Natural Resources
Conservation Service
Ecological site R083BY017TX
Blackland
Last updated: 9/19/2023
Accessed: 11/13/2024
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.
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): 083B–Western Rio Grande Plain
Major Land Resource Area (MLRA) 83B It makes up about 9,285 square miles (24,060 square kilometers). The border towns of Del Rio, Eagle Pass, Laredo, and Zapata are in this MLRA. Interstate 35 crosses the area just north of Laredo. The Amistad National Recreation Area is just outside this MLRA, northwest of Del Rio, and the Falcon State Recreation Area is southeast of Laredo. Laughlin Air Force Base is just east of Del Rio. This area is comprised of inland, dissected coastal plains.
Classification relationships
USDA-Natural Resources Conservation Service, 2006.
-Major Land Resource Area (MLRA) 83B
Ecological site concept
The Blackland ecological site shows an intact grass community with small clumped dispersal of woody species. The soils are moderately deep to very deep, richly black in color, and characterized by their shrink-swell nature. The sites are widely distributed across the uplands and terraces throughout the region.
Associated sites
R083BY002TX |
Shallow Ridge |
---|---|
R083BY025TX |
Clay Loam |
Similar sites
R083AY017TX |
Blackland |
---|---|
R083CY017TX |
Blackland |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
Not specified |
Herbaceous |
(1) Schizachyrium scoparium |
Physiographic features
These nearly level to gently sloping soils occur on interfluves and hills of inland, dissected coastal plains. Slope ranges from 0 to 3 percent.
Table 2. Representative physiographic features
Landforms |
(1)
Coastal plain
> Interfluve
(2) Coastal plain > Hill |
---|---|
Runoff class | Medium to very high |
Flooding frequency | None |
Ponding frequency | None |
Elevation | 200 – 600 ft |
Slope | 3% |
Aspect | Aspect is not a significant factor |
Climatic features
MLRA 83B mainly has a subtropical steppe climate along the Rio Grande River and subtropical subhumid climates in La Salle and McMullen counties. Winters are dry and mild and the summers are hot. Tropical maritime air masses predominate throughout spring, summer and fall. Modified polar air masses exert considerable influence during winter, creating a continental climate characterized by large variations in temperature. Peak rainfall occurs late in spring and a secondary peak occurs early in fall. Most heavy thunderstorm activities occur during the summer months. July is hot and dry with little weather variations. Rainfall increases again in late August and September as tropical disturbances increase and become more frequent as the storms dissipate. Tropical air masses from the Gulf of Mexico dominate during the spring, summer and fall. Prevailing winds are southerly to southeasterly throughout the year except in December when winds are predominately northerly.
Table 3. Representative climatic features
Frost-free period (characteristic range) | 231-321 days |
---|---|
Freeze-free period (characteristic range) | 313-365 days |
Precipitation total (characteristic range) | 20 in |
Frost-free period (actual range) | 214-365 days |
Freeze-free period (actual range) | 260-365 days |
Precipitation total (actual range) | 19-21 in |
Frost-free period (average) | 270 days |
Freeze-free period (average) | 340 days |
Precipitation total (average) | 20 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly minimum temperature range
Figure 4. Monthly maximum temperature range
Figure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7. Annual average temperature pattern
Climate stations used
-
(1) FALCON DAM [USC00413060], Roma, TX
-
(2) LAREDO 2 [USC00415060], Laredo, TX
-
(3) ZAPATA 1 S [USC00419976], Zapata, TX
-
(4) DEL RIO INTL AP [USW00022010], Del Rio, TX
-
(5) CATARINA [USC00411528], Asherton, TX
-
(6) CRYSTAL CITY [USC00412160], Crystal City, TX
-
(7) DEL RIO 2 NW [USC00412361], Del Rio, TX
-
(8) EAGLE PASS 3N [USC00412679], Eagle Pass, TX
Influencing water features
Water features do not influence this site.
Wetland description
N/A
Soil features
The Dosrios series consist of soils that are very deep, well drained, moderately slowly to very slowly permeable soils, that formed in clayey sediments overlying clayey residuum. Soil series correlated to this site include: Dosrios and Monteola.
Table 4. Representative soil features
Parent material |
(1)
Residuum
–
sedimentary rock
|
---|---|
Surface texture |
(1) Clay |
Family particle size |
(1) Fine |
Drainage class | Well drained |
Permeability class | Moderately slow to very slow |
Soil depth | 70 – 80 in |
Surface fragment cover <=3" | Not specified |
Surface fragment cover >3" | Not specified |
Available water capacity (0-40in) |
4 – 7 in |
Calcium carbonate equivalent (0-40in) |
15% |
Electrical conductivity (0-40in) |
4 mmhos/cm |
Sodium adsorption ratio (0-40in) |
12 |
Soil reaction (1:1 water) (0-40in) |
7.4 – 9 |
Subsurface fragment volume <=3" (Depth not specified) |
5% |
Subsurface fragment volume >3" (Depth not specified) |
1% |
Ecological dynamics
The accounts of early explorers and settlers suggest that the Rio Grande Plains was likely a vast mosaic of open grassland, savannah, and shrubland. While moving in 1691 out of Maverick County and into Zavala County, Don Domingo de Teran found after crossing the Nueces River “the country was level and covered with mesquites and cats’ claw.” In 1849, Michler described south Texas as “concerning the land both on the Frio and the Leona, from these rivers back, that it may be divided into four parallel strips-the first, next to the river, consisting of heavy timber, and a heavy black soil, the second, a mesquite flat, of small width, and the soil of a lighter nature, and very fertile; the third, a range of low hills, covered with loose stones, and thick chaparral; the fourth, a wide-open prairie.” Lehman indicates, “thus while it is quite true that the Rio Grande Plains once had fewer woody plants and more grass than now, it is also true that an ample seed stock of shrubs and trees has been widely distributed for as long as man has known.” The vegetation structure likely varied from place-to-place depending on topography, soil properties, and time since the last major disturbance.
Large numbers of domestic livestock grazed South Texas as early as the mid-1700’s. Formal deeds to properties from the Spanish and Mexican governments came in the late 1760’s with much larger blocks granted in the decades to follow. Lehman indicated, “in 1757, the official Spanish census showed residents of Camargo and Reynosa in the lower Rio Grande owning over 90,000 sheep and goats. By way of contrast, combined numbers of cattle, oxen, horses, mules and burros were less than 16,000.” By the mid-1800’s, according to Lehman’s figures from the U. S. Census of 1889, “there were a minimum of 1,644,268 sheep-fully 45 percent of Texas total population, grazing south of the Nueces River.” According to Inglis, “the Rio Grande Plains had the four-leading sheep producing counties in the state and ten of the top fifteen sheep producing counties were in South Texas. The peak decade was 1880 to 1890, at times exceeding two million head.” These domestic animals were in addition to bison, antelope, deer, and large herds of wild horses. It is obvious from early accounts, that much of the Rio Grande Plains was periodically grazed hard by both domestic animals and wild populations as early as the early to mid-1700’s. It may be that overgrazing by sheep and goats could have suppressed the many shrubs, reduced shrub canopy, and arrested shrub seedlings.
With the arrival of European man, the South Texas area was fenced and, in many instances, stocked beyond its capability to sustain forage. This overstocking led to a reduced fire frequency and intensity, creating an opportunity for woody shrubs to increase across the landscape. As the natural graze-rest cycles were altered and stocking rates continued to exceed the natural carrying capacity of the land, midgrasses were replaced by shortgrasses and the ground cover was opened so additional annual and perennial forbs also increased. Drought certainly enhanced this effect. As prolonged overgrazing continued, shrub cover increased. Shortgrasses became dominant and forage production decreased. This change in plant cover and structure further decreased fire frequency and intensity, favoring shrub establishment and dominance.
The plant communities of this site are dynamic varying in relation to fire, periodic drought, and wet cycles. Periodic fires were set by either Native Americans or started naturally by lightning. Fire did not play as important a role on this site as in deeper more productive sites due to lower production of grasses to burn. Because of large amounts of gravel in the soil, available water holding capacity is greatly reduced. This causes highly variable forage production and minimal grass production during dry years. The historic community of this site was influenced to some extent by periodic grazing by herds of buffalo and wild horses. Herds of buffalo and wild horses would come into an area, graze it down, and then not come back for many months or even years depending upon the availability of water. This long deferment period allowed recovery of the grasses and forbs which served as fuel load. More than likely, fire occurred following years of good rainfall followed by a dry season. The fire frequency for this area is interpreted to be four to six years (Frost, 1998).
State and transition model
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Click on state and transition labels to scroll to the respective text
Ecosystem states
T1A | - | Absence of disturbance and natural regeneration over time coupled with excessive grazing pressure |
---|---|---|
T1B | - | Extensive soil disturbance and seeding with improved forage species |
R2A | - | Reintroduction of historic disturbance regimes |
T2A | - | Extensive soil disturbance followed by seeding with improved forage species |
R3B | - | Absence of disturbance and natural regeneration over time |
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Grassland
Dominant plant species
-
little bluestem (Schizachyrium scoparium), grass
-
Indiangrass (Sorghastrum nutans), grass
Community 1.1
Native Tall/Midgrass Prairie
This Native Tall/Midgrass Prairie Community (1.1) developed under natural disturbance regimes spanning thousands of years. Composition of tall grasses makes up over 60 percent of annual production, midgrasses approximately 30 percent, and associated grasses, forbs, shrubs, and woody vines make up the remainder. Annual forbs occur in varying amounts in response to grazing intensity, fire, drought, or excessive precipitation. This community is highly productive and can be managed to attain many landowner goals for livestock, wildlife, or recreation. The deep clay soils of this site, when managed in this state, will contain high amounts of organic matter, nutrients, and microbial activity. The soil also has a high available water capacity which can provide moisture to plants for extended amounts of time after rainfall events. These soil properties make this state of the Blackland site one of the most productive in the area. On the Blackland site rainfall can vary from lows on the western side to highs on the eastern side of the range. This difference in rainfall will cause subtle changes in plant community and overall productivity, which is displayed as high and low values in the annual production tables. Although the values provided in this report are representative, doing an onsite inventory of plant community and production when planning management decisions will help land managers make sound decisions based on actual conditions on the ground.
Figure 8. 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 | 3600 | 4000 | 4400 |
Forb | 200 | 235 | 275 |
Tree | 0 | 40 | 75 |
Shrub/Vine | 0 | 0 | 0 |
Total | 3800 | 4275 | 4750 |
Table 6. Ground cover
Tree foliar cover | 0-1% |
---|---|
Shrub/vine/liana foliar cover | 0-1% |
Grass/grasslike foliar cover | 70-90% |
Forb foliar cover | 5-10% |
Non-vascular plants | 0% |
Biological crusts | 0% |
Litter | 5-25% |
Surface fragments >0.25" and <=3" | 0% |
Surface fragments >3" | 0% |
Bedrock | 0% |
Water | 0% |
Bare ground | 0-5% |
Table 7. Canopy structure (% cover)
Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
---|---|---|---|---|
<0.5 | 0-1% | 0-1% | 10-40% | 5-10% |
>0.5 <= 1 | 0-1% | 0-1% | 10-40% | 5-10% |
>1 <= 2 | 0-1% | 0-1% | 40-100% | 5-10% |
>2 <= 4.5 | 0-1% | – | 40-100% | – |
>4.5 <= 13 | 0-1% | – | – | – |
>13 <= 40 | 0-1% | – | – | – |
>40 <= 80 | – | – | – | – |
>80 <= 120 | – | – | – | – |
>120 | – | – | – | – |
Figure 9. Plant community growth curve (percent production by month). TX4537, Mid/Tallgrass Community. Mid and tallgrasses dominant with less than 5% woody canopy species..
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
0 | 0 | 5 | 10 | 20 | 15 | 5 | 10 | 15 | 10 | 5 | 5 |
Community 1.2
Mid/Shortgrass Priaire
The Mid/Shortgrass Prairie Community (1.2) developed because of continued heavy grazing, an absence of the historic fire regime, and brush management. This community could also be driven by precipitation and may have been more common than the Native Tall/Midgrass Prairie Community (1.1) in drier parts of the MLRA. In comparison to the reference plant community (1.1) the Mid/Shortgrass Prairie Community (1.2) has reduced biomass production and litter accumulation which causes subtle impacts to the water, mineral, and energy cycles. For instance, this plant community has a slight decrease in live herbaceous cover which is replaced with litter and bare ground. The loss of thermal protection will start to negatively affect the available water in the soil. In this situation reduced rainfall and prolonged droughts will begin to have more of an impact of plant production. As tallgrasses decrease, midgrasses such as little bluestem, sideoats grama, plains bristlegrass, and silver bluestem increase. Reduced fuel loads result in reduced fire frequency/intensity. Annual and perennial forbs often increase as a result of decreased competition for sunlight and moisture. Introduced grass species such as common bermudagrass (Cynodon dactylon), Kleberg bluestem, and other introduced bluestems may start to invade. For the first time on this site, woody invader seedlings such as mesquite and huisache, attain shrub and then tree status. While the appearance of introduced plants prevents a full restoration to the reference plant community, some of these plants do perform the same functions as native species. Management activities can slow down the increase of introduced plants if this is the management goal.
Figure 10. Annual production by plant type (representative values) or group (midpoint values)
Table 8. Annual production by plant type
Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
---|---|---|---|
Grass/Grasslike | 3200 | 3600 | 3800 |
Tree | 300 | 375 | 450 |
Forb | 200 | 235 | 275 |
Shrub/Vine | 50 | 75 | 100 |
Total | 3750 | 4285 | 4625 |
Figure 11. Plant community growth curve (percent production by month). TX4525, Midgrass Dominant, 5% woodies. Midgrass plant community with less than a 5 percent canopy of woody plants. Growth occurs with peak in spring and fall seasons..
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
2 | 2 | 5 | 10 | 18 | 15 | 5 | 9 | 15 | 9 | 5 | 5 |
Pathway 1.1A
Community 1.1 to 1.2
The Native Tall/Midgrass Prairie Community (1.1) is the Reference Plant Community that would have dominated the Blackland site for thousands of years. Because of human influence this community is rarely found today. The tall grasses that dominated the landscape are highly preferred by livestock and are easily eliminated from the plant community with heavy continuous grazing. This is because less palatable plants are left ungrazed and will eventually be able to out-compete the dominant grasses for resources and space. The historic fire regime has also been changed so that intermittent fires every 3 to 8 years, which would decrease woody plant encroachment and encourage tall/midgrass dominance, have been prevented to protect livestock and societal interests. These factors cause a shift from a Native Tall/Midgrass Prairie Community (1.1) to a Mid/Shortgrass Prairie Community (1.2).
Pathway 1.2A
Community 1.2 to 1.1
The restoration to the reference plant community (1.1) is relatively simple at this point in time and can be accomplished by installation of prescribed grazing with appropriate stocking rates. If the herbaceous component of this community remains healthy and maintains at least 85 to 90 percent ground cover, including live plants and litter, the woody component of this site will remain stable and new seedling growth will be inhibited. Individual Plant Treatment (IPT) and prescribed burning will be the most efficient and economical ways to manage brush species encroachment. The use of prescribed fire in conjunction with prescribed grazing enhances the recovery process. Mechanical or chemical brush management is also feasible and relatively economical because this community has less than a 10 percent canopy of mesquite or huisache. Once initial woody plant management has been achieved, periodic burning, reduced stocking, and prescribed grazing will cause a transition towards the reference plant community over time. If the landowner wants to speed this transition, some range planting can be done to increase the number of desired species.
State 2
Tree/Shrubland Complex
Dominant plant species
-
sweet acacia (Acacia farnesiana), shrub
-
spiny hackberry (Celtis ehrenbergiana), shrub
Community 2.1
Mesquite/Huisache Grassland
A threshold has been crossed between the Grassland State (1) and the Tree/Shrubland Complex (2). This Mesquite/Huisache Grassland Community (2.1) has developed because of continuous heavy grazing, loss of fire as a management tool, greatly altered water and energy cycles, and invasion of woody plants. Episodic droughts will also hasten this process. The shift from the Mid/Shortgrass Prairie Community (1.2) to the Mesquite/Huisache Grassland Community (2.1) can happen within a period of 5 to 10 years under certain conditions. Mesquite and huisache will be the dominate woody species on this site, but other woody species such as lotebush (Zizyphus obtusifolia), granjeno (Celtis ehrenbergiana), whitebrush (Aloysia gratissima), desert yaupon (Schaefferia cuneifloia), prickly pear (Opuntia engelmannii), and algerita (Mahonia trifoliolata) will occur as part of the plant community. Although there has been an increase in woody plant numbers, the amount of canopy cover they create is the main difference driving the transition. The increased size or number of the woody plants creates more canopy cover and shades out the herbaceous component. This state will have an increased amount of bare ground which will negatively affect the amount of available water for plants in the soil. This will favor the woody species because their root systems can out-compete herbaceous plants for water. In this state forbs will respond quickly to rainfall events and in some cases they will also out-compete grass species for resources, causing an overall decrease in grass production. This community can be quite productive for cattle and wildlife and can be maintained indefinitely with continued management. To do so will require judicious grazing, periodic fire(s), and almost continuous brush management on an individual plant basis or other means that can achieve landowner priorities. The community in this state may be much better wildlife habitat than the previous state because of the increased amount of woody cover and the increased production of both perennial and annual forbs. With increased emphasis on white-tailed deer and bobwhite quail many landowners choose to manage their land in this condition to enhance wildlife populations.
Figure 12. Annual production by plant type (representative values) or group (midpoint values)
Table 9. Annual production by plant type
Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
---|---|---|---|
Grass/Grasslike | 2600 | 3000 | 3400 |
Tree | 550 | 625 | 825 |
Forb | 375 | 450 | 550 |
Shrub/Vine | 200 | 225 | 250 |
Total | 3725 | 4300 | 5025 |
Figure 13. Plant community growth curve (percent production by month). TX4528, Shrub/Woodland Community, 20-50% canopy. Shrub/Woodland Community with 20-50% woody canopy..
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
2 | 2 | 5 | 10 | 18 | 15 | 5 | 9 | 15 | 9 | 5 | 5 |
Community 2.2
Mesquite/Huisache Shrubland
Over time, with continued heavy grazing, no fire, and no brush management the Blackland site will be transformed into a Mesquite/Huisache Shrubland Community (2.2) with canopies from 50 to 100 percent. Extended droughts will hasten this process. Once the tree canopy reaches approximately 50 percent, the understory composition and production is driven more by shade than competition for moisture. At this point, no amount of deferred grazing will restore the plant community to the Grassland State. The herbaceous production is dominated by threeawn species, Hall’s panicum (Panicum hallii), Texas wintergrass, silver bluestem, and annual forbs and grasses. The same grass species present in the Grassland state can be found in this community phase, but they will be much less productive and more infrequent. Because of the higher amounts of bare ground, opportunistic forbs like giant ragweed (Ambrosia trifida) and annual broomweed, will be able to quickly take advantage of timely rain events. This allows them to dominate the herbaceous plant community at the expense of grass production. The dramatic increase in brush canopy does not necessarily mean an improvement in deer or wildlife habitat. Although there is adequate visual and thermal protection other components of quality habitat, such as an adequate food source, are missing and will affect this areas use. Livestock management also becomes problematic in this plant community because of drastically reduced grass production.
Figure 14. Annual production by plant type (representative values) or group (midpoint values)
Table 10. Annual production by plant type
Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
---|---|---|---|
Tree | 1700 | 2000 | 2475 |
Grass/Grasslike | 1150 | 1400 | 1650 |
Shrub/Vine | 550 | 625 | 825 |
Forb | 375 | 450 | 550 |
Total | 3775 | 4475 | 5500 |
Figure 15. Plant community growth curve (percent production by month). TX4529, Shrub Woodland Community with >50% Woodies. Shrub Woodland Community with >50% Woodies.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
2 | 2 | 5 | 10 | 18 | 15 | 5 | 9 | 15 | 9 | 5 | 5 |
Pathway 2.1A
Community 2.1 to 2.2
Without diligent brush management along with prescribed grazing and other conservation practices this phase will inevitably transition from a Mesquite/Huisache Grassland Community (2.1) to a Mesquite/Huisache Shrubland Community (2.2). This transition can happen within a 5 to 10 year period and is based on an increase of woody canopy cover to more than 50 percent and a severe decrease in herbaceous plant production. Short grasses and forbs will dominate the herbaceous vegetation and while this transition may be desirable for some wildlife, it will be detrimental for a cattle or livestock operation. Cool-season grasses like Texas wintergrass will also become a more dominant part of the plant community.
Pathway 2.2A
Community 2.2 to 2.1
Major inputs, both chemical and mechanical, are often required to restore this community to the Mesquite/Huisache Grassland Community (2.1). A common practice is the use of aerial applied herbicides to reduce the canopy, allow sunlight to penetrate to the soil surface, and grow enough herbaceous fuel loads for suitable burning. Aerial spraying is followed by the use of prescribed fire to remove some of the woody vegetation and maintain semi-open wooded grassland for several years following treatment. Although these practices kill some of the woody vegetation, plants that are not killed by the herbicide application will re-sprout from the crown and in a relatively short period of time, can attain a 90 to 100 percent canopy again. Often with this community, mechanical means such as root plowing and raking are utilized along with dozing and grubbing. Species like mesquite and huisache will re-sprout if not removed completely from the ground. Chaining and roller chopping are mechanical practices which will be short lived and will typically result in thicker, harder to manage brush stands and will encourage brush seedlings. Follow-up conservation practices such as Individual Plant Treatment (IPT) for woody re-growth and new seedlings and prescribed grazing will be necessary for several years after the initial brush management to maintain an improved plant community. Depending on local conditions it may also be necessary to re-introduce a seed source for desired native plant species through range planting.
Community 3.1
Planted Pasture/Cropland
To go from the Mesquite/Huisache Shrubland Community (2.2) to the Converted Land State, (3) mechanical brush management must be applied. Typically rootplowing and raking is utilized to remove the woody vegetation. A seedbed is then prepared and the area is planted into grass or crops. Typical crops planted on this site include small grains like oats or feed grains like sorghum and hay grazer. If introduced species are planted with the addition of moderate to high rates of commercial fertilizer, this site may be more productive than the original plant community. Because these soils are so productive, this site has historically been planted to bermudagrass or introduced bluestems. Inputs such as fertilizer, herbicide, and adequate precipitation or irrigation may be necessary to maintain high productivity. Now, because of the availability of seed, landowners can also replant with native species. To maintain this seeded state, herbicides must be used to control woody seedlings that seek to invade as soon as the pasture is established. Not only is there a long-lived seed source of mesquite, huisache, and other woody species, additional seed are brought in by grazing animals and domestic livestock.
Figure 16. Annual production by plant type (representative values) or group (midpoint values)
Table 11. Annual production by plant type
Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
---|---|---|---|
Grass/Grasslike | 4500 | 5250 | 6000 |
Total | 4500 | 5250 | 6000 |
Figure 17. Plant community growth curve (percent production by month). TX4531, Converted Land - Introduced Grass Seeding. Seeding Coverted Land into Introduced grass species..
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
0 | 0 | 5 | 10 | 20 | 15 | 5 | 10 | 15 | 10 | 5 | 5 |
Community 3.2
Go Back Land
This community develops after land has been cropped and left to fallow without management inputs. It can also develop after a mechanical brush management practice has been applied but not followed up with appropriate management practices. It is typified by the dominance of woody species, very little herbaceous grass production, high amounts of annual forbs and grasses and large areas covered by tree leaf litter or bare ground. Because of the seed bank present in the soil and the constant addition of new seed from grazing/browsing animals and seed eating birds, re-infestation of woody seedlings happens in a relatively short time period of 2 to 5 years. Typically, pastureland will transition to the Mesquite/Huisache Grassland Community (2.1) and not to Go Back Land (3.2).
Figure 18. Plant community growth curve (percent production by month). TX4534, Converted Land - Woody Seedlings Encroachment. Woody seedling encroachment on converted lands such as abandoned cropland, native seeded land, and introduced seeding lands..
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
J | F | M | A | M | J | J | A | S | O | N | D |
2 | 2 | 5 | 10 | 18 | 15 | 5 | 9 | 15 | 9 | 5 | 5 |
Pathway 3.1A
Community 3.1 to 3.2
The transition from Planted Pasture/Cropland (3.1) to Go Back Land (3.2) can occur when crop fields are left to fallow without management. Generally, pastureland will transition to the Tree/Shrubland Complex (2) and not to the Go Back Land plant community.
Pathway 3.2A
Community 3.2 to 3.1
Many land managers may want to utilize this site as cropland or pastureland. To achieve this transition land clearing practices such as land clearing, dozing and raking will be necessary. After the land has been cleared and an appropriate seedbed prepared, the crop or pasture can be planted.
Transition T1A
State 1 to 2
The transition from the Grassland State (1) to the Tree/Shrubland Complex (2) can happen within 5 to 10 years. This transition can be driven by persistently dry weather conditions, grazing management, and the lack of fire and brush management practices. Overstocking the site with grazing animals will put pressure on the herbaceous plant component of the community. This will create a more favorable environment with bare ground and open spaces for woody plants to germinate and grow. If the woody component is not managed it will begin to dominate the landscape and out-compete grasses and forbs for water, sunlight, and other resources.
Transition T1B
State 1 to 3
Land managers may want to utilize this site as cropland or pastureland. To achieve this transition from the Grassland State (1) brush management and heavy disking with a Rhome disk, or other heavy implement, will be necessary to incorporate the vegetation into the soil. Prescribed burning can also be used prior to the disking operation to eliminate excessive vegetation. After the land has been cleared and an appropriate seedbed prepared the crop or pasture can be planted.
Restoration pathway R2A
State 2 to 1
Major inputs, both chemical and mechanical, are often required to restore the Tree/Shrubland Complex State (2) to the Grassland State (1). Often with this community, mechanical means such as rootplowing and raking are utilized along with dozing and grubbing. Species like mesquite and huisache will re-sprout if not removed completely from the ground. Chaining and rollerchopping are mechanical practices which will be short lived and will typically result in thicker, harder to manage brush stands and will encourage brush seedlings. Follow-up conservation practices such as Individual Plant Treatment (IPT) for woody re-growth and new seedlings and prescribed grazing will be necessary for several years after the initial brush management to maintain an improved plant community. Depending on local conditions, it may also be necessary to prepare an appropriate seedbed and, re-introduce a seed source for desired native plant species through range planting.
Transition T2A
State 2 to 3
Land managers may want to utilize this site as cropland or pastureland. To achieve this transition practices such as dozing and raking will be necessary. After the land has been cleared and an appropriate seedbed prepared the crop or pasture can be planted.
Restoration pathway R3B
State 3 to 2
In time, this site will revert to the Tree/Shrubland Complex (2) on its own, but usually this timeline is impractical for landowners. Prescribed grazing along with various brush management practices will be necessary to achieve this transition. This phase is very unproductive for herbaceous plants and it could take years for desirable plant species to begin to reestablish.
Additional community tables
Table 12. Community 1.1 plant community composition
Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
---|---|---|---|---|---|---|
Grass/Grasslike
|
||||||
1 | Perennial Tall/Midgrasses | 1700–2475 | ||||
little bluestem | SCSC | Schizachyrium scoparium | 1700–2475 | – | ||
Indiangrass | SONU2 | Sorghastrum nutans | 1700–2475 | – | ||
multiflower false Rhodes grass | TRPL3 | Trichloris pluriflora | 1700–2475 | – | ||
2 | Perennial Midgrasses | 570–825 | ||||
Indiangrass | SONU2 | Sorghastrum nutans | 1700–2475 | – | ||
little bluestem | SCSC | Schizachyrium scoparium | 1700–2475 | – | ||
alkali sacaton | SPAI | Sporobolus airoides | 0–825 | – | ||
sideoats grama | BOCU | Bouteloua curtipendula | 570–825 | – | ||
silver beardgrass | BOLA2 | Bothriochloa laguroides | 570–825 | – | ||
Arizona cottontop | DICA8 | Digitaria californica | 570–825 | – | ||
Texas cupgrass | ERSE5 | Eriochloa sericea | 380–550 | – | ||
streambed bristlegrass | SELE6 | Setaria leucopila | 380–550 | – | ||
vine mesquite | PAOB | Panicum obtusum | 380–550 | – | ||
white tridens | TRAL2 | Tridens albescens | 190–275 | – | ||
false Rhodes grass | TRCR9 | Trichloris crinita | 190–275 | – | ||
pink pappusgrass | PABI2 | Pappophorum bicolor | 190–275 | – | ||
3 | Perennial Shortgrasses | 380–550 | ||||
buffalograss | BODA2 | Bouteloua dactyloides | 380–550 | – | ||
curly-mesquite | HIBE | Hilaria belangeri | 380–550 | – | ||
4 | Cool Season Grasses | 380–550 | ||||
Texas wintergrass | NALE3 | Nassella leucotricha | 380–550 | – | ||
Scribner's rosette grass | DIOLS | Dichanthelium oligosanthes var. scribnerianum | 190–275 | – | ||
Virginia wildrye | ELVI3 | Elymus virginicus | 190–275 | – | ||
Forb
|
||||||
5 | Forbs | 190–275 | ||||
Forb, annual | 2FA | Forb, annual | 190–275 | – | ||
Cuman ragweed | AMPS | Ambrosia psilostachya | 190–275 | – | ||
Illinois bundleflower | DEIL | Desmanthus illinoensis | 190–275 | – | ||
snow on the prairie | EUBI2 | Euphorbia bicolor | 190–275 | – | ||
Maximilian sunflower | HEMA2 | Helianthus maximiliani | 190–275 | – | ||
coastal indigo | INMI | Indigofera miniata | 190–275 | – | ||
dotted blazing star | LIPU | Liatris punctata | 190–275 | – | ||
yellow puff | NELU2 | Neptunia lutea | 190–275 | – | ||
fogfruit | PHYLA | Phyla | 190–275 | – | ||
upright prairie coneflower | RACO3 | Ratibida columnifera | 190–275 | – | ||
American snoutbean | RHAM | Rhynchosia americana | 190–275 | – | ||
bushsunflower | SIMSI | Simsia | 190–275 | – | ||
silverleaf nightshade | SOEL | Solanum elaeagnifolium | 190–275 | – | ||
Tree
|
||||||
6 | Trees/Shrubs | 0–75 | ||||
sweet acacia | ACFA | Acacia farnesiana | 0–55 | – | ||
spiny hackberry | CEEH | Celtis ehrenbergiana | 0–55 | – | ||
hackberry | CELTI | Celtis | 0–55 | – | ||
honey mesquite | PRGLG | Prosopis glandulosa var. glandulosa | 0–55 | – | ||
live oak | QUVI | Quercus virginiana | 0–55 | – |
Interpretations
Animal community
As a historic tall/midgrass prairie, this site was occupied by bison, antelope, deer, quail, turkey, and dove. This site was also used by many species of grassland songbirds, migratory waterfowl, and coyotes. This site now provides forage for livestock and is still used by quail, dove, migratory waterfowl, grassland birds, coyotes, and deer.
Feral hogs (Sus scrofa) can be found on most ecological sites in Texas. Damage caused by feral hogs each year includes, crop damage by rutting up crops, destroyed fences, livestock watering areas, and predation on native wildlife. Feral hogs have few natural predators, thus allowing their population to grow to high numbers.
Wildlife habitat is a complex of many different plant communities and ecological sites across the landscape. Most animals use the landscape differently to find food, shelter, protection, and mates. Working on a conservation plan for the whole property, with a local professional, will help managers make the decisions that allow them to realize their goals for wildlife and livestock.
Grassland State(1): This state provides the maximum amount of forage for livestock such as cattle. It is also utilized by deer, quail and other birds as a source of food. When a site is in the reference plant community phase (1.1) it will also be used by some birds for nesting, if other habitat requirements like thermal and escape cover are near.
Shrubland State (2): This state can be maintained to meet the habitat requirements of cattle and wildlife. Land managers can find a balance that meets their goals and allows them flexibility to manage for livestock and wildlife. Forbs for deer and birds like quail will be more plentiful in this state. There will also be more trees and shrubs to provide thermal and escape cover for birds as well as cover for deer.
Converted Land State (3): The quality of wildlife habitat this site will produce is extremely variable and is influenced greatly by the timing of rain events. This state is often manipulated to meet landowner goals. If livestock production is the main goal, it can be converted to pastureland. It can also be planted to a mix of grasses and forbs that will benefit both livestock and wildlife. A mix of forbs in the pasture could attract pollinators, birds and other types of wildlife. Food plots can also be planted to provide extra nutrition for deer.
This rating system provides general guidance as to animal preference for plant species. It also indicates possible competition between kinds of herbivores for various plants. Grazing preference changes from time to time, especially between seasons, and between animal kinds and classes. Grazing preference does not necessarily reflect the ecological status of the plant within the plant community. For wildlife, plant preferences for food and plant suitability for cover are rated. Refer to habitat guides for a more complete description of a species habitat needs.
Recreational uses
Hunting and bird watching are common activities.
Supporting information
Inventory data references
Information presented was derived from the revised Range Site, literature, limited NRCS clipping data (417s), field observations, and personal contacts with range-trained personnel.
Other references
Archer, S. 1995. Herbivore mediation of grass-woody plant interactions. Tropical Grasslands, 29:218-235.
Archer, S. 1995. Tree-grass dynamics in a Prosopis-thornscrub savanna parkland: reconstructing the past and predicting the future. Ecoscience, 2:83-99.
De Leon, A. 2003. Itineraries of the De Léon Expeditions of 1689 and 1690. In Spanish Exploration in the Southwest, 1542-1706. Edited by H. E. Bolton. Charles Scribner’s Sons, New York, NY.
Dillehay T. 1974. Late quaternary bison population changes on the Southern Plains. Plains Anthropologist, 19:180-96.
Duaine, C. L. 1971. Caverns of Oblivion. Packrat Press, Oak Harbor, WA.
Everitt, J. H., D. L. Drawe, and R. I. Leonard. 2002. Trees, Shrubs, and Cacti of South Texas. Texas Tech University Press, Lubbock, TX.
Everitt, J. H., D. L. Drawe, and R. I. Lonard. 1999. Field Guide to the Broad-Leaved Herbaceous Plants of South Texas. Texas Tech University Press. Lubbock, TX.
Frost, C. C. 1998. Presettlement fire frequency regimes of the United States: a first approximation. In Fire in ecosystem management: shifting the paradigm from suppression to prescription. Tall Timbers Fire Ecology Conference Proceedings. 20:70-81.
Gilbert, L. E. 1982. An ecosystem perspective on the role of woody vegetation, especially mesquite, in the Tamaulipan biotic region of South Texas. Proceeding Symposium of the Tamaulipan Biotic Province, Corpus Christi, TX.
Hanselka, W., R. Lyons, and M. Moseley. 2009. Grazing Land Stewardship: A Manual for Texas Landowners. Texas AgriLife Extension Service, College Station, TX.
Hart, C. R., T. Garland, A. C. Barr, B. B. Carpenter, and J.C. Reagor. 2003. Toxic Plants of Texas: Integrated Management Strategies to Prevent Livestock Losses. Texas Cooperative Extension Bulletin B-6103 11-03.
Heitschmidt R. K., Stuth J. W., eds. 1991. Grazing management: an ecological perspective. Timberline Press, Portland, OR.
Inglis, J. M. 1964. A history of vegetation of the Rio Grande Plains. Texas Parks and Wildlife Department Bulletin No. 45, Austin, TX.
Lehman, V. W. 1969. Forgotten legions: sheep in the Rio Grande Plains of Texas. Texas Western Press, University of Texas at El Paso, El Paso, TX.
McGinty A., D. N. Ueckert. 2001. The Brush Busters success story. Rangelands, 23:3-8.
McLendon T. 1991. Preliminary description of the vegetation of South Texas exclusive of coastal saline zones. Texas Journal of Science, 43: 13-32
Norwine, J. 1978. Twentieth-century semiarid climates and climatic fluctuations in Texas and northeastern Mexico. Journal of Arid Environments, 1:313-325.
Norwine, J. and R. Bingham. 1986. Frequency and severity of droughts in South Texas: 1900-1983, 1-17. In Livestock and wildlife management during drought. Edited by R. D. Brown. Caesar Kleberg Wildlife Research Institute, Kingsville, TX.
Parvin, R. W. 2003. Rio Bravo Resource Conservation and Development. Llanos Mestenos South Texas Heritage Trail. Zapata, TX.
Scifres, C. J. and W. T. Hamilton. 1993. Prescribed burning for brushland management: the South Texas example. Texas A&M Press, College Station, TX.
Scifres C. J., W. T. Hamilton, J. R. Conner, J. M. Inglis, and G. A. Rasmussen. 1985. Integrated Brush Management Systems for South Texas: Development and Implementation. Texas Agricultural Experiment Station, College Station, TX.
Texas Parks and Wildlife Department. 2007. List of White-tailed Deer Browse and Ratings. District 8.
Thurow, T. L. and J. W. Hester. 1997. How an increase or reduction in juniper cover alters rangeland hydrology. Juniper Symposium Proceedings. Texas A&M University, San Angelo, TX.
Weltz, M. A. and W. H. Blackburn. 1995. Water budget for south Texas rangelands. Journal of Range Management, 48:45-52.
Wright, B. D., R. K. Lyons, J. C. Cathey, and S. Cooper. 2002. White-tailed deer browse preferences for South Texas and the Edwards Plateau. Texas Cooperative Extension Bulletin B-6130.
Contributors
Gary Harris, MSSL, NRCS, Robstown, Texas
Approval
Bryan Christensen, 9/19/2023
Acknowledgments
Technical reviewers and contributors include:
Jason Hohlt, RMS, NRCS, Kingsville, Texas
Tim Reinke, RMS, NRCS, Victoria, Texas
Clark Harshbarger, RSS, NRCS, Robstown, Texas
Shanna Dunn, RSS, NRCS, Corpus Christi, Texas
Harvey Kahlden, Karnes SWCD, Kenedy, Texas
Ann Graham, Editor, Temple, Texas
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) | David Hinojosa, RMS, NRCS, Robstown, TX |
---|---|
Contact for lead author | (361) 241-0609 |
Date | 08/08/2011 |
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:
Few water flow patterns are normal for this site due to landscape position and slopes. -
Number and height of erosional pedestals or terracettes:
Pedestals would have been uncommon for this site. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Less than five percent bare ground. -
Number of gullies and erosion associated with gullies:
None. -
Extent of wind scoured, blowouts and/or depositional areas:
None. -
Amount of litter movement (describe size and distance expected to travel):
Small-to-medium sized litter may move short distances during intense storms. -
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 stability class range is expected to be 4 to 6. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil surface struture is 10 to 60 inches thick with colors ranging from black to dark grayish brown with subangular blocky structure. Soil organic matter is one to six percent. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
A high canopy cover of bunch, rhizomatous, and stoliniferous grasses will help minimize runoff and maximize infiltration. Grasses and forbs should comprise approximately 90 percent of total plant compostion by weight. Trees and shrubs will comprise about 10 percent by weight. -
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:
Perennial Tall/Midgrasses >> Perennial Midgrasses >>Sub-dominant:
Perennial Shortgrasses> Forbs > Cool Season grasses>> Trees/ShrubsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Little apparent mortality or decadence for any functional groups. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
4,000 to 5,500 pounds per acre. -
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:
Mesquite, huisache, willow baccharis, and Old World bluestems. -
Perennial plant reproductive capability:
All species should be capable of reproducing.
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Absence of disturbance and natural regeneration over time coupled with excessive grazing pressure |
---|---|---|
T1B | - | Extensive soil disturbance and seeding with improved forage species |
R2A | - | Reintroduction of historic disturbance regimes |
T2A | - | Extensive soil disturbance followed by seeding with improved forage species |
R3B | - | Absence of disturbance and natural regeneration over time |