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Ecological site NX118A01Y007

Seasonally Wet Terraces and Footslopes

Last updated: 9/22/2023
Accessed: 12/21/2024

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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.

MLRA notes

Major Land Resource Area (MLRA): 118A–Arkansas Valley and Ridges, Eastern Part

Major Land Resource Area 118A, Arkansas Valley and Ridges Eastern Part, is in Arkansas and Oklahoma. This MLRA is about 6,755 square miles (17,495 square kilometers). The Ozark National Forest and the northern portion of the Ouachita National Forest occur in this MLRA.

This area is mostly in the Arkansas Valley Section of the Ouachita Province of the Interior Highlands. Small areas in the southeast corner and the south-central part of the MLRA are in the Ouachita Mountains. This MLRA consists of long, narrow ridges and high flat-topped mountains capped with sandstone that trend northeastward. Crests are narrow and rolling on ridges, while broad and flat on mountaintops. The intervening valleys are broad and smooth. Elevations generally range from 310 feet (90 meters) to 760 feet (230 meters) with higher and lower elevations on the valleys and ridgetops.

The ridgetops and valleys in this MLRA are underlain by slightly folded to level beds of sandstone and shale of the Pennsylvanian age. The terrace deposits along the Arkansas River include a complex sequence of unconsolidated gravel, sandy gravel, sands, silty sands, silts, clayey silts, and clays. The individual deposits are commonly lenticular and discontinuous. At least three terrace levels are recognized with the lowest being the youngest.

The dominant soil orders in this MLRA are Ultisols. The soils in the area have a thermic soil temperature regime, a udic soil moisture regime, and mixed or siliceous mineralogy.

Ecological site concept

The Seasonally Wet Terraces and Footslopes ecological site is on hills and valleys along hillslopes, flood plains, and paleoterraces. This site has slopes between 0 and 5 percent with elevations ranging from 190 to 1,970 feet (57 to 600 meters). The soils associated with this site are deep to very deep and formed in alluvium derived from sandstone, siltstone, and shale. Important abiotic characteristics associated with this site are a greater than 18 percent clay content in the particle size control section, a root restrictive layer (clay) within 20 inches (50 cm) of the soil surface, redox reactions below 20 inches (50 cm), and an acidic pH decreasing in strength down the soil profile. A perched water table is present during winter and spring.

Associated sites

NX118A01Y008	Fluventic Flood Plain This ecological site is differentiated from the Seasonally Wet Terraces and Footslopes by landscape position and less than 18 percent clay in the particle size control section.

NX118A01Y008

Fluventic Flood Plain

This ecological site is differentiated from the Seasonally Wet Terraces and Footslopes by landscape position and less than 18 percent clay in the particle size control section.

Similar sites

NX118A01Y003	Rarely Flooded Terrace This ecological site is differentiated from the Seasonally Wet Terraces and Footslopes by less than 18 percent clay in the particle size control section.

NX118A01Y003

Rarely Flooded Terrace

This ecological site is differentiated from the Seasonally Wet Terraces and Footslopes by less than 18 percent clay in the particle size control section.

Table 1. Dominant plant species

Tree	(1) Quercus (2) Platanus
Shrub	Not specified
Herbaceous	(1) Panicum virgatum (2) Schizachyrium scoparium

Legacy ID

F118AY007AR

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Physiographic features

This ecological site is on hills and river valleys along hillslopes, flood plains, and paleoterraces. This site has slopes between 0 and 5 percent. Elevations range from 190 to 1,970 feet (57 to 600 meters). Runoff class varies from medium to high, with no ponding or flooding.

Table 2. Representative physiographic features

Landforms	(1) River valley > Flood plain (2) Paleoterrace (3) Hills > Hillslope
Runoff class	Medium to high
Flooding frequency	None
Ponding frequency	None
Elevation	190 – 1,970 ft
Slope	5%
Water table depth	9 – 30 in
Aspect	Aspect is not a significant factor

Climatic features

This ecological site is characterized by hot summers, cool winters, and mild spring and fall temperatures. Mean annual precipitation is 49 inches. The average frost-free period is 193 days, and the average freeze-free period is 212 days. The highest precipitation occurs in May (6 inches), and the lowest occurs in January (2.8 inches). The warmest month of the year is August (94°F average high), and the coolest is January (26°F average low).

Thunderstorms and heat waves are common and occur frequently during summer months. Catastrophic storm events, such as tornados, ice-storms, floods, and hail-storms are also known to occasionally occur within this ecological site. According to the Oklahoma Water Resource Board, drought occurs on 5 to 10 year cycles. The EPA predicts that droughts will become more severe throughout Arkansas due to longer periods without rain and an increase in very hot days (EPA, 2016).

Data was provided by the Blue Mountain Dam, Clarksville, Greers Ferry Dam, Poteau, Sallisaw, and Subiaco climate stations. Site specific data should be obtained by accessing the database provided by the National Centers for Environmental Information (https://www.ncdc.noaa.gov/cdo-web/search).

Table 3. Representative climatic features

Frost-free period (characteristic range)	178-192 days
Freeze-free period (characteristic range)	198-218 days
Precipitation total (characteristic range)	49-50 in
Frost-free period (actual range)	170-194 days
Freeze-free period (actual range)	193-222 days
Precipitation total (actual range)	47-51 in
Frost-free period (average)	183 days
Freeze-free period (average)	209 days
Precipitation total (average)	49 in

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) CONWAY [USC00031596], Conway, AR
(2) WOOSTER [USC00038010], Greenbrier, AR
(3) GREENBRIER [USC00032962], Greenbrier, AR
(4) SEARCY [USC00036506], Judsonia, AR
(5) MORRILTON [USC00034938], Morrilton, AR
(6) FT SMITH RGNL AP [USW00013964], Fort Smith, AR
(7) OZARK [USC00035508], Ozark, AR
(8) CABOT [USC00031102], Cabot, AR

Soil features

The soils associated with this ecological site are formed in alluvium derived from sandstone siltstone, and shale. These soils are deep to very deep, somewhat poorly to moderately well drained, and have a moderate permeability class. A silt surface texture is common. Important abiotic characteristics associated with this site are a greater than 18 percent clay content in the particle size control section, a root restrictive layer (clay) within 20 inches (50 cm) of the soil surface, redox reactions below 20 inches (50 cm), and an acidic pH decreasing in strength down the soil profile.

The soil series associated with this site are Leadvale, Vian, Taft, and Falkner.

Table 4. Representative soil features

Parent material	(1) Alluvium – shale and siltstone (2) Alluvium – sandstone and shale
Surface texture	(1) Silt
Drainage class	Somewhat poorly drained to moderately well drained
Permeability class	Moderate
Soil depth	40 – 80 in
Surface fragment cover <=3"	2%
Surface fragment cover >3"	Not specified
Available water capacity (Depth not specified)	5 – 7 in
Soil reaction (1:1 water) (Depth not specified)	4.4 – 6.5
Subsurface fragment volume <=3" (Depth not specified)	3 – 5%
Subsurface fragment volume >3" (Depth not specified)	2%

Ecological dynamics

The Seasonally Wet Terraces and Footslopes reference state consists of a bottomland hardwood forest. The common trees species for this state are oaks, hickories, loblolly pine, and sweet gum (Eldredge, 1937).

Fire has a significant influence on this ecological site. The historical average fire-return interval was likely between 3 and 25 years (Guyette and Spetich, 2003; Hallgren, DeSantic, and Burton, 2012). These fires would occur naturally through lightning strikes, but the majority were probably ignited by anthropogenic sources (DeSantis, Hallgren, and Stahle, 2010). Native species evolved with and responded well to fires (Spetich and Hong He, 2008; Engle and Bidwell, 2001). Fires on upland ecological sites are likely moderate to low severity, due to forested conditions and lower amounts of ground vegetation (Carey, 1992).

Grazing and farming can occur on this ecological site. Changes to the ecological dynamics are proportional to the intensity of livestock grazing and can be accelerated by overgrazing (Angerer, Fox, and Wolfe, 2013; Kohl, 2016). For example, desirable grasses and forbs are repeatedly grazed by livestock, weakening, and potentially killing or replacing these species with less desirable species (Smith, 1940).

Climate related events, such as hail-storms, tornados, thunderstorms, and extreme precipitation, occur on these sites. Hail-storms can reduce canopy size, increase litter deposition, and increase tree bark removal. When paired with other disturbances, such as fire, the effects on tree species were much greater than in areas not affected by hail-storms (Gower et al., 2015). Tornados have been shown to change plant community compositions in savanna ecosystems, favoring hardwoods and eliminating softwoods (Liu et al., 1997). Thunderstorms greatly effect ecosystem dynamics. Thunderstorms generally occur during summer months but can occur during every season. If a fire is started by a lightning strike, there will be different effects in the ecosystem depending on the season (Hiers, Wyatt, and Mitchell, 2000).

A state and transition model has been created to explain this Ecological Site. However, sparse data availability only allowed basic principles to be explored and a small number of species to be recorded. More data will be collected to provide a greater understanding of the ecological dynamics, as well as the resources consumption and distribution.

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

1. Reference

2. Plantation

3. Pasture

T1A	-	Tree removal, brush management, plantation tree establishment and management.
T1B	-	Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species.
T2A	-	Woody species removal, prescribed fire, seeding, and grazing.
T3A	-	Forage species suppression, brush management, plantation tree establishment and management.

State 1 submodel, plant communities

1.1. Water Hickory-Overcup Oak

1.2. Nuttall Oak- Southern Hackberry- Sweetgum

1.3. Shagbark Hickory- Southern Red Oak

1.1A	-	Less water during vegetation establishment.
1.2B	-	More water during vegetation establishment.
1.2A	-	Less water during vegetation establishment.
1.3A	-	More water during vegetation establishment.
1.3B	-	More water during vegetation establishment.

State 2 submodel, plant communities

2.1. Loblolly Pine

State 3 submodel, plant communities

3.1. Bermudagrass

State 1
Reference

The reference state is considered to be representative of the natural range of variability without major anthropogenic influences. Drivers- Climate (decadal scale), insect and disease presence or establishment, wildlife grazing or browsing, and wildfire frequency and intensity. Feedbacks- Water tolerant tree species dominate this ecological site, rare flooding events limit what species can grow and survive inundation.

Characteristics and indicators. The reference state consists of a bottomland hardwood forest. The common trees species for this state are oak, hickory, and hackberry.

Dominant plant species

oak (Quercus), tree
hybrid hickory (Carya), tree
hackberry (Celtis), tree
sycamore (Platanus), tree
pine (Pinus), tree
sweetgum (Liquidambar), tree

Community 1.1
Water Hickory-Overcup Oak

Community 1.2
Nuttall Oak- Southern Hackberry- Sweetgum

Community 1.3
Shagbark Hickory- Southern Red Oak

Pathway 1.1A
Community 1.1 to 1.2

This pathway consists of less water during vegetation establishment.

Pathway 1.2B
Community 1.2 to 1.1

This pathway consists of more water during vegetation establishment.

Pathway 1.2A
Community 1.2 to 1.3

This pathway consists of less water during vegetation establishment.

Pathway 1.3A
Community 1.3 to 1.1

This pathway consists of more water during vegetation establishment.

Pathway 1.3B
Community 1.3 to 1.2

This pathway consists of more water during vegetation establishment.

State 2
Plantation

The plantation state is characterized by the planting of merchantable trees species. The most common species for a plantation is loblolly pine. Community phases differ by tree type (softwood or hardwood) and the harvesting process. Drivers: Prescribed fires, pest management, vegetation management, canopy density. Feedbacks: Timber harvesting. Planted tree species dominate this ecological site, shading out other vegetation. Anthropogenic management decreases competition with other species and assists in growth.

Characteristics and indicators. A plantation state consists of tree species that are planted and managed to maximize the production of merchantable timber. The most common plantation species is loblolly pine, followed by hardwood trees. Community phases differ by tree type (softwood or hardwood), timber harvest method, management, and reforesting practices.

Dominant plant species

loblolly pine (Pinus taeda), tree
oak (Quercus), tree

Community 2.1
Loblolly Pine

Loblolly pine is planted to maximize timber production.

State 3
Pasture

The Pasture State is characterized by the dominance of improved forage species. The quality and quantity of forb, grass, and legume species within this state will depend on the level of management inputs including seeding, weed management, and land uses. Species of both warm-season and cool-season grasses are feasible for these sites. Drivers: Mechanical soil disturbance and seed planting, climate (decadal scale), seed dispersal, and wildlife or livestock grazing or browsing. Feedbacks: Land managers use mechanical and chemical equipment to increase forage. Inputs of fertilizer and brush management are required to maintain high productivity. Wildlife and livestock grazing and browsing decrease the amount of available forage.

Characteristics and indicators. The Pasture State consists of species that are grown for specific management goals, mainly livestock grazing. Common pasture species include buffalograss, western wheatgrass, little bluestem, sideoats grama, Bermudagrass, and bahiagrass. Quality and quantity of forb, grass, and legume species within this state depend on the level of management inputs (seeding, weed management, and land uses). Species of both warm-season and cool-season grasses are feasible for these sites.

Dominant plant species

Bermudagrass (Cynodon dactylon), grass
red clover (Trifolium pratense), grass

Community 3.1
Bermudagrass

Herbaceous species have been planted to maximize forage production for grazing livestock.

Transition T1A
State 1 to 2

Trigger: Merchantable tree planting, targeted vegetation suppression, prescribed fire, and fertilization. Slow Variables: Increased production and management of merchantable trees. Tree thinning when appropriate. Thresholds: Vegetation is removed and timber species are planted.

Transition T1B
State 1 to 3

Trigger: Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species. Slow Variables: Increase production and management of forage species. Thresholds: Changes in soil properties, such as structure, organic matter, and nutrient cycling, as well as changes in type and frequency of disturbance.

Transition T2A
State 2 to 3

Trigger: Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species. Slow Variables: Increase production and management of forage species. Thresholds: Changes in soil properties such as structure, organic matter, and nutrient cycling as well as changes in type and frequency of disturbance.

Transition T3A
State 3 to 2

Trigger: Merchantable tree planting, targeted vegetation suppression, prescribed fire, and fertilization. Slow Variables: Increased production and management of merchantable trees. Tree thinning when appropriate. Thresholds: Introduced forage species are suppressed due to management strategies and shading.

Additional community tables

Interpretations

Animal community

Common wildlife species include whitetail deer, coyote, armadillo, beaver, raccoon, skunk, opossum, muskrat, cottontail, mourning dove, turkey, fox squirrel, and gray squirrel.

Hydrological functions

Following are the estimated withdrawals of freshwater by use in this MLRA:

Public supply—surface-water, 24.4%; ground-water, 5.1%
Livestock—surface-water, 8.1%; ground-water, 0.6%
Irrigation—surface-water, 0.0%; ground-water, 0.0%
Other—surface-water, 61.8%; ground-water, 0.0%

The total withdrawals average 95 million gallons per day (360 million liters per day). About 6 percent is from ground-water sources, and 94 percent is from surface-water sources. The moderately high precipitation is adequate for crops and pasture. Large reservoirs on a few of the major streams are sources of municipal water and provide flood control and opportunities for recreation. The surface water is generally of good quality and is suitable for most uses. Shallow wells are the principal sources of water for domestic use. Deep wells are needed to obtain moderate to large quantities of ground water. Water from the Ozark aquifer system in the northern half of this area is suitable for drinking.

Recreational uses

Mountain biking, camping, fishing, hiking, horseback riding, hunting, mineral prospecting, nature viewing, off-highway vehicle riding, and water activities can all be enjoyed throughout this MLRA on public land where permitted and on private land where allowed. The Ozark National Forest is throughout this MLRA.

Wood products

Public and private timberland comprise large areas throughout this MLRA. Loblolly pine is the most popular species to harvest and produces products such as lumber, pulpwood, posts, and poles. Hardwood species are also harvested and used to produce lumber, flooring, and pulpwood.

Other products

Poultry production is a major industry throughout the MLRA. Small grains, soybeans, and hay are major crops.

Supporting information

References

Angerer, J., W. Fox, and J. Wolfe. 2016. Land Degradation in Rangeland Ecosystems. Biological and Environmental hazards, Risks, and Disasters. Academic Press.
Bailey, R.G. 1995. Description of the ecoregions of the United States.
Cannon, J.B. and J.S. Brewer. 2013. Effects of Tornado Damage, Prescribed Fire, and Salvage Logging on Natural Oak Regeneration in a Xeric Southern USA Coastal Plain Oak and Pine Forest.
Carey, J. 1992. Quercus stellata, Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. Fire Sciences Laboratory.
Clark, J.A. and K.R. Covey. 2012. Tree species richness and the logging of natural forests: A meta analysis. Forest Ecology and Management. Elsevier, Yale School of Forestry and Environmental Studies. 146–153.
DeSantis, R.D., S.W. Hallgreen, and D.W. Stahle. 2010. Historic Fire Regime of an Upland Oak Forest in South Central North America. Fire Ecology. USDA Forest Service, Northern Research Station, Saint Paul, Minnesota.
Eldredge, I. 1937. Forest Resources of Southern Arkansas. Southern Forest Experiment Station. US Forest Service.
Engle, D. and T. Bidwell. 2001. The response of central North American prairies to seasonal fire. Range Management 54:2–10.
Engle, D.M. 2017. Fire in North American Tallgrass Prairies. Weed Technology 5:247–248.
Gower, K., J. Fontaine, C. Birnbaum, and N. Enright. 2015. Sequential Disturbance Effects of Hailstorms and Fire on Vegetation in a Mediterranean-Type Ecosystem. Ecosystems 18:1121–1134.
Guldin, J.M. and M.W. Fitzpatrick. 1991. Comparison of Log Quality from Even-Aged and Uneven-Aged Loblolly Pine Stands in South Arkansas. Southern Journal of Applied Forestry 15:10–17.
Guyette, R.P. and M. A. Spetich. 2003. Fire History of Oak-Pine Forests in the Lower Boston Mountains, Arkansas, USA. Forest Ecology and Management. Elsevier. 463–474.
Guyette, R.P., M.A. Spetich, and M.C. Stambaugh. 2006. Historic fire regime dynamics and forcing factors in the Boston Mountains, Arkansas, USA. Forest Ecology and Management 234:293–304.
Hallgren, S.W., DeSantis. R. D., and J.A. Burton. 2012. Fire and vegetation Dynamics in the Cross Timbers Forests of South-Central North America. Proceedings of the 4th Fire in Eastern Oak Forests Conference. USDA Forest Service General Techincal Report NRS-P-102, Springfield, Missouri. 52–66.
Heikens, A. 2007. Glade Communities of the Ozark Plateaus Province. Pages 220–230 in Savannas, Barrens, and Rock Outcrop Plant Communities of North America.
Hiers, K., R. Wyatt, and R. Mitchell. 2000. The effects of fire regime on legume reproduction in longleaf pine savannas: is a season selective?. Oecologia 125:521–530.
Jenks, J.A., Leslie, R.L. Lochmiller, M.A. Melchiors, and McCollum. 1996. Competition in sympatric white-tailed deer and cattle populations in southern pine forests of Oklahoma and Arkansas, USA. Acta Theriologica 41:287–306.
Klos, R.J. and G.G. Wang. 2009. Drought impact on forest growth and mortality in the southeast USA: an analysis using Forest Health and Monitoring data. Ecological Applications 19:699–708.
Kohl, M., P. Krausman, K. Kunkel, and D. Williams. 2013. Bison Versus Cattle: Are They Ecologically Synonymous. Rangeland Ecology and Management 66:721–731.
Linzon, S.N. 1962. Hail Damage to White Pine and Other Trees. The Forestry Chronicle. Canadian Institute of Forestry.
Liu, C., J. Glitzenstein, P. Harcombe, and R. Knox. 1997. Tornado and fire effects on tree species composition in a savanna in the Big Thicket National Preserve, southeast Texas, USA. Forest Ecology and Management 91:279–289.
Owens, D. 2005. First report of a geological reconnaissance of the northern counties of Arkansas, made during the years 1857 and 1858. Arkansas Geological Survey.
Siemann, E., J.A. Carrillo, C.A. Gabler, R. Zipp, and W.E. Rogers. 2009. Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US. Forest Ecology and Management. Elsevier. 546–553.
Smith, C. 1940. The Effects of Overgrazing and Erosion Upon the Biota of the Mixed-Grass Prairie of Oklahoma. Ecology. Wiley. 381–397.
Spetich, M. and H. He. 2008. Oak decline in the Boston Mountains, Arkansas, USA: Spatial and temporal patterns under two fire regimes. Forest Ecology and Management 254:454–462.
Varner, J.M., D.R. Gordon, F.E. Putz, and J.K. Hiers. 2005. Restoring Fire to Long-Unburned Pinus palustris Ecosystems: Novel Fire Effects and Consequences for Long-Unburned Ecosystems. Restoration Ecology 13:536–544.
Warrillow, M. and P. Mou. 1999. Ice Storm Damage to Forest Tree Species in the Ridge and Valley Region of Southwestern Virginia. The Journal of the Torrey Botanical Society. Torrey Botanical Society. 147–158.
Woods, A. and J. Omernik. 1996. Level IV Ecoregions of EPA Region 3, US Environmental Protection Agency National Health and Environmental Effects. Research Laboratory, Corvallis, Oregon.
Zhang, H. 2017. Interpreting Soil Salinity Analysis. Oklahoma Cooperative Extension Service Fact Sheet. Oklahoma State University.
Zou, C., D. Twidwell, and C. Bielski. 2018. Impact of Eastern Redcedar Proliferation on Water Resources in the Great Plains USA- Current State of Knowledge.

Other references

Arkansas Soil Survey
Ouachita National Forest
Arkansas State Parks
The Nature Conservancy
US Fish and Wildlife Service
Encyclopedia of Arkansas
United States Forest Service Southern Research Station
NatureServe
Oklahoma Water Resource Board
National Centers For Environmental Information
University of Arkansas
Oklahoma State University
Arkansas Department of Forestry
Oklahoma Department of Forestry

Contributors

Trevor Crandall, Ecological Site Specialist

Approval

Bryan Christensen, 9/22/2023

Acknowledgments

Larry Gray
Elizabeth Gray
Erin Hourihan

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)
Contact for lead author
Date	09/25/2023
Approved by	Bryan Christensen
Approval date
Composition (Indicators 10 and 12) based on	Annual Production