Common (Translated Scientific) Name: White Oak - Southern Red Oak - Shortleaf Pine Forest & Woodland Macrogroup
Colloquial Name: Southern & South-Central Oak - Pine Forest & Woodland
Hierarchy Level: Macrogroup
Type Concept: This wide-ranging vegetation type encompasses fire-dependent forests and woodlands found in a broad band across the southeastern United States and dominated by various combinations of Quercus species, Pinus species, and other hardwood trees. It occurs primarily in the unglaciated part of the Interior Low Plateaus, the Appalachian, Piedmont, Ozark-Ouachita, and upper coastal plain regions (north of the primary range of Pinus palustris), as well as to the west in eastern Oklahoma, southeastern Kansas, and the Inner Coastal Plain of central Texas. In many areas, this is the predominant natural upland vegetation of the landscape. Stands of these forests are dominated by combinations of upland Quercus spp., particularly Quercus alba, Quercus coccinea, Quercus falcata, Quercus rubra, Quercus stellata, and Quercus velutina, along with Carya tomentosa, Carya glabra, Carya ovata, Carya pallida, and other Carya spp. In some drier examples on more acidic substrates, Quercus montana is typical. Pines may be abundant or even dominant in some examples, including Pinus echinata, Pinus palustris (rarely), Pinus taeda, and Pinus virginiana. Fire-intolerant species such as Acer rubrum, Liquidambar styraciflua, Liriodendron tulipifera, and Nyssa sylvatica may be common in some examples. In the western part of the range, examples are dominated by short, stunted Quercus stellata and/or Quercus marilandica with Carya texana. These patches of forest and woodland are often interspersed with patches of tall- and midgrass prairie. On limestone-derived soils examples contain various combinations of Fraxinus quadrangulata, Juniperus virginiana, Quercus muehlenbergii, Quercus pagoda, and Quercus shumardii. Shrub and herb layer species vary considerably, depending on aspect, soil, and moisture relations. More open canopies and grass-dominated understories may have been more prevalent prior to the mid-twentieth century, when open grazing and surface fires were more common. Substrates also vary widely, including soils derived from felsic and mafic metamorphic rocks; sedimentary limestones, sandstones, and shales; as well as some coastal plain poorly consolidated sediments of silts and clays, as well as more rarely shell deposits or limesands. These soils range from calcareous to acidic; soils may be very shallow and well- to excessively well-drained in the dry expressions, and moderately well-drained in the submesic to dry-mesic ones. Examples may also occur on dense clay hardpans over mafic rocks. Examples can occur on a variety of topographic and landscape positions, including ridgetops and upper and midslopes.
Diagnostic Characteristics: These forests cover a broad range of floristics over a broad geographic range, and typically are fire-dependent. Typical hardwoods include Quercus alba, Quercus coccinea, Quercus falcata, Quercus rubra, Quercus stellata, and Quercus velutina, along with Carya tomentosa, Carya glabra, Carya ovata, Carya pallida, and other Carya spp. Pines include Pinus echinata, Pinus taeda, and Pinus virginiana. At the mafic/circumneutral end, they may contain Quercus muehlenbergii; at the acidic end, Quercus montana. Some examples contain Pinus species and some do not. Many, if not most, examples in the early 21st century landscape represent habitats altered and possibly degraded by the absence of fire.
Rationale for Nominal Species or Physiognomic Features: Most of the range of the associations in the group are consistent with the range of Quercus falcata, so this is included as a nominal, but it also is found in parts of the coastal plains south of the range of this vegetation. Pinus echinata is an obligate and characteristic taxon, and dominates some examples. The Quercus taxa vary with geography, with Quercus montana being generally absent south and west of the Appalachian and Piedmont regions. Quercus stellata and/or Quercus marilandica characterize and dominate the western components.
Classification Comments: This type represents the bulk of what is often called the southern oak-hickory pine type (Küchler 1964), but also includes the unglaciated parts of his oak-hickory type. There is abundant variation among stands within this macrogroup, between dry and dry-mesic forests and also between those on acidic or circumneutral substrates. This variation will inform the limits of the different component groups and alliances, but a broadly similar canopy composition and similar dynamics tie them together at this broader level. In the Interior Low Plateaus, the range of this group is consistent with the non-coastal plain portion of the "Western Mesophytic" Forest region of Braun (1950), Keever (1971), and Greller (1988).
Examples with substantial Pinus echinata mainly occur in three general areas: the Appalachians (broadly defined to include the Cumberlands and Piedmont, particularly to the south); the East Gulf Coastal Plain north of the range of Pinus palustris; and the Ozark-Ouachita areas of Missouri and Arkansas. Stands found outside of the coastal plains in which Pinus palustris is a component are also included here. These were formerly included in Montane & Piedmont Longleaf Pine Woodland Group (G164). Examples in the Ozark-Ouachita area and the Upper Coastal Plain will lack Pinus rigida, Pinus virginiana, and Quercus montana.
Cross Timbers & East-Central Texas Plains Oak Forest & Woodland Group (G017) is currently circumscribed at the group level, separate from somewhat similar vegetation occurring farther east that is also characterized by Quercus stellata and Quercus marilandica. This group represents the western edge of the eastern deciduous forests, and as such is lacking many of the eastern "dry-site" woody species, such as Gaylussacia spp., Pinus echinata, Quercus alba, Quercus coccinea, Quercus falcata, Vaccinium pallidum, and Vaccinium stamineum, among others, and by the presence of Carya texana. In addition, it represents a transition of forests to grasslands, and some evidence suggests this group once had a higher grass cover, linking it more closely with the Great Plains grasslands. Many factors are thought to have contributed to this increase in woody cover, primarily the imbalance in two main natural processes that helped maintain this grassland state: fire and grazing.
There is an overlap in species composition (including some of the key calcareous diagnostic species) between Chinquapin Oak - Shumard Oak - Blue Ash Alkaline Forest & Woodland Group (G601) and Northeastern Chinquapin Oak - Red-cedar Alkaline Forest & Woodland Group (G016), the full composition of species found in sites of the former shows stronger affinities with the south-central forests of M016.
The forests of Piedmont-Central Atlantic Coastal Plain Oak Forest Group (G165) have often been called "oak-hickory" (Braun 1950) or "oak-pine-hickory" (Küchler 1964, Greller 1989, Skeen et al. 1993). However, Monk et al. (1990) concluded there was insufficient abundance of Carya spp. to justify including this genus in the name of such forests "at a regional level." They do, however, acknowledge that "(t)here are many oak-hickory forest stands." There are fairly dramatic differences in the amount of pine present across the modern day Piedmont landscape, with it being especially prevalent in South Carolina, Georgia, and Alabama (USGS 1992). To some extent, the prevalence of pine in these southern portions of the region may represent natural conditions (Nelson 1957). It is possible that the more heavily mixed or pine-dominated forests of the southern Piedmont should be recognized as a different group, but distinguishing natural examples is difficult given a long history of land-use impacts and resulting vegetational changes in the region (Brender 1974). In addition, Skeen et al. (1993) assert that "the oak-hickory-pine designationmay be reflective of past land use and disturbance history and that the [current] steady-state typal forest of the southeastern Piedmont is in reality oak-hickory-yellow poplar."
This macrogroup also includes mixed evergreen-deciduous forests dominated by Pinus taeda and/or Pinus echinata in combination with a suite of dry- to dry-mesic-site hardwoods, including Quercus alba, Quercus falcata, and Quercus stellata, and the scrub oaks Quercus incana, Quercus margarettae, and Quercus arkansana. They are primarily found in the West Gulf Coastal Plain of Arkansas, Louisiana and Texas.
Similar NVC Types:
M008 Southern Mesic Mixed Broadleaf Forest, note:
M012 Central Midwest Oak Forest, Woodland & Savanna, note:
M502 Appalachian-Northeastern Oak - Hardwood - Pine Forest & Woodland, note:
M509 Central Interior Acidic Scrub & Grassland, note:
M882 Central Midwest Mesic Forest, note:
M883 Appalachian-Interior-Northeastern Mesic Forest, note:
M885 Southeastern Coastal Plain Evergreen Oak - Mixed Hardwood Forest, note:
Physiognomy and Structure: Physiognomies in this wide-ranging and variable vegetation type include forests and woodlands as well as savannas and barrens, which may be interspersed with patches of prairie on the western end of the range. The density of stands may vary from open to closed, depending on moisture regime, climate and management, particularly time since last fire, and average fire frequency over a period of several decades. More open stands are more likely to have a graminoid-dominated ground layer; otherwise the low-shrub stratum may be dense, with herbs correspondingly lower in cover. The density and diversity of the ground layer may vary from sparse to moderate in density in drier, acidic examples, to dense and diverse in more circumneutral examples as well as more mesic ones.
Stands of ~South-Central Interior Oak Forest & Woodland Group (G159)$$ are moderately tall, closed-canopy upland forests under current conditions, but more open canopies and grass-dominated understories may have been more prevalent prior to the mid-twentieth century. Short, stunted Quercus stellata and/or Quercus marilandica characterize and dominate ~Southeastern Great Plains Post Oak - Blackjack Oak Forest & Woodland Group (G017)$$. The physiognomy includes scattered trees with high herbaceous cover, open-canopied woodlands, and closed-canopied patches of trees interspersed with grasslands.
Floristics: Stands of these forests are dominated by combinations of upland Quercus spp., particularly Quercus alba, Quercus coccinea, Quercus falcata, Quercus rubra, Quercus stellata, and Quercus velutina, along with Carya tomentosa (= Carya alba), Carya glabra, Carya ovata, Carya pallida, and other Carya spp. Piedmont mafic examples exhibit a pronounced abundance of Carya spp. relative to other Piedmont forests (Farrell and Ware 1991, Ware 1992). Quercus alba may also be present but not necessarily dominant, but will typically exhibit dominance in the submesic to dry-mesic examples, possibly with Quercus velutina or Quercus falcata. In addition, Quercus coccinea, Quercus marilandica, and Quercus stellata will also share dominance or be prominent in many of the dry examples. Quercus muehlenbergii, Quercus pagoda, and/or Quercus shumardii are typical of examples with high base status. Mesic hardwoods are typically absent, but may increase with lack of fire; they include Acer floridanum (= Acer barbatum), Acer rubrum, Acer saccharum (in more mesic examples), Cercis canadensis, Cornus florida, Fagus grandifolia, Fraxinus americana, Gleditsia triacanthos, Gymnocladus dioicus, Juglans nigra, Juniperus virginiana var. virginiana, Kalmia latifolia, Liquidambar styraciflua, Liriodendron tulipifera, Ostrya virginiana, Oxydendrum arboreum, Styrax americanus, Vaccinium arboreum, Vaccinium pallidum, Vaccinium stamineum, Viburnum acerifolium, Ulmus americana, Ulmus serotina, and Vitis aestivalis. East of the Mississippi River, in some drier examples on more acidic substrates, Quercus montana (= Quercus prinus) is typical, reflecting relations with similar Appalachian forest groups further to the east and north.
Pines may be abundant or even dominant in some examples, including Pinus echinata, Pinus palustris (rarely), Pinus taeda, and Pinus virginiana. The shrub layer of these pine-dominated examples may be well-developed, with Gaylussacia baccata, Vaccinium arboreum, Vaccinium pallidum, Vaccinium stamineum, or other acid-tolerant species being most characteristic. In more open stands, the understory is characterized by Andropogon gerardii, Schizachyrium scoparium, and other prairie graminoid elements. Herbs are usually sparse but may include Pityopsis graminifolia and Tephrosia virginiana. Fire-intolerant species such as Acer rubrum, Liquidambar styraciflua, Liriodendron tulipifera, and Nyssa sylvatica may be common in examples that lack recent fires.
In the West Gulf Coastal Plain, examples are dominated by Pinus taeda and/or Pinus echinata in combination with a suite of dry- to dry-mesic-site hardwoods, including Quercus alba, Quercus falcata, and Quercus stellata, and the scrub oaks Quercus incana, Quercus margarettae, and Quercus arkansana. This is the dominant upland vegetation of the West Gulf Coastal Plain, with an extension into central Texas, locally known as the "Bastrop Pines."
In the western part of the range, examples are dominated by short, stunted Quercus stellata and/or Quercus marilandica with Carya texana. These patches of forest and woodland are often interspersed with patches of tall- and midgrass prairie. Other component species may include Carya cordiformis, Quercus fusiformis, Quercus prinoides, Ulmus alata, and Ulmus crassifolia within their respective ranges. Small trees or shrubs such as Callicarpa americana, Ilex decidua, Ilex vomitoria, Juniperus ashei, Juniperus virginiana, Prosopis glandulosa, Rhus spp., Sideroxylon lanuginosum, Smilax spp., Symphoricarpos orbiculatus. Toxicodendron radicans, and Vaccinium arboreum may be present. The ground layer often contains species typical of the surrounding prairies, in particular Schizachyrium scoparium, but also including Andropogon gerardii, Bothriochloa laguroides ssp. torreyana, Paspalum plicatulum (to the south), Sorghastrum nutans, and Sporobolus cryptandrus.
On limestone-derived soils, various combinations of oaks, including Quercus muehlenbergii, Quercus pagoda, and Quercus shumardii, are dominant or may codominate with Acer saccharum, Celtis spp., Cercis canadensis, Cotinus obovatus, Fraxinus americana, Fraxinus quadrangulata, Juniperus virginiana, and Ulmus alata. Shrub and herb layer species vary considerably, depending on aspect, canopy closure, soils, and moisture relations.
Dynamics: Wind effects, drought, lightning, and occasional fires can influence the physiognomy and composition of stands of this vegetation. In successional examples of ~Piedmont-Central Atlantic Coastal Plain Oak Forest Group (G165)$$, Pinus spp. (e.g., Pinus echinata, Pinus taeda) may be present to dominant in stands for a number of decades (Oosting 1942), with Quercus spp. and Carya spp. gradually invading the understory and then entering the canopy. In some areas, fire-intolerant species such as Acer spp., Fagus grandifolia, Ilex opaca, Liquidambar styraciflua, Liriodendron tulipifera, and Nyssa sylvatica are invading the understories of older stands on dry-mesic, acidic sites. When natural fires were more frequent, the forests presumably had less understory and shrub density and probably a grassy herb layer. Fire was probably once the most important natural dynamic process, but the almost universal elimination of fire in the Piedmont makes this difficult to tell. The xeric nature of sites with clay hardpans may have allowed fire to create open vegetation there while allowing forests to develop on more typical soils. Fire would have kept canopies open by limiting or slowing tree regeneration and would have promoted a more diverse, grass-dominated herb layer. Bison may have once been a significant influence in the pre-settlement and historic landscape as well.
On circumneutral sites, Carya spp. and Fraxinus americana often dominate the understory. There is a current tendency for Quercus-dominated stands to become invaded by more mesophytic and/or fire-intolerant tree species. Oak recruitment is decreasing or virtually absent in many of these forests, particularly the dry-mesic ones. This may be a result of the lengthening of fire-return times during the latter part of the twentieth century. In stands of ~Shortleaf Pine - Oak Forest & Woodland Group (G012)$$, fire is clearly an important influence and may be the sole factor determining the relative dominance of pines versus hardwoods under natural conditions. An extensive hardwood component may partly be the result of lack of fire. Fires probably were frequent and of low intensity, or a mix of low and higher intensity. Pinus echinata is fairly resilient to fire once mature, while Pinus virginiana individuals are fairly susceptible to fire but well-adapted to establishing in areas opened by intense fire. Pinus echinata is a shade-intolerant species and does not survive or grow well without fire. Dendroctonus frontalis (southern pine beetle) outbreaks are an important factor in examples of this group, at least under present conditions. These beetle outbreaks can kill all the pines without creating the conditions for the pines to regenerate. Under current conditions, the understories are typically shrub- and small tree-dominated, with the typical species varying with aspect, soil, and moisture relations. More open and grass-dominated understories may have been more prevalent prior to the mid-twentieth century, when open grazing and surface fires were more common.
In examples of ~Cross Timbers & East-Central Texas Plains Oak Forest & Woodland Group (G017)$$, drought, grazing, and fire are the primary natural processes. Overgrazing, lack of fire, and conversion to improved pasture or other agricultural uses have led to increased woody cover on most extant occurrences of this group and the invasion of some areas by problematic brush species such as Juniperus virginiana var. virginiana and Prosopis glandulosa within their respective ranges. These factors have also led to decreases in native grass cover allowing for annual grasses and forbs to invade.
Environmental Description: This is the matrix vegetation over much of its range, and occurs on ridges and gentle to moderately steep slopes. Soils are typically moderately to well-drained and more fertile than those associated with oak woodlands. This group encompasses a variety of associations ranging along a moisture gradient from submesic to dry. The submesic to dry-mesic expressions tend to be found on midslopes with northerly to easterly aspects; the dry expressions are found on southerly to westerly aspects and on broad ridges. Parent material can range from calcareous to acidic with very shallow, well- to excessively well-drained soils in the drier expressions and moderately well-drained soils in the submesic to dry-mesic ones.
Examples of ~Shortleaf Pine - Oak Forest & Woodland Group (G012)$$ can occur on a variety of topographic and landscape positions, including ridgetops, upper and midslopes, as well as lower elevations (generally below 700 m [2300 feet]) in the Southern Appalachians such as mountain valleys, as well as on rolling uplands in the Upper East Gulf Coastal Plain. Examples occur on a variety of acidic soils or bedrock types. In the Ozark Highlands, this group was historically prominent only in the southeastern part, where sandstone-derived soils were common (USFS 1999), being limited in other areas by inadequate winter precipitation and non-conducive soils. In contrast, pine was "virtually ubiquitous in the historical forests of the Ouachitas" (USFS 1999). Wide variation in vegetation composition across this gradient is also strongly related to fire frequency and intensity (White and Lloyd 1998).
Examples of ~Chinquapin Oak - Shumard Oak - Blue Ash Alkaline Forest Group (G601)$$ are associated with dry calcareous substrates such as limestone and dolomite. They occur on a variety of topographic and landscape positions, including ridgetops and upper and midslopes, or very rarely on the Atlantic Coastal Plain where erosion has exposed Tertiary-aged shell deposits or limesands. The soil moisture regime is dry to dry-mesic.
~Cross Timbers & East-Central Texas Plains Oak Forest & Woodland Group (G017)$$ is located where the forests of the eastern U.S. transition into grasslands of the central U.S. Rainfall can be moderate, generally ranging from 66 to 110 cm (26-43 inches) per year and is somewhat erratic, therefore moisture is often limiting during part of the growing season. Its habitat consists of irregular plains and rugged scarps with primarily sandy to loamy soils that range from shallow to moderately deep.
~Western Gulf Coastal Plain Pine - Oak Forest & Woodland Group (G013)$$ contain mixed evergreen-deciduous forests that are dominated by Pinus taeda and/or Pinus echinata in combination with a suite of dry- to dry-mesic-site hardwoods, including Quercus alba, Quercus falcata, and Quercus stellata, and the scrub oaks Quercus incana, Quercus margarettae, and Quercus arkansana. Examples are primarily found in the west gulf coastal plain of Arkansas, Louisiana and Texas.
Geographic Range: This vegetation is found over most of the southeastern United States, in of the coastal plains and adjacent interior regions, from the Piedmont and adjacent Atlantic Coastal Plain from Maryland to Alabama; the lower elevations of the Appalachians, westward through the unglaciated Interior Low Plateau (with northern limits in extreme southeastern Ohio, southern Indiana, and southern Illinois), and the Ozarks and Ouachitas of Arkansas, Missouri, southeastern Kansas and Oklahoma, and southward into Virginia, the Carolinas and the East Gulf Coastal Plain from Georgia to Mississippi, the West Gulf Coastal Plain and the Inner Coastal Plain of Texas.
States/Provinces: AL, AR, FL?, GA, IA?, IL, IN, KS, KY, LA, MD, MO, MS, NC, OH, OK, SC, TN, TX, VA
|US Forest Service Ecoregions (2007)|
Southeastern Mixed Forest Province
Confident or certain
White and Black River Alluvial Plains Section
Confident or certain
Confidence Level: Moderate
Confidence Level Comments:
Synonomy: < Chinquapin Oak - Ash - Red-cedar Forest Group (Faber-Langendoen and Menard 2006) [This group includes forests further west in which Juniperus ashei is characteristic.]
< Deciduous Forest (Greller 1988) [This concept is much broader, covering deciduous forests of the entire eastern United States.]
< Deciduous Forest (Delcourt and Delcourt 2000) [This concept is much broader, covering deciduous forests of the entire eastern United States.]
>< Deciduous Forest Formation: Western Mesophytic Forest Region, Oak-Hickory Forest Region, Oak-Chestnut Forest Region, Oak-Pine Forest Region (Braun 1950) [The concept of this macrogroup is generally a combination of the dominant forest vegetation of several of Braun's forest regions: the Western Mesophytic Forest Region, the Oak-Hickory Forest Region, the Oak-Chestnut Forest Region, and the Oak-Pine Forest]
= Dry Oak-Hickory Forest (Schafale and Weakley 1990) [includes both their Coastal Plain and Piedmont manifestations.]
= Dry-Mesic Oak-Hickory Forest (Schafale and Weakley 1990) [includes both their Coastal Plain and Piedmont manifestations.]
>< Küchler 101 (oak-hickory pine; primarily the noncoastal plain and east of the Mississippi part) (Küchler 1985) [The unglaciated part of Küchler 91 (oak-hickory forest) and primarily the non-coastal plain and east of the Mississippi part of 101 (oak-hickory pine).]
>< Küchler 91 (oak-hickory forest; the unglaciated part) (Küchler 1985) [The unglaciated part of Küchler 91 (oak-hickory forest) and primarily the non-coastal plain and east of the Mississippi part of 101 (oak-hickory pine).]
> Loblolly Pine-Southern Red Oak/Callicarpa Loamy Mesic Lower Slopes and Terraces Landtype Phase (Turner et al. 1999)
? Mid Slope Oak Pine Forest (Marks and Harcombe 1981)
> Mixed Hardwood - Loblolly Forest (Martin and Smith 1991)
> Mixed Hardwood - Loblolly Forest (Martin and Smith 1993)
> Oak - hickory savanna (Bruner 1931)
= Oak-Hickory Forest (Bennett and Nelson 1991)
>< Oak-Hickory Forest Region, Southern Division Forest Prairie Transition (Braun 1950) [Conceptually, Braun's types are vegetation regions, but the forested part of the region corresponds very closely to the group (G017) concept described here.]
> Oak-Hickory-Pine Forest Region (Küchler 1964) [This concept covers the Piedmont and Upper Coastal Plain only.]
>< Oak-Hickory-Pine Forests (Skeen et al. 1993) [This concept covers the Piedmont and Upper Coastal Plain only.]
> Osage Savanna (Blair and Hubbell 1938)
? Piedmont Flatwoods (Wharton 1978)
> Shortleaf Pine - Oak: 76 (Eyre 1980)
> Shortleaf Pine / Oak - Hickory Forest (Martin and Smith 1993)
> Shortleaf Pine / Oak - Hickory Forest (Martin and Smith 1991)
> Shortleaf Pine-(Longleaf Pine)-Post Oak/Callicarpa-Chasmanthium Loamy Dry-Mesic Uplands Landtype Phase (Turner et al. 1999)
> Shortleaf Pine-Post Oak/Chasmanthium Clayey Dry-Mesic Uplands Landtype Phase (Turner et al. 1999)
> Shortleaf Pine-Post Oak/Chasmanthium Clayey Uplands Landtype Phase (Turner et al. 1999)
> Shortleaf Pine-White Oak/Callicarpa-Chasmanthium Sandy/Loamy Dry-Mesic Uplands Landtype Phase (Turner et al. 1999)
> White Oak-Loblolly Pine/Callicarpa Loamy Mesic Lower Slopes and Terraces Landtype Phase (Turner et al. 1999)
> White Oak-Loblolly Pine/Callicarpa Loamy/Sandy Mesic Lower Slopes and Terraces Landtype Phase (Turner et al. 1999)
> White Oak-Loblolly Pine/Callicarpa Loamy/Sandy Mesic Slopes Landtype Phase (Turner et al. 1999)
Concept Author(s): E.L. Braun (1950)
Author of Description: M. Pyne
Acknowledgements: We have incorporated significant descriptive information previously compiled by J. Teague, D. Faber-Langendoen, and A.S. Weakley.
Version Date: 25Nov2014
- Bennett, S. H., and J. B. Nelson. 1991. Distribution and status of Carolina bays in South Carolina. South Carolina Wildlife and Marine Resources Department, Nongame and Heritage Trust Section, Columbia. 88 pp.
- Blair, W. F., and T. H. Hubbell. 1938. The biotic districts of Oklahoma. The American Midland Naturalist 20:425-454.
- Braun, E. L. 1950. Deciduous forests of eastern North America. Hafner Press, New York. 596 pp.
- Brender, E. V. 1974. Impact of past land use on the lower Piedmont forest. Journal of Forestry 72:34-36.
- Bruner, W. E. 1931. The vegetation of Oklahoma. Ecological Monographs 1:99-188.
- Campbell, J. J. N. 1989b. Historical evidence of presettlement forest composition in the Inner Bluegrass of Kentucky. Pages 231-246 in: G. Rink and C. A. Budelsky, editors. Proceedings of the Seventh Central Hardwood Forest Conference, Southern Illinois University, Carbondale.
- Campbell, J. J. N. 1996. Classification of forest, soil and land types on Daniel Boone National Forest. Technical report to Daniel Boone National Forest. The Nature Conservancy, Kentucky Chapter, Lexington, KY.
- Campbell, J. J. N., and T. Simmons. 1999. Fire management plan for Mammoth Cave National Park. The Nature Conservancy, Kentucky Chapter, Lexington, KY.
- Campbell, J. J. N., and W. Meijer. 1989. The flora and vegetation of Jessamine Gorge, Jessamine County, Kentucky: A remarkable concentration of rare species in the Bluegrass region. Transactions of the Kentucky Academy of Science 50:27-45.
- Campbell, J. J. N., and W. R. Seymour. 2011a. A review of native vegetation types in the Black Belt of Mississippi and Alabama, with suggested relationships to the catenas of soil series. Journal of the Mississippi Academy of Sciences 56(2-3):166-184.
- Clark, G. T. 1974. A preliminary ecological study of Crowley's Ridge. Pages 213-241 in: Arkansas Department of Planning. Arkansas natural area plan. Arkansas Department of Planning. Little Rock. 248 pp.
- Crites, G. D., and E. E. C. Clebsch. 1986. Woody vegetation in the inner Nashville Basin: An example from the Cheek Bend area of the central Duck River valley. ASB Bulletin 33:167-177.
- Dale, E. E., Jr., and S. Ware. 1999. Analysis of oak-hickory-pine forests of Hot Springs National Park in the Ouachita Mountains, Arkansas. Castanea 64(2):163-174.
- Delcourt, H. R., and P. A. Delcourt. 2000. Eastern deciduous forests. Pages 357-395 in: Barbour, M. G., and W. D. Billings, editors. North American terrestrial vegetation. Second edition. Cambridge University Press, New York. 434 pp.
- Dyksterhuis, E. J. 1948. The vegetation of the Western Cross Timbers. Ecological Monographs 18:325-376.
- EPA [Environmental Protection Agency]. 2004. Level III and IV Ecoregions of EPA Region 4. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, Corvallis, OR. Scale 1:2,000,000.
- Eyre, F. H., editor. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.
- Faber-Langendoen, D., and S. Menard. 2006. A key to eastern forests of the United States: Macrogroups, groups, and alliances. September 15, 2006. NatureServe, Arlington, VA.
- Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
- Farrell, J. D., and S. Ware. 1991. Edaphic factors and forest vegetation in the Piedmont of Virginia. Bulletin of the Torrey Botanical Club 118:161-169.
- Fenneman, N. M. 1938. Physiography of eastern United States. McGraw-Hill Book Company, New York. 714 pp.
- Ferguson, E. R. 1958. Age of rough (ground cover) affects shortleaf pine establishment and survival. Journal of Forestry 56:422-423.
- Fleming, G. P. 2001a. Community types of Coastal Plain calcareous ravines in Virginia. Preliminary analysis and classification. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond, VA. 4 pp.
- Garren, K. H. 1943. Effects of fire on vegetation of the southeastern United States. Botanical Review 9:617-654.
- Greller, A. M. 1988. Deciduous forest. Pages 288-316 in: M. G. Barbour and W. D. Billings, editors. North American terrestrial vegetation. Cambridge University Press, New York.
- Greller, A. M. 1989. Correlation of warmth and temperateness with the distributional limits of zonal forests in eastern North America. Bulletin of the Torrey Botanical Club 116:145-163.
- Griffith, G. E., S. A. Bryce, J. M. Omernik, J. A. Comstock, A. C. Rogers, B. Harrison, S. L. Hatch, and D. Bezanson. 2004. Ecoregions of Texas (two-sided color poster with map, descriptive text, summary tables, and photographs). U.S. Geological Survey, Reston, VA. Scale 1:2,500,000.
- Harper, R. M. 1920b. Resources of southern Alabama: A statistical guide for investors and settlers, with an exposition of some of the general principles of economic geography. Geological Survey of Alabama. Special Report No. 11. University of Alabama. 151 pp.
- Harper, R. M. 1943. Forests of Alabama. Geological Survey of Alabama Monograph 10. University of Alabama. 230 pp.
- Harrod, J. C., and R. D. White. 1999. Age structure and radial growth in xeric pine-oak forests in western Great Smoky Mountains National Park. Journal of the Torrey Botanical Society 126(2):139-146.
- Hoagland, B. 2000. The vegetation of Oklahoma: A classification for landscape mapping and conservation planning. The Southwestern Naturalist 45(4):385-420.
- Keever, C. 1971. A study of the mixed mesophytic, western mesophytic, and oak chestnut regions of the eastern deciduous forest, including a review of the vegetation and sites recommended as potential natural landmarks. National Park Service. 340 pp.
- Küchler, A. W. 1964. Potential natural vegetation of the conterminous United States. American Geographic Society Special Publication 36. New York, NY. 116 pp.
- Küchler, A. W. 1985. Potential natural vegetation: Reston, Virginia. National atlas of the United States of America, U.S. Department of the Interior, U.S. Geological Survey.
- MacRoberts, B. R., M. H. MacRoberts, and J. C. Cathey. 2002b. Floristics of xeric sandylands in the Post Oak Savanna region of east Texas. Sida 20(1):373-386.
- MacRoberts, M. H., and B. R. MacRoberts. 2004. The Post Oak Savanna ecoregion: A floristic assessment of its uniqueness. Sida 21(1):399-407.
- Marks, P. L., and P. A. Harcombe. 1981. Forest vegetation of the Big Thicket, southeast Texas. Ecological Monographs 51:287-305.
- Martin, D. L., and L. M. Smith. 1991. A survey and description of the natural plant communities of the Kisatchie National Forest, Winn and Kisatchie districts. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA. 372 pp.
- Martin, D. L., and L. M. Smith. 1993. A survey and description of the natural plant communities of the Kisatchie National Forest, Evangeline and Catahoula districts. Louisiana Department of Wildlife and Fisheries, Baton Rouge. 274 pp.
- McBride, J. B. 1933. The vegetation and habitat factors of the Carrizo sands. Ecological Monographs 3:247-297.
- Monk, C. D., D. W. Imm, and R. L. Potter. 1990. Oak forests of eastern North America. Castanea 55(2):77-96.
- NatureServe. 2002. Notes on shortleaf pine ecosystems and restoration efforts in the Southern Appalachians. Report prepared for USDA Forest Service, Cherokee National Forest, Cleveland, TN. 39 pp.
- Nelson, P. 2005. The terrestrial natural communities of Missouri. Third edition. Missouri Natural Areas Committee, Department of Natural Resources and the Department of Conservation, Jefferson City, MO. 550 pp.
- Nelson, T. C. 1957. The original forests of the Georgia Piedmont. Ecology 38:390-397.
- Oosting, H. J. 1942. An ecological analysis of the plant communities of Piedmont, North Carolina. The American Midland Naturalist 28:1-127.
- Ricketts, T. H., E. Dinerstein, D. M. Olson, C. J. Loucks, and W. Eichbaum. 1999. Terrestrial ecoregions of North America: A conservation assessment. Island Press, Washington, DC. 485 pp.
- Schafale, M. P., and A. S. Weakley. 1990. Classification of the natural communities of North Carolina. Third approximation. North Carolina Department of Environment, Health, and Natural Resources, Division of Parks and Recreation, Natural Heritage Program, Raleigh. 325 pp.
- Shantz, H. L., and R. Zon. 1924. The natural vegetation of the United States. Pages 1-29 in: O. E. Baker, compiler. Atlas of American Agriculture, Part 1, Section E. U.S. Department of Agriculture, Government Printing Office, Washington, DC. 29 pp. with map at 1:8,000,000. [Date on map given as 1923.]
- Skeen, J. N., P. D. Doerr, and D. H. Van Lear. 1993. Oak-hickory-pine forests. Pages 1-33 in: W. H. Martin, S. G. Boyce, and A. C. Echternacht, editors. Biodiversity of the Southeastern United States: Upland Terrestrial Communities. John Wiley & Sons, New York. 373 pp.
- Turner, R. L., J. E. Van Kley, L. S. Smith, and R. E. Evans. 1999. Ecological classification system for the national forests and adjacent areas of the West Gulf Coastal Plain. The Nature Conservancy, Nacogdoches, TX. 95 pp. plus appendices.
- USFS [U.S. Forest Service]. 1999. Ozark-Ouachita Highlands assessment: Terrestrial vegetation and wildlife. Report 5 of 5. General Technical Report SRS-35. USDA Forest Service, Southern Research Station, Asheville, NC. 201 pp.
- USGS [U.S. Geological Survey]. 1992. National land cover dataset. U.S. Geological Survey, EROS Data Center, Sioux Falls, SD.
- Ware, S. 1992. Where are all the hickories in the Piedmont oak-hickory forest? Castanea 57:4-12.
- Wharton, C. H. 1978. The natural environments of Georgia. Georgia Department of Natural Resources, Atlanta. 227 pp.
- White, D. L., and F. T. Lloyd. 1998. An old-growth definition for dry and dry-mesic oak-pine forests. General Technical Report SRS-23. USDA Forest Service, Southern Research Station, Asheville, NC. 42 pp.