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.
Dry Footslope Forests occur at the base of slopes between the uplands and stream terraces. The reference plant community is well developed forest dominated by an overstory of white oak and black oak. The canopy is moderately tall (60 to 75 feet) but more dense (70 to 90 percent canopy) than exposed slopes.
Fire played a moderate role in the maintenance of these systems. It is likely that these ecological sites burned at least once every 10 to 20 years. These periodic fires kept the forest somewhat 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.
Dry Footslope Forests were also subjected to occasional disturbances from wind and ice, as well as grazing by native large herbivores. Wind and ice would have periodically opened the canopy up by knocking over trees or breaking substantial branches off canopy trees. Grazing by large native herbivores, such as bison, elk, and white-tailed deer, 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.
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 coralberry, gooseberry, and Virginia creeper. Grazed sites also have a more open understory. In addition, soil compaction and soil erosion can be a problem and lower productivity. Prescribed fire can play a beneficial but limited role in the management of this ecological site. Control of woody species will be more difficult. Footslope forests did evolve with some fire, but their composition often reflects more closed, forested conditions, with fewer woodland ground flora species that can respond to fire. Consequently, while having these sites in a burn unit is acceptable, targeting them solely for woodland restoration is not advisable.
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 reference state was dominated by white oak and black oak. Periodic disturbances from fire, wind or ice maintained the dominance of oaks by opening up the canopy and allowing more light for oak reproduction. Long disturbance-free periods allowed an increase in more shade tolerant species such as hickory and sugar maple. Two community phases are recognized in this state, with shifts between phases based on disturbance frequency.
The reference state is rare today. Some 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 also resulted in increased canopy density, which has affected the abundance and diversity of ground flora. Many reference sites have been managed for timber harvest, resulting in either even-age (State 2) or uneven-age (State 3) forests.
Community 1.1
White Oak – Black Oak/ Flowering Dogwood/ Eastern Bottlebrush Grass
Two community phases are recognized in this state, with shifts between phases based on disturbance frequency.
Forest overstory. Forest 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. Forest 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/ Flowering Dogwood – Hickory/ Eastern Bottlebrush Grass
Two community phases are recognized in this state, with shifts between phases based on disturbance frequency.
Pathway P1.1A
Community 1.1 to 1.2
This pathway is a gradual transition that results from extended, disturbance-free periods.
Pathway P1.2A
Community 1.2 to 1.1
This pathway is a transition that results from extended, disturbance periods returning, such as native fire, wind, and ice storms.
State 2
Even-Age Managed Forest
These former woodland are now rather dense, with an under developed understory and ground flora. Thinning can increase overall tree vigor and improve understory diversity. Continual timber management, depending on the practices used, will either maintain this state, or convert the site to uneven-age (State 3) forests.
Community 2.1
White Oak – Black Oak/ Hophornbeam / Wildrye
State 3
Uneven-Age Managed Forest
Uneven-Age Managed forests can resemble the reference state but are denser. The biggest differences are tree age, most being only 50 to 90 years old, and canopy closure. 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 such as hickory and white oak will become less dominant.
Community 3.1
Black Oak – Northern Red Oak – White Oak /Flowering Dogwood/ Indian Woodoats
State 4
Grassland
Conversion of forests to planted, non-native pasture species such as tall fescue has been common in this MLRA. Fragipans, surface fragments, low organic matter contents and soil acidity make non-native pastures challenging to maintain in a healthy, productive state on this ecological site. If grazing and active pasture management is discontinued, the site will eventually transition, over time, to State 2 (Even-Age).
Community 4.1
Tall Fescue - Red Clover
Community 4.2
Tall fescue - Broomsedge/Oak Sprouts
Pathway P4.1A
Community 4.1 to 4.2
This pathway is the result of over grazing and lack of proper grassland management.
Pathway P4.2A
Community 4.2 to 4.1
This pathway is the result of brush management, grassland reseeding and proper grassland management.
State 5
High-Graded/Grazed Woodland
Woodland sites subjected to repeated, high-graded timber harvests and uncontrolled domestic grazing transition to this 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 vegetation offers little nutritional value for cattle, and excessive stocking damages tree boles, degrades understory species composition and results in soil compaction and accelerated erosion and runoff. Exclusion of livestock from sites in this state coupled with uneven-age management techniques will cause a transition to State 3 (Uneven-Age).
Community 5.1
Black Oak – Hickory/ Hophornbeam/Coralberry
Transition T1A
State 1 to 2
This transition typically results from even-aged management, younger canopy ages, and prescribed fire.
Transition T1B
State 1 to 3
This transition typically results from uneven-age timber management practices, such as single tree or group selection harvest and fire suppression.
Transition T1C
State 1 to 4
This transition is the result of clearing and conversion to non-native cool season grassland.
Transition T1D
State 1 to 5
This transition is the result of high-grade harvesting and uncontrolled domestic livestock grazing.
Restoration pathway R1B
State 2 to 1
This restoration transition generally requires extended rotations that allow mature trees to exceed ages of about 120 years along with prescribed fire.
Transition T2A
State 2 to 3
This transition typically results with initial uneven-age management and eventual cessation of any management.
Restoration pathway R1A
State 3 to 1
This restoration transition generally requires extended rotations that allow mature trees to exceed ages of about 120 years along with prescribed fire.
Transition T3A
State 3 to 2
This transition typically results from active even-age management.
Transition T4A
State 4 to 2
This transition typically results with tree planting, long-term succession, and no grazing.
Transition T5B
State 5 to 3
This transition typically results with uneven-age management, tree planting and livestock exclusion.
Restoration pathway T5A
State 5 to 4
This transition is the result of clearing and conversion to non-native cool season grassland.
