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Ecological site R087AY012TX

Clayey Bottomland

Last updated: 9/21/2023
Accessed: 11/23/2024

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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): 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) 87A

Ecological site concept

The Clayey Bottomland has soils that are very deep clays and are associated with flooding regimes. Their heavy-textured soils cause water to drain slowly and may potentially pond for many days.

Associated sites

R087AY003TX	Claypan Savannah Claypan Savannah
R087AY005TX	Sandy Loam Sandy Loam
R087AY006TX	Sandy Sandy
R087AY010TX	Sandy Bottomland Sandy Bottomland
R087AY011TX	Loamy Bottomland Loamy Bottomland

Similar sites

R087AY011TX	Loamy Bottomland Loamy Bottomland

R087AY011TX

Loamy Bottomland

Loamy Bottomland

Table 1. Dominant plant species

Tree	(1) Fraxinus pennsylvanica (2) Ulmus crassifolia
Shrub	(1) Ilex decidua (2) Crataegus marshallii
Herbaceous	(1) Elymus virginicus (2) Carex

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Physiographic features

This site is nearly level and occurs along major rivers and their tributaries. The sites flood throughout the year, especially during late fall to early spring. Sites can pond water as well.

Table 2. Representative physiographic features

Landforms	(1) Plains > Flood plain
Runoff class	High
Flooding duration	Brief (2 to 7 days) to very long (more than 30 days)
Flooding frequency	Rare to frequent
Ponding duration	Brief (2 to 7 days) to long (7 to 30 days)
Ponding frequency	Rare to occasional
Elevation	61 – 229 m
Slope	0 – 2%
Ponding depth	0 – 15 cm
Water table depth	61 – 203 cm
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)	241 days
Freeze-free period (average)	276 days
Precipitation total (average)	1,041 mm

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Figure 2. Monthly precipitation range

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Line

Figure 3. Monthly average minimum and maximum temperature

Figure 4. Annual precipitation pattern

Figure 5. Annual average temperature pattern

Climate stations used

(1) BELLVILLE 6NNE [USC00410655], Bellville, TX
(2) GONZALES 1N [USC00413622], Gonzales, TX
(3) LA GRANGE [USC00414903], La Grange, TX
(4) MADISONVILLE [USC00415477], Madisonville, TX
(5) SMITHVILLE [USC00418415], Smithville, TX
(6) FRANKLIN [USC00413321], Franklin, TX
(7) FAIRFIELD 3W [USC00413047], Fairfield, TX
(8) COLLEGE STN [USW00003904], College Station, TX
(9) BARDWELL DAM [USC00410518], Ennis, TX
(10) CROCKETT [USC00412114], Crockett, TX
(11) ELGIN [USC00412820], Elgin, TX
(12) SOMERVILLE DAM [USC00418446], Somerville, TX

Influencing water features

This site is adjacent to rivers and streams. It receives overflow from watercourses and runoff from higher adjacent sites.

Wetland description

All soils in this site are hydric and may be wetlands, but onsite delineations are required to make certain.

Soil features

The soils of this site are deep clays. They receive extra water as overflow from watercourses or as runoff from adjacent higher sites. Having high shrink-swell characteristics, the soils crack when dry. In this condition, they take in water rapidly. When the soil becomes wet and the cracks close, permeability becomes very slow. The soils are very fertile and hold large amounts of water for plant use. They have a high wilting point which reduces forage yields in extremely dry years. Soils correlated include: Navaca, Navasota, Oletha, Roetex, Texark, and Zilaboy.

Table 4. Representative soil features

Parent material	(1) Alluvium – mudstone
Surface texture	(1) Clay
Family particle size	(1) Clayey
Drainage class	Somewhat poorly drained to moderately well drained
Permeability class	Very slow
Soil depth	203 cm
Surface fragment cover <=3"	0%
Surface fragment cover >3"	0%
Available water capacity (0-101.6cm)	12.7 – 17.78 cm
Calcium carbonate equivalent (0-101.6cm)	0 – 15%
Electrical conductivity (0-101.6cm)	0 – 16 mmhos/cm
Sodium adsorption ratio (0-101.6cm)	0 – 15
Soil reaction (1:1 water) (0-101.6cm)	5.1 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	0 – 3%
Subsurface fragment volume >3" (Depth not specified)	0%

Ecological dynamics

Natural fertility, presence of shade, proximity to water, and nutritious forage make this site a preferred grazing area. The wet nature of the site protects it from grazing at times, but during dry conditions it is often the first site to be overused. Virginia wildrye (Elymus virginicus), eastern gamagrass (Tripsacum dactyloides), switchcane (Arundinaria gigantea), switchgrass (Panicum virgatum), and sedges (Carex spp.) decrease in abundance and are replaced by dallisgrass (Paspalum dilatatum), common Bermudagrass (Cynodon dactylon), and carpetgrass (Axonopus fissifolius) as abusive grazing continues. Shrubs and hardwood saplings invade the site in the absence of proper grazing management and brush management. Prolonged mismanagement or abandonment allows the site to become a hardwood forest dominated by water oak (Quercus nigra), willow oak (Quercus phellos), overcup oak (Quercus lyrata), and cedar elm (Ulmus crassifolia) on non-calcareous sites or green ash (Fraxinus pennsylvanica), eastern cottonwood (Populus deltoides), pecan (Carya illinoinensis), cedar elm, and sugarberry (Celtis laevigata) on calcareous sites.

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

T1A	-	Heavy continuous grazing, no brush management, no fire
T1B	-	Invasion by invasive introduced species
T1C	-	Brush management, crop cultivation, pasture planting
R2A	-	Brush management, prescribed grazing, fire
T2A	-	Invasion by invasive introduced species
T2B	-	Brush management, crop cultivation, pasture planting
R3A	-	Brush management, invasive species control, range planting, prescribed grazing
T3A	-	Brush management, crop cultivation, pasture planting
R4A	-	Brush management, invasive species control, range planting, prescribed grazing
T4A	-	Invasion by invasive introduced species

State 1 submodel, plant communities

1.1. Wildrye/Sedge Savannah

1.2. Shrub

1.1A	-	Heavy continuous grazing, no brush management, no fire
1.2A	-	Brush management, prescribed grazing, fire

State 1
Savannah

Two communities exist in the Savannah State: the 1.1 Wildrye/Sedge Savannah Community and the 1.2 Shrub Community. Community 1.1 is characterized by tall and midgrass dominating the understory, with 20 percent woody cover by ash and elm. Community 1.2 is characterized by a an increase in shade tolerant grasses and 20 to 40 percent canopy cover of woody species.

Community 1.1
Wildrye/Sedge Savannah

The reference plant community of this site is a savannah. Oak, elm, hackberry (Celtis spp.), cottonwood, ash, black willow (Salix nigra), pecan, and other large trees provide about a 20 percent canopy. The overstory canopy is denser immediately adjacent to the watercourse. The understory includes hawthorn (Crataegus spp.), greenbriar (Smilax spp.), rattan (Calamus spp.), peppervine (Ampelopsis arborea), grape (Vitis spp.), and trumpet creeper (Campsis radicans). Sedges, Virginia wildrye, switchcane, broadleaf woodoats (Chasmanthium latifolium), and rustyseed paspalum (Paspalum langei) are in shaded and wet areas and dominate the herbaceous plant community. Various combinations of beaked panicum (Panicum anceps), switchgrass, Indiangrass, big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), eastern gamagrass, vinemesquite (Panicum obtusum), and Florida paspalum (Paspalum floridanum) may dominate drier, open areas. Continuous yearlong grazing grazing with no weed or brush management or abandoning the site for several years will tend to move towards a shrub-sapling community. Once woody shrubs and saplings invade the site, brush management in some form must be used to move back toward the savannah state. Prescribed burning is not a viable management tool on this site.

Figure 6. Annual production by plant type (representative values) or group (midpoint values)

Table 5. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	3138	5044	5492
Tree	897	1121	1569
Shrub/Vine	224	308	392
Forb	224	308	392
Total	4483	6781	7845

Community 1.2
Shrub

This plant community is a transitional community between the Savannah and Woodland State. It develops in the absence of proper grazing management and mechanical or chemical brush control treatments. It is usually the result of abandonment following cropping or yearly continuous grazing. Trees and shrubs begin to replace the grassland component of the savannah community. In addition to the naturally occurring cedar elm, water oak, hackberry, pecan, cottonwood, and green ash - honey locust (Gleditsia triacanthos), Chinese tallow (Triadica sebifera), and eastern persimmon (Diospyros virginiana) increase in density and canopy coverage (20 to 40 percent). Species whose seeds are windblown (elm, cottonwood, ash) or animal dispersed (persimmon, pecan, Chinese tallow) are the first to colonize and dominate the site. Remnants of Virginia wildrye and eastern gamagrass may still occur but the herbaceous component of the community becomes dominated by lesser producing grasses and forbs. Shade-tolerant species such as broadleaf woodoats, longleaf woodoats (Chasmanthium sessiliflorum), Cherokee sedge (Carex cherokeensis), ironweed (Veronia baldwinii), buttercup (Ranunculus spp.), and goldenrod (Solidago spp.) are the most abundant species as canopy cover increases. Prescribed burning is not a viable option for returning this community to a savannah due to the moisture content in and lack of quantity of herbaceous fine fuels. Mechanical or chemical brush control as well as prescribed grazing must be applied to move this vegetative state back towards the reference plant community.

Figure 7. Annual production by plant type (representative values) or group (midpoint values)

Table 6. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Tree	1457	1961	2466
Grass/Grasslike	1289	1905	2186
Shrub/Vine	336	560	673
Forb	280	504	616
Total	3362	4930	5941

Pathway 1.1A
Community 1.1 to 1.2

The Wildrye/Sedge Savannah will transition to the Shrubland Community when continued heavy grazing pressure, no brush management, and/or field abandonment continues. The transition is evident when woody species canopy cover exceeds 20 percent and grasses shift composition to more shade-tolerant species.

Pathway 1.2A
Community 1.2 to 1.1

Restoration back to the Wildrye/Sedge Community requires brush management and prescribed grazing. Mechanical or chemical controls can be used to remove the woody species and shrubs. Prescribed grazing may require destocking and/or deferment.

State 2
Woodland

One community exists in the Woodland State, the Ash/Elm Woodland Community. It is characterized by shade tolerant grasses and an overstory canopy of 40 to 80 percent.

Community 2.1
Ash/Elm Woodland

This plant community is a closed overstory (40 to 80 percent) woodland dominated by green ash, cedar elm, overcup oak, water oak, willow oak, pecan, cottonwood, sycamore (Plantanus occidentalis), and black willow. Understory shrubs and sub-shrubs include yaupon, farkleberry (Vaccinium arboreum), possumhaw (Ilex decidua), American beautyberry (Callicarpa americana), and hawthorn. Woody vines also occur and include Alabama supplejack (Berchemia scandens), poison ivy (Toxicodendron radicans), grape, greenbrier, trumpet creeper, Virginia creeper (Parthenocissus quinquefolia), and peppervine. A herbaceous understory is almost nonexistent but shade tolerant species including longleaf uniola, broadleaf woodoats, sedges, ironweed, ice plant (Verbesina lindheimeri), switchcane, eastern gamagrass, and goldenrod may occur in small amounts. Prescribed fire is not a viable treatment option for conversion of this site back to a semblance of the Wildrye/Sedge Savannah. Broadcast chemical brush control is not a treatment option either, however, individual plant treatment with herbicides on small acreages may be a viable option. Mechanical treatment of this site, along with seeding, is the most viable treatment option although probably not economical.

Figure 8. Annual production by plant type (representative values) or group (midpoint values)

Table 7. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Tree	3138	4315	5492
Shrub/Vine	729	1009	1289
Grass/Grasslike	336	448	560
Forb	112	168	224
Total	4315	5940	7565

State 3
Invasion

One community exists in the Invasion State, the Bermudagrass/Dallisgrass Community. It is characterized by an invasion by tame pasture grasses. The invasive species may have been planted for agriculture purposes or they may have invaded from nearby pastures.

Community 3.1
Bermudagrass/Dallisgrass

The herbaceous community is dominated by common Bermudagrass, dallisgrass, carpetgrass, giant ragweed, and annual sumpweed. White clover (Trifloium repens), vetch (Vicia sativa), and annual ryegrass (Lolium multiflorum) may also occur. This community develops from years of heavy continuous grazing. Prescribed grazing may shift this community back towards the Wildrye/Sedge Savannah Community, but total restoration may not be possible as invasive species are hard to control.

Figure 9. Annual production by plant type (representative values) or group (midpoint values)

Table 8. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	2242	2802	3363
Forb	1121	1401	1681
Tree	897	1233	1569
Shrub/Vine	224	308	392
Total	4484	5744	7005

State 4
Converted Land

The Converted Land State contains one community, the 4.1 Converted Land Community. The state is characterized by the land manager farming crops or planted grasses.

Community 4.1
Converted Land

Conversion of this site to cropland (primarily cotton) occurred from the middle 1800's to the early 1900's. Some remains in cropland today, typically cotton (Gossypium spp.), corn (Zea mays), sorghum (Sorghum spp.), and soybeans (Glycine max). Ditching, land leveling, and levee construction has significantly changed the topography and hydrology on many acres of this site. While restoration of this site to a semblance of the reference plant community is possible with seeding and prescribed grazing, complete restoration of the reference community in a reasonable time is very unlikely. Following crop production, this site is often planted to native or introduced grasses and legumes for livestock grazing or hay production. Typical species planted include improved Bermudagrass varieties, bahiagrass, switchgrass, dallisgrass, eastern gamagrass, annual ryegrass (Lolium multiflorum), and white clover. Many of the introduced species (bahiagrass, Bermudagrass, and dallisgrass) are invasive - moving by wind, water, and animals. Once established, they are extremely difficult to remove and will hinder the reestablishment of native species. The establishment and maintenance of these species requires cultivation, fertilization, weed control, and prescribed grazing management.

Figure 10. Annual production by plant type (representative values) or group (midpoint values)

Table 9. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	5604	7061	8518
Forb	2242	3082	3923
Total	7846	10143	12441

Transition T1A
State 1 to 2

The Savannah State will transition to the Woodland State when continued heavy grazing pressure, no brush management, and/or field abandonment continues. The transition is evident when woody species canopy cover exceeds 40 percent and grasses shift composition to more shade-tolerant species.

Transition T1B
State 1 to 3

The Savannah State will transition to the Invasion State when continuous, yearlong heavy grazing occurs, coupled with the invasion of species like Bermudagrass and Dallisgrass.

Transition T1C
State 1 to 4

The transition to the Converted State occurs when the site is plowed for planting crops or pasture. The driver for the transition is the land manager's decision to farm the site.

Restoration pathway R2A
State 2 to 1

Restoration back to the Savannah State requires substantial energy inputs. Brush management and prescribed grazing will be needed to shift the community back to the reference state. Mechanical or chemical controls can be used to remove the woody overstory species back below 20 percent. Prescribed grazing may require destocking and/or deferment to manage the understory grasses back to those found in the reference community.

Transition T2A
State 2 to 3

The Woodland State will transition to the Invasion State when invasion by species like Bermudagrass and Dallisgrass occur. These species will invade from nearby pastures and compete with native vegetation.

Transition T2B
State 2 to 4

The transition to the Converted State occurs when the site is plowed for planting crops or pasture. The driver for the transition is the land manager's decision to farm the site.

Restoration pathway R3A
State 3 to 1

Restoration back to the Savannah State requires substantial energy inputs. If woody species are present, chemical or mechanical brush management will be required. Range planting may be required if invasive species have taken over completely. Total restoration back to the reference community may not be possible due to the challenge of completely removing invasive species from the community.

Transition T3A
State 3 to 4

The transition to the Converted State occurs when the site is plowed for planting crops or pasture. The driver for the transition is the land manager's decision to farm the site.

Restoration pathway R4A
State 4 to 1

The restoration to State 1 can occur when the land manager ceases agronomic practices. Range planting of native species found in the reference community will be required to bring back a similar community as the State 1 plant composition. The extent of previous soil disturbances will determine how much seedbed preparation will be needed, as well as the ability to be restored. Proper grazing and brush management will be required to ensure success.

Transition T4A
State 4 to 3

The Converted Land State will transition to the Invasion State when continued heavy grazing pressure, no brush management, and/or field abandonment occurs. The transition is evident when forbs, shrubs, and woody species begin to limit the production of planted crops or pasture grasses.

Additional community tables

Table 10. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (kg/hectare)	Foliar cover (%)
Grass/Grasslike
1	Cool-season grasses			1608–2746
	sedge	CAREX	Carex	1608–2746	–
	Virginia wildrye	ELVI3	Elymus virginicus	1608–2746	–
2	Tallgrasses			1126–1922
	beaked panicgrass	PAAN	Panicum anceps	1126–1922	–
	rustyseed paspalum	PALA11	Paspalum langei	1126–1922	–
	switchgrass	PAVI2	Panicum virgatum	1126–1922	–
	eastern gamagrass	TRDA3	Tripsacum dactyloides	1126–1922	–
3	Warm-season grasses			482–824
	big bluestem	ANGE	Andropogon gerardii	482–824	–
	buffalograss	BODA2	Bouteloua dactyloides	482–824	–
	Indian woodoats	CHLA5	Chasmanthium latifolium	482–824	–
	longleaf woodoats	CHSE2	Chasmanthium sessiliflorum	482–824	–
	cylinder jointtail grass	COCY	Coelorachis cylindrica	482–824	–
	deertongue	DICL	Dichanthelium clandestinum	482–824	–
	twoflower melicgrass	MEMU	Melica mutica	482–824	–
	nimblewill	MUSC	Muhlenbergia schreberi	482–824	–
	Florida paspalum	PAFL4	Paspalum floridanum	482–824	–
	vine mesquite	PAOB	Panicum obtusum	482–824	–
	redtop panicgrass	PARI4	Panicum rigidulum	482–824	–
	little bluestem	SCSC	Schizachyrium scoparium	482–824	–
	marsh bristlegrass	SEPA10	Setaria parviflora	482–824	–
	Indiangrass	SONU2	Sorghastrum nutans	482–824	–
	gaping grass	STHI3	Steinchisma hians	482–824	–
	purpletop tridens	TRFL2	Tridens flavus	482–824	–
	longspike tridens	TRST2	Tridens strictus	482–824	–
Forb
4	Forbs			196–392
	great ragweed	AMTR	Ambrosia trifida	196–392	–
	annual marsh elder	IVAN2	Iva annua	196–392	–
	giant goldenrod	SOGI	Solidago gigantea	196–392	–
	Baldwin's ironweed	VEBA	Vernonia baldwinii	28–392	–
	white crownbeard	VEVI3	Verbesina virginica	28–392	–
	fuzzybean	STROP	Strophostyles	196–336	–
	lespedeza	LESPE	Lespedeza	196–336	–
	prairie snoutbean	RHLA5	Rhynchosia latifolia	196–336	–
	ticktrefoil	DESMO	Desmodium	196–336	–
Shrub/Vine
5	Shrubs/Vines			224–392
	Alabama supplejack	BESC	Berchemia scandens	224–392	–
	parsley hawthorn	CRMA5	Crataegus marshallii	224–392	–
	possumhaw	ILDE	Ilex decidua	224–392	–
	yaupon	ILVO	Ilex vomitoria	224–392	–
	oakwoods dewberry	RULA5	Rubus largus	224–392	–
	saw greenbrier	SMBO2	Smilax bona-nox	224–392	–
	cat greenbrier	SMGL	Smilax glauca	224–392	–
	grape	VITIS	Vitis	224–392	–
Tree
6	Trees			897–1569
	bitternut hickory	CACO15	Carya cordiformis	897–1569	–
	pecan	CAIL2	Carya illinoinensis	897–1569	–
	sugarberry	CELAL	Celtis laevigata var. laevigata	897–1569	–
	green ash	FRPE	Fraxinus pennsylvanica	897–1569	–
	overcup oak	QULY	Quercus lyrata	897–1569	–
	water oak	QUNI	Quercus nigra	897–1569	–
	willow oak	QUPH	Quercus phellos	897–1569	–
	black willow	SANI	Salix nigra	897–1569	–
	western soapberry	SASAD	Sapindus saponaria var. drummondii	897–1569	–
	bald cypress	TADI2	Taxodium distichum	897–1569	–
	cedar elm	ULCR	Ulmus crassifolia	897–1569	–

Interpretations

Animal community

Historically, the Clayey Bottomland site provided habitat to bison, deer, turkey, migratory birds and large predators such as wolves, coyotes, mountain lions, and black bear. White-tailed deer, turkey, fox and gray squirrels, coyotes, bobcats, and migratory birds find suitable habitat in these savannahs today. The favorable moisture regime of this site attracts many species of wildlife during the hot dry summer months when the quality and quantity of forages on upland sites may be lacking. Where old mast producing oaks and pecan trees are present, this site provides habitat for deer, turkey, squirrels, and ducks - especially during the winter. If the site transitions from the Savannah State towards the Woodland State, the quality of the habitat for deer, turkey, squirrels, and migratory birds declines.

Hydrological functions

Peak rainfall periods occur in May and June from frontal passage thunderstorms and in September and October from tropical systems as well as frontal passages. Rainfall amounts may be high (three to five inches per event) and events may be intense. The site is subject to erosion along adjacent stream banks where adequate herbaceous cover is not maintained and on heavy use areas such as roads and livestock trails. Extended periods (60 days) of little to no rainfall during the growing season are common. The site may be periodically inundated from overflow water from adjacent watercourses and may be ponded or saturated for long periods. This site may be a wetland or contain wetland inclusions as oxbows or stream meanders.

Recreational uses

Hunting, camping, bird watching, and equestrian activities are common.

Wood products

Water oak and willow oak provides material for hardwood flooring, plywood, veneer, and crossties. Green ash is used for bats, tool handles, and furniture. Post oak and water oak are used for firewood.

Other products

Fruit from blackberries, grapes, and plums and nuts from pecans are harvested.

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 Hart

Approval

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	06/08/2004
Approved by	Bryan Christensen
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
None.
Presence of water flow patterns:
Water flow patterns are common and follow old stream meanders. 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 the 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:
Some gullies may be present on side drains into perennial and intermittent streams. Gullies should be vegetated and stable.
Extent of wind scoured, blowouts and/or depositional areas:
None
Amount of litter movement (describe size and distance expected to travel):
This is a flood plain with occasional out-of-bank flow. Under normal rainfall, little litter movement should be expected; however, litter of all sizes may move long distances depending on obstructions under intense storm events.
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. Stability class range is expected to be 5 to 6.
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
The soil structure is 0 to 48 inches thick with colors from dark reddish brown clay to very dark gray clay with generally 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 > Forbs

Additional:
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 group.
Average percent litter cover (%) and depth ( in):
Litter is primarily herbaceous with small to large woody litter common.
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
4,000 pounds per acre for below average moisture years to 7,000 pounds per acre for above average moisture year.
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 Chinese tallow, huisache, honey locust, bois d''arc, elm, ash, McCartney rose, dallisgrass, Bermudagrass, Johnsongrass, annual sumpweed, and giant ragweed.
Perennial plant reproductive capability:
All perennial plants should be capable of reproducing, except for prolonged drought conditions, heavy natural herbivory and intense wildfires.

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Ecosystem states

T1A	-	Heavy continuous grazing, no brush management, no fire
T1B	-	Invasion by invasive introduced species
T1C	-	Brush management, crop cultivation, pasture planting
R2A	-	Brush management, prescribed grazing, fire
T2A	-	Invasion by invasive introduced species
T2B	-	Brush management, crop cultivation, pasture planting
R3A	-	Brush management, invasive species control, range planting, prescribed grazing
T3A	-	Brush management, crop cultivation, pasture planting
R4A	-	Brush management, invasive species control, range planting, prescribed grazing
T4A	-	Invasion by invasive introduced species