State 1
Reference State - Upland Oak/Hickory Forest

The reference state for this ecological site is characterized by a closed-canopy hardwood forest dominated by oaks and hickories. In order for this reference state to be maintained, the oak/hickory species must be present in multiple age classes. In most cases red maple, sugar maple and American beech are colonizing the midstory and understory. A species composition shift toward these more mesophytic species is widely recognized throughout the eastern United States (McEwan et al., 2011).

The reference state described here represents a condition dependent on complex, multiple disturbances, some of which are human caused. In order to get oak to succeed and recruit into the next stand, advanced oak regeneration must be present before a major canopy disturbance. Oaks must be able to reach a size that is competitive (through smaller-scale disturbances such as fire or herbicide of midstory, or tree planting with vigorous seedlings or saplings), then there needs to be a canopy disturbance. There may need to be additional disturbances to get rid of competition.

Community 1.1
White oak - pignut hickory

Figure 10. Oak-Hickory state

Figure 11. Canopy cover

Figure 12. Overstory in spring

Figure 13. Overstory in winter

Figure 14. Spring understory

This phase is dominated by oaks and hickories in the overstory currently, but mid-story composition is shifting toward more shade and moisture-loving species. The understory is relatively rich in herbaceous diversity (including vines) but tree regeneration overwhelmingly favors the shade-tolerant species.

For this phase to regenerate back to oak and hickory, numerous complex and site-specific factors may be necessary. These include acorn production, seedling establishment, advanced regeneration from seedlings, and timely release (Brose et al., 2013). Several types of management can be employed to this end including prescribed fire, mechanical and chemical competition control, site preparation, and planting. However, depending on the stand and its history, management for oak/hickory is typically intensive and often requires multiple treatments over time (~10 - 25 years), (Loftis, 2004).

Without intensive management, in most cases, stands will naturally succeed to a more mesophytic forest type dominated by shade tolerant species (the maples and American beech). Dendroecology studies in nearby, very similar old-growth forest stands indicate that oak species have dominated stands for the past 300 years. They speculate that the recent proliferation of maples in the understory will inhibit regeneration of oak and pine under the current disturbance regime (Hart et al., 2012). Oak and hickory can regenerate in canopy gaps formed by uprooted trees, but only on very dry sites, indicating that gap-phase dynamics will favor maple overall (Hart and Kupfer, 2011).

The American chestnut was an important part of this ecological site prior to decimation by the chestnut blight, but it is unclear how abundant it would have been. Colloquial estimates based on local names like "Chestnut Ridge" indicate that it may have been prolific. Sprouts from old chestnut stumps were noted often during field sampling. Sprouts rarely survive to flowering age, but can often reach as much as 8 inches diameter at breast height (DBH) before they succumb to the blight. Rarely, an American chestnut sprout will reach larger size classes and survive to flower.

Forest overstory.The overstory of this community is dominated by oak and hickory species, most commonly white oak and pignut hickory. Other species include tuliptree, black oak, northern red oak, chestnut oak, blackjack oak, shagbark hickory (Carya carolinae-septentrionalis), mockernut hickory (Carya alba), scarlet oak (Quercus coccinea) and blackgum (Nyssa sylvatica), among others. <br /> <br /> Midstory species include sourwood (Oxydendrum arboreum), sassafras (Sassafras albidum), eastern redbud (Cercis canadensis), flowering dogwood (Cornus florida), Carolina buckthorn (Frangula caroliniana), and common serviceberry (Amelanchier arborea). Shade tolerant hardwoods are a natural part of the dynamic of this ecological site, but have become more dominant in the midstory of most stands than they might naturally be due to lack of disturbance over time. Shade tolerant species include American beech, sugar maple and red maple.<br /> <br /> Please note that species are reported by height class. Some species occur in multiple height classes, and accordingly, have multiple entries.

Forest understory. Herbaceous diversity is high overall, but not as high as in other associated ecological sites (not yet described). Occurrence and abundance vary based on topography and are lowest on ridges and south-facing shoulders and side slopes and highest on lower north-facing side slopes. Commonly occurring species include feathery false lily of the valley (Maianthemum racemosum), littlebrownjug (Hexastylis arifolia), mayapple (Podophyllum peltatum), cutleaf toothwort (Cardamine concatenata), the bellworts (Uvularia spp.), American cancer root (Conopholis americana), trefoil (Desmodium spp.), jack in the pulpit (Arisaema triphyllum), sweet cicely (Osmorhiza spp.), trailing arbutus (Epigaea repens), the violets (Viola spp.), wood sorrel (Oxalis montana), black cohosh (Actaea racemosa), forest licorice bedstraw (Calium circaezans), and yellow wakerobin (Trillium luteum). <br /> <br /> Native vines are important in this ecological site; although, it is unclear how much disturbance plays a role in their abundance. Poison ivy (Toxicodendron radicans), for example, tends to do better in disturbed areas and can often be an indication of a past disturbance, such as grazing, if found in proliferation. Other important vines include greenbriar (Smilax spp.), muscadine (Vitis rotundifolia), Virginia creeper (Parthenocissus quinquefolia), and crossvine (Bignonia capreolata).

Community 1.2
Maple species - American beech

Figure 15. Maple midstory

Figure 16. Maple regeneration

Figure 17. Gap dynamics

This community phase has not yet been attained in most cases because forests currently dominated by oaks and hickories are in transition. Without management or large-scale disturbance, stands will naturally succeed to more mesophytic species composition in the overstory and the oaks and hickories will lose their dominance over time. Small-scale gap dynamics caused by tree throws would likely be a natural part of this state and would favor the maple component in forest stands (Hart et al. 2012).

A recent study of red maple on the nearby Cumberland Plateau found that canopy accession strategy and climate-growth relationships are critical factors in the shift from state 1.1 to state 1.2 (Hart et al., 2012). Red maples are gap-opportunists and can take advantage of smaller-scale disturbances such as tree-throws. Oaks in contrast, seem to have needed high frequency, intense disturbances to establish their current dominance in the forest.

Red maples do best in times of cool, wet springs preceded by wet autumns and warm winters (Hart et al. 2012). Depending on climate conditions in the coming years, the weather may or may not favor their continued establishment. Red maple might also cause local environmental changes that facilitate perpetuation of favorable conditions for regeneration such as modification of understory light levels and soil characteristics (Nowacki and Abrams 2008). The denser canopies might reduce understory temperature and increase relative humidity, which would also favor the more shade-tolerant, moisture loving state (Alexander and Arthur 2010).

Prescribed fire has been suggested as a management tool to reverse the trend. While it may be a useful tool in some cases and most likely in combination with other management approaches, using fire alone is unlikely to produce the desired results in most stands (Clark and Schweitzer 2013).

Forest overstory.The forest overstory is dominated by mature maples and American beech. Tree throws create small-scale gap dynamics in the forest, which favor recruitment of the maples and in some cases, yellow poplar. Oaks and hickories will always be a part of the species composition in this state, but will not be dominant.

Forest understory. Forest understory composition will be similar to community phase 1.1, dominated by native herbs, forbs, and vines. Shade tolerant trees will be present in the regeneration. Spring ephemeral wildflowers will be prolific in places.

Pathway 1.1A
Community 1.1 to 1.2

White oak - pignut hickory

Maple species - American beech

Time (typically >100 years) with little or no large-scale disturbance will favor shade tolerant, late successional species including sugar maple, red maple and American beech.

Pathway 1.2A
Community 1.2 to 1.1

Maple species - American beech

White oak - pignut hickory

Establishment of advanced oak regeneration (natural or planted) is critical to recruiting oak back into the overstory. If that is desirable, a combination of natural and managed steps will likely be required to favor oak. Depending on the residual stand, management recommendations might include timber stand improvement, mechanical or chemical treatment of unwanted species, and prescribed fire. Consultation with a professional forester is recommended prior to implementation of any management practice, especially the use of prescribed fire. Arthur et al. (2012) discusses conditions when fire should and should not be used in oak management.

State 2
High-graded Forest State

Forests in the high graded state have been logged using diameter-limit cut methods multiple times in most cases. This results in a stand with undesirable species composition, low vigor, and poor health. The genetic quality of the forest has been depleted due to the best trees being taken out over time.

While oak and hickory species are often still present in this state, individual trees are often "wolfy" and defective. These are the trees that would have been undesirable from a timber perspective and so left after multiple entries of logging. Notably, hickory has often been left because sawmills historically did not have the capability to process them.

Community 2.1
American beech - Sugar maple/Sourwood - Sassafras

Figure 18. High graded forest

Figure 19. Mid-story

Figure 20. High graded forest in the fall

Canopies in the high graded state are generally thick enough to prevent adequate oak regeneration; more shade tolerant species such as red maple, sugar maple and American beech will predominate. Oak and hickory species that remain are typically of low genetic quality in terms of timber. Stands that have been high graded multiple times often show a conspicuous lack of white oak and northern red oak.

Forest overstory.The overstory is dominated by American beech, sugar maple, and red maple. Tuliptree and red and white oak species can be present but individuals are typically not high quality and do not represent the genetic potential of the stand, nor will they occur in large numbers. Blackgum, sourwood, sassafras, and dogwood can be important midstory species in addition to smaller maples and American beech.

Forest understory. The understory can be diverse across stands. Species noted include buckeye (Aesculus spp.), Virginia creeper (Parthenocissus quinquefolia), greenbrier (Smilax glauca, Smilax rotundifolia), grapevine (Vitis spp.), ebony spleenwort (Asplenium platyneuron), little brown jug (Hexastylis ruthii), nakedflower ticktrefoil (Desmodium nudiflorum), fragrant bedstraw (Galium triflorum), Christmas fern (Polystichum acrostichoides), etc. Forest understories will also include large numbers of regenerating tree seedlings, largely representing the overstory dominants.

State 3
Post Large-scale Disturbance Forest State

Stand initiating disturbances such as a clearcut result in a young, regenerating, even-aged forest stand.

Community 3.1
Tuliptree-red maple/sumac-sassafas/American burnweed-blackberry

Figure 21. Tornado damage

Figure 22. Tornado swath

Figure 23. Small clearcut (recent)

Figure 24. Tuliptree stump sprout

Figure 25. Litter and downed wood

Figure 26. American burnweed, 18 months post tornado

Early after a stand-initiating disturbance, dense stands of Erechtites hieraciifolius (American burnweed) can become established and are a natural part of succession on this site. Blackberry and sumac also occur early in succession and will naturally give way to hardwoods over time.

Species composition of canopy trees in young stands varies, but generally includes abundant tuliptree (McGrath and Clatterbuck, 2013). If the maples are not controlled with herbicide in the early stages of stand development, they may also be prevalent in the canopy.

Other woody species include sassafras, redbud, flowering dogwood, white ash, sourwood, black gum, and Carolina buckthorn, among others. Oak species will generally regenerate by sprouting. White oak can live for long periods as an overtopped tree. It responds to quick release and so can eventually recover its dominant position in the stand canopy. Other advanced-succession species, which will become important in older stands include most of the other upland oaks, blackgum, red maple, and American beech.

Maple and beech are natural components of upland mixed hardwoods. However, if they are not controlled in the early stages of stand development, oaks will have difficulty competing in stands that were severely high-graded. If natural regeneration does not produce enough oaks, artificial regeneration (i.e., planting) may be needed.

Forest overstory.Depending on the successional stage and the stand composition prior to disturbance, yellow poplar will dominate young stands giving way to mixed hardwoods over time. In disturbances where some standing trees remain, such as a typical tornado swath, they will influence the future composition of the stand.

Forest understory. Dense American burnweed can dominate this site early after a disturbance. Pokeberry, poison ivy, muscadine, sumac species, and blackberry are also important in this very early successional stage. Over time, shrub and tree seedlings and sprouts will become more important, eventually pushing into the overstory and assuming dominance of the site.

State 4
Grazed Forest State

This state represents a condition resulting from uncontrolled access to a forest by livestock and is not meant to address plant community changes as a result of prescribed grazing, which can be quite different.

Community 4.1
White oak-sweetgum/Eastern red cedar/blackberry-broomsedge

Figure 27. Grazed forest state

Figure 28. Eastern red cedar and privet in the mid-story

Figure 29. Broomsedge, greenbriar and blackberry understory

Grazing in forested stands results in a reduction of native ground cover plants (Johnson, 1952). Cattle will selectively graze on the plants they find most palatable. Often they leave little in the understory. Plants they avoid include greenbriar, blackberry, broomsedge (Andropogon virginicus), the privets (Ligustrum spp.), Eastern red cedar (Juniperus virginiana), and Christmas fern. Additionally, livestock find seedlings and saplings of the more valuable timber species (such as the oaks) more palatable and lower quality trees will proliferate as a result (SCS, 1992). Eastern red cedar can become invasive in grazed forest stands because cattle do not eat it. Over time, this can result in an overstory dominated by the trees that were present prior to grazing, usually including oaks, hickories, sweetgum, black cherry, tuliptree, and American beech (among others) with an Eastern red cedar (and sometimes privet) dominated midstory and very little understory. Over time if cattle are not removed overstory trees will not regenerate, which will negatively impact the future stand.

Depending on the concentration of animals and frequency of grazing, trampling can expose soil which may result in erosion. Storm runoff may increase (Johnson, 1952). Compaction of the soil surface can damage the fine surface feeder tree roots. Invasive exotic plants like Japanese honeysuckle and multiflora rose are known to follow grazing disturbance into woodlands once grazers are removed. Exotic plants including the privets, honeysuckle, and multiflora rose are a problem and will persist and expand if not controlled.

Forest overstory.Overstory canopies will consist of whatever tree species were present prior to grazing. Typically white oak, scarlet oak, black oak, tuliptree, American beech, sweetgum, honeylocust, black cherry and hickory species will be present, among others.

Forest understory. Understories in this state are not diverse because most plants (including tree seedlings) are being consumed by grazing animals. Depending on the animal (cattle, goats, sheep, etc.), there is selection for the species they do not prefer to eat. Blackberry, greenbriar, broomsedge, Christmas fern, Eastern red cedar and privet are typical.

State 5
Post Agricultural Abandonment Forest State

This state results from natural succession to forest after abandonment of agricultural fields. The resulting forest will vary depending on the amount of time the land was in cultivation, the type of agricultural practice that was used (e.g., row crops, pasture, type of crop, etc.), and the degree of impact to the soil.

In Georgia, parts of this state have been converted to loblolly pine (Pinus taeda) plantations, but that acreage is of relatively small extent and so it is not included as a community phase.

Community 5.1
Pine spp. - tuliptree/poison ivy

Figure 30. Young pine stand

Figure 31. Older mixed pine-hardwood stand 1 in Georgia

Figure 32. Older mixed pine-hardwood stand 2 in Georgia

Figure 33. Older mixed pine-hardwoods in Tennessee

Pine species will often be first to colonize old fields and will dominate the first overstory of trees (Dale, 1990). In most of Tennessee, Virginia and shortleaf pines (Pinus echinata) are the dominant species. Further south in the major land resource area, loblolly pine becomes an important component of this state. Tuliptree is a commonly noted cohort in this state. Sweetgum (Liquidambar styraciflua) has been noted to increase toward the southern extent of this ecological site.

Typically, over the course of time pines will naturally fall out as hardwoods move in, creating oak/pine dominated stands. Southern pine beetle (Dendroctonus frontalis) outbreaks can cause a stand-initiating disturbance in some cases, where aging pine stands are overstocked. This phase naturally succeeds to mixed hardwoods regardless.

In some cases, old fields have been invaded by exotic plants such as Japanese honeysuckle (Lonicera japonica), multiflora rose (Rosa multiflora), and autumn olive (Elaeagnus umbellata). Depending on the extent of the invasion, exotic plants can impede a stand from naturally succeeding back to the reference community state.

An abundance of poison ivy, a native vine, is often an indication of past disturbance and is commonly found in this phase.

Forest overstory.Overstory species will typically consist of pine species initially. As stands age, hardwoods will become more important. Eventually stands will become dominated by hardwood species, mainly oaks and hickories. Pine species included in this ecological site are Virginia pine, shortleaf pine, and loblolly pine (toward the south). Tuliptree, the maples, and sweetgum are important intermediate hardwoods.

Forest understory. Understory composition varies based on the extent of disturbance and the type of agriculture implemented. Vines often include poison ivy, Japanese honeysuckle, greenbriar, trumpet creeper, and muscadine.

State 6
Cleared Grassland State

This state represents a once-forested area now cleared for pasture. 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 6.1
Orchardgrass - tall fescue

Figure 34. Pasture

Figure 35. Pasture landscape

The dominance of orchardgrass (Dactylis glomerata), red clover (Trifolium pratense), and tall fescue (Schedonorus arundinaceus) 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.

Forest overstory.The overstory in the grassland state is minimal and consists of a few trees growing along the parameter 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.

Community 6.2
Tall fescue - nimblewill

This community phase is transitional to a more degraded phase. While some desirable pasture plants are still present [tall fescue, white clover (Trifolium repens)], undesirable species such as nimblewill (Muhlenbergia schreberi), rush (Carex spp.), cinquefoil (Potentilla spp.), thistle (Cirsium spp.) and little barley (Hordeum pusillum) will begin to proliferate. Heavy grazing pressure may favor weedy species over grass (Rhodes and Phillips, 2012). Just removing or reducing livestock will not always be enough to restore desirable conditions after a point. Some type of nutrient improvement may also be needed.

Community 6.3
Multiflora rose - blackberry spp.

Pastures with a history of overgrazing can be susceptible to invasion by weedy plants, brambles, and small trees if grazing pressure is reduced and nothing further is done to improve the site. Indicator plants for this phase include blackberry, broomsedge, and multi-flora rose. Clipping undesirable plants and adding nutrient input can help pastures in this phase recover. Goats, mowing and herbicide can be useful for clearing unwanted plants.

Pathway 1.1A
Community 6.1 to 6.2

Overstocked pasture with infrequent rotation.

Pathway 2.2B
Community 6.2 to 6.1

Rotational grazing with a longer recovery period and higher grazing height; improved fertility.

Pathway 2.2A
Community 6.2 to 6.3

Overgrazed; low fertility

Pathway 3.3A
Community 6.3 to 6.2

Clipping pasture with nutrient improvement or controlled grazing.

Transition T1A
State 1 to 2

Selective harvesting and high grading multiple times results in degradation of forest stand quality in terms of altered species composition, forest structure, and genetic fitness. Diameter limit cuts, incorrectly implemented, remove the biggest and best trees and leave those of lowest quality in terms of both timber and ecology.

Transition T1B
State 1 to 3

Large-scale, stand replacing disturbance (natural or human-caused) such as a catastrophic fire, tornado, ice storm or management practices such as clearcutting will result in the majority of the overstory being removed. This effectively hits the reset button on natural succession and the stand begins to regenerate. Advanced oak regeneration must be present for oak to be well represented in the next stand. In some cases, competition control will also be necessary.

Transition T1C
State 1 to 4

Uncontrolled access by livestock and subsequent browsing and selective removal of desirable trees can result in loss of hardwood tree species and invasion by invasive, exotic plants. In some cases, soil compaction and erosion can become a problem.

Transition T1D
State 1 to 6

Forest clearing, herbicide application, and establishment of pasture plants, hay or crops will convert forested stands to a grassland state. Most pastures in this site are old and were converted many years ago.

Restoration pathway R2A
State 2 to 3

Stand initiating disturbance such as a silvicultural clearcut, tornado, major ice storm or in rare cases, a really hot wildfire, will effectively push the "reset" button on succession, allowing superior stock to regain dominance in most cases. Disturbance loving species like the oaks will typically respond well to this. However, where seed banks and seed sources are severely depleted, oaks may need to be planted if they are desirable. Fire has varying effects, depending on the intensity of the fire and stand conditions prior to burning. Typically, pine species would initially colonize burned areas before other species.

Restoration pathway R3A
State 3 to 1

Favor desirable species such as the oaks by treating sprouts and seedlings or saplings of undesirable species (i.e., red maple) with herbicide. Multiple herbicide treatments may be merited. Follow-up treatments such as thinning or crop tree release might be needed, depending on management objectives and stand conditions.

Restoration pathway R4A
State 4 to 1

Remove livestock, control weedy species, and conduct site-based forest management over time. In most cases, natural succession will occur if invasive plants, including Eastern red cedar, are controlled. Tree planting with desirable species may often be merited. In most cases, time and natural processes will heal any soil compaction caused by grazing.

Transition T4A
State 4 to 6

Mechanical vegetation control and herbicide application will likely be needed to keep exotic plant species from becoming problematic in newly established pastures. Seeding with desirable species and fertilizing will be necessary to establish pasture conditions. Rotational grazing can be used as a management tool to achieve goals.

Restoration pathway R5B
State 5 to 1

Allowing natural succession to take place over time will most often result in a mixture of oak and pine, which will eventually turn into an oak/hickory mixed stand. In some cases, exotic plant control (mechanical, chemical, etc.) may be merited. Where necessary, oak planting or planting some other desirable species could be beneficial. If planting is done, control of competition through several mechanical and chemical treatments may be necessary for the best results.

Transition T5A
State 5 to 3

When pine naturally colonizes abandoned agricultural land, the result can be establishment of overstocked pine stands (~40 years). These stands are attractive to southern pine beetle, which has naturally occurring outbreaks in the Southeast periodically. Pine beetle kills result in loss of pine in the overstory (Dale 1990) and can be stand replacing in some cases.

Restoration pathway R5A
State 5 to 6

Land clearing, seeding, fertilizing, and prescribed grazing on a site by site basis will help push the phase back to pasture. Control of invasive exotic plant species and poison ivy may be merited. Control methods typically include herbicide application and mechanical control, such as mowing.

Transition T6A
State 6 to 5

Abandonment