Home/Ecosystems/ Crowley's Ridge Sand Forest

Crowley's Ridge Sand Forest

EVT 7510

CES203.072GNRTreeConifer-hardwood

Summary

This system of upland shortleaf pine - hardwood forests is confined to Crowley's Ridge on the western side of the Mississippi River. This vegetation is very distinctive from that of the adjacent alluvial plain, and the ridge itself also contrasts sharply with the adjacent alluvial plain. Crowley's Ridge is a remnant loess-capped feature rising from 30 m to over 60 m (100-200 feet) above the alluvial plain surface, to about 150 m (450 feet) above sea level. The base of the northern ridge is composed of Tertiary substrates overlain by alluvial deposits and capped with generally thin layers of Pleistocene loess. The Pleistocene alluvial deposits are often sandy, and in a very limited area, there are outcrops of sandstone of uncertain origin. Forests on the ridgetops are dominated by Pinus echinata with varying amounts of Quercus alba, Quercus rubra, Quercus falcata, Quercus stellata, Carya texana, and Quercus velutina. Loess slopes and ravines are dominated by mesic or dry-mesic hardwood forests such as those of the southern ridge, but are of relatively limited extent.

Source: NatureServe Explorer

Vegetation

This system consists of forests that are typically dominated by shortleaf pine with oaks and other hardwoods. Depending upon local soil moisture and other factors, canopy oaks can vary from Quercus stellata and Quercus falcata on the driest sites to Quercus alba and other oaks on more mesic sites. Associated species in the subcanopy and understory vary along this moisture gradient as well (refer to association-level descriptions for more details).

Source: NatureServe Explorer

Environment

These forests occur on sandy ridges and slopes in a dissected environment. The system is best expressed on northern Crowley's Ridge, but there are limited occurrences on the southern ridge as well, on sandy, exposed sites. They generally lie to the east of hydroxeric Pleistocene terrace flatwoods (now usually converted to cropland) that burned frequently. Those fires would have continued into these dry to dry-mesic forests, thereby increasing the fire frequency.

Source: NatureServe Explorer

Dynamics

These are fire-adapted forests. There is presumably some natural disturbance from the effects of windstorms and collapse of the fragile loess. This vegetation is classed as Fire Regime I, with frequent surface fire (mean fire-return interval is approximately five years) and less frequent mixed fire. In addition, straight-line winds or microbursts may cause blowdowns on a scale of 1 to 100 acres. Stand-replacement fires happen very infrequently (Landfire 2007a).

Source: NatureServe Explorer

Threats

Conversion of this type has primarily resulted from canopy removal and habitat fragmentation. Sites are typically impacted by sand and gravel mining, urbanization, and conversion to pastures. Degradation occurs from logging, as well as from lack of fire. Due to lack of fire for many years, the current forests are uncharacteristic (D. Zollner pers. comm. 2013).

Aside from actual site conversion, feral hogs represent one of the greatest threats to biodiversity in these forests (Engeman et al. 2007). In addition, invasive exotic species, including Ailanthus altissima, Macrothelypteris torresiana, Microstegium vimineum, Paulownia tomentosa, Phyllostachys aurea, and Pueraria montana var. lobata, can become dominant in the ground and shrub layers following canopy disturbance. For forests containing Fraxinus species, emerald ash borer (which as of October 2013 has been reported from southeastern Missouri) may also be (or become) a significant stressor.

Source: NatureServe Explorer

Distribution

This system is endemic to Crowley's Ridge in the Mississippi River Alluvial Plain of Arkansas and Missouri (Nelson 2010).

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, Pinus echinata, Quercus alba, Quercus falcata, Quercus rubra, Quercus stellata, Quercus velutina

Source: NatureServe Ecological System assessment

Ecologically Associated Animals (5)

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 (4)

Common Name	Scientific Name	G-Rank
North American Racer	Coluber constrictor	G5
Eastern Hog-nosed Snake	Heterodon platirhinos	G5
Eastern Milksnake	Lampropeltis triangulum	G5
Eastern Fence Lizard	Sceloporus undulatus	G5

Other (1)

Common Name	Scientific Name	G-Rank
Western Ratsnake	Pantherophis obsoletus	G5

Source: NatureServe Ecological System assessment

Component Associations (2)

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
Pinus echinata Crowley's Ridge Forest	G3	NatureServe
Quercus stellata - Quercus falcata / Ostrya virginiana Forest	G1	NatureServe

State Conservation Ranks (2)

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.

State	S-Rank
AR	SNR
MO	SNR

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.