Ecological dynamics

Provisional Ecological Site (PES): F123XY003TN – Limestone Glades (and Dry Woodlands)

Major Land Resource Area (MLRA) 123

This PES describes ecological communities likely to be found on soil in the PES soil grouping. Future field work is required to develop detailed and accurate ecological site descriptions (ESDs) that can be used by conservation planners for restoration and planning activities. This PES describes hypotheses based on available data from many different sources and scales and has not been developed using site specific ecological field monitoring. Future ESD development will result in this initial PES group being split into more refined ecological communities.

Soil series currently included in this project are

Forest Vegetation as listed in Official Series Descriptions (OSDs):

Gladeville: Most areas are in forest consisting chiefly of redcedar and a few scattered hackberry, hickory, ash, sumac, and winged elm. Prickly pears and lichens are common on most areas with grasses in openings.

Barfield: original hardwood trees consisting chiefly of oak, hickory, red cedar, elm, maple, and redbud.

Dilton: About 50 percent has been cleared of original hardwood trees consisting chiefly of oak, hickory, red cedar, elm, maple, and redbud. Most of the cleared areas are used for pasture. (2003)

Talbott: Originally hardwoods, chiefly oak, hickory, elm, maple, and redcedar.
(Talbott mapunits in this PES group are Talbott- rock outcrop and Talbott very rocky mapunits)

Trees listed for PES map units in the USDA-NRCS Tennessee County Soil Surveys include eastern red cedar, southern red oak, loblolly pine, pignut hickory, and hackberry.

Ecological Dynamics
This PES describes shallow, rocky limestone woodlands and glade communities on mapunits in the Nashville Basin of Tennessee. There are multiple zonal components on these landscapes. Variations in plant composition on these sites ranging from grass glades to dry woodlands to dry and dry-mesic oak forests. True edaphic glades are small acreage areas and may transition into cedar woodlands and dry oak forest communities. These shallow and rocky sites form a mosaic of unique plant communities on the landscape and plant communities on these mapunits will vary depending on aspect, soil depth, seed sources, management, disturbance history, fire regime, micro-topography and rock content. Future field work is required to develop a full ecological site description (ESD) and accurate plant community phases to support future conservation planning. Multiple MLRA 123 dry woodland, forest and glade communities have been identified by NatureServe for the Nashville Basin and detailed information is available at http://explorer.natureserve.org/index.htm. A summary of pertinent NatureServe Associations possible for rocky/shallow limestone soils is described at the end of this document. Multiple ESDs may result from this initial PES grouping.

State 1, Phase 1.1:
Plant species dominants: eastern redcedar (Juniperus virginiana) / cedarglade St. Johnswort (Hypericum frondosum) - white crownbeard (Verbesina virginica L.) / Andropogon spp. (bluestem) – Sporobolus spp. (dropseed)

The shrub layer may be variable and include fragrant sumac (Rhus aromatica), smooth sumac (Rhus glabra), winged sumac (Rhus copallinum), winged elm (Ulmus alata), coral berry Symphoricarpos orbiculatus, blue ash (Fraxinus quadrangulata), and rusty blackhaw (Viburnum rufidulum. The herbaceous layer may vary greatly depending on soil depth, rock content, aspect, and disturbances. Detailed descriptions of probable NatureServe associations for these sites are included at the end of this narrative.

State 2. Pastureland
Phase 2.1: Managed Pasture.
Plant species dominants: Schedonorus arundinaceus (tall fescue)

Some mapunits in this group may be appropriate for managed pasture. Some of the mapunits in this group are too rocky and shallow to support a productive pasture or crops. The pasture state is included in this initial PES until field work can be conducted to better delineate mapunits into different ESDs.


The following are association descriptions taken directly from http://explorer.natureserve.org/

Classification Approach: International Vegetation Classification (IVC)

Unique Identifier: CEGL003754
Juniperus virginiana var. virginiana - Fraxinus quadrangulata / Polymnia canadensis - (Astranthium integrifolium) Woodland
Translated Name: Eastern Red-cedar - Blue Ash / White-flower Leafcup - (Entireleaf Western-daisy) Woodland. Common Name: Red-cedar - Blue Ash Limestone Woodland

Summary: This woodland community is found on shallow soils of limestone slopes in the Central Basin and Cumberland Plateau escarpment of Tennessee and the Moulton Valley of Alabama; it may occur in association with limestone glades, on isolated eroded limestone knobs, on limestone ridges in the Highland Rim escarpment, or as a small patch within a matrix of dry to dry-mesic limestone oak forest (e.g., Quercus alba - Quercus rubra - Quercus muehlenbergii / Cercis canadensis Forest (CEGL002070) or Quercus muehlenbergii - Quercus shumardii - Carya (carolinae-septentrionalis, ovata) Forest (CEGL007808)). Fraxinus quadrangulata and Juniperus virginiana var. virginiana dominate the canopy and the subcanopy, but the composition of these strata may vary. Juniperus may share canopy dominance with the Fraxinus or other deciduous trees or it may be present as a distinct subcanopy. Quercus spp. do not dominate the relatively short canopy or the open subcanopy, either of which may include Celtis laevigata, Celtis occidentalis, Cercis canadensis, Ulmus alata, and Ulmus serotina. The shrub stratum may include Quercus muehlenbergii, Forestiera ligustrina, Rhus aromatica, Symphoricarpos orbiculatus, Frangula caroliniana, Hypericum frondosum, and Viburnum rufidulum. Vines may include Bignonia capreolata and Smilax rotundifolia. Herbs which may be present include Polymnia canadensis (= var. radiata), Symphyotrichum shortii (= Aster shortii), Astranthium integrifolium, Sedum pulchellum, Minuartia patula (= Arenaria patula), Verbesina virginica, Opuntia humifusa, Commelina erecta var. angustifolia, Croton monanthogynus, Ruellia humilis, and Euphorbia dentata. The 'herbaceous' stratum in some examples may contain greater coverage of ferns (Cheilanthes lanosa, Pellaea atropurpurea), mosses (e.g., Pleurochaete squarrosa, Thuidium delicatulum, Climacium americanum), and foliose lichens (Cladonia spp.) than of flowering herbs. Scattered individuals of the near-endemic legume Astragalus tennesseensis may be found in some examples adjacent to glades. This woodland develops on rocky sites, which contain outcrops of Ordovician (or Mississippian) limestone. Soils primarily accumulate in fissures between the limestone. The exotics Ailanthus altissima and Lonicera maackii may invade examples of this vegetation in the vicinity of Nashville, Tennessee.

Global Status: G3 (13Dec1999) Rounded Global Status: G3 - Vulnerable
Reasons: This vegetation has a naturally restricted range of distribution, being limited to dry limestone rocky areas in central Tennessee, northern Alabama, and related areas of Kentucky. This association occurs on lands which are intermediate in soil depth and available moisture between hardwood forests and glade/barren environments. These areas are very slow to succeed to forest and maintain a Juniperus-dominated aspect. Most examples seen are limited in extent and restricted to a particular habitat type. The effect of fire on this association is not known; some examples are on isolated knobs or on slopes where fire might have been less frequent than in flatter areas.


Unique Identifier: CEGL003938
Juniperus virginiana var. virginiana - Forestiera ligustrina - Rhus aromatica - Hypericum frondosum Shrubland
Translated Name: Eastern Red-cedar - Upland Swamp-privet - Fragrant Sumac - Cedar Glade St. John's-wort Shrubland
Common Name: Southern Limestone Glade Margin Shrubland

Summary: This shrubland is a zonal component of Central Basin (Tennessee) limestone cedar glades. It is also found on limestone outcrops of the Alabama Cumberland Plateau and Moulton Valley glade systems, and as a component of cedar glade complexes at Chickamauga-Chattanooga National Military Park. It also occurs on the Pennyroyal Karst Plain of Kentucky. Alabama and Kentucky occurrences are rare and of restricted distribution and limited extent. The substrate consists of broken fragments of flat-bedded sedimentary limestone, with accumulations of shallow soil. Characteristic shrubs include Juniperus virginiana var. virginiana, Rhus aromatica var. aromatica, Frangula caroliniana, Forestiera ligustrina, Berchemia scandens, Hypericum frondosum, Sideroxylon lycioides, and stunted individuals of Acer saccharum, Quercus muehlenbergii, Quercus shumardii, Fraxinus americana, and Ulmus alata. Alabama occurrences may contain an occasional Aesculus pavia. A low 'herbaceous' stratum is dominated by Cheilanthes lanosa, Pleurochaete squarrosa, Thuidium delicatulum, Climacium americanum, Cladonia spp., and Opuntia humifusa. Typically grades into open, herbaceous-dominated glades, or into woodlands or forests commonly dominated by Quercus muehlenbergii, Fraxinus americana, and Celtis laevigata.

Global Status: G3G4 (31Jan2007). Rounded Global Status: G3 - Vulnerable
Reasons: This vegetation type is restricted to dry limestone substrates in the Nashville Basin of Tennessee and related areas of Alabama, Georgia and Kentucky. Although this shrubland type can be dominant at some extensive glade sites and is more stable than some other glade communities, its overall coverage of the landscape is limited, and it is threatened by development and land-use conversion in this area of rapidly increasing human population. Examples which are not conserved on national parks, nature preserves, state forests, or Army Corps of Engineers lands are highly vulnerable to development pressure. This shrub zone does not typically provide habitat for rare plant species, but it is an important component of this threatened landscape. Alabama, Georgia and Kentucky examples are rare and limited in extent.


Unique Identifier: CEGL003712
Quercus stellata / Viburnum rufidulum - Forestiera ligustrina / Andropogon gerardii Woodland
Translated Name: Post Oak / Rusty Blackhaw - Upland Swamp-privet / Big Bluestem Woodland
Common Name: Nashville Basin Post Oak Woodland
Classification Approach: International Vegetation Classification (IVC)

Summary: This woodland is restricted to the Inner Nashville Basin of Tennessee, where it occurs in association with Limestone Cedar Glades, in deeper soils than those of the annual grass zone. The prevalent tree is Quercus stellata. The open subcanopy may contain Juniperus virginiana var. virginiana. Shrubs include Forestiera ligustrina, Hypericum frondosum, Rhus aromatica, and Viburnum rufidulum. Fire suppression in these sites may lead to dense undergrowth of Juniperus.

Graminoids present may include Andropogon gerardii and/or Schizachyrium scoparium. Some other herbaceous species include Baptisia australis var. aberrans (= Baptisia minor var. aberrans), Comandra umbellata, Eryngium yuccifolium, Hypoxis hirsuta, Lithospermum canescens, Parthenium integrifolium, and Viola pedata.

The state-listed Echinacea simulata, Liatris cylindracea, and Polygala boykinii are also found here.

Global Status: G2? (31Dec1997) Rounded Global Status: G2 - Imperiled
Reasons: This oak woodland is restricted to the Inner Nashville Basin of Tennessee, where it occurs in association with Limestone Cedar Glades, in deeper soils than those of the annual grass zone. Few examples of this highly ranked association have been reported, and these are limited in extent. Many deeper soil areas of the Nashville Basin have been cleared of trees, pastured or cropped, and then allowed to succeed to shrub thicket or forest. Fire suppression in these sites may lead to dense undergrowth of Juniperus. Most of those occurrences which have not been destroyed are severely degraded.


Unique Identifier: CEGL004340
Sporobolus (neglectus, vaginiflorus) - Aristida longispica - Panicum flexile - Panicum capillare Grassland
Translated Name: (Barrens Dropseed, Poverty Dropseed) - Slimspike Three-awn - Wiry Panicgrass - Witchgrass Grassland
Common Name: Limestone Annual Grass Glade
Classification Approach: International Vegetation Classification (IVC)

Summary: This annual herbaceous community is a zonal component of Nashville Basin (Tennessee) and Moulton Valley (Alabama) Limestone Cedar Glades. Much of this vegetation is a mixture of annual grasses and perennial forbs, with enormous seasonal variation in dominance. Additional associations may be named. Relations with related vegetation in other ecoregions needs further investigation. Stands are dominated by Sporobolus neglectus, Sporobolus vaginiflorus var. vaginiflorus, and/or Sporobolus vaginiflorus var. ozarkanus (= Sporobolus ozarkanus). Some of the co-occurring forbs are the endemic or near-endemic Dalea gattingeri and Pediomelum subacaule, along with Croton capitatus, Grindelia lanceolata, Hedyotis nigricans var. nigricans, Heliotropium tenellum, Isanthus brachiatus, Manfreda virginica, and Ruellia humilis. Dalea gattingeri is present in most examples of this vegetation type. Grindelia lanceolata has become abundant in some examples; this may merit recognition as an association, or it may be a symptom of disturbance.

Global Status: G3 (20Dec2000) Rounded Global Status: G3 - Vulnerable
Reasons: This annual herbaceous community is restricted to the Nashville Basin (Tennessee) and Moulton Valley (Alabama) Limestone Cedar Glades. It may cover large parts of some glade sites. Succession is limited on the thin soils on which this type is found, so it is relatively stable. However, its overall coverage of the landscape is limited, and it is threatened by development and land-use conversion in areas of rapidly increasing human population (e.g., the Nashville Basin). Threats include destruction by recreational off-road vehicle traffic, gravel and mineral surface mining, and land-use change related to suburban development. It is restricted to the Inner Nashville Basin subsection of Tennessee and a few limited areas of Alabama and Kentucky. Examples which are not conserved on nature preserves, state forests, national forests, or U.S. Corps of Engineers lands are highly vulnerable to development pressure.



Unique Identifier: CEGL005131
Quercus muehlenbergii - Juniperus virginiana / Schizachyrium scoparium - Manfreda virginica Wooded Grassland
Translated Name: Chinquapin Oak - Eastern Red-cedar / Little Bluestem - False Aloe Wooded Grassland
Common Name: Central Limestone Glade
Classification Approach: International Vegetation Classification (IVC)

Summary: This limestone glade or barrens community is found in the central and eastern United States. Stands occur on gentle to steep slopes of hills, knobs, ridges, bluffs along streams, and broad terraces. Aspect is variable, but this vegetation is generally best developed on southern and western exposures. Parent material is limestone, cherty limestone, dolomite, or calcareous shale which is exposed at the surface, resulting in a very shallow, well-drained substrate. Soils are neutral to alkaline, shallow to moderately deep, and contain a homogenous mixture of rock fragments of various sizes. Herbaceous cover is very uneven, ranging from very dense in some areas to absent in others. Some dominant or characteristic grasses include Schizachyrium scoparium, Sorghastrum nutans, Aristida spp., and Sporobolus compositus. In deeper soil areas Andropogon gerardii may be present. At some sites Bouteloua curtipendula is present, but it may be rare or absent at others. Forbs vary in dominance by site. Quercus muehlenbergii and Juniperus virginiana var. virginiana can form a sparse canopy. Quercus stellata may be common in parts of the range. Other scattered trees which may be present include Cercis canadensis, Fraxinus quadrangulata, Quercus velutina, Quercus alba, Quercus marilandica, and Liriodendron tulipifera. The subcanopy is absent or very sparse. Commonly encountered shrubs include Celtis tenuifolia, Cornus florida, Ulmus alata, Rhus aromatica, Rhus copallinum, and Symphoricarpos orbiculatus. This vegetation may exist as more extensive areas, or in some southeastern cases, it may be limited to a more narrow zone between vegetation dominated by woody plants and that dominated by annual grasses.

Global Status: G2G3 (02Nov1999) Rounded Global Status: G2 - Imperiled
Reasons: There are probably over 100 occurrences range wide. Eighty-three have been documented: 32 in Illinois (S2), 48 in Indiana (S2S3), and 3 in Ohio (S2). Although no other occurrences are documented, the community is also reported in Alabama, Georgia, Kentucky, Tennessee, West Virginia, and Virginia (all S?). It is found in 15 ecoregional subsections. The present range of this community is probably very close to its pre-settlement range, but lack of fire permits increased dominance by woody species.