according to USDA/NRCS Texas Plant List (Unpublished)

Pyne, S.J. 1982. Fire in America. Princeton University Press, Princeton, NJ.

Roemer, Ferdinand Von. 1983. Roemer’s Texas. Eakins Press.

Schmidly, D.J. 2002. Texas natural history: a century of change. Texas Tech University Press, Lubbock.

Scifres, C.J. and W.T. Hamilton. 1993. Prescribed Burning for Brush Management: The South Texas Example. Texas A & M University Press, 245 pp.

Smeins, F., S. Fuhlendorf, and C. Taylor, Jr. 1997. Environmental and Land Use Changes: A Long Term Perspective. Chapter 1 in: Juniper Symposium 1997. Texas Agricultural Experiment Station. Pp 1-21.

Taylor, C.A. (Ed.). 1997. Texas Agriculture Experiment Station Technical Report 97-1 (Proceedings of the 1997 Juniper Symposium), Sonora Texas, pp. 9-22.

Teer, J.G., J.W. Thomas, and E.A. Walker. 1965. Ecology and Management of White-tailed Deer in the Llano Basin of Texas. Wildlife Monographs 10: 1-62.

Thurow, T.O. and J.W. Hester. 1997. 1997 Juniper Symposium. Texas Agricultural Experiment Station, The Texas A&M University System. Tech. Rep. 97-1. January 9-10, 1997. San Angelo, Texas

USDA-NRCS (Formerly Soil Conservation Service) Range Site Description (1972)

Vines, R.A. 1984. Trees of Central Texas. University of Texas Press. Austin, Texas.

Weninger, D. 1984. The Explorer’s Texas. Eakin Press; Waco, Texas.

Wilcox. B.P. and T.L. Thurow. 2006. Emerging Issues in Rangeland Ecohydrology: Vegetation Change and the Water Cycle. Rangeland Ecol. Management. 59:220-224, March.

Wilcox, B.P., Y. Huang, and J.W. Walker. 2008. Long-term trends in stream flow from semiarid rangeland: uncovering drivers of change. Global Change Biology 14: 1676-1689, doi:10.1111/j.1365.2486.2008.01578.

Wilcox, B.P., W.A. Dugas, M.K. Owens, D.N Ueckert, and C.R. Hart. 2005. Shrub Control and Water Yield on Texas Rangelands: Current State of Knowledge. Texas Agricultural Experiment Station Research Report 05-1.

Wills, Frederick. 2006. Historic Vegetation of Camp Bullis and Camp Stanley, Southeastern Edwards, Plateau. Texas. Texas Journal of science. 58(3):219-230.

Wright, H.A. and A.W. Bailey. 1982. Fire Ecology: United States and Southern Canada. John Wiley & Sons, Inc.

Wu. B.X., E.J. Redeker, and T.L. Thurow. 2001. Vegetation and Water Yield Dynamics in an Edwards Plateau Watershed.

Journal of Range Management. 54:98-105. March 2001.
http://extension.usu.edu/behave/(Accessed 8/13/13)

Contributors

Carl Englerth
Joe Franklin, RMS, NRCS, Texas
Mark Moseley
Travis Waiser, MLRA Leader, NRCS, Kerrville, TX

Approval

Bryan Christensen, 9/19/2023

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.

QC/QA completed by:
Bryan Christensen, SRESS, NRCS, Temple, TX
Erin Hourihan, ESDQS, NRCS, Temple, TX