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UNITED STATES
DEPARTMENT OF AGRICULTURE
NATURAL RESOURCES CONSERVATION SERVICE
ECOLOGICAL SITE DESCRIPTION
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ECOLOGICAL SITE CHARACTERISTICS
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Site Type: Rangeland
Site Name: Very Shallow 16-21" PZ
Site ID: R077CY037TX
Major Land Resource Area: 077C - Southern High Plains, Southern Part
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Physiographic Features
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This site is classified as an upland. It occurs on nearly level to gently sloping plains, typically adjacent to escarpments, along relict drainageways, and summit positions of knolls and interfluves. Soils are very shallow to shallow with caliche fragments throughout. The caliche beds in which the site occurs may be fairly soft or may be indurated. The site is generally located in the upper Ogallala formation and often occurs immediately above the hard caliche outcrops of the high plains escarpment; and in the erosional slopes just below.
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| Land Form: |
(1) |
Interfluve |
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(2) |
Knoll |
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(3) |
Plain |
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Minimum |
Maximum |
| Elevation (feet): |
2000 |
5300 |
| Slope (percent): |
0 |
5 |
| Water Table Depth (inches): |
0 |
0 |
| Flooding: |
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| Frequency: |
None |
None |
| Duration: |
None |
None |
| Ponding: |
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| Depth (inches): |
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| Frequency: |
None |
None |
| Duration: |
None |
None |
| Runoff Class: |
Negligible |
Very high |
| Aspect: |
No Influence on this site
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Climatic Features
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Climate is semi-arid dry steppe. Summers are hot with winters being generally mild with numerous cold fronts that drop temperatures into the single digits for 24 to 48 hours. Temperature extremes are the rule rather than the exception. Humidity is generally low and evaporation high. Wind speeds are highest in the spring and are generally southwesterly. Canadian and Pacific cold fronts come through the region in fall, winter and spring with predictability and temperature changes can be rapid. Most of the precipitation comes in the form of rain and during the period from May through October. Snowfall averages around 15 inches but may be as little as 8 inches or as much as 36 inches. Rainfall in the growing season often comes as intense showers of relatively short duration. Long term droughts occur on the average of once every 20 years and may last as long as five to six years (during these drought years, moisture during the growing season is from 50 to 60 % of the mean). Based on long term records, approximately 60% of the years are below the mean rainfall and approximately 40% are above the mean. May, June and July are the main growth months for perennial warm season grasses. Forbs make their growth somewhat earlier.
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Minimum |
Maximum |
| Frost-free period (days): |
195 |
220 |
| Freeze-free period (days): |
190 |
225 |
| Mean annual precipitation (inches): |
16.0 |
21.0 |
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| Monthly precipitation (inches) and temperature (°F): |
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Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| Precip. Min. |
0.17 |
0.24 |
0.2 |
0.38 |
1.29 |
1.47 |
0.94 |
1.53 |
1.07 |
0.35 |
0.34 |
0.25 |
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| Precip. Max. |
0.73 |
0.77 |
0.7 |
1.26 |
2.86 |
3.39 |
2.7 |
3.61 |
3.92 |
1.9 |
1.08 |
1.01 |
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| Temp. Min. |
23.6 |
27.1 |
33.0 |
41.8 |
52.0 |
60.6 |
63.7 |
62.2 |
55.6 |
44.1 |
32.5 |
25.2 |
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| Temp. Max. |
53.6 |
59.1 |
67.2 |
75.5 |
82.9 |
91.1 |
92.7 |
90.3 |
83.9 |
75.7 |
63.2 |
54.9 |
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| Climate Stations: |
(1) TX5183, Levelland, TX. Period of record 1971 - 2000 |
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Influencing Water Features
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No non-stream characteristics. No perennial streams are associated with this site. It has no surface water features.
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| Wetland Description: |
System |
Subsystem |
Class |
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(Cowardin System)
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None |
N/A |
N/A |
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Representative Soil Features
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The soils on this site are very shallow, well drained, calcareous, gravelly soils. They commonly have light colored, gravelly loam surfaces over thick beds of caliche. Caliche may be soft, or petrocalcic horizons (indurated caliche) may be present. Permeability of the surface layer and soft caliche is very slow to moderate. Petrocalcic horizons are impermeable. Available water holding capacity is very low and the inherent fertility is low. Plant growth and production is restricted by shallow depth and the presence of calcium carbonates.
Major Soil Taxonomic Units correlated to this site include: Kimberson gravelly loam, Sharvana fine sandy loam, Sharvana loamy fine sand, Sharvana sandy loam, Slaughter fine sandy loam and Slaughter loamy fine sand.
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Predominant Parent Materials:
Kind: Eolian deposits
Origin: Limestone
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| Surface Texture: |
(1) Gravelly Loam |
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(2) Fine sandy loam |
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(3) Loamy fine sand |
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Subsurface Texture Group: Loamy
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Minimum |
Maximum |
| Surface Fragments <=3" (% Cover): |
5 |
40 |
| Surface Fragments > 3" (% Cover): |
3 |
5 |
| Subsurface Fragments <=3" (% Volume): |
15 |
60 |
| Subsurface Fragments > 3" (% Volume): |
3 |
5 |
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| Drainage Class: Well drained
To Well drained
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| Permeability Class: Impermeable
To Moderately slow
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Minimum |
Maximum |
| Depth (inches): |
4 |
20 |
| Electrical Conductivity (mmhos/cm): |
0 |
2 |
| Sodium Absorption Ratio: |
0 |
0 |
| Calcium Carbonate Equivalent (percent): |
0 |
30 |
| Soil Reaction (1:1 Water): |
7.4 |
9.0 |
| Soil Reaction (0.01M CaCl2): |
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| Available Water Capacity (inches): |
1.4 |
4.7 |
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Plant Communities
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| Ecological Dynamics of the Site |
The assumed Historic Natural Plant Community (HCPC) is a mixture of grasses, forbs, and low growing shrubs. Vegetation is generally sparse. Soil depth limits plant density. Areas of bare ground are common. The limey nature of the soil further defines the species occupying the site. The plant community is more productive where less limey conditions occur. Production is low and palatability of forage is less than sites with deeper soil resources. Tall, mid, and shortgrass species are found on the site along with several species of forbs and shrubs. Little bluestem (Schizachyrium scoparium) and sideoats grama (Bouteloua curtipendula) are often the most common grasses. Grasses such as hairy grama (Bouteloua hirsuta), blue grama (Bouteloua gracilis), New Mexico feathergrass (Hesperostipa neomexicana), and perennial three-awns (Aristida spp.) are also frequently present, with occasional sand bluestem (Andropogon hallii) and Indiangrass (Sorghastrum nutans). The more common shrubs are feather dalea (Dalea formosa), skunkbush sumac (Rhus trilobata), and juniper (Juniper monosperma). Broom snakeweed (Gutierrezia sarothrae) typically increases when grasses decline. However, broom snakeweed is a cyclic plant sensitive to fall moisture, once broom snakeweed dominates a site, it tends to be persistent. Small amounts of plains greasebush (Glossopetalon planitierum) may occur on areas along escarpment edges. Areas occur within the site where the shrubs may make up a large percent of the vegetation. Likewise, there are areas where grasses dominate. Forbs are generally fairly well dispersed throughout the entire site. This site is not a preferred grazing area for most domestic livestock. Plants growing on shallow, limey soils tend not to be as palatable as when growing on deep, fertile soil. Nutrients are tied up by the large amounts of lime present, and are not available to plants. This site is seldom as heavily grazed as associated upland sites. The site is frequently utilized by browsing species such as mule deer, and the largely forb-consuming pronghorn.
Natural fire played a role in the ecology of the site. The general effects of fire were to promote grasslands and suppress woody shrubs. The shallow, limey soils on this site have much more influence on the plant community than does any external ecological influence. Sparse vegetation and lower production limited the heat generated by natural fire and may have limited the degree of damage to woody plants. This site takes longer to recover from a burn than some associated sites. Overgrazing causes the taller grasses to decline and shrubby species to increase. Bare ground and runoff will be increased. It is somewhat uncommon to find this site severely degraded due to grazing abuse, but it can occur.
The site is not very susceptible to wind erosion due to coarse fragments on the surface. Water erosion can occur with poor cover. Severe degradation causes a drought-like condition and it becomes very difficult to restore the plant community close to the historic climax. This site has limited production potential and it quickly loses the ability to support sufficient cover to protect the soil resource when degraded.
If heavy or even moderately heavy continuous grazing does occur for prolonged periods of time the most palatable plants will be severely pressured. As retrogression proceeds, this site will move towards a Midgrass/Shrub Community (2.1). Tallgrasses will decline and midgrass species will increase along with a dramatic increase in the shrub component. The plant community will be less diverse than HCPC. In this phase, the ecological processes have changed somewhat, but the pathway back toward the HCPC can be initiated through prescribed grazing and prescribed burning. Limited fine fuel may prevent effective suppression of the woody plants.
If heavy continuous grazing occurs for long periods of time, along with periodic droughts, retrogression will move towards a Shrub/Shortgrass Community (3.1). In extreme cases, shrubs such as yucca, skunkbush and juniper along with a high percentage of broom snakeweed will dominate the site. Numerous bare areas with surface rock fragments will be exposed increasing the potential for excessive soil erosion from water. This plant community is so degraded that retrogression can not be reversed without extensive energy and management inputs. At this point, a major threshold has been crossed. Restoration of the Shrub/Shortgrass plant community will be difficult due the droughty and rocky nature of the site. Prescribed grazing (3–5 consecutive years of deferment during the growing season), brush management (chemical and/or mechanical) and range planting will be necessary. At this point, prescribed burning is not an option due to the lack of fine fuel and poor continuity.
NOTE: Rangeland Health Reference Worksheets have been posted for this site on the Texas NRCS website (www.tx.nrcs.usda.gov) in Section II of the eFOTG under (F) Ecological Site Descriptions.
PLANT COMMUNITIES AND TRANSITIONAL PATHWAYS (DIAGRAM)
The following diagram suggests some pathways that the vegetation on this site might take. There may be other states not shown on the diagram. This information is intended to show what might happen in a given set of circumstances; it does not mean that this would happen the same way in every instance. Local professional guidance should always be sought before pursuing a treatment scenario.
Changes in the structure and composition of the plant community may be due to management and/or natural occurrences. At some point thresholds are crossed as indicated by the lined box on the State and Transition Diagram. This suggests that once changes have progressed to a certain point, the plant community has been altered to the extent that a return to the former state is not possible unless some form of energy is applied. These changes take place on all ecological sites. Some sites support communities that are more resistant to change than others. Also, some sites are more resilient and can heal or restore themselves more easily. Usually, changes in management practices alone, such as grazing techniques, will not be sufficient to restore former plant communities. An example of energy input might be the implementation of chemical brush management to decrease the amount of woody/cacti shrubs and increase the amount of grasses and forbs. This shift in community balance could not be brought about with grazing alone. The amount of energy required to bring about a change in plant community balance may vary a great deal depending on the present state and the desired result.
STATE AND TRANSITIONAL PATHWAYS (DIAGRAM)
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MLRA 77C - Very Shallow State & Transition Diagram
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| 1.1 Mixed Grass Community |
The interpretive plant community for this site is the assumed Historic Climax Plant Community. It is difficult to precisely describe this plant community, as the amount of actual soil material over parent material is variable. The depth of soil influences the species more than any other factor. The tallgrasses such as sand bluestem and Indiangrass usually occur in crevices or fissures in the rock. The site is generally dominated by little bluestem and sideoats grama with smaller amounts of shortgrasses. A moderate amount of forbs are usually present and are usually well distributed. This site can have as many as 25 different forb species. Major shrubs are feather dalea and yucca. Shrubs make up <10 % of the production, but may be localized in occurrence. This community is very stable and shifts little from year to year. It is somewhat uncommon to find this site severely degraded due to grazing abuse, but it can occur.
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1.1 Mixed Grass Community
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| 1.1 Mixed Grass Community Plant Species Composition: |
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| Annual Production by Plant Type: |
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Annual Production (lbs/AC) |
| Plant Type |
Low |
Representative Value |
High |
| Forb |
40 |
85 |
130 |
| Grass/Grasslike |
570 |
810 |
1050 |
| Microbiotic Crusts |
10 |
15 |
20 |
| Shrub/Vine |
30 |
55 |
80 |
| Tree |
0 |
5 |
10 |
Total: |
650 |
970 |
1290 |
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Plant Growth Curve:
Growth Curve Number: TX1041
Growth Curve Name: Mixed Grass Community
Growth Curve Description: Growth is predominantly tall/mid/shortgrasses from April to October with a peak growth May through July.
| Percent Production by Month |
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| 0 |
2 |
4 |
7 |
18 |
22 |
18 |
9 |
12 |
5 |
2 |
1 |
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| 2.1 Midgrass/Shrub Community |
This plant community is a midgrass/shrub dominant with lesser amounts of tallgrasses. If heavy or even moderately heavy continuous grazing does occur for prolonged periods of time the most palatable plants will be severely pressured. Little bluestem will be replaced with perennial three-awns. The tallgrasses found in depressions and other favorable niches on the site have been reduced and are only found in small amounts. Perennial forb diversity is still good with increasing amounts of annuals. Shrubs such as yucca, juniper, skunkbush and broom snakeweed will increase. The plant community will be less diverse than HCPC. In this phase, the ecological processes have changed somewhat, but the pathway back toward the HCPC cab be initiated through prescribed grazing, selective brush management and prescribed burning. Limited fine fuel may prevent effective suppression of the woody plants.
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2.1 Midgrass/Shrub Community
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| Annual Production by Plant Type: |
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Annual Production (lbs/AC) |
| Plant Type |
Low |
Representative Value |
High |
| Forb |
35 |
75 |
110 |
| Grass/Grasslike |
440 |
620 |
800 |
| Microbiotic Crusts |
0 |
0 |
0 |
| Shrub/Vine |
30 |
50 |
70 |
| Tree |
0 |
0 |
0 |
Total: |
505 |
745 |
980 |
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Plant Growth Curve:
Growth Curve Number: TX1023
Growth Curve Name: Midgrass Dominant Community
Growth Curve Description: Growth is predominantly mid and shortgrasses from April through October with a peak growth occurring from May through July.
| Percent Production by Month |
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| 0 |
1 |
3 |
5 |
20 |
25 |
17 |
8 |
15 |
4 |
1 |
1 |
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| 3.1 Shrub/Shortgrass Community |
Depending on the topsoil depth, this site may be dominated by broom snakeweed, juniper, yucca and low quality shortgrasses. Large areas of bare ground with exposed rock fragments will be common throughout the site. Excessive soil erosion will be evident with limited topsoil in areas. This plant community is so degraded that retrogression can not be reversed without extensive energy and management inputs. At this point, a major threshold has been crossed. Restoration of the Shrub/Shortgrass plant community will be difficult due the droughty and rocky nature of the site combined with the loss of valuable topsoil. Prescribed grazing (3–5 consecutive years of deferment during the growing season), brush management (chemical and/or mechanical) and range planting will be necessary. At this point, prescribed burning is not an option due to the lack of fine fuel and poor continuity.
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3.1 Shrub/Shortgrass Community
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| Annual Production by Plant Type: |
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Annual Production (lbs/AC) |
| Plant Type |
Low |
Representative Value |
High |
| Forb |
28 |
35 |
40 |
| Grass/Grasslike |
200 |
310 |
360 |
| Microbiotic Crusts |
0 |
0 |
0 |
| Shrub/Vine |
250 |
260 |
275 |
| Tree |
0 |
0 |
0 |
Total: |
478 |
605 |
675 |
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Plant Growth Curve:
Growth Curve Number: TX1042
Growth Curve Name: Shrub/Shortgrass Community
Growth Curve Description: Growth is predominantly shrubs and shortgrasses from April through October with peak growth from May through July.
| Percent Production by Month |
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| 0 |
1 |
3 |
8 |
16 |
25 |
5 |
5 |
10 |
16 |
8 |
3 |
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Ecological Site Interpretations
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Animal Community:
Native animals that occupy this site include scaled quail, pronghorn antelope, coyote, jackrabbit, swift fox, Texas horned lizard, and mule deer. It is an open grassland site therefore species that require lots of cover may not be present. Several palatable browse species commonly occur, such as skunkbush sumac, baby white aster, mountain mahogany, and plains greasebush. It is not a preferred grazing site for most domestic livestock.
Plant preference by animal kind:
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.
Preferred (P) – Percentage of plant in animal diet is greater than it occurs on the land
Desirable (D) – Percentage of plant in animal diet is similar to the percentage composition on the land
Undesirable (U) – Percentage of plant in animal diet is less than it occurs on the land
Not Consumed (N) – Plant would not be eaten under normal conditions. It is only consumed when other forages not available.
Toxic (T) – Rare occurrence in diet and, if consumed in any tangible amounts results in death or severe illness in animal
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Plant Preference by Animal Kind:
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Hydrology Functions:
This site often occurs above draws and along escarpments. Runoff from the site may enter major drainages.
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Recreational Uses:
Hunting, Camping, Hiking, Birdwatching, Photography, Horseback Riding
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Wood Products:
None.
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Other Products:
At some locations, caliche is mined and used for road base. These are open pit mines and are usually fairly small.
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Other Information:
None.
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Supporting Information
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Associated Sites:
| Site Name |
Site ID |
Site Narrative |
| Limy Upland 16-21" PZ |
R077CY028TX |
Very Shallow sites will generally occur as rocky outcrops scattered throughout the Limy Upland sites with rolling to steep topography. |
| Rough Breaks 16-24" PZ |
R077EY062TX |
Very Shallow sites associated with Rough Breaks will occur near the top edge of the Rough Breaks as a narrow band. |
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Similar Sites:
| Site Name |
Site ID |
Site Narrative |
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State Correlation:
This site has been correlated with the following states:
NM TX
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Inventory Data References:
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Type Locality:
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Relationship to Other Established Classifications:
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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, Ed M Vavra, W Laycock, R Pieper, pp13-68, Denver, CO: society for Range Management
2. Gould F. 1978. Common Texas Grasses: an illustrated guide. College Station, TX: Texas A & M Press.
3. Hatch, Brown and Ghandi, Vascular Plants of Texas (An Ecological Checklist)
4. Heischmidt RK, Stuth, Eds. 1991 Grazing Management: an ecological perspective. Portland OR: Timberline Press
5. North Rolling Plains RC&D, NRCS, and GLCI. 2006 edition. Common Rangeland Plants of the Texas Panhandle.
6. Scifres CJ, Hamilton WT. 1993. Prescribed burning for brushland management: the South Texas example. College Station, TX: Texas A & M Press.
7. Natural Resources Conservation Service - Range Site Descriptions
8. USDA-Natural Resources Conservation Service - Soil Surveys & Website soil database
9. Sosebee, Ron. Timing - the Key to Herbicidal Control of Broom Snakeweed, T-9-421, Department of Natural Resources, Texas Tech University, Lubbock, Texas.
The following individuals assisted with the development of this site description:
Clint Rollins –Rangeland Management Specialist- NRCS; Amarillo, Texas
Justin Clary – Rangeland Management Specialist – NRCS; Temple, Texas
Thomas C. Byrd, USDA-NRCS Soil Scientist, Lubbock, TX
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Site Description Approval:
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| Author |
Date |
Approval |
Date |
| unknown |
5/30/1979 |
Rhett Johnson |
5/30/1979 |
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Site Description Revision Approval:
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| Author |
Date |
Approval |
Date |
| Duckworth-Cole, Inc, Bryan, Texas |
2/15/2007 |
Mark Moseley, RMS, NRCS, San Antonio, Texas |
2/20/2007 |
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Reference Sheet
Author(s)/participant(s):
Clint Rollins, RMS, NRCS, Amarillo, Texas
Contact for lead author:
806-468-8600
Date:
9/4/2007
MLRA:
077C
Ecological Site:
Very Shallow 16-21" PZ
R077CY037TX
This must be verified based on soils and climate (see
Ecological Site Description). Current plant community cannot be used to
identify the ecological site.
Composition (indicators 10 and 12) based on:
X
Annual Production,
Foliar Cover,
Biomass
Indicators. For each indicator, describe the potential for the site. Where
possible, (1) use numbers, (2) include expected range of values for above- and below-average years
for each community and natural disturbance regimes within the reference state, when
appropriate and (3) cite data. Continue descriptions on separate sheet.
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| 1. |
Number and extent of rills: Due to percent slopes, rills will be common. |
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| 2. |
Presence of water flow patterns: Due to percent slopes, water flow patterns will be common. |
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| 3. |
Number and height of erosional pedestals or terracettes: None to slight. |
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| 4. |
Bare ground from Ecological Site Description or other studies (rock, litter, standing dead,
lichen, moss, plant canopy are not bare ground): 20-25%. |
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| 5. |
Number of gullies and erosion associated with gullies: None to slight |
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| 6. |
Extent of wind scoured, blowouts and/or depositional areas: None to slight. |
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| 7. |
Amount of litter movement (describe size and distance expected to travel): None to slight. |
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| 8. |
Soil surface (top few mm) resistance to erosion (stability values are averages -
most sites will show a range of values): Moderate resistance to erosion. |
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| 9. |
Soil surface structure and SOM content (include type and strength of structure, and A-horizon color
and thickness): Loam; friable surface; low SOM. |
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| 10. |
Effect on plant community composition (relative proportion of different functional groups) and
spatial distribution on infiltration and runoff: Low vegetative cover and percent slopes makes this site susceptible to erosion. This site is a moderately permeable soil, runoff is medium, and available water holding capacity is very low. |
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| 11. |
Presence and thickness of compaction layer (usually none; describe soil profile features which
may be mistaken for compaction on this site): None. |
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| 12. |
Functional/Structural Groups (list in order of descending dominance by above-ground weight using
symbols: >>, >, = to indicate much greater than, greater than, and equal to) with dominants and
sub-dominants and "others" on separate lines:
Dominant: Warm-season midgrasses > Warm-season tallgrasses >
Sub-dominant: Warm-season shortgrasses = Cool-season grasses >
Other: Shrubs/Vines > Forbs > Trees
Additional: |
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| 13. |
Amount of plant mortality and decadence (include which functional groups are expected to show
mortality or decadence): Grasses due to their growth habit will exhibit some mortality and decadence though minimal. |
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| 14. |
Average percent litter cover (5%) and depth (0.25-0.5
inches): Litter is dominantly herbaceous. |
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| 15. |
Expected annual production (this is TOTAL above-ground production, not just forage production:
500 to 900 pounds per acre. |
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| 16. |
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 indicator, we are
describing what in NOT expected in the reference state for the ecological site: Yucca, Juniper and Broom snakeweed are potential invasive species for this site. |
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| 17. |
Perennial plant reproductive capability: All plant species are capable of reproduction except during periods of prolonged drought conditions, heavy natural herbivory and intense wildfires. |
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| |
| Reference Sheet Approval: |
| Approval |
Date |
| Mark Moseley, RMS, NRCS, San Antonio, Texas |
2/21/2008 |
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Ecological Site Description
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