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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
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Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 087A–Texas Claypan Area, Southern Part
This area is entirely in south-central Texas. It makes up about 10,535 square miles (27,295 square kilometers). The towns of Bastrop, Bryan, Centerville, College Station, Ennis, Fairfield, Franklin, Giddings, Gonzales, Groesbeck, La Grange, Madisonville, and Rockdale are in this MLRA. Interstate 45 crosses the northern part of the area, and Interstate 10 crosses the southern part. A number of State Parks are located throughout this area. The parks are commonly associated with reservoirs.
Classification relationships
USDA-Natural Resources Conservation Service, 2006.
-Major Land Resource Area (MLRA) 87AEcological site concept
The Wet Sandy Draw exists on sandy upland depressions and the head of drainageways. The poorly drained sandy soils create a unique and productive plant community.
Associated sites
R087AY008TX Very Deep Sand
Very Deep Sand
Similar sites
R087AY010TX Sandy Bottomland
Sandy Bottomland
Table 1. Dominant plant species
Tree (1) Quercus phellos
(2) Quercus nigraShrub (1) Morella cerifera
(2) Baccharis halimifoliaHerbaceous (1) Panicum hemitomon
(2) Phanopyrum gymnocarponPhysiographic features
This site occurs as a nearly level to moderately sloping concave prairie that occupies foot slopes and heads of drains. A water table is near the surface throughout most of year, except during prolonged droughty conditions. The soils can pond water for very brief to brief durations during wet periods.
Table 2. Representative physiographic features
Landforms (1) Plains > Drainageway
(2) Plains > Depression
Runoff class Negligible Flooding frequency None Ponding duration Very brief (4 to 48 hours) to brief (2 to 7 days) Ponding frequency None to rare Elevation 300 – 650 ft Slope 0 – 2 % Ponding depth 0 – 6 in Water table depth 9 – 80 in Aspect Aspect is not a significant factor Climatic features
The climate for MLRA 87A is humid subtropical and is characterized by hot summers, especially in July and August, and relatively mild winters. The summer months have little variation in day-to-day weather except for occasional thunderstorms that dissipate the afternoon heat. The moderate temperatures in spring and fall are characterized by long periods of mild days and cool nights. The average annual precipitation in this area is 41 inches. Most of the rainfall occurs in spring and fall. The freeze-free period averages about 276 days and the frost-free period 241 days.
Table 3 Representative climatic features
Frost-free period (average) 240 days Freeze-free period (average) 280 days Precipitation total (average) 40 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
Figure 4. Annual precipitation pattern
Figure 5 Annual average temperature pattern
Climate stations used
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(1) BARDWELL DAM [USC00410518], Ennis, TX
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(2) ELGIN [USC00412820], Elgin, TX
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(3) FRANKLIN [USC00413321], Franklin, TX
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(4) BELLVILLE 6NNE [USC00410655], Bellville, TX
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(5) LA GRANGE [USC00414903], La Grange, TX
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(6) MADISONVILLE [USC00415477], Madisonville, TX
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(7) SMITHVILLE [USC00418415], Smithville, TX
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(8) CROCKETT [USC00412114], Crockett, TX
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(9) FAIRFIELD 3W [USC00413047], Fairfield, TX
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(10) GONZALES 1N [USC00413622], Gonzales, TX
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(11) SOMERVILLE DAM [USC00418446], Somerville, TX
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(12) COLLEGE STN [USW00003904], College Station, TX
">Influencing water features
This is a wet site receiving water from runoff and seepage of adjacent sandy sites. It often has a perched water table at or near the surface for much of the year.
Wetland description
This site is considered hydric, but onsite delineations are needed to verify wetlands status.
Soil features
The soils of this site are very deep, poorly drained, rapidly permeable soils formed in sandy sediments. Because of the seepage from the adjoining slopes, water seeps to the surface for some time following rains. The soil is saturated or nearly saturated most of the year because of the seepage. Soil correlated to this site include: Cadelake, Melhomes, and Sealy.
Table 4. Representative soil features
Parent material (1) Colluvium – sandstone
Surface texture (1) Fine sandy loam
Family particle size (1) Sandy
Drainage class Poorly drained Permeability class Rapid Soil depth 80 in Surface fragment cover <=3" Not specified Surface fragment cover >3" Not specified Available water capacity
(0-40in)3 – 4 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)3.5 – 6 Subsurface fragment volume <=3"
(Depth not specified)0 – 1 % Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
This site resembles a wet prairie or savannah occupied by a predominance of hydrophytic plants. The dominant herbaceous species include maidencane (Panicum hemitomon), velvet dichanthelium (Dichanthelium scoparium), plumegrass (Erianthus spp.), southern wildrice (Zizaniopsis miliacea), Vasey's grass (Paspalum urvillei), rice cutgrass (Leersia oryzoides), common rush (Juncus effusus), and bulrush (Scirpus spp.). Little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), switchgrass (Panicum virgatum), broomsedge bluestem (Andropogon virginicus), and bushy bluestem (Andropogon glomeratus) occur on the higher slopes. Smartweed (Polygonum spp.), swamp sunflower (Helenium autumnale), and swamp rosemallow (Hibiscus moscheutos) are common forbs. Woody species such as black willow (Salix nigra), willow oak (Quercus phellos), water oak (Quercus nigra), eastern baccharis (Baccharis halimifolia), yaupon (Ilex vomitoria), and wax myrtle (Morella cerifera) may also occur on the site. The savannah structure of this site was probably influenced by the herding and grazing effects of bison and cattle. Wildfires occurring during extreme drought may also have played a role in the maintenance of the savannah landscape.
State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
T1A - Abandonment, no fire, and/or no grazing management R2A - Prescribed grazing, fire, and/or brush management T2A - Abandonment, no fire, and/or no grazing management R3A - Extensive brush management and/or herbicide applications State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
SavannhahOne community exists in the Savannah State, the Tallgrass/Wax Myrtle Community. The site is dominated by warm season perennial grasses and has a presence of 5 to 10 percent woody species intermixed.
Community 1.1
Tallgrass/Wax Myrtle Savannah
This reference plant community resembles a wet prairie or wet meadow and is dominated by warm season perennial grasses including maidencane, rice cutgrass, plumegrass, and common rush. Wax myrtle, possumhaw (Ilex decidua), and blackberry (Rubus spp.) are woody shrubs and vines that commonly occur throughout the site. Water oak, willow oak, and black willow provide a 5 to 10 percent canopy and occupy locations influenced by wetness. Water oak occurs on the higher/dryer upslopes while black willow occurs on the lower/wetter position of the site. Willow oak is intermediate between the two.
Fire may play a part in the maintenance of the savannah landscape in years of prolonged drought. This site has the potential to produce heavy fine fuel loads but is usually too wet to have fine fuel moisture conditions conducive for burning. Since this site has such favorable moisture regimes, especially during the summer, grazing and browsing by bison, deer, and cattle probably had more influence on the maintenance of the savannah landscape.
Due to the wetness of the site, mechanical brush management is rarely a treatment option for this site. The inability to selectively apply broadcast herbicide normally precludes this treatment option, although individual plant treatment with herbicides may be a viable option. Abandonment of the site allows a transitional shift in vegetation towards a shrub-dominated community that, over time, results in a tree/shrub state. The maintenance of the reference plant community seems to require the presence of grazing and browsing animals and periodic fire when conditions permit.Figure 6. 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 4800 6400 8000 Shrub/Vine 600 800 1000 Tree 300 400 500 Forb 300 400 500 Total 6000 8000 10000 State 2
ShrublandOne community exists in the Shrubland State, the Wax Myrtle/Blackberry Shrubland Community. The state is defined by woody canopy cover from 20 to 40 percent. Herbaceous production is limited compared to the Savannah State (1).
Community 2.1
Wax Myrtle/Blackberry Shrubland
This is a transitional community moving from the Savannah State (1) to Woodland State (3). It occurs when the site is abandoned and no grazing, burning, or brush management is applied over time. Wax myrtle, blackberry, yaupon, and baccharis increase in density and canopy coverage (20 to 40 percent) and begin to hinder herbaceous production. Saplings of water oak, willow oak, black willow, and water elm (Planera aquatica) appear. The invasive Chinese tallow (Sapium sebiferum) will invade the site.
If abandonment continues and no brush management or burning occurs, shrubs and vines continue to increase in density and canopy coverage is greater than 40 percent, which represents a transition to the Woodland State. Saplings begin to become trees and the resulting shading severely reduces the herbaceous production of the site where grazing and fire are no longer treatment options for recovery of the site.Figure 7. Annual production by plant type (representative values) or group (midpoint values)
Table 6. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Shrub/Vine 1200 1800 2400 Forb 900 1500 1800 Grass/Grasslike 600 900 1200 Tree 300 450 600 Total 3000 4650 6000 State 3
WoodlandOne community exists in the Woodland State, the Cottonwood/Elm Community. The site is defined by woody canopy cover over 40 percent. The site has reduced herbaceous production compared to the Savannah and Shrubland States.
Community 3.1
Wax Myrtle/Oak Woodland
This is a steady state community that occurs following long periods, greater than 20 years, of little or no management (grazing, burning, or brush control). Water oak, willow oak, black willow, wax myrtle, and yaupon become the dominant plants in the community and severely limit herbaceous production through shading. The herbaceous community will be dominated by sedges (Carex spp.), rushes (Juncus spp.), and shade tolerant forbs.
Available treatment options to move this community back to the Savannah State are limited to tree dozing during drought periods or individual plant treatments with herbicides. Neither of these treatments may be economically feasible.Figure 8. Annual production by plant type (representative values) or group (midpoint values)
Table 7. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Shrub/Vine 1920 2560 3200 Tree 1440 1920 2400 Forb 960 1280 1600 Grass/Grasslike 480 640 800 Total 4800 6400 8000 Transition T1A
State 1 to 2The driver for this transition is abandonment, lack of fire, and/or lack of prescribed grazing. Woody species are allowed to continue to grow until reaching over the threshold of 20 percent. This signifies the transition to the Shrubland State.
Restoration pathway R2A
State 2 to 1Prescribed grazing, periodic fire, and brush management are practices that will restore the site back to the reference state. The key to successful restoration is controlling the growth of woody species throughout the site.
Transition T2A
State 2 to 3The driver for the transition to the Woodland State is further abandonment, lack of fire, and lack of prescribed grazing. The woody species have grown to a canopy cover greater than 40 percent, which signifies this transition.
Restoration pathway R3A
State 3 to 1The driver for restoration from the Woodland State to the Savannah State is management of woody species. Extensive brush management is required to open up the overstory canopy and allow for more herbaceous growth.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Grasses 2400–4000 velvet panicum DISC3 Dichanthelium scoparium 2400–4000 – maidencane PAHE2 Panicum hemitomon 2400–4000 – 2 Grasses 960–1600 rice cutgrass LEOR Leersia oryzoides 960–1600 – giant cutgrass ZIMI Zizaniopsis miliacea 960–1600 – 3 Tall/midgrasses 720–1200 field paspalum PALA10 Paspalum laeve 720–1200 – Vasey's grass PAUR2 Paspalum urvillei 720–1200 – savannah-panicgrass PHGY2 Phanopyrum gymnocarpon 720–1200 – tall horned beaksedge RHMA6 Rhynchospora macrostachya 720–1200 – sortbeard plumegrass SABRC3 Saccharum brevibarbe var. contortum 720–1200 – 4 tallgrasses 480–800 bushy bluestem ANGL2 Andropogon glomeratus 480–800 – switchgrass PAVI2 Panicum virgatum 480–800 – little bluestem SCSC Schizachyrium scoparium 480–800 – Indiangrass SONU2 Sorghastrum nutans 480–800 – 5 Grasses 240–400 common carpetgrass AXFI Axonopus fissifolius 240–400 – common rush JUEF Juncus effusus 240–400 – softstem bulrush SCTA2 Schoenoplectus tabernaemontani 240–400 – Forb6 forbs 150–250 swamp smartweed POHY2 Polygonum hydropiperoides 150–250 – Pennsylvania smartweed POPE2 Polygonum pensylvanicum 150–250 – 7 forbs 90–150 swamp sunflower HEAN2 Helianthus angustifolius 90–150 – crimsoneyed rosemallow HIMO Hibiscus moscheutos 90–150 – ovate false fiddleleaf HYOV Hydrolea ovata 90–150 – floating marshpennywort HYRA Hydrocotyle ranunculoides 90–150 – seedbox LUAL2 Ludwigia alternifolia 90–150 – pickerelweed POCO14 Pontederia cordata 90–150 – grassy arrowhead SAGR Sagittaria graminea 90–150 – 8 forbs 60–100 swamp milkweed ASIN Asclepias incarnata 60–100 – tenangle pipewort ERDE5 Eriocaulon decangulare 60–100 – giant goldenrod SOGI Solidago gigantea 60–100 – Baldwin's ironweed VEBA Vernonia baldwinii 60–100 – rough cocklebur XAST Xanthium strumarium 60–100 – Baldwin's yelloweyed grass XYBA Xyris baldwiniana 60–100 – Shrub/Vine9 shrubs/vines 600–1000 eastern baccharis BAHA Baccharis halimifolia 600–1000 – possumhaw ILDE Ilex decidua 600–1000 – yaupon ILVO Ilex vomitoria 600–1000 – wax myrtle MOCE2 Morella cerifera 600–1000 – Oklahoma blackberry RUOK Rubus oklahomus 600–1000 – Tree10 trees 300–500 water oak QUNI Quercus nigra 300–500 – willow oak QUPH Quercus phellos 300–500 – black willow SANI Salix nigra 300–500 – Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
The favorable moisture regimes of this site provide conditions that keep plants green and growing during dry summer months and periods of drought. The site is attractive to domestic livestock as well as many species of wildlife including white-tailed deer, bobcat, raccoon, raptors, rodents, song birds, and feral hogs. Animal species use may change as the plant community changes on this site. Livestock have a higher preference for the site in a Savannah State where white-tailed deer and feral hogs may prefer the site in a Shrubland or Woodland State. Management should be applied to the site to produce the habitat for the species of concern.
Hydrological functions
This site is a collection area for seep water coming from the sandy uplands that always surround it. Ponding may occur for periods throughout the year.
Recreational uses
This site may be used for wildlife viewing or hunting.
Wood products
In the Woodland State, willow oak and water oak could provide timber products for firewood, cross ties, hardwood flooring, and lumber. The wetness of the site in addition to the presence of the deep sandy upland soils that typically surround this site make logging and access to the site by log trucks difficult.
Other products
Fruit from blackberries and grapes may be harvested on this site.
Supporting information
Inventory data references
These site descriptions were developed as part a Provisional Ecological Site project using historic soil survey manuscripts, available site descriptions, and low intensity field traverse sampling. Future work to validate the information is needed. This will include field activities to collect low, medium, and high-intensity sampling, soil correlations, and analysis of that data. A final field review, peer review, quality control, and quality assurance review of the will be needed to produce the final document.
Other references
1. 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, CO.
2. Archer, S. and F.E. Smeins. 1991. Ecosystem-level Processes. Chapter 5 in: Grazing Management: An Ecological Perspective. Edited by R.K. Heitschmidt and J.W. Stuth. Timber Press, Portland, OR.
3. 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. J. Range Manage. 56(2): 114-126.
4. Brown, J.R. and S. Archer. 1999. Shrub invasion of grassland: recruitment is continuous and not regulated by herbaceous biomass or density. Ecology 80(7): 2385-2396.
5. Foster, J.H. 1917. Pre-settlement fire frequency regions of the United States: a first approximation. Tall Timbers Fire Ecology Conference Proceedings No. 20.
6. Gould, F.W. 1975. The Grasses of Texas. Texas A&M University Press, College Station, TX. 653p.
7. Hamilton, W. and D. Ueckert. 2005. Rangeland Woody Plant Control: Past, Present, and Future. Chapter 1 in: Brush Management: Past, Present, and Future. pp. 3-16. Texas A&M University Press.
8. Scifres, C.J. and W.T. Hamilton. 1993. Prescribed Burning for Brush Management: The South Texas Example. Texas A&M University Press, College Station, TX. 245 p.
9. Smeins, F., S. Fuhlendorf, and C. Taylor, Jr. 1997. Environmental and Land Use Changes: A Long Term Perspective. Chapter 1 in: Juniper Symposium 1997, pp. 1-21. Texas Agricultural Experiment Station.
10. Stringham, T.K., W.C. Krueger, and P.L. Shaver. 2001. State and transition modeling: and ecological process approach. J. Range Manage. 56(2):106-113.
11. Texas Agriculture Experiment Station. 2007. Benny Simpson’s Texas Native Trees (http://aggie-horticulture.tamu.edu/ornamentals/natives/).
12. Texas A&M Research and Extension Center. 2000. Native Plants of South Texas (http://uvalde.tamu.edu/herbarium/index.html).
13. Thurow, T.L. 1991. Hydrology and Erosion. Chapter 6 in: Grazing Management: An Ecological Perspective. Edited by R.K. Heitschmidt and J.W. Stuth. Timber Press, Portland, OR.
14. USDA/NRCS Soil Survey Manuals counties within MLRA 87A.
15. USDA, NRCS. 1997. National Range and Pasture Handbook.
16. USDA, NRCS. 2007. The PLANTS Database (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
17. Vines, R.A. 1984. Trees of Central Texas. University of Texas Press, Austin, TX.
18. Vines, R.A. 1977. Trees of Eastern Texas. University of Texas Press, Austin, TX. 538 p.
19. Wright, H.A. and A.W. Bailey. 1982. Fire Ecology: United States and Southern Canada. John Wiley & Sons, Inc.Contributors
Mike Stellbaur
Tyson HartApproval
Bryan Christensen, 9/21/2023
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) Mike Stellbauer, David Polk, and Bill Deauman Contact for lead author Mike Stellbauer, Zone RMS, NRCS, Bryan, Texas Date 05/23/2005 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None. -
Presence of water flow patterns:
Water flow patterns are not uncommon. Deposition or erosion is uncommon for normal rainfall, but may occur during intense rainfall events. -
Number and height of erosional pedestals or terracettes:
Pedestals or terracettes are uncommon for this site when occupied by reference community. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Expect no more than 20 percent bare ground randomly distributed throughout. -
Number of gullies and erosion associated with gullies:
Gullies are uncommon for this site. -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
Under normal rainfall, little litter movement should be expected. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface is resistant to erosion. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil surface structure is 0 to 15 inches thick with colors from dark grayish brown fine sandy loam to black loamy fine sand and subangular blocky structure. SOM is approximately 1 to 6 percent. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
The savannah of trees, shrubs, vines, grasses, and forbs, along with adequate litter and little bare ground provides for maximum infiltration and little runoff under normal rainfall events. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. -
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:
Warm-season tallgrasses > Cool-season midgrasses >>Sub-dominant:
Other:
Trees > Shrubs/Vines > ForbsAdditional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
There should be little mortality or decadence for any functional groups. -
Average percent litter cover (%) and depth ( in):
Small to large woody litter is common on this site. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
6,000 pounds per acre for below average moisture years to 10,000 pounds per acre for above average moisture years. -
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:
Potential invasive species include wax myrtle, blackberry, black willow, baccharis, willow oak, water oak, and Chinese tallow. -
Perennial plant reproductive capability:
All perennial plants should be capable of reproducing, except for periods of prolonged drought conditions, heavy natural herbivory or intense wildfires.
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