East Texas Droughty Sandyland
Summary
This xeric system of east-central Texas is found primarily on the Carrizo geologic formation, but also on other Eocene sandy strata such as Queen City and Sparta. The combination of these very droughty soils with low levels of rainfall create extreme edaphic conditions and a locally unique environment which supports a number of endemic plant taxa. The vegetational component of this system includes open herbaceous-dominated sand "prairies" or "barrens" to open oak-dominated woodlands, with Quercus incana and Quercus margarettae. A large number of narrowly distributed, endemic species are associated with this system, including Abronia macrocarpa, Allium elmendorfii, Brazoria truncata var. pulcherrima (= Brazoria pulcherrima), Brazoria truncata var. truncata, Chaetopappa imberbis, Cryptantha texana, Dalea obovata, Galactia canescens, Hymenopappus carrizoanus, Lechea san-sabeana, Lesquerella grandiflora, Liatris elegans var. carizzana, Liatris elegans var. bridgesii, Polanisia erosa ssp. breviglandulosa, Polygonella parksii, Prunus texana, Rhododon ciliatus, Senecio ampullaceus, Sphaeralcea lindheimeri, Tephrosia lindheimeri, and Tetragonotheca repanda.
Source: NatureServe Explorer
Vegetation
This small-patch system is typically an open, herbaceous-dominated sand "prairie," sometimes with open, oak-dominated woodlands. Species such as Quercus incana, Quercus margarettae, Quercus stellata, and Carya texana (often stunted) occur in the usually sparse overstory. Invasion by Ilex vomitoria is frequent in the absence of fire. Other woody plants that may be encountered include Juniperus virginiana, Rhus aromatica, Vaccinium arboreum, Viburnum rufidulum, Rhus copallinum, and Cornus florida. The herbaceous layer may be sparse, often with exposed sand, and includes Cladonia spp., and species such as Aristida desmantha, Brazoria truncata var. truncata, Cnidoscolus texanus, Dichanthelium spp., Sporobolus junceus, Froelichia floridana, Hymenopappus artemisiifolius, Lechea spp., Loeflingia squarrosa, Opuntia humifusa, Paronychia drummondii, Polanisia erosa, Schizachyrium scoparium, Monarda punctata, Senecio ampullaceus, Sorghastrum elliottii, Stylisma pickeringii, Tetragonotheca spp., Gaillardia amblyodon, Rhynchosia americana, Zornia bracteata, and Triplasis purpurea. Species such as Cyperus grayoides, Penstemon murrayanus, Selaginella arenicola ssp. riddellii, Tradescantia reverchonii, and Yucca louisianensis may be present, but primarily to the east, while Tephrosia lindheimeri and Rhynchosia americana are frequently encountered to the south. Texas endemics, such as Brazoria truncata var. pulcherrima, Rhododon ciliatus, and Hymenopappus carrizoanus may be found in this system (Elliott 2011). Some other narrowly distributed, endemic species that may be associated with this system include Abronia macrocarpa, Allium elmendorfii, Chaetopappa imberbis, Cryptantha texana, Dalea obovata, Galactia canescens, Lechea san-sabeana, Lesquerella grandiflora, Liatris elegans var. carizzana, Polanisia erosa ssp. breviglandulosa, Polygonella parksii, Prunus texana, Sphaeralcea lindheimeri, and Tetragonotheca repanda.
Source: NatureServe Explorer
Environment
This xeric system is found primarily on the Carrizo geologic formation, but also on other Eocene strata such as Queen City and Sparta. The combination of these very droughty soils with low levels of rainfall create extreme edaphic conditions and a locally unique environment which supports a number of endemic plant taxa. It is found on high topographic positions, and this, along with rapidly draining soils, results in conditions that only briefly retain surface moisture. Deep sandy soils typify this system (Elliott 2011).
Source: NatureServe Explorer
Dynamics
This small-patch system is associated higher topographic positions that shed water, and it is underlain by loose sandy soils that are rapidly drained resulting in xeric surface conditions. Fire maintains this system in an open condition with increased cover of herbaceous species. Woody species such as Ilex vomitoria tend to encroach in the absence of fire, leading to a loss of diversity.
Source: NatureServe Explorer
Threats
The primary threat to this system is loss of habitat through conversion to developed land uses. Very little of this system is under conservation ownership (Bezanson 2000). The cessation of a natural fire cycle may lead to conversion to shrub-dominated sites.
Source: NatureServe Explorer
Distribution
This system is endemic to east-central Texas.
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
Quercus incana
Tall shrub/sapling
Prunus texana
Herb (field)
Abronia macrocarpa, Allium elmendorfii, Brazoria truncata var. pulcherrima, Brazoria truncata var. truncata, Chaetopappa imberbis, Cryptantha texana, Cyperus grayoides, Dalea obovata, Galactia canescens, Hymenopappus carrizoanus, Lechea san-sabeana, Liatris elegans var. carizzana, Paysonia grandiflora, Polanisia erosa ssp. breviglandulosa, Polygonella parksii, Rhododon ciliatus, Schizachyrium scoparium, Senecio ampullaceus, Sphaeralcea lindheimeri, Tephrosia lindheimeri, Tetragonotheca repanda
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (8)
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.
Other (1)
| Common Name | Scientific Name | G-Rank |
|---|
| Coachwhip | Coluber flagellum | G5 |
Source: NatureServe Ecological System assessment
At-Risk Species Associated with this Ecosystem (10)
Species with conservation concern that are ecologically associated with this ecosystem type. G-Rank indicates global conservation status: G1 (critically imperiled) through G5 (secure). ESA status indicates U.S. Endangered Species Act listing.
Source: NatureServe Ecological System assessment
Component Associations (1)
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.
| Name | G-Rank | |
|---|
| Schizachyrium scoparium - Lechea tenuifolia - Acalypha radians Grassland | G2 | NatureServe |
State Conservation Ranks (1)
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.
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.