Ecological dynamics
Information contained in this section was developed using historical data, professional experience, field reviews, and scientific studies. The information presented is representative of very complex vegetation communities. Key indicator plants, animals and ecological processes are described to help inform land management decisions. Plant communities will differ across the MLRA because of the naturally occurring variability in weather, soils, and aspect. The Reference Plant Community is not necessarily the management goal. The species lists are representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.
The reference plant community is well developed woodland dominated by an overstory of white oak and black oak. The canopy is moderately tall (60 to 75 feet) but less dense (45 to 85 percent canopy) than protected slopes and the understory is poorly developed with less structural diversity. Increased light causes a diversity of ground flora species to flourish. In addition, proximity to shallow soil glades and open woodlands provides additional opportunity for increased light and species diversity. Woodlands are distinguished from forest, by their relatively open understory, and the presence of sun-loving ground flora species. Characteristic plants in the ground flora can be used to gauge the restoration potential of a stand along with remnant open-grown old-age trees, and tree height growth.
Fire played an important role in the maintenance of Chert Upland Woodlands. It is likely that these ecological sites burned at least once every 5 to 10 years. These periodic fires kept woodlands open, removed the litter, and stimulated the growth and flowering of the grasses and forbs. During fire free intervals, woody understory species increased and the herbaceous understory diminished. The return of fire would open the woodlands up again and stimulate the abundant ground flora.
This ecological site was also subjected to occasional disturbances from wind and ice, as well as grazing by native large herbivores, such as bison, elk, and white-tailed deer. Wind and ice would have periodically opened the canopy up by knocking over trees or breaking substantial branches off canopy trees. Grazing by native herbivores would have effectively kept understory conditions more open, creating conditions more favorable to oak reproduction and sun-loving ground flora species.
Today, these ecological sites have been cleared and converted to pasture or have undergone repeated timber harvest and domestic grazing. Most existing forested ecological sites have a younger (50 to 80 years) canopy layer whose species composition and quality has been altered by timber harvesting practices. In the long term absence of fire, woody species, especially hickory, encroach into these woodlands. Once established, these woody plants can quickly fill the existing understory increasing shade levels with a greatly diminished ground flora. Removal of the younger understory and the application of prescribed fire have proven to be effective restoration means.
Domestic grazing has also impacted these communities, further diminishing the diversity of native plants and introducing species that are tolerant of grazing, such as coralberry, gooseberry, and Virginia creeper. Grazed sites also have a more open understory. In addition, soil compaction and soil erosion can be a problem along with lower site productivity.
Chert Upland Woodlands are moderately productive. Oak regeneration is typically problematic. Sugar maple, red elm, and hickory are often dominant competitors in the understory. Maintenance of the oak component will require disturbances that will encourage more sun adapted species and reduce shading effects. Single tree selection timber harvests are common in this region and often results in removal of the most productive trees (high grading) in the stand leading to poorer quality timber and a shift in species composition away from more valuable oak species. Better planned single tree selection or the creation of group openings can help regenerate and maintain more desirable oak species and increase vigor on the residual trees.
Clearcutting also occurs and results in dense, even-aged stands dominated by oak. This may be most beneficial for existing stands whose composition has been highly altered by past management practices. However, without some thinning of the dense stands and prescribed burning the ground flora diversity can be shaded out and diversity of the stand may suffer.
A state-and-transition model diagram follows. Detailed descriptions of each state, transition, plant community, and pathway follow the model. This model is based on available experimental research, field observations, professional consensus, and interpretations. It is likely to change as knowledge increases.
State 1
Reference
The historical reference state for this ecological site was old growth, oak woodland dominated by white oak and black oak. Periodic disturbances from fire, wind or ice maintained the woodland structure and diverse ground flora species. Long disturbance-free periods allowed an increase in both the density of trees and the abundance of shade tolerant species. Two community phases are recognized in the reference state, with shifts between phases based on disturbance frequency. Reference states are rare today. Many sites have been converted to grassland (State 5). Others have been subject to repeated, high-graded timber harvest coupled with uncontrolled domestic livestock grazing (State 6). Fire suppression has resulted in increased canopy density, which has affected the abundance and diversity of ground flora. Some former reference states have been managed effectively for timber harvests, resulting in either even-age (State 2) or uneven-age (State 3) woodlands.
Community 1.1
White Oak - Black Oak/Fragrant Sumac/Sedge - Little Bluestem
Forest overstory. The Overstory Species list is based on field reconnaissance as well as commonly occurring species listed in Nelson 2010; names and symbols are from USDA PLANTS database.
Forest understory. The Understory Species list is based on field reconnaissance as well as commonly occurring species listed in Nelson 2010; names and symbols are from USDA PLANTS database.
Community 1.2
White Oak - Black Oak/Hickory/Sedge - Little Bluestem
Pathway 1.1A
Community 1.1 to 1.2
This pathway is a gradual transition that results from extended, disturbance-free periods of roughly 50 years or longer.
Pathway 1.2A
Community 1.2 to 1.1
This pathway results from ecological disturbances such as fire, ice storms, or violent wind storms. Historically, native grazers such as bison provided disturbance events as well.
State 2
Even-Age Managed Woodland
This state can start with a sequence of early seral mixed oak woodlands, which mature over time. These woodlands tend to be rather dense, with a depauperate understory and ground flora. Thinning can increase overall tree vigor and improve understory diversity. However, in the absence of fire, the diversity and cover of the ground flora is still diminished. Continual timber management, depending on the practices used, will either maintain this state, or convert the site to uneven-age (State 3) woodlands. Prescribed fire along with a more open canopy and prescribed grazing can transition this state to a Managed Silvopasture state (State 4).
Dominant resource concerns
Community 2.1
Black Oak-White Oak-Post Oak/Aromatic Sumac
This woodland community has a single-tiered structure, with canopy height that varies with age, and 80 to 100 percent canopy closure. The understory and ground flora is depauperate. Thinning can increase overall tree vigor and improve understory diversity. However, in the absence of fire, the diversity and cover of the ground flora is still diminished.
State 3
Uneven-Age Managed Woodland
Uneven-Age Managed Woodlands can resemble a reference state. The biggest difference is tree age, most sites being only 50 to 90 years old. Composition is also likely altered from the reference state depending on tree selection during harvest. In addition, without a regular 15 to 20 year harvest re-entry into these stands, they will slowly increase in more shade tolerant species and white oak will become less dominant. Uneven Age Managed Woodland is also denser because of fire suppression. Consequently, the woodland ground flora is more suppressed and structural diversity is not as well maintained. Without periodic disturbance, stem density and fire intolerant species, like sassafras and hickory, increase in abundance.
Dominant resource concerns
Community 3.1
Black Oak-Hickory/Sassafras/Bottlebrush grass
This woodland community has a multi-tiered structure, and 60-90% canopy closure.
State 4
Managed Silvopasture
The Managed Silvopasture state results from managing woodland communities (States 2 or 3) with prescribed fire, canopy thinning, and controlled grazing. This state can resemble the reference state, but with younger maximum tree ages, more open canopies and lower ground flora diversity. Cessation of grazing and controlled harvesting will allow transition to various managed woodland states.
Community 4.1
White Oak-Black Oak/Little Bluestem
This woodland community has a single to two-tiered structure, and 70 to 90 percent canopy closure.
State 5
Grassland
Conversion of woodlands to planted, non-native cool season grassland species such as tall fescue is common for this region. Steep slopes, surface fragments, low organic matter contents and soil acidity make grasslands harder to maintain in a healthy, productive state on this ecological site.
Two community phases are recognized in the Grassland State, with shifts between phases based on types of management. Poor management will result in a shift to Community 5.2 that shows an increase in oak sprouting and increases in broomsedge densities. If grazing and active pasture management is discontinued, the site will eventually transition to State 2 from this phase.
Community 5.1
Tall Fescue - Red Clover
This is an herbaceous community that is typically dominated by tall fescue. Various other grass and forb species are typically present, in various amounts. Shrub and pioneer tree species such as eastern redcedar and black locust typically invade sites that are not regularly managed.
Dominant resource concerns
Community 5.2
Tall Fescue - Broomsedge/Oak Sprouts
Dominant resource concerns
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Sheet and rill erosion
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Ephemeral gully erosion
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Plant productivity and health
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Plant pest pressure
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Terrestrial habitat for wildlife and invertebrates
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Feed and forage imbalance
State 6
High-Graded/Grazed Woodland
States that were subjected to repeated, high-grading timber harvests and uncontrolled domestic grazing transitioned to a High-Graded Grazed Woodland State. This state exhibits an over-abundance of hickory and other less desirable tree species, and weedy understory species such as buckbrush, gooseberry, poison ivy and Virginia creeper. The existing vegetation offers little nutritional value for cattle, and excessive cattle stocking damages tree boles, degrades understory species composition and results in soil compaction and accelerated erosion and runoff.
Two common transitions from this state are woody clearing and conversion to State 5, Grassland or removing livestock, limited harvesting, and allowing long term succession to occur to some other woodland state.
Community 6.1
Black Oak-Hickory/Sassafras/Buckbrush
This woodland community has a multi-tiered structure, with irregular, variable canopy closure.
Transition T1A
State 1 to 2
This transition typically results from even-age timber management practices, such as clear-cut, seed tree or shelterwood harvest.
Transition T1B
State 1 to 3
This transition typically results from uneven-age timber management practices, such as single tree or group selection harvest.
Restoration pathway R1A
State 1 to 4
This restoration pathway generally requires uneven-age timber management practices, such as single tree or group selection harvest, with extended rotations that allow mature trees to exceed ages of about 150 years. Prescribed fire is part of the restoration process.
Restoration pathway R1B
State 1 to 4
This restoration pathway generally requires uneven-age timber management practices, such as single tree or group selection harvest, with extended rotations that allow mature trees to exceed ages of about 150 years. Prescribed fire is part of the restoration process. Mechanical thinning may be necessary in dense woodlands.
Transition T1C
State 1 to 5
This transition is the result of clearing the woodland community and planting pasture species. Soil erosion can be extensive in this process, along with loss of organic matter. Liming and fertilizing associated with pasture management typically raises the soil pH and increases the cation concentration (such as calcium and magnesium) of the upper soil horizons.
Transition T1D
State 1 to 6
This transition is the result of poorly planned timber harvest techniques such as high-grading, accompanied by unmanaged cattle grazing. Soil erosion and compaction often result from cattle grazing after the understory has been damaged.
Transition T2A
State 2 to 3
This transition typically results from uneven-age timber management practices, such as single tree or group selection harvest.
Transition T2B
State 2 to 4
This transition is the result of the systematic application of prescribed fire. Mechanical thinning may also be used.
Transition T3A
State 3 to 2
This transition typically results from even-age timber management practices, such as clear-cut, seed tree or shelterwood harvest.
Transition T3B
State 3 to 4
This transition is the result of the systematic application of prescribed fire. Mechanical thinning may also be used.
Transition T4A
State 4 to 2
This transition typically results from even-age timber management practices, such as clear-cut, seed tree or shelterwood harvest.
Transition T4B
State 4 to 3
This transition typically results from uneven-age timber management practices, such as single tree or group selection harvest.
Transition T5A
State 5 to 2
This transition results from the cessation of cattle grazing and associated pasture management such as mowing and brush-hogging. Herbicide application, tree planting and timber stand improvement techniques can speed up this otherwise very lengthy transition.
Transition T6B
State 6 to 3
This transition typically results from uneven-age timber management practices, such as single tree or group selection harvest. Tree planting, mechanical thinning and other timber stand improvement techniques may be helpful to decrease the transition time.
Transition T6A
State 6 to 5
This transition is the result of clearing the woodland communities and planting pasture species. Soil erosion can be extensive in this process, along with loss of organic matter. Liming and fertilizing associated with pasture management typically raises the soil pH and increases the cation concentration (such as calcium and magnesium) of the upper soil horizons.
