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 somewhat shallow soils and south to west aspects of Loamy Dolomite Exposed Backslope Woodlands limits the growth of trees and supports an abundance of native grasses and forbs in the understory. While more productive than adjacent glades moderately tall (50 to 70 feet) white oak and chinkapin oak dominated a semi-open overstory, with occasional post oak, black oak, northern red oak and hickory. Shrubs were scattered within a dense matrix of native grasses and forbs. 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 these systems. It is likely that these ecological sites, along with adjacent glades and woodlands burned at least once every 5 years. These periodic fires kept woodlands open, removed the litter, and stimulated the growth and flowering of the grasses and forbs. They would have also further limited the growth and dominance of trees, especially eastern redcedar. During fire free intervals, woody species would have increased and the herbaceous understory diminished. But the return of fire would have re-opened the woodlands and stimulated the ground flora. In the long term absence of fire, woody species, especially eastern red cedar have encroached into these ecological sites. Most of these ecological sites today are dense, and shady with a greatly diminished ground flora. Removal of the younger understory by chainsaw and the application of prescribed fire have proven to be effective restoration methods.
Loamy Dolomite Exposed Backslope Woodlands were 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.
Uncontrolled domestic grazing has also impacted these communities, further diminishing the diversity of native plants and introducing species that are tolerant of grazing, such as buckbrush, gooseberry, and Virginia creeper. It also promotes the invasion of eastern red cedar. Grazed sites have a more open understory. In addition, soil compaction and soil erosion from grazing can be a problem and lower site productivity.
These ecological sites are only moderately productive, especially when compared to adjacent protected slopes and loess covered units. Maintenance of the oak component may require disturbances that will encourage more sun adapted species and reduce shading effects although the droughty site characteristics do help to maintain oak naturally on the site.
Single tree selection timber harvests are common for this ecological site 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 beneficial for existing stands whose composition has been highly altered by past management practices. However, without some thinning of the dense stands and application of prescribed fire, the ground flora diversity can be shaded out and diversity of the stand will suffer.
A State and Transition 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. The reference state was dominated by white oak and chinkapin 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 4). Others have been subject to repeated, high-graded timber harvest coupled with uncontrolled domestic livestock grazing (State 5). 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 as woodlands with fire (State 2) or without fire (State 3).
Community 1.1
White Oak – Chinkapin Oak/Eastern Redbud/Virginia Wildrye
Periodic disturbances from fire, wind or ice maintained the woodland structure and diverse ground flora species.
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 – Chinkapin Oak/Hickory Saplings– Eastern Redbud /Virginia Wildrye
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 and intensity.
Pathway P1.1A
Community 1.1 to 1.2
No disturbance (10+ years)
Pathway P1.2A
Community 1.2 to 1.1
Disturbance (fire, wind, ice) < 10 years
State 2
Fire Excluded Managed Woodland
These stands will slowly increase in more shade tolerant species and white oak will become less dominant. These woodlands tend to be rather dense, with a sparse 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. Without periodic disturbance, stem density and fire intolerant species, like sassafras and hickory, increase in abundance. Prescribed fire along with a more open canopy can transition this state to a Fire Managed Woodland state (State 3).
Community 2.1
Black Oak – White Oak – Chinkapin Oak/Hazelnut/ Virginia Wildrye
State 3
Fire Managed Woodland
The Fire Managed Woodland state results from managing woodland communities (States 2) with prescribed fire and canopy thinning,. This state can resemble the reference state, but with younger maximum tree ages, more open canopies and lower ground flora diversity. Cessation of prescribed fire will allow transition to various managed woodland states.
Community 3.1
Oak – Hickory/Eastern Redbud/ Hairy Woodland Brome
State 4
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 4.2 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 4.1
Tall Fescue-Red Clover
Two community phases are recognized in the grassland state, with shifts between phases based on types of management.
Community 4.2
Tall Fescue-Broomsedge/Oak Sprouts
Poor management will result in a shift to Community 4.2 that shows an increase in oak sprouting and increases in broomsedge density.
Pathway P4.1A
Community 4.1 to 4.2
Over grazing; no fertilization
Pathway P4.2A
Community 4.2 to 4.1
Brush management; grassland seeding; grassland management
State 5
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 coralberry, 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 5.1
Black Oak – Chinkapin Oak – Hickory/Common Serviceberry – Coralberry /Sedge
Transition T1B
State 1 to 2
Fire suppression; uneven-age management
Transition T1A
State 1 to 3
Forest management; prescribed fire
Transition T1C
State 1 to 4
Clearing; pasture planting; grassland management
Transition T1D
State 1 to 5
Poorly planned harvests; uncontrolled grazing
Restoration pathway R1B
State 2 to 1
Prescribed fire; extended rotations
Transition T2A
State 2 to 3
Prescribed fire; forest stand improvement
Restoration pathway R1A
State 3 to 1
Prescribed fire; extended rotations
Transition T3A
State 3 to 2
Forest management; fire exclusion
Transition T4A
State 4 to 2
Tree planting; long-term succession; no grazing
Transition T5B
State 5 to 3
Forest management; no grazing; prescribed fire; access control
Transition T5A
State 5 to 4
Clearing; pasture planting; grassland management
