Ozark-Ouachita Dry Oak Woodland

EVT 7364
CES202.707GNRTreeHardwood
Summary
This system occurs in the Ozark and Ouachita Highlands and far western portions of the Interior Low Plateau regions along gentle to steep slopes and over bluff escarpments with southerly to westerly aspects. Parent material can range from calcareous to acidic with very shallow, well- to excessively well-drained soils, sometimes with a fragipan that causes "xero-hydric" moisture conditions. Historically, this system primarily exhibited a woodland structure with related composition and processes, but now most stands have a more closed canopy. Oak species such as Quercus stellata, Quercus marilandica, and Quercus coccinea dominate this system with an understory of grassland species such as Schizachyrium scoparium and shrub species such as Vaccinium arboreum. Drought stress is the major dynamic influencing and maintaining this system. Some examples are flatwoods with fragipans; in these examples Quercus stellata is the major dominant. In addition, Quercus alba, Quercus falcata, and/or Carya texana may be present in some stands.
Source: NatureServe Explorer
Vegetation
Oak species such as Quercus stellata, Quercus marilandica, and Quercus coccinea dominate this system with an understory of grassland species such as Schizachyrium scoparium and shrub species such as Vaccinium arboreum. Drought stress is the major dynamic influencing and maintaining this system. On flatwoods with fragipans, Quercus stellata is the major dominant. Quercus alba, Quercus falcata, and/or Carya texana may be present in some stands. Other species that may be present include Schizachyrium scoparium, Ulmus alata, and Vaccinium arboreum.
Source: NatureServe Explorer
Environment
This system occurs along gentle to steep slopes and over bluff escarpments with southerly to westerly aspects in the Ozark and Ouachita Highlands and far western portions of the Interior Low Plateau regions. Parent material can range from calcareous to acidic with very shallow, well- to excessively well-drained soils, sometimes with a fragipan that causes "xero-hydric" moisture conditions. Conditions are drier than those of the dry oak woodlands.
Source: NatureServe Explorer
Distribution
This system occurs in the Western Interior Highlands of the Ozark, Ouachita, and western Interior Low Plateau regions.
Source: NatureServe Explorer
Ecologically Associated Plant Species

Plant species that characterize this ecosystem type, organized by vegetation stratum. These are species ecologically associated with the ecosystem, not confirmed present in any specific area.

Tree canopy

Carya texana, Quercus alba, Quercus coccinea, Quercus falcata, Quercus marilandica, Quercus stellata, Quercus velutina, Ulmus alata

Shrub/sapling (tall & short)

Vaccinium arboreum

Herb (field)

Schizachyrium scoparium
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (3)

Animal species ecologically associated with this ecosystem type based on NatureServe assessment. These are species whose habitat requirements overlap with this ecosystem, not confirmed present in any specific roadless area.

Reptiles (3)

Common NameScientific NameG-Rank
Eastern Hog-nosed SnakeHeterodon platirhinosG5
Eastern Fence LizardSceloporus undulatusG5
Little Brown SkinkScincella lateralisG5
Source: NatureServe Ecological System assessment
Component Associations (7)

Plant community associations that occur within this ecological system. Associations are the finest level of the U.S. National Vegetation Classification (USNVC) and describe specific, repeating assemblages of plant species. Each association represents a distinct community type that may be found where this ecosystem occurs.

NameG-Rank
Quercus alba - Quercus stellata - Quercus velutina / Schizachyrium scoparium WoodlandG2 NatureServe
Quercus falcata - Quercus alba - Quercus stellata - Quercus velutina ForestG4 NatureServe
Quercus marilandica / Vaccinium arboreum / Danthonia spicata Scrub WoodlandG3 NatureServe
Quercus stellata - Quercus marilandica - Carya (glabra, texana) / Vaccinium arboreum ForestG4 NatureServe
Quercus stellata - Quercus marilandica - Quercus velutina - Carya texana / Schizachyrium scoparium WoodlandG2 NatureServe
Quercus velutina - Carya (tomentosa, glabra) / Vaccinium arboreum ForestG2 NatureServe
Quercus velutina - Quercus coccinea - Carya texana Dry Ozark ForestGNR NatureServe
State Conservation Ranks (4)

Subnational conservation status ranks (S-ranks) assigned by Natural Heritage Programs in each state where this ecosystem occurs. S1 indicates critically imperiled at the state level, S2 imperiled, S3 vulnerable, S4 apparently secure, and S5 secure. An ecosystem may be globally secure but imperiled in specific states at the edge of its range.

StateS-Rank
ARSNR
ILSNR
MOSNR
OKSNR
Roadless Areas (17)

Inventoried Roadless Areas where this ecosystem is present, identified from LANDFIRE 2024 Existing Vegetation Type spatial analysis. Coverage indicates the proportion of each area occupied by this ecosystem type.

Arkansas (11)

AreaForestCoverageHectares
Clifty CanyonOzark-St. Francis National Forest5.5%43.92
Little BlakelyOuachita National Forest5.3%72
Bear MountainOuachita National Forest3.8%29.16
Devils CanyonOzark-St. Francis National Forest3.4%25.92
Blue MountainOuachita National Forest2.3%92.25
Indian CreekOzark-St. Francis National Forest1.8%57.69
Rich Mountain (AR)Ouachita National Forest1.7%17.64
Dismal CreekOzark-St. Francis National Forest1.5%57.42
Brush HeapOuachita National Forest1.3%22.68
Gee CreekOzark-St. Francis National Forest1.0%31.95
Pedestal RocksOzark-St. Francis National Forest0.6%53.19

Missouri (4)

AreaForestCoverageHectares
Big Creek Rare II Study AreaMark Twain National Forest45.1%1,693.71
Anderson Mountain Rare II Study AreaMark Twain National Forest31.9%353.34
Swan Creek Rare II Study AreaMark Twain National Forest25.0%739.62
Irish Rare II Study AreaMark Twain National Forest24.2%120.78

Oklahoma (2)

AreaForestCoverageHectares
Rich Mountain (OK)Ouachita National Forest2.2%44.91
Beech CreekOuachita National Forest1.6%54.27
Methodology and Data Sources

Ecosystem classification: Ecosystems are classified using the LANDFIRE 2024 Existing Vegetation Type (EVT) layer, mapped to NatureServe Terrestrial Ecological Systems via a curated crosswalk. Each EVT is linked to the USNVC (U.S. National Vegetation Classification) hierarchy through pixel-level co-occurrence analysis of LANDFIRE EVT and NatureServe IVC Group rasters across all roadless areas.

Vegetation coverage: Coverage percentages and hectares are derived from zonal statistics of the LANDFIRE 2024 EVT raster intersected with roadless area boundaries.

Ecosystem narratives and community species: Sourced from the NatureServe Explorer API, representing professional ecological assessments of vegetation composition, environmental setting, dynamics, threats, and characteristic species assemblages.

IVC hierarchy: The International Vegetation Classification hierarchy is sourced from the USNVC v3.0 Catalog, providing the full classification from Biome through Association levels.

Component associations: Plant community associations listed as components of each NatureServe Ecological System. Association data from the NatureServe Explorer API.

State ranks: Conservation status ranks assigned by NatureServe member programs in each state where the ecosystem occurs.