State 1
Dry Calcareous Forest and Glade Reference State

The reference community for this ecological state occurs as a mosaic of dry forests, woodlands and small glades across the landscape. Past disturbance, both human caused and naturally occurring, can influence the degree of openness and thereby the distribution of species. In addition, the strike of limestone bedrock often determines where true glades versus forests occur. Where strike is sharp, solution pipes form and deeper soils accumulate, favoring tree growth. Where bedrock is more level, with shallow soils forming, glades and woodlands tend to occur. This is highly variable across the Major Land Resource Area and species can shift temporally due to edaphic conditions from year to year. For example, in periods of drought, forest species retreat, which creates the open conditions that favor grasses and herbs.

Community 1.1
Chinquapin oak – eastern redcedar/redbud – winged elm/resurrection fern

Figure 9. Chinquapin oak covered in resurrection fern

Figure 10. Resurrection fern

Figure 11. Calcareous forest 1

Figure 12. Calcareous forest 2

Figure 13. Bedrock geology under Barfield soil series

This phase of the reference state occurs over soils derived from limestone that typically have a neutral pH and relatively dry conditions. Forests are dominated by calciphiles, including chinquapin oak, Shumard oak, white ash, eastern red cedar, eastern redbud, and many elms and hickories. Shrubs and small trees include fragrant sumac, rusty blackhaw, dwarf hackberry, and Carolina buckthorn. Plant composition will vary according to the pH and level of moisture in the soil as well as soil depth.

These forests typically occur as part of a vegetation mosaic with cedar glades on more level limestone. They can also occur on limestone outcrop at the base of other geologic formations, such as the Rome formation. In Georgia, these communities occur on the lower slopes of the eastern side of Lookout Mountain and Pigeon Mountain and on parts of Lavender Mountain at Berry College (Edwards, Ambrose and Kirkman 2013). The neutral pH and resulting pattern of calciphytic plants are the main factors that differentiate this ecological site from others.

Without disturbance, such as fire, these forests will succeed from oak dominated canopies to more shade tolerant species such as red maple, sugar maple and American beech (Edwards, Ambrose and Kirkman 2013). The presence of oak and pine possibly reflects past disturbances that opened canopies up enough to facilitate their establishment. Gaps were likely an important component of forest dynamics, especially on steeper bluffs or through openings created by fire (W.L. Lipps 1966; Wharton 1978; Pyne 1982; Schuler and McClain 2003 in Edwards, Ambrose and Kirkman 2013).

The variation in the composition of this plant community complicates fire management. Currently, the Georgia Department of Natural Resources recommends fire-return intervals of five - seven years for some plant communities on this ecological site. However, any fire management plan should be developed with professionals on site, based on local conditions. Fires can foster high herbaceous diversity in these communities but can also damage fire-intolerant trees and shrubs that can be important features of the natural system (Edwards, Ambrose and Kirkman 2013).

Forest overstory.The forests occurring on this phase of the ecological site are closed canopy stands distinguished by calcium-loving species in all strata (Edwards, Ambrose and Kirkman 2013). Important overstory trees include chinquapin oak, Shumard oak, white oak, eastern red cedar and numerous hickory species. The ones most commonly noted were shagbark and mockernut hickory. Ashes, especially white ash, are important on this site, as well as slippery elm, winged elm, and the hawthorns. Vines and ferns can be important in this community phase and a common sight is a chinquapin oak or eastern red cedar covered in resurrection fern (pictured above).

Forest understory. Forest understories in this phase tend to be sparse, due to the closed canopy. However, because it favors calciphiles, species composition can be quite different from other ecological sites in the Ridge and Valley. Resurrection fern and purple cliffbrake are common. Typical herbs include Indian pink, hoary puccoon, smallhead blazing star, wild petunia, and trailing lespedeza. Tree and shrub regeneration is well represented in the understory with white ash and sugar maple predominating. Vines can be important, perhaps reflecting past disturbance. Common vines include crossvine, trumpet creeper, common moonseed, and greenbrier. Mosses and lichens can be important components of this site and commonly grow on bedrock outcrops. Depending on the percent of canopy cover, grasses may occur on this phase. Some of the native panic grasses and purpletop tridens are common and can be prolific in places.

Community 1.2
Eastern redcedar – Virginia pine/redbud - fragrant sumac/little bluestem – devil's-tongue

Figure 14. Cedar glade in June

Figure 15. Gravelly surface fragments

Figure 16. Moss and asters in November

Figure 17. Opuntia humifusa blooming in late May

Figure 18. Limestone parent material in winter

The natural forest openings that correspond to glade communities on this ecological site are chiefly scattered in areas underlain by limestone of the Chickamauga group, especially Lenoir limestone (Martin 1989). Stunted cedar and pine and a few shrub species surround an herb-dominated outcrop. Wherever joints in the rock have accumulated soil, woody plants will establish. Climate conditions vary from year to year. Woody plants, especially cedar trees, will do better in years with more precipitation and fall back in hot, dry periods. Vegetation is similar to the cedar glades of middle Tennessee, but pine is a significant component (Martin 1989).

This phase may be considered distinct from other prairie-like areas in that it is chiefly edaphic in nature. The bare rock and shallow soils create moisture and temperature extremes that fluctuate from year to year and season to season, restricting these sites to plant species that have adapted to heat and drought (Edwards, Ambrose and Kirkman 2013). Precipitation differences cause these sites to have radically different appearances from year to year. Correspondingly, these sites can change greatly in appearance with the season. In spring, open glades might be carpeted with wildflowers but when the annuals die, xerophytes such as devil's tongue, false aloe and croton become more conspicuous (Edwards, Ambrose and Kirkman 2013).

Erosion, drought, fire, grazing, frost-heave and shrink-swell soils can all contribute to keeping these systems open (Edwards, Ambrose and Kirkman 2013). The role of fire is not well understood from a management perspective. However, in Georgia, a fire-return interval of 13 - 25 years has been suggested (Frost 1998; NatureServe Ecology South 2008; in Edwards, Ambrose and Kirkman 2013).

Forest overstory.There are very few forest canopy trees in this phase of the reference state but, when present, common species include Virginia pine and eastern red cedar. Occasionally oak species occur, such as chinquapin oak and shumard oak. Trees in this phase are often shrubby and rarely reach their height potential. Shrub and small tree species include redbud, winged elm, persimmon, fragrant sumac and dogwood.

Forest understory. The Natural Communities of Georgia (2013) divides the vegetation into four categories: gravel glades, grassy glades, shrub thickets and glade woodlands, which are all driven by soil depth at very small scales. Understory composition can vary widely, depending on the location within the site. On gravel glades where there is very little soil, lichens, mosses and least glade cress will dominate. In areas with slightly deeper soils, the gravel glades can support other herbs, typically annuals. Grasses can dominate on sites where there is deeper soil, but not deep enough to support shrubs and small trees. Little bluestem is a typical species noted on these areas. <br /> <br /> Some characteristic plants of this phase include hoary puccoon, false aloe, devil's tongue, the ragworts, and the goldenrods.

State 2
Invaded State

Invasive exotic plants are species of plants that have been intentionally or unintentionally introduced into an area outside of their natural range. These plants are rapidly becoming one of the most pressing management issues for land managers. Exotic species can overwhelm native plants by claiming resources such as nutrients, water, light, and space and can ultimately totally displace native species (Tennessee Exotic Pest Plant Council). By modifying or completely altering the vegetation community, exotic plants can significantly threaten native wildlife communities, including insects that act as pollinators for agriculture crops. The effects are cascading and far reaching and can be extremely detrimental to ecosystem health and stability.

Invasion by exotic plants is a significant threat to this ecological site. In the glade phase of the reference state, invasion by the native eastern redcedar due to fire suppression can also be a threat. Prescribed fire and mechanical removal can be useful for creating open conditions conducive to glade plants. For clarification, this state description refers only to invasion by exotic plants.

Exotic plant invasion is particularly problematic on this site for a number of reasons. Most of this site (glades and woodlands) has at one time been grazed by domestic livestock, which both introduced exotic plants into the site and created a disturbance that favored their establishment (Baskin and Baskin 1996; Cofer et al. 2008). Not all grazed sites were entirely cleared for pasture. The degree of disturbance as well as the time since abandonment will determine the extent of invasion. Secondly, the lack of natural disturbances, such as fire, have led to the expansion of invasive exotic plants due to the processes of natural succession. One of the most problematic exotic species on this site is Nepalese browntop, which is extremely tolerant of shade. As open conditions become closed forests, it spreads. Likewise, Chinese privet has invaded both glade and forested phases of this site. Both Nepalese browntop and privet inhibit the use of prescribed fire, complicating restoration efforts.

Two of the protected areas that fall within this ecological site have management plans that describe their issues with exotic plant encroachment into glade/woodland systems. In one, autumn olive, sericea lespedeza, Chinese privet, Amur honeysuckle, Japanese honeysuckle, multiflora rose, crownvetch, Nepalese browntop, and Johnsongrass are listed as threats to their preserve. In another plan, Chinese privet is listed as a significant threat to the natural integrity of the site. Cofer et al. (2008) found that the exotic species Chinese privet, oxeye daisy, and common dandelion occurred on the majority of the glades in their study of 40 cedar glades in Rutherford County, Tennessee.

The occurrence and abundance of exotic plant species on this ecological site will vary based on disturbance history and location. Sites adjacent to roads or disturbed areas are more likely to become invaded. Management plans should be based on local conditions and tailored to the exotic species present. In most cases, if no action is taken to combat invasions, the site will never entirely return to the reference plant community.

Community 2.1
Eastern redcedar/privet/Japanese honeysuckle – Nepalese browntop

Figure 19. Invaded forest

Figure 20. English ivy and Amur honeysuckle

Figure 21. Tree of heaven

Figure 22. Exotic privet

Invasion by exotic plant species is a serious problem on this ecological site. Because of the high pH relative to other sites, and the somewhat fragile nature of plant communities, this site may be more susceptible than others in the Ridge and Valley. This site, especially where bedrock is relatively level, would have been heavily grazed in the past, adding to the potential for invasion. This site does not seem to recover as quickly from negative disturbance. Invaded states may never recover their former plant communities if management intervention is not attempted.

The species listed in this phase represent a typical assemblage on an invaded state. Species composition will vary according to local conditions and past disturbance history. The species list below is a record of all species noted in the field while investigating this phase of the site. No one plot contained all listed species.

Forest overstory.Forest overstories are not typically different from the reference community, except where eastern redcedar has become dominate on glades. Typical species noted in woodlands and forests include eastern redcedar, chinquapin oak, Shumard oak, and post oak. Other oak species can occur as well as the maples and American beech, although this was not noted frequently. Often, disturbance history can be discerned to some extent by the presence of Virginia pine, which is considered a pioneer species.<br /> <br /> Midstory species are also not different from the reference community and include eastern redbud, dwarf hackberry, dogwood, winged elm, and Carolina buckthorn. Notably, mid-story species were less common on highly invaded sites, indicating that their regeneration and establishment potential may be negatively impacted by the presence of invasive exotic plants in the understory. It can be inferred that this also applies to overstory species, given long enough timeframes. Concurrently, grazing animals utilize the mid-story and so would have impacted mid-story species on abandoned sites that were grazed woodlands.

Forest understory. Forest understories are typically highly altered, with invasive exotic species dominating and native species only present in small populations. Species assemblages are altered as well. The presence and abundance of invasive exotic species can be highly variable across the site and is most often an effect of past disturbance history and location.

State 3
Managed Grassland State

This state represents a once-forested area now cleared for pasture. The Official Soil Series description for Barfield states that about 50 percent of the original vegetation has been cleared and that most cleared areas are used for pasture. Pasture may be slightly less common on the other mapped soil series included in this site description. Limestone rock outcrop and bare ground related to rock outcrop is common on this site and is often noted in pastures.

Most pastures are very old and have been established for a long time. Management practices focus primarily on maintaining healthy pasture conditions rather than new pasture establishment, although that is certainly an option. Balancing stocking rates, grazing rotation, and nutrient inputs are the primary management concerns.

In general, pasture management recommendations focus on maximizing desirable forage species to outcompete undesirable or weedy species. Production practices that result in overgrazing and low fertility levels favor emergence, propagation, and growth of weeds (Green et al., 2006). Effective pasture management includes the following practices:

- maintaining proper soil pH and fertility levels

- using controlled grazing practices

- mowing at proper timing and stage of maturity

- allowing new seedlings to become well established before use, and

- renovating pastures when needed (Green et al. 2006).

Tennessee has developed a list of desirable species, intermediate species and undesirable species for use in a Pasture Condition Scoresheet, which can be used to develop management recommendations on a site by site basis. District Conservationists as well as the State Grazing Specialist can be consulted to assist in developing management recommendations.

Perilla (Perilla frutescens) mint is an exotic, invasive weed that has become a major problem in many pastures. It causes more cattle deaths (in Tennessee) than any other toxic plant (Steckel and Rhodes, 2007). Keeping a ready supply of quality feed available for farm animals in the late summer and early fall will help to minimize the risk to livestock. Cattle will not normally feed on perilla unless there is a shortage of other feed.

Community 3.1
Orchardgrass - tall fescue

Figure 23. Typical pasture

The dominance of orchardgrass, red clover and tall fescue in this community phase indicate that nutrient levels are adequate and grazing rotations are long enough to allow pasture plants to recover. Overstocking and infrequent pasture rotation will allow weedier species to invade such as nimblewill and rush. If mowing is infrequent, honey locust and Eastern redcedar will begin to colonize.

Patches of bare ground and rock outcrop are common in pastures on this site.

Forest overstory.The overstory in the grassland state is minimal and consists of a few trees growing along the perimeter of pastures and scattered shade trees within pastures.

Forest understory. Ideally, pastures in the grassland state would be primarily composed of tall fescue, red clover and orchardgrass. Numerous other plants could be present in varying numbers depending on the objectives and management approaches of the landowner.

State 4
Transitional Field State

This is a transitional state representing an important step in the natural succession of this ecological site. In this state, the plant community is moving from a cleared or managed grassland state to a forested state, whether in reference condition or invaded. Typically, the plant community consists of a high number of grasses, both native and introduced. The types and amounts of grasses are largely related to past land-use. If the site was cleared but never grazed by domestic livestock or managed as a pasture, native warm-season grass species would be more common. Obviously, where land was cleared for pasture, species such as tall fescue would be present, along with a higher number of weedy exotics. This state will also contain a high number of native asters, including the goldenrods and the daisies, which can be important to pollinators and wildlife. One plot was on a wildlife management area, which was focused on dove habitat.

Woody species that will begin to encroach include eastern redcedar, honeylocust, winged elm, black walnut (Juglans nigra), and boxelder (Acer negundo). Periodic mowing can keep this state in an open condition. In some areas, rock outcrop will naturally maintain openness. Mowing becomes almost impossible quickly, as honeylocust especially, begins to encroach. If openness is desired, mowing should be done at least once per year, if not more often.

Exotic plant species can become a problem in this state, especially as it transitions over to the invaded state. Because of the openness and relatively short time period since clearance, it is susceptible to a host of non-native plant pests, which can change natural succession pathways and push this state into an invaded state rather than back to the reference community. The type and amount of past disturbance, the degree of interruption of natural disturbance cycles and the surrounding flora will all play a role in which trajectory and to what degree, this state can move. Typical exotic species found in this state include the privets, the exotic lespedezas, Nepalese browntop and the exotic honeysuckles to name a few. In most cases, this state will require some type of exotic plant management if it is to return to the reference plant community.

Community 4.1
Eastern redcedar/honeylocust – winged elm/tall fescue – red clover

Figure 24. Transitional field

Figure 25. Mowed field being colonized by trees

This state is succeeding to forest in most cases. It will have varying degrees of openness based on depth to bedrock and, relatedly, soil depth. Naturally shallow areas will largely remain open while areas with deeper soil will host woody plant species. Typical early colonizers include eastern redcedar, honeylocust and winged elm. Succession happens rapidly on this state and so, if openness is desirable, mowing regimes must occur with regularity and relative frequency.

In many cases, this site will be susceptible to invasion by exotic invasive plant species. If restoration to the reference plant community is desired, exotic plant management will likely be needed. It should be site based and species specific. The reintroduction of natural disturbances such as fire could be beneficial in some cases. However, it has also been known to spread invasive, exotic plants and so should be used with caution.

Forest overstory.This site has none to very little forest overstory but in some cases an individual tree will occur. In that case, species might include eastern redcedar, boxelder (Acer negundo), honeylocust, and black walnut (Juglans nigra).

Forest understory. Forest understories can be variable, depending on the type and degree of past disturbance and the plant composition of the surrounding landscape. If invasive exotics occur all around a site in this state, it will be much more likely to be colonized by problematic species. Concurrently, clearings that represent this state within a larger mosaic of forests and woodlands will be colonized by native pioneer woody species more rapidly and to a greater degree. Typical understory species can include native and exotic grasses, numerous genera in the Asteraceae family, lespedezas, and tree and shrub seedlings.

Transition 1A
State 1 to 2

The reference community can become susceptible to invasion by exotic plants if natural disturbance regimes are hampered, if there is a history of human-caused disturbance such as unrestricted grazing, and/or if a site is located close to an invaded area, such as a roadside. In some cases, eastern redcedar, a native species, can become invasive on glades.

Transition 1B
State 1 to 3

The reference community can be and has been in many cases, transitioned into a managed grassland. This requires typical pasture establishment techniques such as clearing trees, establishing pasture grasses and forbs and continuing management such as fertilizing, rotational grazing, etc.

Transition 1C
State 1 to 4

If an area is cleared of trees and abandoned, natural succession will begin and in a short amount of time, woody species such as eastern redcedar, honeylocust (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=GLTR" target="_blank" title="Open in plants.usda.gov"><i>Gleditsia triacanthos</i></a>) and winged elm will dominate the site, making mowing almost impossible. In some places, these areas are intentionally kept open for wildlife. Mowing schedules should consider the rapid colonization of native woody species. In areas where succession starts from an abandoned pasture, species such as tall fescue and red clover may be present. These areas are particularly susceptible to invasion by exotic plant species.

Restoration pathway 2A
State 2 to 1

For glade areas where eastern redcedar has encroached, some mechanical/chemical clearing may be in order before any use of prescribed fire would be effective. In areas where there is a severe exotic plant invasion in addition to cedar encroachment, prescribed fire should be used with extreme caution. Fire is known to favor exotic plants and a misapplication could result in exacerbating the invasion extent. Management of exotic, invasive plants is critical to restore this state to reference conditions. Most invasions require long-term management over years, involving multiple treatments which can vary by species and extent of invasion. Management should be site based and species specific. Technical resources should be consulted to develop site-based management prescriptions.

Transition 3A
State 3 to 4

The managed grassland state will quickly begin to revert to forest, in most cases, once management and grazing stops. Typically, redcedar and honeylocust will be the first woody invaders and will dominate the site in very little time. Once established, these woody species, especially honeylocust, make it difficult to push this state back to a managed grassland because mowing becomes impossible at a point. Exotic plant species are commonly noted in areas transitioning from a managed grassland state to a different plant community. In some cases, exotic plant management will be needed, depending on management objectives.

Restoration pathway 4B
State 4 to 1

Depending on the degree of ecological degradation present on a site in this state, it can generally be restored back to a reference plant community through natural succession, exotic plant management and mechanical control of undesirable tree species. Encouraging oak regeneration can also help to push this state back into the reference community. In some cases, prescribed fire might be beneficial but care should be taken as it has been known to spread invasive, exotic plants.

Transition 4A
State 4 to 2

This state is likely to transition to the Invaded State if no management is done to control exotic species. Native trees will naturally seed in over time as well.

Restoration pathway 4A
State 4 to 3

This state can be returned to a managed grassland state with appropriate pasture management such as mowing, seeding and fertilizing.